Edit README.md

release: 0.2.5
feat: Настройки › Автообновление - clients compare their version with the server's every N and update themselves; the server looks at GitLab every N and, when a newer release is out, offers it to an administrator at login (after the PIN) with «Обновить» and «Отказаться»; the words of a made picture's result are the model's only
2026-10-20 14:21:10 +03:00 · 2026-10-18 12:33:40 +03:00 · 2026-10-18 12:33:24 +03:00 · 2026-10-18 12:13:47 +03:00 · 2026-10-18 12:13:29 +03:00 · 2026-10-18 12:12:54 +03:00
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@@ -34,7 +34,6 @@ go.work.sum


 bin
-dist
 *.db
 .DS_Store
 */.DS_Store
@@ -1,63 +1,238 @@
-# LPRA — LongPolling Remote Access
+# LPRA - LongPolling Remote Access

 Лёгкий self-hosted сервис для доступа к Linux-машинам **без белого IP** (за NAT).
-Агент на клиенте сам исходяще подключается к серверу по HTTP long-polling; админ
-в веб-панели видит список машин и открывает по каждой **терминал в браузере** (по умолчанию от root, пользователя можно сменить).
+Агент на клиенте сам исходяще подключается к серверу - по WebSocket, а где он не проходит,
+по HTTP long-polling. В веб-панели видно список машин, и по каждой есть терминал в браузере,
+файловый менеджер, проброс портов и статус.

 ```
-браузер ──WS──> [nginx :8445 TLS] ──> [Go server 127.0.0.1:8091] <──long-poll── агент (root, за NAT)
-                                          │
-                                        SQLite
+браузер ──HTTPS/WS──> [Cloudflare] ──> [nginx TLS] ──> [Go server 127.0.0.1:8091] <──WS / long-poll── агент (за NAT)
+                                                              │         ▲
+                                                            SQLite      └──── прямой TCP/UDP-туннель :8446 (проброс tcp/udp)
 ```

+## Возможности
+- **Одна страница** - Машины, WorkSpace (терминалы и файлы), Настройки; переходы без перезагрузки.
+  Вкладки WorkSpace живут, пока открыта вкладка браузера: уход на другие страницы их не
+  закрывает, перезагрузка сбрасывает (браузер сначала спросит). «Порты», «Статус» и «Изменить»
+  машины открываются окном поверх текущей страницы - из списка машин или правым кликом
+  по заголовку вкладки или панели.
+- **WorkSpace** - вкладки на нескольких машинах сразу, до четырёх панелей в одной вкладке -
+  терминал или файловый менеджер (перетаскиванием, с изменяемыми размерами), переименование
+  вкладок. На телефоне - панель клавиш (Esc, Ctrl, Alt, стрелки и т.д.).
+- **SSH-терминал** - в меню «+»: агент открывает SSH-соединение к другому хосту (по паролю,
+  ключу - можно загрузить файл - или своими ключами из `~/.ssh`), шелл открывается во вкладке,
+  а шаги подключения видны в статусе. Ключ хоста запоминается при первом входе
+  (`ssh_known_hosts` рядом с `state.json` агента); если он сменится, вход откажет.
+- **Файлы** - просмотр, редактор с подсветкой, hex-редактор, предпросмотр картинок, видео, PDF,
+  баз SQLite с правкой (значение по клику, добавление и удаление строк, вкладка SQL; агент меняет базу через сам SQLite, так что работающая база не ломается); загрузка и скачивание до 512 МБ кусками по 4 МБ (проходит через Cloudflare);
+  свойства (chmod/chown), zip/unzip.
+- **Файлы по SSH** - в меню «+» › «Файловый менеджер» › «SSH-хост…»: машина подключается к хосту
+  и работает с файлами командами по SSH, SFTP не нужен. Есть всё, кроме редактора SQLite;
+  zip и распаковка - если на хосте установлены `zip` и `unzip`. Оборвалось подключение -
+  панель предложит переподключиться.
+- **Перетаскивание файлов** - строку (или все отмеченные) в другую файловую панель или в папку
+  в ней: окно «Переместить / Копировать» у места броска, между машинами и SSH-хостами - с
+  прогрессом. В терминал той же машины или того же SSH-хоста - вставляется путь в кавычках,
+  в терминал другой - нельзя, с подсказкой почему. Задержать над заголовком вкладки - она
+  откроется. Только на компьютере.
+- **Перемещение и копирование** - внутри машины или, кнопкой «сеть» в том же окне, **на другую
+  машину или на SSH-хост**: папка уходит потоком tar без промежуточных файлов, с прогрессом,
+  скоростью и отменой. «Переместить» удаляет исходник после успешной отправки. Правила для
+  существующего: сообщить / заменить / оставить как есть.
+- **ИИ-ассистент** - круглая кнопка чата (на компьютере её и окно можно перетаскивать); каждый
+  включает себе сам в профиле. Видит вкладки, активный терминал или папку и список ваших машин,
+  отвечает потоком. Действия - кнопками: выполнить команду в терминале нужной машины, прочитать,
+  показать или записать файл - всё с правами пользователя. Плашка «Агент» - делает шаги сам,
+  спрашивая перед каждой командой и записью; «Думать» - сначала рассуждает (свёрнуто над
+  ответом). Модели задаёт администратор в «Настройки › ИИ-ассистент»: их может быть несколько, у каждой своё
+  название в чате (и короткое, до 12 символов, - для кнопки выбора), тип - Gradio (по умолчанию - прокси к Qwen Omni), OpenAI-совместимый API или Anthropic,
+  адрес, модель и ключ (хранится на сервере, в браузер не уходит). Если моделей несколько, в чате рядом с
+  плашками появляется выбор, первая - по умолчанию; выбор запоминается за пользователем. В «Аккаунт › Вид»
+  можно показывать выбор всегда.
+  Плашка «Поиск» даёт ассистенту искать в интернете; поисковик выбирается там же: DuckDuckGo
+  (по умолчанию, без настройки), свой SearXNG (нужен `search.formats: [json]`), Brave Search API
+  или Tavily (по ключу). Если выбранный не ответил, поиск идёт через DuckDuckGo.
+  **Картинки**: если администратор задал API-ключ в «Настройки › ИИ-ассистент › Генерация изображений»
+  ([Vertex API](https://s2.x-grk.com/api/vertex/docs)), модели сами, по смыслу разговора и без плашки, рисуют картинки
+  и правят фото - то, что пользователь прикрепил к сообщению, или последнюю созданную картинку
+  (блоки ```` ```image ```` и ```` ```image edit ````, формат и качество - в первой строке; улучшение описания
+  можно отключить: `noenhance`). Картинка показывается в чате, описание в карточке сворачивается.
+  Название прикреплённого файла открывает его (или скачивает). Удаление чата стирает его содержимое, в том числе
+  текст вложений, из файлов базы; картинки хранятся на сервисе Vertex и оттуда не удаляются.
+- **Сохранённые SSH-хосты** - в окне SSH-подключения галочка «Сохранить»: хост и вход (пароль или
+  ключ) хранятся на сервере, у каждого пользователя свои, зашифрованы AES-256-GCM ключом сервера.
+  Ключ берётся из `LPRA_SECRET_KEY` (32 байта, hex или base64) или из файла `<база>.key` рядом с
+  базой, который создаётся сам - храните его вместе с бэкапом базы, без него сохранённые входы
+  не расшифровать.
+- **Проброс портов** - `http` через панель, `tcp`/`udp` через прямой туннель.
+- **Статус** - нагрузка, память, диски, сеть, тест скорости канала до сервера.
+- **Автообновление** («Настройки › Автообновление», обе части выключены, пока не включены):
+  *клиентов* - агенты раз в N минут/часов/суток сверяют свою версию с версией сервера и, если у сервера новее,
+  обновляются сами (как по кнопке «Обновить»; нужен root или sudo без пароля; агентам до 0.2.5 один раз обновиться
+  придётся вручную); *сервера* - сервер раз в N сверяет себя с последним релизом на GitLab, и когда вышел новый,
+  администратору при входе (после PIN) показывается окно «Обновить / Отказаться» - отказ запоминается для этой
+  версии. «Обновить» запускает `server-install.sh` отдельной службой systemd (нужны root и systemd); там же кнопки
+  «Проверить сейчас» и «Обновить сейчас».
+- **Вход** - пароль и/или ключи доступа (passkeys); пароль можно выключить, когда есть ключ.
+- **PIN-код** (необязательный, 4 цифры) - спрашивается в каждой новой вкладке браузера, но не при
+  перезагрузке. На устройстве можно не спрашивать его 5/15/30/60 минут после ввода.
+  Пять неверных попыток - выход из сессии.
+
+## Пользователи и роли
+- **Администратор** видит всё: все машины, настройки, пользователей, ufw.
+- **Пользователь** видит только выданные ему машины (терминал, файлы, порты, статус, «Изменить» без удаления);
+  настроек, других пользователей и чужих машин для него нет.
+
+Роль и машины задаются в «Настройки → Пользователи» (квадратная кнопка у пользователя открывает список машин).
+Там же галочка «Пароль» включает или выключает вход по паролю (выключить можно, когда у человека есть ключ доступа),
+а «Закрепить» не даёт ему поменять это самому. Последнего администратора нельзя удалить или понизить.
+
+## База данных
+По умолчанию - SQLite (файл из `-db`, по умолчанию `lpra.db`). В «Настройки › База данных» можно выбрать
+PostgreSQL: хост, порт, база, пользователь, пароль, SSL; кнопка «Проверить и сохранить» подключается и
+записывает выбор в `<база>.backend.json` рядом с SQLite-файлом (права 0600), «Перезапустить сервер»
+завершает процесс - systemd (`Restart=always`) поднимает его уже на PostgreSQL. При первом запуске на
+пустой PostgreSQL все данные копируются из SQLite-файла, сам файл остаётся как был (к нему можно
+вернуться тем же выбором). История ИИ-ассистента тоже хранится в базе - у каждого пользователя
+последние 200 сообщений.
+
 ## Компоненты
- **Сервер** (`cmd/server`) — админ-панель + точка встречи для агентов. За nginx (TLS).
- **Агент** (`cmd/agent`) — Linux-бинарь, systemd-сервис от root, PTY по запросу.
- **install.sh** — интерактивный установщик, отдаётся сервером как статика.
+- **Сервер** (`cmd/server`) - панель и точка встречи для агентов. Ставится за nginx (TLS).
+- **Агент** (`cmd/agent`) - бинарь для Linux (amd64/arm64), systemd-сервис от root.
+- **install.sh** - установщик агента, отдаётся сервером.

 ## Сборка
 ```sh
 ./build.sh
 ```
-Получаются `bin/lpra-server` и `dist/agent-linux-{amd64,arm64}`.
+Получаются `bin/lpra-server*` и `dist/agent-linux-{amd64,arm64}`.
+Версия задаётся в одном месте - `VERSION.txt`, она вшивается в сервер и агент.
+
+## Установка сервера одной командой
+На Linux-сервере (amd64 или arm64, systemd):
+```sh
+wget -qO- https://gitlab.com/itzredtea/lpra/-/raw/main/server-install.sh | sudo sh
+```
+Скрипт `server-install.sh`:
+- качает бинарник сервера под архитектуру машины из [последнего релиза](https://gitlab.com/itzredtea/lpra/-/releases/permalink/latest)
+  и папку `dist/` (бинарники агентов) из ветки `main`, кладёт всё в `/opt/lpra`;
+- ставит службу systemd `lpra-server` (порт спросит, по умолчанию `8091`);
+- по желанию настраивает nginx: спросит домен, создаст сайт на порт 80 (при необходимости поставит nginx),
+  затем `certbot --nginx` - если certbot с плагином nginx не установлен, этот шаг пропускается;
+- если включён ufw - предложит открыть 80, 443 и туннель `8446` tcp/udp;
+- запускает службу, перезагружает nginx и проверяет, что сервер отвечает.
+
+Вопросы задаются в терминале, даже когда скрипт идёт через `| sudo sh`. Без терминала ответы берутся
+из переменных: `LPRA_PORT`, `LPRA_NGINX` (y/n), `LPRA_DOMAIN`, `LPRA_EMAIL`, `LPRA_CERTBOT` (y/n), `LPRA_UFW` (y/n):
+```sh
+wget -qO- https://gitlab.com/itzredtea/lpra/-/raw/main/server-install.sh | sudo LPRA_NGINX=y LPRA_DOMAIN=lpra.example.com sh
+```
+Повторный запуск той же командой - **обновление**: бинарник и `dist/` заменяются, база (`/opt/lpra/lpra.db`
+и её ключ `lpra.db.key`), настройки службы и nginx остаются. После установки откройте `/setup` - мастер
+создаст администратора.

 ## Запуск сервера
 ```sh
 ./bin/lpra-server -addr 127.0.0.1:8091 -dist ./dist -db ./lpra.db
 ```
-Поставьте перед ним nginx по `deploy/nginx.conf.example` (TLS, long-poll/WS).
-Локально без TLS можно добавить `-insecure-cookies`.
+| Флаг | Переменная | По умолчанию | |
+|---|---|---|---|
+| `-addr` | `LPRA_ADDR` | `127.0.0.1:8091` | адрес HTTP (за nginx) |
+| `-db` | `LPRA_DB` | `lpra.db` | база SQLite |
+| `-dist` | `LPRA_DIST` | `dist` | бинарники агента для `/download/` |
+| `-tunnel` | `LPRA_TUNNEL_ADDR` | `:8446` | прямой туннель TCP+UDP (пусто - выключен) |
+| `-insecure-cookies` | `LPRA_INSECURE_COOKIES=1` | | куки без Secure - только для локального запуска без TLS |

-Первый запуск: откройте `/setup` — мастер создаст администратора. Дальше `/settings`:
-адрес хоста (по умолчанию `https://localhost:8445`), enroll-секрет и готовая
-команда установки.
+Пример юнита - `deploy/lpra-server.service`.

-## Установка агента на клиент
-Одной командой (под root):
-```sh
-curl -fsSL https://localhost:8445/install.sh | sudo HOST=https://localhost:8445 ENROLL_SECRET=<секрет> sh
+Первый запуск: откройте `/setup` - мастер создаст администратора. Дальше в `/settings`:
+адрес хоста, enroll-секрет, короткий код установки и готовая команда.
+
+### nginx
+Конфиг - `deploy/nginx.conf.example`. Обязательно:
+- заголовки `Upgrade` / `Connection` (через `map $http_upgrade $connection_upgrade`) - без них
+  WebSocket не пройдёт, и агенты и терминалы останутся на long-polling (работает, но медленнее
+  на больших выводах);
+- `proxy_read_timeout` больше 25 с (удержание long-poll), `proxy_buffering off`.
+
+### Прямой адрес (без Cloudflare)
+В «Настройки → Адрес хоста» можно задать второй, прямой адрес - например `https://direct.lpra.example.com`,
+DNS-запись без проксирования. Тогда:
+- агенты, не достучавшись до основного адреса 30 секунд, переходят на прямой и каждые 5 минут проверяют,
+  не ожил ли основной; уже установленные агенты получают прямой адрес с сервера сами (он хранится в `state.json`);
+- установщик берёт адреса с того домена, с которого его скачали: с основного - агент работает через основной
+  с резервом на прямой, с прямого - наоборот (и бинарник качается с прямого); если первый адрес не отвечает,
+  бинарник качается со второго. В «Полных вариантах» есть короткая команда и через прямой адрес;
+- в «Изменить → Связь с сервером» у клиента, подключённого через прямой адрес, после статуса стоит «(direct)»;
+- если хост туннеля не задан, агентам отдаётся хост прямого адреса;
+- ключи доступа основного домена работают и на его поддомене.
+
+### Cloudflare
+Работает за проксирующим Cloudflare: WebSocket он пропускает, файлы идут кусками меньше лимита
+на запрос, статика с хешем в имени кэшируется. Чтобы панель видела настоящие IP (ограничение
+попыток входа и кода установки считается по адресу), включите в nginx real IP:
+```nginx
+real_ip_header CF-Connecting-IP;
+set_real_ip_from 173.245.48.0/20;   # и остальные диапазоны с https://www.cloudflare.com/ips/
 ```
-Или интерактивно (спросит секрет, а если агент уже стоит — предложит удалить):
+Прямой туннель (`:8446`) - это не HTTP, через проксирующий Cloudflare он не идёт: в
+«Настройки → Прямой туннель» укажите для агентов IP хоста или DNS-имя без проксирования.
+
+## Установка агента
+Короткой командой из `/settings` (код из 3-24 букв и цифр, кнопка «Новый код» меняет его):
 ```sh
-curl -fsSL https://localhost:8445/install.sh | sudo sh
+curl -fsSL https://panel.example/i/<код> | sudo sh
 ```
+Или полной:
+```sh
+curl -fsSL https://panel.example/install.sh | sudo HOST=https://panel.example ENROLL_SECRET=<секрет> sh
+```
+Без параметров установщик спросит секрет, а если агент уже стоит - предложит удалить.
+Обновить агента можно кнопкой в панели («Изменить» → обновить).
+
+## Связь агента с сервером
+В «Изменить» → «Связь с сервером» для каждой машины:
+- **auto** (по умолчанию) - WebSocket; если он не подключается, long-polling ровно минуту, потом
+  снова попытка WebSocket;
+- **ws** - только WebSocket;
+- **lp** - только long-polling.
+
+## Проброс портов и прямой туннель
+Правила создаются на странице машины «Порты». Режим `http` (в панели - http-lp) идёт через
+соединение агента с панелью: по WebSocket, а если он недоступен - по long-polling;
+`tcp`/`udp` - через прямой туннель: агент держит исходящее соединение к порту туннеля хоста,
+по нему мультиплексируются все соединения.
+
+Порт туннеля и хост для агентов меняются в `/settings` → «Прямой туннель»; агенты забирают их
+сами, переустановка не нужна. Локальные `TUNNEL_ADDR` / `TUNNEL_PORT` в окружении агента имеют
+приоритет (`TUNNEL_ADDR=off` отключает туннель).
+
+Если на хосте активен ufw и сервер запущен от root, панель сама открывает порты правил и порт
+туннеля, а при удалении правила закрывает. При `ProtectSystem=strict` в юните нужно
+`ReadWritePaths=/etc/ufw /run`.

 ## Пользователь терминала
-По умолчанию терминал открывается от пользователя, под которым запущен агент (на Linux — root).
-В окне «Изменить машину» можно выбрать другого пользователя машины или создать нового
-(имя, пароль, опционально — добавить в sudo). Смена и создание работают, только если агент запущен от root.
-Файловый менеджер по-прежнему работает от пользователя агента.
+По умолчанию терминал открывается от пользователя агента (root). В «Изменить машину» можно выбрать
+другого пользователя или создать нового (с паролем, по желанию с sudo) - если агент запущен от root.
+Файловый менеджер работает от пользователя агента.

 ## Безопасность
- Пароли админов — bcrypt; сессии в HttpOnly/Secure/SameSite куках; CSRF на формах; rate-limit логина.
- Агенты: общий enroll-секрет → индивидуальный токен (хранится хешем, сверка constant-time).
- Открытие терминала пишется в таблицу `audit` (терминал даёт root-доступ), как и смена/создание пользователя.
+- Пароли админов - bcrypt; сессии в HttpOnly/Secure/SameSite куках; CSRF на формах;
+  ограничение попыток входа, PIN и кода установки.
+- Ключи доступа (WebAuthn) - вход без пароля; пароль можно выключить совсем.
+- Агенты: общий enroll-секрет → индивидуальный токен (хранится хешем, сверка constant-time);
+  туннель авторизуется HMAC от токена.
+- SSH-пароли и ключи передаются агенту один раз для подключения и нигде не сохраняются.
+- Открытие терминала и SSH, перенос файлов на другие машины, смена пользователя пишутся в `audit`.

 ## Скриншоты
-<img width="1256" height="709" alt="image" src="https://github.com/user-attachments/assets/5f0b30f1-d5e3-4b62-817e-4041641df6e3" />
+<img width="1256" height="709" alt="image" src="docs/screenshots/1.png" />

-<img width="1254" height="532" alt="image" src="https://github.com/user-attachments/assets/0207a7f0-2b59-40ee-abd1-d8673059cc24" />
+<img width="1254" height="532" alt="image" src="docs/screenshots/2.png" />

-<img width="1255" height="526" alt="image" src="https://github.com/user-attachments/assets/4dcbe907-33f5-493e-a56f-01cd8bf0fea1" />
+<img width="1255" height="526" alt="image" src="docs/screenshots/3.png" />

-<img width="1260" height="654" alt="image" src="https://github.com/user-attachments/assets/fdf59733-8e5d-46e3-b232-235ddfe1be73" />
+<img width="1260" height="654" alt="image" src="docs/screenshots/4.png" />
+
+*Автор иконки репозитория - * [grafixpoint](https://www.flaticon.com/authors/grafixpoint)
@@ -1 +1 @@
-0.0.2
+0.2.5
@@ -5,10 +5,9 @@ set -eu

 cd "$(dirname "$0")"

-VERSION="${VERSION:-$(cat VERSION.txt 2>/dev/null || echo 0.0.0)}"
-PKG="github.com/x-grk/longpolling-remote-access"
-LDFLAGS="-s -w -X $PKG/internal/server.Version=$VERSION -X $PKG/internal/agent.Version=$VERSION"
-echo ">> version $VERSION"
+# The version comes from VERSION.txt, which is embedded into every binary.
+LDFLAGS="-s -w"
+echo ">> version $(cat VERSION.txt)"

 mkdir -p dist bin

@@ -10,19 +10,25 @@ import (
 	"net/url"
 	"os"
 	"os/signal"
+	"strconv"
+	"strings"
 	"syscall"

 	"github.com/x-grk/longpolling-remote-access/internal/agent"
+	"github.com/x-grk/longpolling-remote-access/internal/tunnel"
 )

 func main() {
 	host := envOr("HOST", "https://REDACTED:8445")
 	cfg := agent.Config{
 		Host:         host,
+		Fallback:     strings.TrimRight(os.Getenv("FALLBACK_HOST"), "/"),
 		EnrollSecret: os.Getenv("ENROLL_SECRET"),
 		Name:         os.Getenv("AGENT_NAME"),
 		StatePath:    envOr("STATE_PATH", "/etc/lpagent/state.json"),
 		TunnelAddr:   tunnelAddr(host),
+		// A locally set address wins over the one from the panel settings.
+		TunnelPinned: os.Getenv("TUNNEL_ADDR") != "" || os.Getenv("TUNNEL_PORT") != "",
 	}
 	if cfg.EnrollSecret == "" {
 		// Only required for the very first run (before enrollment).
@@ -34,7 +40,11 @@ func main() {
 	ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
 	defer stop()

-	if err := agent.New(cfg).Run(ctx); err != nil {
+	err := agent.New(cfg).Run(ctx)
+	// Stopping (an update, a restart): hang the terminals up, so their shells
+	// save their history instead of being killed.
+	agent.CloseTerminals()
+	if err != nil {
 		log.Fatalf("agent: %v", err)
 	}
 }
@@ -46,9 +56,10 @@ func envOr(key, def string) string {
 	return def
 }

-// tunnelAddr derives the direct-tunnel address (host:8446) from the server URL.
-// TUNNEL_ADDR overrides it entirely; TUNNEL_PORT overrides just the port.
-// Set TUNNEL_ADDR=off to disable the direct tunnel.
+// tunnelAddr derives the direct-tunnel address (host:port) from the server URL.
+// It is only the starting point: the agent follows the host and port set in
+// the panel settings, unless TUNNEL_ADDR (the whole address) or TUNNEL_PORT
+// (just the port) pins it here. Set TUNNEL_ADDR=off to disable the tunnel.
 func tunnelAddr(hostURL string) string {
 	if v := os.Getenv("TUNNEL_ADDR"); v != "" {
 		if v == "off" {
@@ -60,5 +71,5 @@ func tunnelAddr(hostURL string) string {
 	if err != nil || u.Hostname() == "" {
 		return ""
 	}
-	return net.JoinHostPort(u.Hostname(), envOr("TUNNEL_PORT", "8446"))
+	return net.JoinHostPort(u.Hostname(), envOr("TUNNEL_PORT", strconv.Itoa(tunnel.DefaultPort)))
 }
@@ -6,25 +6,28 @@
 package main

 import (
+	"context"
 	"flag"
 	"log"
 	"net/http"
 	"os"
+	"strconv"
 	"time"

 	"github.com/x-grk/longpolling-remote-access/internal/server"
+	"github.com/x-grk/longpolling-remote-access/internal/tunnel"
 )

 func main() {
 	addr := flag.String("addr", envOr("LPRA_ADDR", "127.0.0.1:8091"), "listen address (behind nginx)")
 	dbPath := flag.String("db", envOr("LPRA_DB", "lpra.db"), "path to SQLite database")
 	distDir := flag.String("dist", envOr("LPRA_DIST", "dist"), "directory with agent binaries served at /download/")
-	tunnelAddr := flag.String("tunnel", envOr("LPRA_TUNNEL_ADDR", ":8446"), "listen address for the direct TCP+UDP forward tunnel (empty disables)")
+	tunnelAddr := flag.String("tunnel", envOr("LPRA_TUNNEL_ADDR", ":"+strconv.Itoa(tunnel.DefaultPort)), "listen address for the direct TCP+UDP forward tunnel (empty disables)")
 	insecureCookies := flag.Bool("insecure-cookies", envOr("LPRA_INSECURE_COOKIES", "") == "1",
 		"do not mark cookies Secure (plain-HTTP local testing only)")
 	flag.Parse()

-	db, err := server.OpenDB(*dbPath)
+	db, err := server.OpenStore(*dbPath)
 	if err != nil {
 		log.Fatalf("open db: %v", err)
 	}
@@ -40,6 +43,9 @@ func main() {
 		log.Fatalf("init server: %v", err)
 	}

+	// The server updates itself, if told to (Настройки › Автообновление).
+	go srv.RunAutoUpdate(context.Background())
+
 	httpSrv := &http.Server{
 		Addr:    *addr,
 		Handler: srv.Handler(),
@@ -1,24 +1,24 @@
 # systemd unit for the LPRA host (server).
 #
-# Unlike the agent, the server does NOT need root: it listens on a high local
-# port (127.0.0.1:8091) behind nginx, so run it as an unprivileged user.
+# The server runs as root so that the panel can open forwarded ports in ufw;
+# it listens on a high local port (127.0.0.1:8091) behind nginx.
 #
 # Install:
-#   sudo useradd --system --home /opt/lpra --shell /usr/sbin/nologin lpra
-#   sudo mkdir -p /opt/lpra /var/lib/lpra
+#   sudo mkdir -p /opt/lpra
 #   sudo cp bin/lpra-server /opt/lpra/
 #   sudo cp -r dist /opt/lpra/dist           # agent binaries served at /download/
-#   sudo chown -R lpra:lpra /opt/lpra /var/lib/lpra
 #   sudo cp deploy/lpra-server.service /etc/systemd/system/
 #   sudo systemctl daemon-reload && sudo systemctl enable --now lpra-server
 #
-# Config overrides can go in /etc/lpra-server.env (see EnvironmentFile below),
-# e.g.  LPRA_ADDR=127.0.0.1:8091
+# Direct port forwarding (tcp/udp modes) uses the tunnel port on the host, which
+# has to be open in the firewall for tcp and udp. (The "http" forward mode and
+# terminal/files go through nginx :8445 and need nothing extra.) Set the tunnel
+# address with LPRA_TUNNEL_ADDR, or set it empty to disable.
+# The port, and the host agents dial for it, can also be changed in the panel
+# settings; agents pick the new address up from the panel by themselves.
 #
-# Direct port forwarding (tcp/udp modes) uses port 8446 on the host — open it in
-# the firewall:  ufw allow 8446/tcp ; ufw allow 8446/udp
-# (The "http" forward mode and terminal/files go through nginx :8445 and need
-# nothing extra.) Override with LPRA_TUNNEL_ADDR, or set it empty to disable.
+# ufw integration (the panel opening forwarded ports itself) needs root and a
+# writable /etc/ufw and /run - see ReadWritePaths below.

 [Unit]
 Description=LPRA remote access host (admin panel + agent rendezvous)
@@ -26,17 +26,11 @@ After=network-online.target
 Wants=network-online.target

 [Service]
-Type=simple
-User=lpra
-Group=lpra
 WorkingDirectory=/opt/lpra

-# Optional environment overrides; "-" means the file is not required.
-EnvironmentFile=-/etc/lpra-server.env
-
 ExecStart=/opt/lpra/lpra-server \
    -addr 127.0.0.1:8091 \
-    -db /var/lib/lpra/lpra.db \
+    -db /opt/lpra/lpra.db \
    -dist /opt/lpra/dist

 Restart=always
@@ -51,8 +45,11 @@ PrivateDevices=true
 ProtectKernelTunables=true
 ProtectControlGroups=true
 RestrictSUIDSGID=true
-# The server only needs to write its SQLite database here.
-ReadWritePaths=/var/lib/lpra
+# The SQLite database, plus what ufw writes: its rules in /etc/ufw and the
+# ufw/xtables locks in /run. Without the last two "ufw status" works but
+# "ufw allow" fails with "'/etc/ufw/user.rules' is not writable".
+ReadWritePaths=/opt/lpra /etc/ufw /run
+ReadWritePaths-=/etc/ufw /run

 [Install]
 WantedBy=multi-user.target
@@ -0,0 +1,51 @@
+# nginx reverse proxy for the LPRA server.
+# TLS is terminated here; the Go server listens on 127.0.0.1:8091.
+#
+# Put this in /etc/nginx/sites-available/lp_agent and symlink it into
+# sites-enabled, then:  sudo nginx -t && sudo systemctl reload nginx
+#
+# Agents connect by WebSocket (from 0.1.0), with HTTP long polling to fall
+# back on; the browser uses plain HTTP. The settings that matter:
+#   - Upgrade / Connection headers -> let the agents' WebSocket through
+#   - proxy_buffering off          -> deliver long-poll responses immediately
+#   - proxy_read_timeout 300s      -> longer than the 25s long-poll hold
+#
+# NOTE: proxy_pass MUST start with "http://". A bare "proxy_pass 127.0.0.1:8091;"
+# causes nginx error:  [emerg] invalid URL prefix.
+
+# "Connection: upgrade" for a WebSocket, "close" for everything else.
+
+
+map $http_upgrade $connection_upgrade {
+    default upgrade;
+    ''      close;
+}
+
+server {
+    listen 80;
+    server_name example.ru;
+
+    client_max_body_size 120m;
+
+    location / {
+        proxy_pass http://127.0.0.1:8091;
+
+        proxy_http_version 1.1;
+        proxy_set_header Host              $host;
+        proxy_set_header X-Real-IP         $remote_addr;
+        proxy_set_header X-Forwarded-For   $proxy_add_x_forwarded_for;
+        proxy_set_header X-Forwarded-Proto $scheme;
+        # Agents' WebSocket.
+        proxy_set_header Upgrade           $http_upgrade;
+        proxy_set_header Connection        $connection_upgrade;
+
+        # Long-poll behaviour: no buffering, generous read timeout.
+        proxy_buffering     off;
+        proxy_cache         off;
+        # Pass uploads on as they arrive: the speed test through the browser
+        # times them on the client.
+        proxy_request_buffering off;
+        proxy_read_timeout  300s;
+        proxy_send_timeout  300s;
+    }
+}
@@ -4,25 +4,35 @@
 # Put this in /etc/nginx/sites-available/lp_agent and symlink it into
 # sites-enabled, then:  sudo nginx -t && sudo systemctl reload nginx
 #
-# Everything (agent + browser terminal) is plain HTTP long-polling, so NO
-# WebSocket config is needed. The two settings that matter:
-#   - proxy_buffering off      -> deliver long-poll responses immediately
-#   - proxy_read_timeout 120s  -> longer than the 25s long-poll hold
+# Agents connect by WebSocket (from 0.1.0), with HTTP long polling to fall
+# back on; the browser uses plain HTTP. The settings that matter:
+#   - Upgrade / Connection headers -> let the agents' WebSocket through
+#   - proxy_buffering off          -> deliver long-poll responses immediately
+#   - proxy_read_timeout 300s      -> longer than the 25s long-poll hold
 #
 # NOTE: proxy_pass MUST start with "http://". A bare "proxy_pass 127.0.0.1:8091;"
 # causes nginx error:  [emerg] invalid URL prefix.

+# "Connection: upgrade" for a WebSocket, "close" for everything else.
+
+
+map $http_upgrade $connection_upgrade {
+    default upgrade;
+    ''      close;
+}
+
 server {
-    listen 8445 ssl;
-    server_name REDACTED;
+    listen 443 ssl;
+    server_name example.ru;

    ssl_certificate /etc/letsencrypt/live/REDACTED/fullchain.pem; # managed by Certbot
    ssl_certificate_key /etc/letsencrypt/live/REDACTED/privkey.pem; # managed by Certbot
    include /etc/letsencrypt/options-ssl-nginx.conf; # managed by Certbot
    ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem; # managed by Certbot

-    # Agent binaries can be large; allow the download.
-    client_max_body_size 64m;
+    # Files go through the panel in 4 MB pieces; 64m leaves room for a client
+    # that predates the pieces, which takes a file of up to 32 MB in one request.
+    client_max_body_size 120m;

    location / {
        proxy_pass http://127.0.0.1:8091;
@@ -32,11 +42,17 @@ server {
        proxy_set_header X-Real-IP         $remote_addr;
        proxy_set_header X-Forwarded-For   $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
+        # Agents' WebSocket.
+        proxy_set_header Upgrade           $http_upgrade;
+        proxy_set_header Connection        $connection_upgrade;

        # Long-poll behaviour: no buffering, generous read timeout.
        proxy_buffering     off;
        proxy_cache         off;
-        proxy_read_timeout  120s;
-        proxy_send_timeout  120s;
+        # Pass uploads on as they arrive: the speed test through the browser
+        # times them on the client.
+        proxy_request_buffering off;
+        proxy_read_timeout  300s;
+        proxy_send_timeout  300s;
    }
 }
@@ -0,0 +1,144 @@
+# Перенос проекта с GitHub на GitLab с сохранением истории и дат
+
+Инструкция для локального репозитория, когда GitHub недоступен (аккаунт заблокирован) и
+переносить приходится из своей копии. Так был перенесён `lpra`: 195 коммитов, 8 тегов,
+3 релиза - хэши и даты совпали.
+
+## Что сохраняется, а что нет
+
+| Что | Сохраняется? |
+|---|---|
+| Даты коммитов (автора и коммита) | **Да, точно.** Они хранятся внутри коммита; push той же истории не меняет ни одного хэша |
+| Ветки и теги | Да, если они есть локально (см. шаг 2) |
+| Дата создания проекта | **Нет.** На gitlab.com она всегда - день создания проекта, задним числом не ставится. Начало проекта видно по первому коммиту |
+| Релизы | Создаются заново, **с исходной датой** (`--released-at`); файлы релизов - заново собрать или взять свои копии |
+| Issues, PR, звёзды, Actions | Нет: при заблокированном GitHub их не выгрузить |
+
+**Нельзя:** `rebase`, `squash`, `filter-branch`, `filter-repo`, `commit --amend` по старым
+коммитам, «Import from GitHub» с чужой копии - всё это переписывает коммиты и их даты.
+
+## 0. Один раз: вход в GitLab
+
+```sh
+brew install glab
+glab auth login --hostname gitlab.com --web --git-protocol https
+```
+
+Вход через браузер даёт права и на push, и на релизы. Git берёт пароль у glab - для каждого
+репозитория это настраивается в шаге 4 (или один раз для всех:
+`git config --global credential.https://gitlab.com.helper '!glab auth git-credential'`).
+
+SSH-ключ тоже подойдёт, но в GitLab у ключа должен быть **Usage type: Authentication & Signing**
+(с типом «Signing» по SSH не пускает).
+
+## 1. Пустой проект в GitLab
+
+https://gitlab.com/projects/new → **Create blank project** → имя, владелец `itzredtea`.
+**Снять галочку «Initialize repository with a README»** - иначе в проекте появится свой первый
+коммит, и историю придётся склеивать.
+
+Или из терминала:
+
+```sh
+glab repo create itzredtea/ИМЯ --public      # или --private; README не создаётся
+```
+
+## 2. Проверить, что всё есть локально
+
+```sh
+cd ~/CodeRepos/ИМЯ
+git status                 # незакоммиченное закоммитить или убрать
+git branch -a              # ветки: свои и remotes/origin/*
+git tag -l                 # теги
+```
+
+- Ветки, которых нет локально, но есть `remotes/origin/X`, тоже переносятся (шаг 3).
+- **Теги, созданные на GitHub при публикации релиза, могут не быть локально** - если их не
+  делали `git fetch --tags`. Такой тег создаётся заново на нужном коммите (шаг 5). Коммит
+  ищется по дате публикации релиза: последний коммит перед ней
+  (`git log --format='%h %cd %s' --date=iso --until='ДАТА'`).
+
+Снимок до переноса - для сверки:
+
+```sh
+git log --branches --remotes=origin --tags --format='%H %aI %cI' | sort > /tmp/before.txt
+git show-ref --tags | sort > /tmp/tags-before.txt
+```
+
+## 3. Отправить историю
+
+```sh
+git remote rename origin github                      # GitHub остаётся под своим именем
+git remote add origin https://gitlab.com/itzredtea/ИМЯ.git
+H='!glab auth git-credential'
+git -c credential.helper= -c "credential.helper=$H" push origin --all          # все локальные ветки
+git -c credential.helper= -c "credential.helper=$H" push origin 'refs/remotes/github/*:refs/heads/*'  # ветки, что были только на GitHub
+git -c credential.helper= -c "credential.helper=$H" push origin --tags
+```
+
+Вторая команда push может сказать про `HEAD` - это не ветка, сообщение можно не смотреть.
+
+## 4. Сверить и переключиться
+
+Сверка - по свежей копии из GitLab:
+
+```sh
+rm -rf /tmp/check && git clone -q https://gitlab.com/itzredtea/ИМЯ.git /tmp/check
+cd /tmp/check && git log --remotes=origin --tags --format='%H %aI %cI' | sort > /tmp/after.txt
+git show-ref --tags | sort > /tmp/tags-after.txt
+diff /tmp/before.txt /tmp/after.txt && echo "коммиты и даты совпали"
+diff /tmp/tags-before.txt /tmp/tags-after.txt && echo "теги совпали"
+```
+
+Пустой `diff` - история перенесена один в один. Дальше работать с GitLab:
+
+```sh
+cd ~/CodeRepos/ИМЯ
+git config --local credential.https://gitlab.com.helper '!glab auth git-credential'
+git fetch origin && git branch -u origin/main main
+```
+
+## 5. Релизы с исходными датами
+
+Дата - время публикации релиза на GitHub (UTC). Файлы - свои копии или сборка из коммита
+релиза во временной папке:
+
+```sh
+git worktree add --detach /tmp/rel-1.2.0 1.2.0      # тег или хэш коммита релиза
+cd /tmp/rel-1.2.0 && ./build.sh                       # как проект собирается
+glab release create 1.2.0 bin/файл1 bin/файл2 \
+  -R itzredtea/ИМЯ --name "Release 1.2.0" \
+  --released-at "2026-10-15T16:34:53Z" \
+  --notes "Перенесено с GitHub, дата публикации исходная."
+# тега нет (его делал GitHub) - добавить: --ref <полный хэш коммита>
+git worktree remove /tmp/rel-1.2.0
+```
+
+Создавать по порядку, от старых к новым. Последним GitLab считает релиз с самой поздней
+датой. Ссылки на файлы:
+
+- конкретный релиз: `https://gitlab.com/itzredtea/ИМЯ/-/releases/ТЕГ/downloads/ФАЙЛ`
+- последний: `https://gitlab.com/itzredtea/ИМЯ/-/releases/permalink/latest/downloads/ФАЙЛ`
+
+## 6. Ссылки в самом проекте
+
+Найти и заменить всё, что смотрит на GitHub:
+
+```sh
+grep -rn "github.com\|githubusercontent" --exclude-dir=.git .
+```
+
+| GitHub | GitLab |
+|---|---|
+| `https://raw.githubusercontent.com/USER/ИМЯ/main/ПУТЬ` | `https://gitlab.com/itzredtea/ИМЯ/-/raw/main/ПУТЬ` |
+| `https://github.com/USER/ИМЯ/releases/latest/download/ФАЙЛ` | `https://gitlab.com/itzredtea/ИМЯ/-/releases/permalink/latest/downloads/ФАЙЛ` |
+| `https://api.github.com/repos/USER/ИМЯ/releases/latest` (`tag_name`) | `https://gitlab.com/api/v4/projects/itzredtea%2FИМЯ/releases/permalink/latest` (`tag_name`) |
+| `https://api.github.com/repos/USER/ИМЯ/contents/ПАПКА?ref=main` | `https://gitlab.com/api/v4/projects/itzredtea%2FИМЯ/repository/tree?path=ПАПКА&ref=main` (поле `path`) |
+| картинки `github.com/user-attachments/...` | скачать, пока открываются, в `docs/` и ссылаться на файлы |
+
+Путь Go-модуля (`module github.com/...` в `go.mod`) можно не трогать: это только имя.
+
+## 7. После переноса
+
+- Описание проекта в GitLab: «Перенесён с GitHub, начат ДД.ММ.ГГГГ» - раз дата создания новая.
+- Токены, которые светились в чатах и логах, - отозвать и выпустить новые.
@@ -0,0 +1,73 @@
+# План: управление потоком в прямом туннеле (tcp-проброс)
+
+Статус: **отложено** - сделать, если на практике упрёмся. Записано 2026-10-16.
+
+## Что сейчас
+
+Прямой туннель (`:8446`, режим проброса `tcp`) - одно TCP-соединение на агента, по нему
+мультиплексируются все проброшенные соединения этого агента кадрами
+`type(1) | stream(4) | length(4) | payload` (`internal/tunnel/frame.go`).
+
+Ёмкости хватает с запасом: на агента - одно соединение и одна горутина чтения, на проброшенное
+соединение - горутина и буфер 32 КБ; шифрования в туннеле нет. 20 агентов и тысячи соединений -
+десятки МБ памяти и почти ноль CPU. Потолок - сеть хоста (1 Гбит/с), через которую весь трафик
+идёт дважды (пользователь ↔ хост ↔ агент).
+
+## Проблема: блокировка всего туннеля агента одним соединением
+
+Управления потоком (окон, как в HTTP/2 или yamux) нет, поэтому внутри одного агента медленное
+соединение тормозит остальные:
+
+- **Хост** (`internal/server/tunnelserver.go`, `agentTunnel.readLoop`): кадр `TypeData` пишется
+  пользователю синхронно, `c.Write(f.Payload)`, без дедлайна. Клиент, который медленно читает или
+  завис, останавливает чтение туннеля - встают все пробросы этого агента, пока клиент не отвалится.
+- **Агент** (`internal/agent/tunnel.go`, `tunClient.readLoop`): данные кладутся в канал потока
+  `in` (256 кусков, до ~8 МБ). Если локальный сервис не читает и канал полон, `readLoop`
+  блокируется на `s.in <- f.Payload` - встаёт весь туннель агента.
+
+Между агентами влияния нет: у каждого свой `readLoop`.
+
+Когда проявится: через одного агента одновременно большая отдача медленному клиенту и что-то
+интерактивное (SSH, веб) - интерактивное подвисает. Худший случай - зависший клиент держит
+туннель агента до разрыва TCP.
+
+## Предлагаемое решение
+
+1. **Своя очередь записи у каждого потока** - на хосте и на агенте. `readLoop` только кладёт
+   кадр в очередь потока и никогда не пишет в сокет сам; пишет отдельная горутина потока.
+2. **Окно (кредиты) на поток.** Новый тип кадра `TypeWindow` (stream, uint32 байт): получатель
+   сообщает, сколько ещё байт готов принять. Отправитель не шлёт `TypeData` сверх окна.
+   Начальное окно - 256 КБ; получатель возвращает кредит по мере записи в сокет (например, когда
+   записана половина окна). Так очередь потока ограничена окном, а медленный поток тормозит
+   только себя.
+3. **Дедлайны записи.** Запись в пользовательский или локальный сокет - с `SetWriteDeadline`
+   (например, 60 с без прогресса). Не успел - поток закрывается (`TypeClose`), туннель живёт.
+4. **Справедливость отправки.** Отправка в туннель уже сериализована (`wmu`); кадры данных
+   ограничить 32 КБ (сейчас так и есть), чтобы большой поток не занимал канал надолго.
+
+## Совместимость со старыми агентами
+
+Рукопожатие `LPRA-TUN1` не меняем: старый агент отвергает другое приветствие, а старый сервер -
+ответ не из двух полей. Вместо этого:
+
+- сервер знает версию агента (из БД, `versionAtLeast`) и, если агент новый, сразу после
+  рукопожатия шлёт кадр `TypeHello` (флаги: `flowControl`);
+- агент включает окна, только получив `TypeHello`. Старый сервер его не шлёт - новый агент
+  работает с ним по-старому. Старому агенту сервер `TypeHello` не шлёт и окна не включает (а
+  пришедший неизвестный кадр старый агент и так пропустил бы: в его `readLoop` нет `default`).
+
+Новые типы кадров: `TypeHello = 5`, `TypeWindow = 6`.
+
+## Тесты
+
+- Медленный читатель на одном потоке не задерживает другой поток того же агента (замер задержки
+  эха на втором потоке при забитом первом).
+- Зависший клиент закрывается по дедлайну, туннель и остальные потоки живы.
+- Новый сервер + старый агент и старый сервер + новый агент - проброс работает, как раньше.
+- Пропускная способность одного потока не падает заметно (окно 256 КБ на RTT до 50 мс даёт
+  ~40 Мбит/с на поток; если мало - окно больше или автоподстройка).
+
+## Объём
+
+Сервер: `tunnelserver.go` (~150 строк), агент: `tunnel.go` (~150 строк), `frame.go` (типы), тесты.
+Нужна новая версия агента; панель после обновления помечает старых как устаревших.
@@ -0,0 +1,159 @@
+# LPRA 0.2.0 — рабочее пространство (подпроект 1)
+
+Дата: 2026-10-15. Статус: спецификация утверждена.
+Подпроект 2 (встроенный ИИ-помощник) — отдельная спецификация, делается после этого.
+
+## Цель
+
+Работа с несколькими машинами в одном месте, без потери открытых терминалов при переходах по панели.
+Терминалы, файловые менеджеры (своих машин и по SSH) живут во вкладках одного рабочего пространства;
+файлы перетаскиваются между панелями и в терминал.
+
+Критерии готовности:
+- переход Машины ↔ Терминал ↔ Настройки не обрывает сессии терминалов и не сбрасывает вкладки;
+- перезагрузка страницы сбрасывает пространство (с предупреждением браузера, если есть живые сессии);
+- файловый менеджер — тип панели во вкладке, в том числе по SSH;
+- перетаскивание файлов: между файловыми панелями (окно «переместить / копировать»), в терминал той же машины (вставка путей), в терминал другой машины — запрет с сообщением.
+
+## Решения, принятые в обсуждении
+
+| вопрос | решение |
+|---|---|
+| Страницы «Порты», «Статус», «Изменить» | окна поверх текущей страницы |
+| Файлы рядом с терминалами в одной вкладке | да: любая из до 4 панелей — терминал, SSH-терминал, файлы, SSH-файлы |
+| Перезагрузка при живых сессиях | вопрос браузера «Покинуть сайт?» |
+| Архитектура | одностраничная оболочка, остальное — HTML-фрагменты с сервера (вариант A) |
+| Файлы по SSH | без SFTP-библиотеки: команды на хосте через SSH, как у существующей передачи tar |
+| Состояние | одно на вкладку браузера, в памяти страницы; не сохраняется при перезагрузке |
+
+## 1. Каркас и маршруты
+
+**Оболочка.** Адреса `/`, `/terminal`, `/settings` отдают один шаблон `app.html`: шапка (LPRA, «Машины · Терминал · Настройки» — «Настройки» только администраторам, статус активной панели, аккаунт) и три области `<section data-view="machines|terminal|settings">`.
+Старые адреса `/agents/{id}/terminal` и `/agents/{id}/files` отдают ту же оболочку и при загрузке создают вкладку нужного типа для этой машины (закладки не ломаются).
+
+**Роутер** (`static/app.js`, без библиотек):
+- перехватывает клики по внутренним ссылкам и `popstate`; меняет видимую область через `history.pushState`, подсвечивает пункт шапки;
+- область «Терминал» создаётся один раз и потом только скрывается (`hidden`) — сессии, WebSocket и xterm живут, пока жива вкладка браузера;
+- «Машины» и «Настройки» при каждом показе подгружаются заново как фрагмент: `GET /?frag=1`, `GET /settings?frag=1`.
+
+**Фрагменты на сервере.** `render()` получает режим фрагмента (параметр `frag=1`): шаблон отдаёт только содержимое, без `<html>`, шапки и подключений. Общая разметка `head` и `topbar`, сейчас скопированная в каждый шаблон, выносится в `{{define}}`-блоки.
+
+**Формы во фрагментах** (`app.js`, перехват `submit` внутри областей и окон):
+1. `onsubmit`-обработчики (`confirm(...)`) срабатывают как обычно; отказ — ничего не происходит;
+2. форма отправляется через `fetch` (`redirect: 'follow'`, тело — `FormData`);
+3. итоговый адрес ответа определяет, что перерисовать: тот же фрагмент по этому адресу (сохраняются `?err=...`, `?updated=1`, `#users`);
+4. формы на `/logout` и ссылки наружу работают обычной загрузкой страницы.
+
+**Скрипты фрагментов.** Встроенные `<script>` во фрагментах не исполняются. Поведение страниц оформляется модулями с `mount(root)` / `unmount()`, которые вызывает роутер: копирование команд и коды установки (настройки), `users.js`, список машин с опросом присутствия.
+`pin.js`, `scroll.js`, `account.js` подключаются один раз в оболочке.
+
+**Предупреждение при уходе.** `beforeunload` спрашивает «Покинуть сайт?», только если в рабочем пространстве есть живая сессия терминала или SSH-терминала.
+
+## 2. Рабочее пространство и типы панелей
+
+**Модель.** Вкладка содержит 1–4 панели в существующих раскладках (`1`, `h`, `v`, сетка), с изменением размеров и перетаскиванием панелей и вкладок, как сейчас. Тип панели:
+
+| тип | что это |
+|---|---|
+| `term` | терминал на машине (как сейчас) |
+| `ssh` | SSH-терминал через машину (как сейчас) |
+| `files` | файловый менеджер на машине |
+| `sshfiles` | файловый менеджер на SSH-хосте через машину |
+
+**Разделение кода** (сейчас всё в `terminal.js` и `files.html`):
+- `workspace.js` — вкладки, раскладки, разделение, перетаскивание панелей и вкладок, меню «+». С панелями работает через общий интерфейс: `el`, `kind`, `agent`, `title`, `state` и `text` (точка и строка статуса), `fit()`, `focus()`, `close()`, `acceptsDrop(item)`, `drop(item)`;
+- `termpane.js` — нынешний класс `Session` (терминал и SSH-терминал), вынесенный почти без изменений;
+- `filepane.js` — файловая панель (часть 3);
+- `fileviews.js` — общие окна файлов (просмотр и правка, hex, свойства, перемещение, загрузка, редактор SQLite).
+
+**Меню «+»** (на компьютере и телефоне):
+- «Терминал ›» — «здесь (машина)», другие машины в сети, «SSH-хост…»;
+- «Файловый менеджер ›» — «здесь (машина)», другие машины в сети, «SSH-хост…».
+
+«SSH-хост…» открывает существующее окно SSH-подключения; тип панели зависит от пункта меню. Последний SSH-хост (без секретов) запоминается, как сейчас.
+
+**Из списка машин:** кнопка терминала → новая вкладка-терминал этой машины и переход в «Терминал»; кнопка файлов → новая вкладка «Файлы». Если пространства ещё нет, оно создаётся.
+
+**Заголовки.** Вкладка файлов — иконка папки и `машина · папка`, путь обрезается слева, обновляется при смене папки. Переименование двойным кликом — как у терминалов. Точка статуса файловой панели — машина в сети / офлайн / ошибка.
+
+**Телефон.** Вкладки и меню те же; разделения и перетаскивания, как и сейчас, только на компьютере.
+
+## 3. Файловая панель
+
+Содержимое нынешней страницы файлов как компонент `FilePane(source)`: строка пути, «Вверх», «Обновить», «Папка / Файл / Загрузить», таблица с отметками, «В zip», «Удалить выбранное», загрузка перетаскиванием из ОС.
+Состояние (текущая папка, список, отметки) — у экземпляра; элементы ищутся внутри корня панели, без глобальных `id`. Две файловые панели в одной вкладке не мешают друг другу.
+
+**Общие окна** (`fileviews.js`) — одно на страницу. При открытии окну передаётся панель-источник: машина или SSH, путь, что обновить после действия.
+
+**Источник данных** — один интерфейс (`list`, `read`, `write`, `mkdir`, `delete`, `move`, `copy`, `stat`, `chmod`, `download`, `upload`) с двумя реализациями:
+- машина — существующий `/api/panel/agents/{id}/fs/...`;
+- SSH-хост — новые задачи агента `sshfs.*` (ниже).
+
+**Узкие панели** (меньше ~520 px, в разделённой вкладке): прячется колонка «Изменён», кнопки строки сворачиваются в меню «⋯» — как сейчас на телефоне.
+
+### Файлы по SSH (`sshfiles`)
+
+Агент держит одно SSH-подключение на панель: `sshConnect` и проверка ключа хоста из SSH-терминала. Подключение открывается при создании панели (окно «SSH-хост…»), получает id, закрывается при закрытии панели или через 10 минут простоя. Секреты передаются агенту один раз, панель их не хранит.
+
+Операции — команды на хосте, пути в одинарных кавычках (`shq`):
+
+| операция | команда |
+|---|---|
+| список | `stat` по содержимому папки; формат выбирается один раз при подключении: GNU/busybox `stat -c`, BSD/macOS `stat -f`; без `stat` — разбор `ls -la` без точного времени |
+| чтение, скачивание | `cat -- 'файл'`, поток через stdout |
+| запись, загрузка | `cat > 'файл.tmp' && mv 'файл.tmp' 'файл'`, поток через stdin |
+| папка, удаление, переименование | `mkdir -p`, `rm -rf`, `mv` |
+| права, владелец | `chmod`, `chown` |
+| копирование, перенос внутри хоста | `cp -a`, `mv` |
+| перенос между хостом и машинами | существующая передача tar по SSH |
+
+Новые задачи агента: `sshfs.open` (подключиться, вернуть id и домашнюю папку), `sshfs.close`, `sshfs.list`, `sshfs.read`, `sshfs.write`, `sshfs.mkdir`, `sshfs.delete`, `sshfs.move`, `sshfs.copy`, `sshfs.stat`, `sshfs.chmod`, `sshfs.send` (скачивание через существующие куски `xfer`), `sshfs.put` (загрузка через куски `xfer`).
+Серверу — те же правила доступа, что у файловых операций машины; изменения пишутся в аудит.
+
+Не входит: zip и распаковка на SSH-хосте, редактор SQLite по SSH — эти кнопки в `sshfiles` скрыты. Новых зависимостей нет.
+
+## 4. Перетаскивание
+
+**Что тащится:** строка файла или папки; если строка отмечена — все отмеченные строки панели. У курсора бейдж (имя или «N элементов»).
+Механизм — на `pointer`-событиях внутри страницы, тот же, что уже двигает вкладки и панели; подсказка над целью говорит, что произойдёт.
+
+| цель | результат |
+|---|---|
+| другая файловая панель (любая машина или SSH-хост) | небольшое окно у места броска: «Переместить / Копировать / Отмена», куда (папка цели), «если уже есть: сообщить ▾». Внутри машины — `fs.copy`; внутри SSH-хоста — `cp`/`mv`; между разными — существующая передача tar с прогрессом в этом же окне |
+| папка в списке панели | то же, цель — эта папка |
+| терминал той же машины / того же SSH-хоста | пути в одинарных кавычках через пробел вставляются в терминал, без Enter |
+| терминал другой машины | цель подсвечивается красным, подсказка «Нельзя: файл на X, терминал на Y» |
+| заголовок вкладки | через 0,5 с наведения вкладка активируется, бросить можно в её панель |
+| пустое место / Esc | отмена |
+
+Правила конфликтов имён — те же, что в окне «Переместить или копировать». Загрузка из ОС перетаскиванием — в любую файловую панель. На телефоне перетаскивания нет; остаётся окно перемещения с выбором машины или SSH.
+
+## 5. Окна машины
+
+«Порты», «Статус», «Изменить» — нынешние страницы как фрагменты (`?frag=1`) в общем окне `machinedlg` (заголовок «машина · раздел», закрытие; на телефоне — на весь экран).
+Открываются из кнопок строки в списке машин и из меню заголовка вкладки или панели (её машина). Формы — перехватом из части 1; результат (например, обновления клиента) показывается в окне.
+Живые части (графики и опрос статуса, тест скорости, присутствие) — модули `mount` / `unmount`; при закрытии окна останавливаются.
+
+## Ошибки и крайние случаи
+
+- Машина офлайн: терминал — как сейчас; файловая панель — «машина офлайн» и «повторить», при возвращении машины обновляется сама.
+- Нет доступа (роль «пользователь»): чужих машин нет в меню и списке; если доступ отобран при открытой вкладке — панель показывает «нет доступа».
+- Сессия истекла (401 или редирект на `/login`): сообщение и переход на вход.
+- Агент без `sshfs.*`: пункт «Файлы по SSH» сообщает «обновите агента».
+- Фрагмент не загрузился: ошибка и «повторить» в его области, остальное приложение работает.
+- SSH-подключение файловой панели оборвалось: следующая операция переподключается один раз; не вышло — панель сообщает и предлагает переподключиться.
+
+## Проверка
+
+На стенде (сервер, агент, тестовый sshd), Chrome на компьютере и в эмуляции телефона:
+1. Переходы Машины ↔ Терминал ↔ Настройки при идущем выводе в терминале — вывод не прерывается; «Назад / Вперёд»; перезагрузка — сброс и «Покинуть сайт?».
+2. Вкладки с терминалом, файлами, SSH-файлами; разделение, изменение размеров, перетаскивание панелей и вкладок.
+3. Файловая панель машины и SSH-хоста: список, просмотр, правка, загрузка, скачивание, создание, удаление, переименование, права.
+4. Перетаскивание: в соседнюю панель (своя машина, SSH), в папку, в терминал той же машины (вставка путей), в терминал чужой (запрет).
+5. Окна машины: формы, обновление клиента, остановка графиков при закрытии.
+6. Роли: обычный пользователь видит в меню и списке только свои машины.
+7. Регрессия: PIN, ключи доступа, установщик, редактор SQLite, перенос на другие машины, прямой адрес.
+
+## Версия и документация
+
+Версия 0.2.0. README — разделы о рабочем пространстве, файлах по SSH и перетаскивании.
@@ -3,18 +3,34 @@ module github.com/x-grk/longpolling-remote-access
 go 1.26

 require (
+	github.com/coder/websocket v1.8.12
 	github.com/creack/pty v1.1.21
-	golang.org/x/crypto v0.31.0
+	github.com/jackc/pgx/v5 v5.7.5
+	golang.org/x/crypto v0.37.0
+	golang.org/x/sys v0.32.0
 	modernc.org/sqlite v1.24.0
 )

 require (
 	github.com/dustin/go-humanize v1.0.1 // indirect
 	github.com/google/uuid v1.6.0 // indirect
+	github.com/jackc/pgpassfile v1.0.0 // indirect
+	github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761 // indirect
+	github.com/jackc/puddle/v2 v2.2.2 // indirect
+	github.com/kballard/go-shellquote v0.0.0-20180428030007-95032a82bc51 // indirect
 	github.com/mattn/go-isatty v0.0.16 // indirect
 	github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec // indirect
-	golang.org/x/sys v0.28.0 // indirect
+	golang.org/x/mod v0.17.0 // indirect
+	golang.org/x/sync v0.13.0 // indirect
+	golang.org/x/text v0.24.0 // indirect
+	golang.org/x/tools v0.21.1-0.20240508182429-e35e4ccd0d2d // indirect
+	lukechampine.com/uint128 v1.2.0 // indirect
+	modernc.org/cc/v3 v3.40.0 // indirect
+	modernc.org/ccgo/v3 v3.16.13 // indirect
 	modernc.org/libc v1.22.5 // indirect
 	modernc.org/mathutil v1.5.0 // indirect
 	modernc.org/memory v1.5.0 // indirect
+	modernc.org/opt v0.1.3 // indirect
+	modernc.org/strutil v1.1.3 // indirect
+	modernc.org/token v1.0.1 // indirect
 )
@@ -1,28 +1,86 @@
+github.com/coder/websocket v1.8.12 h1:5bUXkEPPIbewrnkU8LTCLVaxi4N4J8ahufH2vlo4NAo=
+github.com/coder/websocket v1.8.12/go.mod h1:LNVeNrXQZfe5qhS9ALED3uA+l5pPqvwXg3CKoDBB2gs=
 github.com/creack/pty v1.1.21 h1:1/QdRyBaHHJP61QkWMXlOIBfsgdDeeKfK8SYVUWJKf0=
 github.com/creack/pty v1.1.21/go.mod h1:MOBLtS5ELjhRRrroQr9kyvTxUAFNvYEK993ew/Vr4O4=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/dustin/go-humanize v1.0.1 h1:GzkhY7T5VNhEkwH0PVJgjz+fX1rhBrR7pRT3mDkpeCY=
 github.com/dustin/go-humanize v1.0.1/go.mod h1:Mu1zIs6XwVuF/gI1OepvI0qD18qycQx+mFykh5fBlto=
+github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
+github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
+github.com/google/pprof v0.0.0-20221118152302-e6195bd50e26 h1:Xim43kblpZXfIBQsbuBVKCudVG457BR2GZFIz3uw3hQ=
+github.com/google/pprof v0.0.0-20221118152302-e6195bd50e26/go.mod h1:dDKJzRmX4S37WGHujM7tX//fmj1uioxKzKxz3lo4HJo=
 github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
 github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
-github.com/gorilla/websocket v1.5.3 h1:saDtZ6Pbx/0u+bgYQ3q96pZgCzfhKXGPqt7kZ72aNNg=
-github.com/gorilla/websocket v1.5.3/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
+github.com/jackc/pgpassfile v1.0.0 h1:/6Hmqy13Ss2zCq62VdNG8tM1wchn8zjSGOBJ6icpsIM=
+github.com/jackc/pgpassfile v1.0.0/go.mod h1:CEx0iS5ambNFdcRtxPj5JhEz+xB6uRky5eyVu/W2HEg=
+github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761 h1:iCEnooe7UlwOQYpKFhBabPMi4aNAfoODPEFNiAnClxo=
+github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761/go.mod h1:5TJZWKEWniPve33vlWYSoGYefn3gLQRzjfDlhSJ9ZKM=
+github.com/jackc/pgx/v5 v5.7.5 h1:JHGfMnQY+IEtGM63d+NGMjoRpysB2JBwDr5fsngwmJs=
+github.com/jackc/pgx/v5 v5.7.5/go.mod h1:aruU7o91Tc2q2cFp5h4uP3f6ztExVpyVv88Xl/8Vl8M=
+github.com/jackc/puddle/v2 v2.2.2 h1:PR8nw+E/1w0GLuRFSmiioY6UooMp6KJv0/61nB7icHo=
+github.com/jackc/puddle/v2 v2.2.2/go.mod h1:vriiEXHvEE654aYKXXjOvZM39qJ0q+azkZFrfEOc3H4=
+github.com/kballard/go-shellquote v0.0.0-20180428030007-95032a82bc51 h1:Z9n2FFNUXsshfwJMBgNA0RU6/i7WVaAegv3PtuIHPMs=
+github.com/kballard/go-shellquote v0.0.0-20180428030007-95032a82bc51/go.mod h1:CzGEWj7cYgsdH8dAjBGEr58BoE7ScuLd+fwFZ44+/x8=
 github.com/mattn/go-isatty v0.0.16 h1:bq3VjFmv/sOjHtdEhmkEV4x1AJtvUvOJ2PFAZ5+peKQ=
 github.com/mattn/go-isatty v0.0.16/go.mod h1:kYGgaQfpe5nmfYZH+SKPsOc2e4SrIfOl2e/yFXSvRLM=
+github.com/mattn/go-sqlite3 v1.14.16 h1:yOQRA0RpS5PFz/oikGwBEqvAWhWg5ufRz4ETLjwpU1Y=
+github.com/mattn/go-sqlite3 v1.14.16/go.mod h1:2eHXhiwb8IkHr+BDWZGa96P6+rkvnG63S2DGjv9HUNg=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/remyoudompheng/bigfft v0.0.0-20200410134404-eec4a21b6bb0/go.mod h1:qqbHyh8v60DhA7CoWK5oRCqLrMHRGoxYCSS9EjAz6Eo=
 github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec h1:W09IVJc94icq4NjY3clb7Lk8O1qJ8BdBEF8z0ibU0rE=
 github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec/go.mod h1:qqbHyh8v60DhA7CoWK5oRCqLrMHRGoxYCSS9EjAz6Eo=
-golang.org/x/crypto v0.28.0 h1:GBDwsMXVQi34v5CCYUm2jkJvu4cbtru2U4TN2PSyQnw=
-golang.org/x/crypto v0.28.0/go.mod h1:rmgy+3RHxRZMyY0jjAJShp2zgEdOqj2AO7U0pYmeQ7U=
-golang.org/x/crypto v0.31.0 h1:ihbySMvVjLAeSH1IbfcRTkD/iNscyz8rGzjF/E5hV6U=
-golang.org/x/crypto v0.31.0/go.mod h1:kDsLvtWBEx7MV9tJOj9bnXsPbxwJQ6csT/x4KIN4Ssk=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
+github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.8.1 h1:w7B6lhMri9wdJUVmEZPGGhZzrYTPvgJArz7wNPgYKsk=
+github.com/stretchr/testify v1.8.1/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
+golang.org/x/crypto v0.37.0 h1:kJNSjF/Xp7kU0iB2Z+9viTPMW4EqqsrywMXLJOOsXSE=
+golang.org/x/crypto v0.37.0/go.mod h1:vg+k43peMZ0pUMhYmVAWysMK35e6ioLh3wB8ZCAfbVc=
+golang.org/x/mod v0.17.0 h1:zY54UmvipHiNd+pm+m0x9KhZ9hl1/7QNMyxXbc6ICqA=
+golang.org/x/mod v0.17.0/go.mod h1:hTbmBsO62+eylJbnUtE2MGJUyE7QWk4xUqPFrRgJ+7c=
+golang.org/x/sync v0.13.0 h1:AauUjRAJ9OSnvULf/ARrrVywoJDy0YS2AwQ98I37610=
+golang.org/x/sync v0.13.0/go.mod h1:1dzgHSNfp02xaA81J2MS99Qcpr2w7fw1gpm99rleRqA=
 golang.org/x/sys v0.0.0-20220811171246-fbc7d0a398ab/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.28.0 h1:Fksou7UEQUWlKvIdsqzJmUmCX3cZuD2+P3XyyzwMhlA=
-golang.org/x/sys v0.28.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/sys v0.32.0 h1:s77OFDvIQeibCmezSnk/q6iAfkdiQaJi4VzroCFrN20=
+golang.org/x/sys v0.32.0/go.mod h1:BJP2sWEmIv4KK5OTEluFJCKSidICx8ciO85XgH3Ak8k=
+golang.org/x/term v0.31.0 h1:erwDkOK1Msy6offm1mOgvspSkslFnIGsFnxOKoufg3o=
+golang.org/x/term v0.31.0/go.mod h1:R4BeIy7D95HzImkxGkTW1UQTtP54tio2RyHz7PwK0aw=
+golang.org/x/text v0.24.0 h1:dd5Bzh4yt5KYA8f9CJHCP4FB4D51c2c6JvN37xJJkJ0=
+golang.org/x/text v0.24.0/go.mod h1:L8rBsPeo2pSS+xqN0d5u2ikmjtmoJbDBT1b7nHvFCdU=
+golang.org/x/tools v0.21.1-0.20240508182429-e35e4ccd0d2d h1:vU5i/LfpvrRCpgM/VPfJLg5KjxD3E+hfT1SH+d9zLwg=
+golang.org/x/tools v0.21.1-0.20240508182429-e35e4ccd0d2d/go.mod h1:aiJjzUbINMkxbQROHiO6hDPo2LHcIPhhQsa9DLh0yGk=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+lukechampine.com/uint128 v1.2.0 h1:mBi/5l91vocEN8otkC5bDLhi2KdCticRiwbdB0O+rjI=
+lukechampine.com/uint128 v1.2.0/go.mod h1:c4eWIwlEGaxC/+H1VguhU4PHXNWDCDMUlWdIWl2j1gk=
+modernc.org/cc/v3 v3.40.0 h1:P3g79IUS/93SYhtoeaHW+kRCIrYaxJ27MFPv+7kaTOw=
+modernc.org/cc/v3 v3.40.0/go.mod h1:/bTg4dnWkSXowUO6ssQKnOV0yMVxDYNIsIrzqTFDGH0=
+modernc.org/ccgo/v3 v3.16.13 h1:Mkgdzl46i5F/CNR/Kj80Ri59hC8TKAhZrYSaqvkwzUw=
+modernc.org/ccgo/v3 v3.16.13/go.mod h1:2Quk+5YgpImhPjv2Qsob1DnZ/4som1lJTodubIcoUkY=
+modernc.org/ccorpus v1.11.6 h1:J16RXiiqiCgua6+ZvQot4yUuUy8zxgqbqEEUuGPlISk=
+modernc.org/ccorpus v1.11.6/go.mod h1:2gEUTrWqdpH2pXsmTM1ZkjeSrUWDpjMu2T6m29L/ErQ=
+modernc.org/httpfs v1.0.6 h1:AAgIpFZRXuYnkjftxTAZwMIiwEqAfk8aVB2/oA6nAeM=
+modernc.org/httpfs v1.0.6/go.mod h1:7dosgurJGp0sPaRanU53W4xZYKh14wfzX420oZADeHM=
 modernc.org/libc v1.22.5 h1:91BNch/e5B0uPbJFgqbxXuOnxBQjlS//icfQEGmvyjE=
 modernc.org/libc v1.22.5/go.mod h1:jj+Z7dTNX8fBScMVNRAYZ/jF91K8fdT2hYMThc3YjBY=
 modernc.org/mathutil v1.5.0 h1:rV0Ko/6SfM+8G+yKiyI830l3Wuz1zRutdslNoQ0kfiQ=
 modernc.org/mathutil v1.5.0/go.mod h1:mZW8CKdRPY1v87qxC/wUdX5O1qDzXMP5TH3wjfpga6E=
 modernc.org/memory v1.5.0 h1:N+/8c5rE6EqugZwHii4IFsaJ7MUhoWX07J5tC/iI5Ds=
 modernc.org/memory v1.5.0/go.mod h1:PkUhL0Mugw21sHPeskwZW4D6VscE/GQJOnIpCnW6pSU=
+modernc.org/opt v0.1.3 h1:3XOZf2yznlhC+ibLltsDGzABUGVx8J6pnFMS3E4dcq4=
+modernc.org/opt v0.1.3/go.mod h1:WdSiB5evDcignE70guQKxYUl14mgWtbClRi5wmkkTX0=
 modernc.org/sqlite v1.24.0 h1:EsClRIWHGhLTCX44p+Ri/JLD+vFGo0QGjasg2/F9TlI=
 modernc.org/sqlite v1.24.0/go.mod h1:OrDj17Mggn6MhE+iPbBNf7RGKODDE9NFT0f3EwDzJqk=
+modernc.org/strutil v1.1.3 h1:fNMm+oJklMGYfU9Ylcywl0CO5O6nTfaowNsh2wpPjzY=
+modernc.org/strutil v1.1.3/go.mod h1:MEHNA7PdEnEwLvspRMtWTNnp2nnyvMfkimT1NKNAGbw=
+modernc.org/tcl v1.15.2 h1:C4ybAYCGJw968e+Me18oW55kD/FexcHbqH2xak1ROSY=
+modernc.org/tcl v1.15.2/go.mod h1:3+k/ZaEbKrC8ePv8zJWPtBSW0V7Gg9g8rkmhI1Kfs3c=
+modernc.org/token v1.0.1 h1:A3qvTqOwexpfZZeyI0FeGPDlSWX5pjZu9hF4lU+EKWg=
+modernc.org/token v1.0.1/go.mod h1:UGzOrNV1mAFSEB63lOFHIpNRUVMvYTc6yu1SMY/XTDM=
+modernc.org/z v1.7.3 h1:zDJf6iHjrnB+WRD88stbXokugjyc0/pB91ri1gO6LZY=
+modernc.org/z v1.7.3/go.mod h1:Ipv4tsdxZRbQyLq9Q1M6gdbkxYzdlrciF2Hi/lS7nWE=
@@ -0,0 +1,95 @@
+package agent
+
+import (
+	"context"
+	"log"
+	"net/http"
+	"strconv"
+	"sync"
+	"time"
+
+	"github.com/x-grk/longpolling-remote-access/internal/proto"
+)
+
+// Auto-update, the agent's part: the server tells (with every poll, on its
+// config and on the WebSocket) its own version and how often to compare -
+// in minutes, 0 for never. When the server's version is newer, the agent
+// takes the new one from it, as the panel's «Обновить» does.
+
+// autoUpdate is what the agent was told, and when it last looked.
+type autoUpdate struct {
+	mu        sync.Mutex
+	minutes   int
+	serverVer string
+	last      time.Time
+}
+
+func (a *Agent) applyUpdateInfo(minutes int, serverVersion string) {
+	a.auto.mu.Lock()
+	defer a.auto.mu.Unlock()
+	if minutes < 0 {
+		minutes = 0
+	}
+	a.auto.minutes = minutes
+	if serverVersion != "" {
+		a.auto.serverVer = serverVersion
+	}
+}
+
+// applyUpdateHeaders takes the settings from the headers of an answer; an
+// answer without them (an older server) changes nothing.
+func (a *Agent) applyUpdateHeaders(h http.Header) {
+	v := h.Get(proto.AutoUpdateHeader)
+	if v == "" {
+		return
+	}
+	m, err := strconv.Atoi(v)
+	if err != nil {
+		m = 0
+	}
+	a.applyUpdateInfo(m, h.Get(proto.ServerVersionHeader))
+}
+
+func (a *Agent) updateInfo() (int, string) {
+	a.auto.mu.Lock()
+	defer a.auto.mu.Unlock()
+	return a.auto.minutes, a.auto.serverVer
+}
+
+func (a *Agent) autoUpdateOn() bool { m, _ := a.updateInfo(); return m > 0 }
+
+// autoUpdateTick: one look at the clock. Out of the interval since the last
+// look, it looks; the server's version newer than its own, it updates.
+// Reports whether it did.
+func (a *Agent) autoUpdateTick(now time.Time, update func() proto.TaskResult) bool {
+	a.auto.mu.Lock()
+	if a.auto.minutes <= 0 || (!a.auto.last.IsZero() && now.Sub(a.auto.last) < time.Duration(a.auto.minutes)*time.Minute) {
+		a.auto.mu.Unlock()
+		return false
+	}
+	a.auto.last = now
+	server := a.auto.serverVer
+	a.auto.mu.Unlock()
+	if !proto.VersionNewer(server, Version) {
+		return false
+	}
+	log.Printf("auto-update: server has %s, this is %s - updating", server, Version)
+	if res := update(); !res.OK {
+		log.Printf("auto-update: %s", res.Error)
+	}
+	return true
+}
+
+// autoUpdateLoop watches the clock until ctx ends.
+func (a *Agent) autoUpdateLoop(ctx context.Context) {
+	t := time.NewTicker(30 * time.Second)
+	defer t.Stop()
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case now := <-t.C:
+			a.autoUpdateTick(now, a.doUpdate)
+		}
+	}
+}
@@ -0,0 +1,78 @@
+package agent
+
+import (
+	"net/http"
+	"testing"
+	"time"
+
+	"github.com/x-grk/longpolling-remote-access/internal/proto"
+)
+
+// updates counts what an agent was made to update with.
+type updates struct{ n int }
+
+func (u *updates) do() proto.TaskResult { u.n++; return proto.TaskResult{OK: true} }
+
+// The agent is told, by headers or by the WebSocket's message, how often to
+// compare versions; nothing told, nothing done.
+func TestAutoUpdateIsTold(t *testing.T) {
+	a := New(Config{})
+	if a.autoUpdateOn() {
+		t.Fatal("on with nothing told")
+	}
+	h := http.Header{}
+	h.Set(proto.AutoUpdateHeader, "90")
+	h.Set(proto.ServerVersionHeader, "9.9.9")
+	a.applyUpdateHeaders(h)
+	if m, v := a.updateInfo(); m != 90 || v != "9.9.9" {
+		t.Fatalf("by headers: %d %q", m, v)
+	}
+	a.applyUpdateInfo(0, "9.9.9")
+	if a.autoUpdateOn() {
+		t.Fatal("still on after being told 0")
+	}
+	a.applyUpdateInfo(30, "9.9.9")
+	if m, _ := a.updateInfo(); m != 30 {
+		t.Fatalf("by the message: %d", m)
+	}
+	// Rubbish is not taken for a number.
+	h.Set(proto.AutoUpdateHeader, "soon")
+	a.applyUpdateHeaders(h)
+	if m, _ := a.updateInfo(); m != 0 {
+		t.Fatalf("rubbish: %d", m)
+	}
+}
+
+// When the interval is out the agent looks; it updates only to a newer
+// version of the server's, and tries again the next time if it did not work.
+func TestAutoUpdateTick(t *testing.T) {
+	a := New(Config{})
+	u := &updates{}
+	now := time.Now()
+	a.applyUpdateInfo(60, "9.9.9")
+
+	if !a.autoUpdateTick(now, u.do) || u.n != 1 {
+		t.Fatalf("a newer server: %d updates", u.n)
+	}
+	if a.autoUpdateTick(now.Add(30*time.Minute), u.do) || u.n != 1 {
+		t.Fatalf("before the interval is out: %d updates", u.n)
+	}
+	if !a.autoUpdateTick(now.Add(61*time.Minute), u.do) || u.n != 2 {
+		t.Fatalf("at the next time: %d updates", u.n)
+	}
+
+	// The same, an older one, a build that is not a version: nothing.
+	for _, v := range []string{Version, "0.0.1", "dev", ""} {
+		b := New(Config{})
+		b.applyUpdateInfo(60, v)
+		if b.autoUpdateTick(now, u.do) {
+			t.Fatalf("updated to %q", v)
+		}
+	}
+	// Off: nothing, whatever the server has.
+	c := New(Config{})
+	c.applyUpdateInfo(0, "9.9.9")
+	if c.autoUpdateTick(now, u.do) || u.n != 2 {
+		t.Fatalf("off, yet updated: %d", u.n)
+	}
+}
@@ -13,38 +13,59 @@ import (
 	"log"
 	"net"
 	"net/http"
+	"net/url"
 	"os"
 	"path/filepath"
 	"runtime"
+	"sync"
+	"sync/atomic"
 	"time"

+	lpra "github.com/x-grk/longpolling-remote-access"
 	"github.com/x-grk/longpolling-remote-access/internal/proto"
 )

-// Version is the agent build version, injected at compile time via -ldflags
-// (-X .../internal/agent.Version=...).
-var Version = "dev"
+// Version is the agent build version (see VERSION.txt).
+var Version = lpra.Version

 // Config is the agent's runtime configuration (from env / config.env).
 type Config struct {
 	Host         string // e.g. https://REDACTED:8445
+	Fallback     string // the direct address, from the installer (FALLBACK_HOST); may be empty
 	EnrollSecret string
 	Name         string // optional friendly name
 	StatePath    string // where the enrolled id+token are persisted
-	TunnelAddr   string // host:port for the direct forward tunnel (e.g. REDACTED:8446); empty disables
+	TunnelAddr   string // host:port for the direct forward tunnel (e.g. panel.example:port); empty disables
+	// TunnelPinned keeps TunnelAddr as configured locally (TUNNEL_ADDR /
+	// TUNNEL_PORT) instead of following the address set in the panel.
+	TunnelPinned bool
 }

 type state struct {
 	AgentID string `json:"agent_id"`
 	Token   string `json:"token"`
+	// Fallback is the direct address as the server told it.
+	Fallback string `json:"fallback,omitempty"`
 }

 // Agent is a running client.
 type Agent struct {
 	cfg       Config
 	http      *http.Client
+	stream    *http.Client
 	state     state
+	stateMu   sync.Mutex
+	hosts     hostState
 	pollCount int
+
+	// Direct tunnel currently running (see setTunnelAddr).
+	transport atomic.Value // string: auto, ws or lp, as the server says
+	link      atomic.Pointer[wsLink]
+	tunMu     sync.Mutex
+	tunAddr   string
+	tunCancel context.CancelFunc
+
+	auto autoUpdate // what the server told of auto-update
 }

 // New builds an agent. It does not perform any network I/O.
@@ -71,6 +92,8 @@ func New(cfg Config) *Agent {
 		cfg: cfg,
 		// Timeout must exceed the server's long-poll hold (25s) plus slack.
 		http: &http.Client{Timeout: 60 * time.Second, Transport: tr},
+		// File streams take as long as the file needs.
+		stream: &http.Client{Transport: tr},
 	}
 }

@@ -81,37 +104,165 @@ func (a *Agent) Run(ctx context.Context) error {
 		return err
 	}
 	if a.state.AgentID == "" || a.state.Token == "" {
-		if err := a.enroll(ctx); err != nil {
+		err := a.enroll(ctx)
+		// The main address out of reach at install: the direct one.
+		if err != nil && a.cfg.Fallback != "" && a.cfg.Fallback != a.cfg.Host {
+			log.Printf("enroll at %s: %v - trying %s", a.cfg.Host, err, a.cfg.Fallback)
+			a.setHost(a.cfg.Fallback)
+			a.hostChanged()
+			err = a.enroll(ctx)
+		}
+		if err != nil {
 			return fmt.Errorf("enroll: %w", err)
 		}
 	}
-	log.Printf("agent %s connected to %s", a.state.AgentID, a.cfg.Host)
+	go a.watchMain(ctx)
+	go a.autoUpdateLoop(ctx)
+	log.Printf("agent %s connected to %s", a.state.AgentID, a.host())

-	// Direct forward tunnel (low-latency TCP mux + UDP) on 8446, if configured.
-	if a.cfg.TunnelAddr != "" {
-		go a.runTunnel(ctx)
-		go a.runUDP(ctx)
+	// Direct forward tunnel (low-latency TCP mux + UDP). Its address comes
+	// from the panel; fall back to the configured one when the server sends
+	// none (tunnel port left at the default on an older server).
+	if a.cfg.TunnelPinned || !a.fetchConfig(ctx) {
+		a.setTunnelAddr(ctx, a.cfg.TunnelAddr)
 	}

+	// The control channel: a WebSocket, or long polls. In "auto" a failed or
+	// dropped WebSocket gives way to long polling for a minute, then is tried
+	// again; "ws" keeps trying the WebSocket; "lp" only polls.
 	backoff := time.Second
 	for ctx.Err() == nil {
-		if err := a.pollOnce(ctx); err != nil {
-			log.Printf("poll: %v (retry in %s)", err, backoff)
+		if a.mode() == proto.TransportLP {
+			a.longPoll(ctx, 0)
+			continue
+		}
+		err := a.runWS(ctx)
+		if ctx.Err() != nil {
+			return nil
+		}
+		// Moved to the other address: the WebSocket goes there at once.
+		if a.hostChanged() {
+			backoff = time.Second
+			continue
+		}
+		a.failed()
+		if a.hostChanged() {
+			continue
+		}
+		switch a.mode() {
+		case proto.TransportWS:
+			log.Printf("websocket: %v (retry in %s)", err, backoff)
 			select {
 			case <-time.After(backoff):
 			case <-ctx.Done():
 				return nil
 			}
-			if backoff < 15*time.Second {
-				backoff *= 2
-			}
+			backoff = min(backoff*2, retryCap)
 			continue
+		case proto.TransportAuto:
+			log.Printf("websocket: %v - long polling, websocket again in a minute", err)
 		}
 		backoff = time.Second
+		a.longPoll(ctx, time.Minute)
 	}
 	return nil
 }

+// mode is the transport the server set for this agent.
+func (a *Agent) mode() string {
+	if v, ok := a.transport.Load().(string); ok {
+		return v
+	}
+	return proto.TransportAuto
+}
+
+func (a *Agent) applyTransport(v string) {
+	switch v {
+	case proto.TransportAuto, proto.TransportWS, proto.TransportLP:
+		if v != a.mode() {
+			log.Printf("transport: %s", v)
+			a.transport.Store(v)
+		}
+	}
+}
+
+// longPoll runs control polls: for d, or with d zero until the transport is
+// no longer long polling.
+func (a *Agent) longPoll(ctx context.Context, d time.Duration) {
+	until := time.Now().Add(d)
+	backoff := time.Second
+	// The server was out of reach (a network down, a machine asleep): once
+	// a poll gets through again, "auto" tries the WebSocket at once rather
+	// than at the end of the minute - it was the network, not the WebSocket.
+	lost := false
+	for ctx.Err() == nil {
+		if d > 0 && (time.Now().After(until) || a.mode() == proto.TransportWS) {
+			return
+		}
+		if d == 0 && a.mode() != proto.TransportLP {
+			return
+		}
+		// Back from out of reach in "auto": a quick request tells when the
+		// server answers again, and the WebSocket is tried then; a poll
+		// would sit held on the server first.
+		if lost && d > 0 {
+			if a.reachable(ctx) {
+				a.reached()
+				return
+			}
+			a.failed()
+			if a.hostChanged() {
+				return
+			}
+			select {
+			case <-time.After(backoff):
+			case <-ctx.Done():
+				return
+			}
+			backoff = min(backoff*2, retryCap)
+			continue
+		}
+		// In "auto" the minute is a minute: a poll still held then is cut
+		// short (the server keeps its job for the next one).
+		reqCtx, cancel := ctx, context.CancelFunc(func() {})
+		if d > 0 {
+			reqCtx, cancel = context.WithDeadline(ctx, until)
+		}
+		err := a.pollOnce(ctx, reqCtx)
+		cut := reqCtx.Err() == context.DeadlineExceeded
+		cancel()
+		if err != nil && cut && ctx.Err() == nil {
+			return
+		}
+		if err != nil {
+			a.failed()
+			if a.hostChanged() {
+				return
+			}
+			log.Printf("poll: %v (retry in %s)", err, backoff)
+			select {
+			case <-time.After(backoff):
+			case <-ctx.Done():
+				return
+			}
+			backoff = min(backoff*2, retryCap)
+			lost = true
+			continue
+		}
+		a.reached()
+		backoff = time.Second
+	}
+}
+
+// reachable reports whether the server answers a quick request.
+func (a *Agent) reachable(ctx context.Context) bool {
+	return a.reachableAt(ctx, a.host())
+}
+
+// retryCap bounds the wait between attempts to reach the server, so a
+// machine back from sleep or a network back up is reconnected in seconds.
+const retryCap = 5 * time.Second
+
 func (a *Agent) enroll(ctx context.Context) error {
 	host, _ := os.Hostname()
 	body, _ := json.Marshal(proto.EnrollRequest{
@@ -122,7 +273,7 @@ func (a *Agent) enroll(ctx context.Context) error {
 		Version:  Version,
 		User:     currentUser(),
 	})
-	req, _ := http.NewRequestWithContext(ctx, http.MethodPost, a.cfg.Host+"/api/agent/enroll", bytes.NewReader(body))
+	req, _ := http.NewRequestWithContext(ctx, http.MethodPost, a.host()+"/api/agent/enroll", bytes.NewReader(body))
 	req.Header.Set("X-Enroll-Secret", a.cfg.EnrollSecret)
 	req.Header.Set("Content-Type", "application/json")
 	resp, err := a.http.Do(req)
@@ -143,8 +294,10 @@ func (a *Agent) enroll(ctx context.Context) error {
 }

 // pollOnce performs one control long-poll and dispatches any instruction.
-func (a *Agent) pollOnce(ctx context.Context) error {
-	req, _ := http.NewRequestWithContext(ctx, http.MethodGet, a.cfg.Host+"/api/agent/poll", nil)
+// The poll itself runs on reqCtx, which may end early; what it starts runs on
+// ctx.
+func (a *Agent) pollOnce(ctx, reqCtx context.Context) error {
+	req, _ := http.NewRequestWithContext(reqCtx, http.MethodGet, a.host()+"/api/agent/poll", nil)
 	a.authHeaders(req)
 	// Report the version and our OS user occasionally (not every poll), so the
 	// panel can flag outdated agents without extra traffic.
@@ -168,16 +321,95 @@ func (a *Agent) pollOnce(ctx context.Context) error {
 	if err := json.NewDecoder(resp.Body).Decode(&msg); err != nil {
 		return err
 	}
-	// Dispatch in the background so we keep polling for more work.
+	a.applyTunnelHeader(ctx, resp.Header)
+	a.learnAddrs(resp.Header.Get(proto.MainHeader), resp.Header.Get(proto.FallbackHeader))
+	a.applyTransport(resp.Header.Get(proto.TransportHeader))
+	a.applyUpdateHeaders(resp.Header)
+	a.dispatch(ctx, msg)
+	return nil
+}
+
+// dispatch starts what a control message asks for, in the background, so the
+// control channel keeps listening.
+func (a *Agent) dispatch(ctx context.Context, msg proto.ControlMessage) {
 	switch msg.Type {
 	case proto.CtrlOpenTerminal:
-		go a.runTerminal(ctx, msg.SessionID, msg.User)
+		go a.runTerminal(ctx, msg.SessionID, msg.User, msg.Dir)
 	case proto.CtrlOpenForward:
 		go a.runForward(ctx, msg.SessionID, msg.Port)
 	case proto.CtrlTask:
 		go a.runTask(ctx, msg.TaskID)
+	case proto.CtrlOpenSSH:
+		if msg.SSH != nil {
+			go a.runSSH(ctx, msg.SessionID, *msg.SSH)
+		}
 	}
-	return nil
+}
+
+// fetchConfig asks the server for the settings it hands to agents and reports
+// whether it named a tunnel address.
+func (a *Agent) fetchConfig(ctx context.Context) bool {
+	ctx2, cancel := context.WithTimeout(ctx, 10*time.Second)
+	defer cancel()
+	req, _ := http.NewRequestWithContext(ctx2, http.MethodGet, a.host()+"/api/agent/config", nil)
+	a.authHeaders(req)
+	resp, err := a.http.Do(req)
+	if err != nil {
+		return false
+	}
+	defer resp.Body.Close()
+	a.applyTransport(resp.Header.Get(proto.TransportHeader))
+	a.learnAddrs(resp.Header.Get(proto.MainHeader), resp.Header.Get(proto.FallbackHeader))
+	a.applyUpdateHeaders(resp.Header)
+	return a.applyTunnelHeader(ctx, resp.Header)
+}
+
+// applyTunnelHeader follows the tunnel address the server advertises as
+// "host:port"; an empty host means the host we already reach the server on.
+func (a *Agent) applyTunnelHeader(ctx context.Context, h http.Header) bool {
+	return a.applyTunnelAddr(ctx, h.Get("X-Tunnel-Addr"))
+}
+
+func (a *Agent) applyTunnelAddr(ctx context.Context, v string) bool {
+	if v == "" || a.cfg.TunnelPinned {
+		return false
+	}
+	host, port, err := net.SplitHostPort(v)
+	if err != nil {
+		return false
+	}
+	if host == "" {
+		u, err := url.Parse(a.host())
+		if err != nil || u.Hostname() == "" {
+			return false
+		}
+		host = u.Hostname()
+	}
+	a.setTunnelAddr(ctx, net.JoinHostPort(host, port))
+	return true
+}
+
+// setTunnelAddr points the direct tunnel at addr, restarting it if it was
+// running against another address. An empty addr stops it.
+func (a *Agent) setTunnelAddr(ctx context.Context, addr string) {
+	a.tunMu.Lock()
+	defer a.tunMu.Unlock()
+	if addr == a.tunAddr {
+		return
+	}
+	if a.tunCancel != nil {
+		a.tunCancel()
+		a.tunCancel = nil
+	}
+	a.tunAddr = addr
+	if addr == "" {
+		return
+	}
+	log.Printf("tunnel: using %s", addr)
+	tctx, cancel := context.WithCancel(ctx)
+	a.tunCancel = cancel
+	go a.runTunnel(tctx, addr)
+	go a.runUDP(tctx, addr)
 }

 func (a *Agent) authHeaders(req *http.Request) {
@@ -202,7 +434,9 @@ func (a *Agent) saveState() error {
 	if err := os.MkdirAll(filepath.Dir(a.cfg.StatePath), 0o700); err != nil {
 		return err
 	}
+	a.stateMu.Lock()
 	b, _ := json.MarshalIndent(a.state, "", "  ")
+	a.stateMu.Unlock()
 	return os.WriteFile(a.cfg.StatePath, b, 0o600)
 }

@@ -9,7 +9,9 @@ import (
 	"io"
 	"os"
 	"os/exec"
+	"os/user"
 	"path/filepath"
+	"runtime"
 	"sort"
 	"strings"
 	"unicode/utf8"
@@ -17,8 +19,8 @@ import (
 	"github.com/x-grk/longpolling-remote-access/internal/proto"
 )

-// fsReadCap bounds how many bytes a view/read returns (5 MiB).
-const fsReadCap = 5 * 1024 * 1024
+// fsReadCap bounds how many bytes a view/read returns.
+const fsReadCap = proto.FSReadCap

 // fsDownloadCap bounds a browser download (kept under the 64 MiB result/body
 // limit once base64-encoded).
@@ -70,6 +72,18 @@ func dispatchFS(env proto.TaskEnvelope) (any, error) {
 		var a proto.FSZipArgs
 		_ = json.Unmarshal(env.Args, &a)
 		return fsZip(a.Paths, a.Dest)
+	case proto.TaskFSStat:
+		var a proto.FSPathArgs
+		_ = json.Unmarshal(env.Args, &a)
+		return fsStat(a.Path)
+	case proto.TaskFSChmod:
+		var a proto.FSChmodArgs
+		_ = json.Unmarshal(env.Args, &a)
+		return fsChmod(a)
+	case proto.TaskFSCopy:
+		var a proto.FSCopyArgs
+		_ = json.Unmarshal(env.Args, &a)
+		return fsCopy(a)
 	default:
 		return nil, fmt.Errorf("неизвестная операция %q", env.Type)
 	}
@@ -79,8 +93,18 @@ func fsList(path string) (proto.FSListResult, error) {
 	if path == "" {
 		path = "/"
 	}
+	// "~" / "~name" is where the file manager starts: the home directory, or
+	// the root when there is none to open.
+	home := strings.HasPrefix(path, "~") && !strings.Contains(path, "/")
+	if home {
+		path = homeDir(path[1:])
+	}
 	abs, _ := filepath.Abs(path)
 	entries, err := os.ReadDir(abs)
+	if err != nil && home && abs != "/" {
+		abs = "/"
+		entries, err = os.ReadDir(abs)
+	}
 	if err != nil {
 		return proto.FSListResult{}, err
 	}
@@ -90,13 +114,21 @@ func fsList(path string) (proto.FSListResult, error) {
 		if err != nil {
 			continue
 		}
-		out = append(out, proto.FSEntry{
+		ent := proto.FSEntry{
 			Name:  e.Name(),
 			IsDir: e.IsDir(),
 			Size:  info.Size(),
 			Mode:  info.Mode().String(),
 			MTime: info.ModTime().Unix(),
-		})
+		}
+		// A link to a folder opens like one.
+		if info.Mode()&os.ModeSymlink != 0 {
+			ent.Link = true
+			if t, err := os.Stat(filepath.Join(abs, e.Name())); err == nil && t.IsDir() {
+				ent.IsDir = true
+			}
+		}
+		out = append(out, ent)
 	}
 	// Directories first, then alphabetical.
 	sort.Slice(out, func(i, j int) bool {
@@ -222,3 +254,30 @@ func fsZip(paths []string, dest string) (any, error) {
 	}
 	return map[string]string{"dest": dest}, nil
 }
+
+// homeDir returns the home directory of the named user ("" = the user the
+// agent runs as), or "/" when it cannot be told.
+func homeDir(name string) string {
+	if name != "" {
+		if validUserName(name) {
+			if u, err := user.Lookup(name); err == nil && u.HomeDir != "" {
+				return u.HomeDir
+			}
+		}
+		return "/"
+	}
+	if u, err := user.Current(); err == nil && u.HomeDir != "" {
+		return u.HomeDir
+	}
+	if h := os.Getenv("HOME"); h != "" {
+		return h
+	}
+	// A root service often has neither a passwd entry we can read nor $HOME.
+	if os.Geteuid() == 0 {
+		if runtime.GOOS == "darwin" {
+			return "/var/root"
+		}
+		return "/root"
+	}
+	return "/"
+}
@@ -0,0 +1,166 @@
+package agent
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"strings"
+	"syscall"
+
+	"github.com/x-grk/longpolling-remote-access/internal/proto"
+)
+
+// fsCopy copies or moves Src to Dst, following Conflict when Dst exists.
+func fsCopy(a proto.FSCopyArgs) (any, error) {
+	src, dst := filepath.Clean(a.Src), filepath.Clean(a.Dst)
+	if a.Src == "" || a.Dst == "" {
+		return nil, errors.New("не указан путь")
+	}
+	if src == dst {
+		return nil, errors.New("откуда и куда - одно и то же")
+	}
+	if strings.HasPrefix(dst, src+string(filepath.Separator)) {
+		return nil, errors.New("нельзя положить папку внутрь неё самой")
+	}
+	if _, err := os.Lstat(src); err != nil {
+		return nil, err
+	}
+	if _, err := os.Stat(filepath.Dir(dst)); err != nil {
+		return nil, fmt.Errorf("нет папки %s", filepath.Dir(dst))
+	}
+	c := &copier{move: a.Move, conflict: a.Conflict}
+	if err := c.place(src, dst); err != nil {
+		return map[string]int{"done": c.done, "skipped": c.skipped}, err
+	}
+	return map[string]int{"done": c.done, "skipped": c.skipped}, nil
+}
+
+type copier struct {
+	move          bool
+	conflict      string
+	done, skipped int
+}
+
+// place puts src at dst. Two folders merge when the rule allows it; anything
+// else that is in the way stops, is replaced or is kept, by the rule.
+func (c *copier) place(src, dst string) error {
+	si, err := os.Lstat(src)
+	if err != nil {
+		return err
+	}
+	di, err := os.Lstat(dst)
+	if err == nil {
+		if c.conflict != "replace" && c.conflict != "skip" {
+			return fmt.Errorf("%s уже существует", dst)
+		}
+		if si.IsDir() && di.IsDir() {
+			entries, err := os.ReadDir(src)
+			if err != nil {
+				return err
+			}
+			for _, e := range entries {
+				if err := c.place(filepath.Join(src, e.Name()), filepath.Join(dst, e.Name())); err != nil {
+					return err
+				}
+			}
+			if c.move {
+				// Whatever was skipped stays where it was.
+				_ = os.Remove(src)
+			}
+			return nil
+		}
+		if c.conflict == "skip" {
+			c.skipped++
+			return nil
+		}
+		if err := os.RemoveAll(dst); err != nil {
+			return err
+		}
+	} else if !errors.Is(err, fs.ErrNotExist) {
+		return err
+	}
+	if c.move {
+		err := os.Rename(src, dst)
+		if err == nil {
+			c.done++
+			return nil
+		}
+		// Another file system: copy, then take the original away.
+		if !errors.Is(err, syscall.EXDEV) {
+			return err
+		}
+		if err := c.copyTree(src, dst); err != nil {
+			return err
+		}
+		return os.RemoveAll(src)
+	}
+	return c.copyTree(src, dst)
+}
+
+// copyTree copies a file, a symlink or a whole folder, keeping modes and
+// times.
+func (c *copier) copyTree(src, dst string) error {
+	return filepath.WalkDir(src, func(p string, d fs.DirEntry, err error) error {
+		if err != nil {
+			return err
+		}
+		rel, _ := filepath.Rel(src, p)
+		to := filepath.Join(dst, rel)
+		info, err := os.Lstat(p)
+		if err != nil {
+			return err
+		}
+		switch {
+		case info.Mode()&fs.ModeSymlink != 0:
+			link, err := os.Readlink(p)
+			if err != nil {
+				return err
+			}
+			if err := os.Symlink(link, to); err != nil {
+				return err
+			}
+		case info.IsDir():
+			if err := os.Mkdir(to, info.Mode().Perm()); err != nil && !errors.Is(err, fs.ErrExist) {
+				return err
+			}
+		case info.Mode().IsRegular():
+			if err := copyFile(p, to, info); err != nil {
+				return err
+			}
+		default:
+			return nil // sockets, devices: not copied
+		}
+		c.done++
+		if st, ok := info.Sys().(*syscall.Stat_t); ok {
+			_ = os.Lchown(to, int(st.Uid), int(st.Gid))
+		}
+		if info.Mode()&fs.ModeSymlink == 0 {
+			_ = os.Chtimes(to, info.ModTime(), info.ModTime())
+		}
+		return nil
+	})
+}
+
+func copyFile(src, dst string, info fs.FileInfo) error {
+	in, err := os.Open(src)
+	if err != nil {
+		return err
+	}
+	defer in.Close()
+	out, err := os.OpenFile(dst, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, info.Mode().Perm())
+	if err != nil {
+		return err
+	}
+	if _, err := io.Copy(out, in); err != nil {
+		out.Close()
+		os.Remove(dst)
+		return err
+	}
+	if err := out.Close(); err != nil {
+		return err
+	}
+	return os.Chmod(dst, info.Mode()&(fs.ModePerm|fs.ModeSetuid|fs.ModeSetgid|fs.ModeSticky))
+}
@@ -0,0 +1,163 @@
+package agent
+
+import (
+	"bufio"
+	"errors"
+	"fmt"
+	"io/fs"
+	"os"
+	"os/user"
+	"path/filepath"
+	"sort"
+	"strconv"
+	"strings"
+	"syscall"
+
+	"github.com/x-grk/longpolling-remote-access/internal/proto"
+)
+
+// fsStat reports a file's properties, following a symlink to what it points
+// at, and the user and group names to choose an owner from.
+func fsStat(path string) (proto.FSStatResult, error) {
+	res := proto.FSStatResult{Path: path}
+	if li, err := os.Lstat(path); err == nil && li.Mode()&os.ModeSymlink != 0 {
+		res.Link, _ = os.Readlink(path)
+	}
+	info, err := os.Stat(path)
+	if err != nil {
+		return res, err
+	}
+	res.IsDir, res.Size, res.MTime = info.IsDir(), info.Size(), info.ModTime().Unix()
+	if st, ok := info.Sys().(*syscall.Stat_t); ok {
+		res.Mode = uint32(st.Mode) & 07777
+		res.UID, res.GID = int(st.Uid), int(st.Gid)
+	} else {
+		res.Mode = uint32(info.Mode().Perm())
+	}
+	res.Owner, res.Group = strconv.Itoa(res.UID), strconv.Itoa(res.GID)
+	if u, err := user.LookupId(res.Owner); err == nil {
+		res.Owner = u.Username
+	}
+	if g, err := user.LookupGroupId(res.Group); err == nil {
+		res.Group = g.Name
+	}
+	res.Users, res.Groups = namesIn("/etc/passwd"), namesIn("/etc/group")
+	return res, nil
+}
+
+// namesIn lists the first field of a passwd- or group-style file.
+func namesIn(file string) []string {
+	f, err := os.Open(file)
+	if err != nil {
+		return nil
+	}
+	defer f.Close()
+	var out []string
+	sc := bufio.NewScanner(f)
+	for sc.Scan() && len(out) < 1000 {
+		line := sc.Text()
+		if line == "" || line[0] == '#' {
+			continue
+		}
+		if name, _, ok := strings.Cut(line, ":"); ok && name != "" {
+			out = append(out, name)
+		}
+	}
+	sort.Strings(out)
+	return out
+}
+
+// lookupID resolves a user or group given by name or number; -1 for none.
+func lookupID(name string, group bool) (int, error) {
+	if name == "" {
+		return -1, nil
+	}
+	if n, err := strconv.Atoi(name); err == nil && n >= 0 {
+		return n, nil
+	}
+	if group {
+		g, err := user.LookupGroup(name)
+		if err != nil {
+			return -1, fmt.Errorf("группа %s не найдена", name)
+		}
+		return strconv.Atoi(g.Gid)
+	}
+	u, err := user.Lookup(name)
+	if err != nil {
+		return -1, fmt.Errorf("пользователь %s не найден", name)
+	}
+	return strconv.Atoi(u.Uid)
+}
+
+// fsChmod sets mode, owner and group on a path, and with Recursive on all
+// that is inside a folder. Symlinks inside are not followed.
+func fsChmod(a proto.FSChmodArgs) (any, error) {
+	if a.Path == "" {
+		return nil, errors.New("не указан путь")
+	}
+	if a.Recursive && filepath.Clean(a.Path) == "/" {
+		return nil, errors.New("отказ: рекурсивно для корня нельзя")
+	}
+	if a.Mode != nil && *a.Mode > 07777 {
+		return nil, errors.New("неверные права")
+	}
+	uid, err := lookupID(a.Owner, false)
+	if err != nil {
+		return nil, err
+	}
+	gid, err := lookupID(a.Group, true)
+	if err != nil {
+		return nil, err
+	}
+	changed, failed := 0, 0
+	var errs []string
+	// The path itself always gets the change; Only picks among what is in it.
+	apply := func(p string, isDir, isLink, self bool) {
+		if !self && ((a.Only == "files" && isDir) || (a.Only == "dirs" && !isDir)) {
+			return
+		}
+		var err error
+		if uid >= 0 || gid >= 0 {
+			err = os.Lchown(p, uid, gid)
+		}
+		// A symlink has no mode of its own: chmod would change its target.
+		if err == nil && a.Mode != nil && !isLink {
+			err = syscall.Chmod(p, *a.Mode)
+		}
+		if err != nil {
+			failed++
+			if len(errs) < 5 {
+				errs = append(errs, err.Error())
+			}
+			return
+		}
+		changed++
+	}
+	info, err := os.Stat(a.Path)
+	if err != nil {
+		return nil, err
+	}
+	if !a.Recursive || !info.IsDir() {
+		apply(a.Path, info.IsDir(), false, true)
+	} else {
+		err = filepath.WalkDir(a.Path, func(p string, d fs.DirEntry, err error) error {
+			if err != nil {
+				failed++
+				if len(errs) < 5 {
+					errs = append(errs, err.Error())
+				}
+				return nil
+			}
+			apply(p, d.IsDir(), d.Type()&fs.ModeSymlink != 0, p == a.Path)
+			return nil
+		})
+		if err != nil {
+			return nil, err
+		}
+	}
+	res := map[string]any{"changed": changed, "failed": failed, "errors": errs}
+	if failed > 0 && changed == 0 {
+		return res, errors.New(errs[0])
+	}
+	return res, nil
+}
@@ -0,0 +1,337 @@
+package agent
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"sync"
+	"syscall"
+	"time"
+
+	"github.com/x-grk/longpolling-remote-access/internal/proto"
+)
+
+// Files go to and from the browser in pieces, each a request of its own
+// through the server: small enough for any proxy in front, and sent again
+// alone when the link drops it. A few go at once, so a good link is kept as
+// busy as by one long stream.
+
+const (
+	// xferWorkers is how many pieces are in flight at once.
+	xferWorkers = 4
+	// xferPieceTimeout bounds one piece's request: a link that slow, or
+	// stuck, gets the piece sent again.
+	xferPieceTimeout = 5 * time.Minute
+	// xferTries bounds how often a piece is tried over a failing link.
+	xferTries = 30
+)
+
+// errXferGone is the server saying the transfer is over: the browser left
+// or gave up.
+type errXferGone string
+
+func (e errXferGone) Error() string { return string(e) }
+
+func (a *Agent) xferURL(id string, i int) string {
+	return a.host() + "/api/agent/fs/xfer/" + id + "/" + strconv.Itoa(i)
+}
+
+// xferRequest makes one request for a piece, trying again over a failing link.
+// A 503 is the server waiting on the other side: asked again at once.
+func (a *Agent) xferRequest(ctx context.Context, newReq func(context.Context) (*http.Request, error), keep func(*http.Response) error) error {
+	fails := 0
+	for {
+		if err := ctx.Err(); err != nil {
+			return err
+		}
+		rctx, cancel := context.WithTimeout(ctx, xferPieceTimeout)
+		req, err := newReq(rctx)
+		if err != nil {
+			cancel()
+			return err
+		}
+		a.authHeaders(req)
+		resp, err := a.stream.Do(req)
+		if err == nil {
+			switch {
+			case resp.StatusCode == http.StatusGone:
+				msg, _ := io.ReadAll(io.LimitReader(resp.Body, 512))
+				resp.Body.Close()
+				cancel()
+				return errXferGone(strings.TrimSpace(string(msg)))
+			case resp.StatusCode == http.StatusServiceUnavailable:
+				io.Copy(io.Discard, resp.Body)
+				resp.Body.Close()
+				cancel()
+				continue
+			case resp.StatusCode < 300:
+				err = keep(resp)
+				resp.Body.Close()
+				cancel()
+				if err == nil {
+					return nil
+				}
+			default:
+				io.Copy(io.Discard, resp.Body)
+				resp.Body.Close()
+				err = errStatus(resp.StatusCode)
+			}
+		}
+		cancel()
+		if fails++; fails >= xferTries {
+			return fmt.Errorf("сеть не держит передачу: %w", err)
+		}
+		select {
+		case <-time.After(min(time.Duration(fails)*time.Second, 10*time.Second)):
+		case <-ctx.Done():
+			return ctx.Err()
+		}
+	}
+}
+
+// pieces runs fn for every piece, xferWorkers at a time, until one fails.
+func pieces(ctx context.Context, n int, fn func(ctx context.Context, i int) error) error {
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+	var (
+		mu    sync.Mutex
+		next  int
+		first error
+		wg    sync.WaitGroup
+	)
+	for w := 0; w < min(xferWorkers, n); w++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			for {
+				mu.Lock()
+				if first != nil || next >= n {
+					mu.Unlock()
+					return
+				}
+				i := next
+				next++
+				mu.Unlock()
+				if err := fn(ctx, i); err != nil {
+					mu.Lock()
+					if first == nil {
+						first = err
+						cancel()
+					}
+					mu.Unlock()
+					return
+				}
+			}
+		}()
+	}
+	wg.Wait()
+	return first
+}
+
+func pieceCount(size int64, chunk int) int {
+	if size <= 0 {
+		return 1
+	}
+	return int((size + int64(chunk) - 1) / int64(chunk))
+}
+
+// doFSPut writes the file the browser is uploading. It lands in a temporary
+// file next to the target first, so a broken upload leaves the old file as it
+// was.
+func (a *Agent) doFSPut(ctx context.Context, env proto.TaskEnvelope) proto.TaskResult {
+	var args proto.FSXferArgs
+	if err := json.Unmarshal(env.Args, &args); err != nil {
+		return proto.TaskResult{Error: err.Error()}
+	}
+	if args.Size < 0 || args.Size > proto.FSFileCap || args.Chunk <= 0 {
+		return proto.TaskResult{Error: "файл больше 512 МБ"}
+	}
+	dir, base := filepath.Split(args.Path)
+	if dir == "" {
+		dir = "."
+	}
+	if info, err := os.Stat(args.Path); err == nil && info.IsDir() {
+		return proto.TaskResult{Error: "это каталог"}
+	}
+	tmp, err := os.CreateTemp(dir, "."+base+".lpra-*")
+	if err != nil {
+		return proto.TaskResult{Error: err.Error()}
+	}
+	done := false
+	defer func() {
+		if !done {
+			tmp.Close()
+			os.Remove(tmp.Name())
+		}
+	}()
+
+	// Pieces written so far, to tell the server which it can let go.
+	n := pieceCount(args.Size, args.Chunk)
+	var (
+		mu     sync.Mutex
+		got    = make([]bool, n)
+		contig int
+	)
+	err = pieces(ctx, n, func(ctx context.Context, i int) error {
+		want := min(int64(args.Chunk), args.Size-int64(i)*int64(args.Chunk))
+		mu.Lock()
+		ack := contig
+		mu.Unlock()
+		var data []byte
+		err := a.xferRequest(ctx, func(ctx context.Context) (*http.Request, error) {
+			return http.NewRequestWithContext(ctx, http.MethodGet, a.xferURL(args.Xfer, i)+"?ack="+strconv.Itoa(ack), nil)
+		}, func(resp *http.Response) error {
+			b, err := io.ReadAll(io.LimitReader(resp.Body, int64(args.Chunk)+1))
+			if err == nil && int64(len(b)) != want {
+				err = errors.New("кусок не той длины")
+			}
+			data = b
+			return err
+		})
+		if err != nil {
+			return err
+		}
+		if _, err := tmp.WriteAt(data, int64(i)*int64(args.Chunk)); err != nil {
+			return err
+		}
+		mu.Lock()
+		got[i] = true
+		for contig < n && got[contig] {
+			contig++
+		}
+		mu.Unlock()
+		return nil
+	})
+	if err != nil {
+		var gone errXferGone
+		if errors.As(err, &gone) {
+			return proto.TaskResult{Error: "загрузка прервана: " + string(gone)}
+		}
+		return proto.TaskResult{Error: "загрузка прервана: " + err.Error()}
+	}
+	if err := tmp.Truncate(args.Size); err != nil {
+		return proto.TaskResult{Error: err.Error()}
+	}
+	if err := tmp.Close(); err != nil {
+		return proto.TaskResult{Error: err.Error()}
+	}
+	// A file that is being replaced keeps its mode and owner.
+	mode := os.FileMode(0o644)
+	if info, err := os.Stat(args.Path); err == nil {
+		mode = info.Mode().Perm()
+		if st, ok := info.Sys().(*syscall.Stat_t); ok {
+			_ = os.Chown(tmp.Name(), int(st.Uid), int(st.Gid))
+		}
+	}
+	if err := os.Chmod(tmp.Name(), mode); err != nil {
+		return proto.TaskResult{Error: err.Error()}
+	}
+	if err := os.Rename(tmp.Name(), args.Path); err != nil {
+		return proto.TaskResult{Error: err.Error()}
+	}
+	done = true
+	data, _ := json.Marshal(map[string]any{"path": args.Path, "size": args.Size})
+	return proto.TaskResult{OK: true, Data: data}
+}
+
+// doFSSend sends a file to the browser that asked for it.
+func (a *Agent) doFSSend(ctx context.Context, env proto.TaskEnvelope) proto.TaskResult {
+	var args proto.FSXferArgs
+	if err := json.Unmarshal(env.Args, &args); err != nil {
+		return proto.TaskResult{Error: err.Error()}
+	}
+	if args.Chunk <= 0 {
+		return proto.TaskResult{Error: "не задан размер куска"}
+	}
+	f, err := os.Open(args.Path)
+	if err != nil {
+		return proto.TaskResult{Error: err.Error()}
+	}
+	defer f.Close()
+	info, err := f.Stat()
+	if err != nil {
+		return proto.TaskResult{Error: err.Error()}
+	}
+	if info.IsDir() {
+		return proto.TaskResult{Error: "это каталог"}
+	}
+	size := info.Size()
+	if size > proto.FSFileCap {
+		return proto.TaskResult{Error: "файл больше 512 МБ"}
+	}
+	sizeHdr := strconv.FormatInt(size, 10)
+	err = pieces(ctx, pieceCount(size, args.Chunk), func(ctx context.Context, i int) error {
+		off := int64(i) * int64(args.Chunk)
+		buf := make([]byte, min(int64(args.Chunk), size-off))
+		if _, err := f.ReadAt(buf, off); err != nil && err != io.EOF {
+			return err
+		}
+		return a.xferRequest(ctx, func(ctx context.Context) (*http.Request, error) {
+			req, err := http.NewRequestWithContext(ctx, http.MethodPost, a.xferURL(args.Xfer, i), bytes.NewReader(buf))
+			if err == nil {
+				req.Header.Set("X-Size", sizeHdr)
+				req.Header.Set("Content-Type", "application/octet-stream")
+			}
+			return req, err
+		}, func(*http.Response) error { return nil })
+	})
+	if err != nil {
+		return proto.TaskResult{Error: "передача прервана: " + err.Error()}
+	}
+	data, _ := json.Marshal(map[string]any{"path": args.Path, "size": size})
+	return proto.TaskResult{OK: true, Data: data}
+}
+
+// ordered fetches pieces 0..n-1 with up to depth in flight and hands them to
+// use one by one in their order: a stream that must be written in sequence
+// (stdin over SSH) still gets its pieces fetched ahead.
+func ordered(ctx context.Context, n, depth int, fetch func(ctx context.Context, i int) ([]byte, error), use func(i int, b []byte) error) error {
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+	type got struct {
+		b   []byte
+		err error
+	}
+	slots := make([]chan got, n)
+	for i := range slots {
+		slots[i] = make(chan got, 1)
+	}
+	sem := make(chan struct{}, depth)
+	go func() {
+		for i := 0; i < n; i++ {
+			select {
+			case sem <- struct{}{}:
+			case <-ctx.Done():
+				return
+			}
+			go func(i int) {
+				b, err := fetch(ctx, i)
+				slots[i] <- got{b, err}
+			}(i)
+		}
+	}()
+	for i := 0; i < n; i++ {
+		var g got
+		select {
+		case g = <-slots[i]:
+		case <-ctx.Done():
+			return ctx.Err()
+		}
+		<-sem
+		if g.err != nil {
+			return g.err
+		}
+		if err := use(i, g.b); err != nil {
+			return err
+		}
+	}
+	return nil
+}
@@ -0,0 +1,176 @@
+package agent
+
+import (
+	"context"
+	"log"
+	"net/http"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/x-grk/longpolling-remote-access/internal/proto"
+)
+
+// The server can be reached at two addresses: the main one (behind
+// Cloudflare, say) and a direct one that goes to the server itself. The
+// direct one comes from the installer or, for agents installed before it was
+// set, from the server, and is kept in the state file. When the address in
+// use has been out of reach for a while the agent tries the other; on the
+// direct one it keeps checking the main one and goes back when it answers.
+
+const (
+	// switchAfter is how long the address in use may fail before the other
+	// is tried.
+	switchAfter = 30 * time.Second
+	// mainCheck is how often the main address is checked from the direct one.
+	mainCheck = 5 * time.Minute
+)
+
+type hostState struct {
+	mu        sync.Mutex
+	cur       string
+	downSince time.Time
+	changed   bool // the address changed: the WebSocket goes there at once
+}
+
+// host is the server address in use now.
+func (a *Agent) host() string {
+	a.hosts.mu.Lock()
+	defer a.hosts.mu.Unlock()
+	if a.hosts.cur == "" {
+		return a.cfg.Host
+	}
+	return a.hosts.cur
+}
+
+// fallback is the direct address: the installer's, else the one the server
+// told.
+func (a *Agent) fallback() string {
+	if a.cfg.Fallback != "" {
+		return a.cfg.Fallback
+	}
+	a.stateMu.Lock()
+	defer a.stateMu.Unlock()
+	return a.state.Fallback
+}
+
+// learnAddrs keeps the server's other address from the two it tells: the
+// direct one, or the main one when the agent was set to the direct one.
+func (a *Agent) learnAddrs(main, direct string) {
+	main = strings.TrimRight(strings.TrimSpace(main), "/")
+	direct = strings.TrimRight(strings.TrimSpace(direct), "/")
+	v := direct
+	if direct != "" && strings.EqualFold(direct, a.cfg.Host) {
+		v = main
+	}
+	if v == "" || strings.EqualFold(v, a.cfg.Host) || a.cfg.Fallback != "" {
+		return
+	}
+	a.stateMu.Lock()
+	same := a.state.Fallback == v
+	if !same {
+		a.state.Fallback = v
+	}
+	a.stateMu.Unlock()
+	if !same {
+		log.Printf("fallback address: %s", v)
+		_ = a.saveState()
+	}
+}
+
+// setHost moves to addr: requests go there from now on, and the WebSocket
+// is dropped to reconnect there.
+func (a *Agent) setHost(addr string) {
+	a.hosts.mu.Lock()
+	if a.hosts.cur == addr || (a.hosts.cur == "" && addr == a.cfg.Host) {
+		a.hosts.mu.Unlock()
+		return
+	}
+	a.hosts.cur, a.hosts.downSince, a.hosts.changed = addr, time.Time{}, true
+	a.hosts.mu.Unlock()
+	log.Printf("server address: %s", addr)
+	if l := a.link.Load(); l != nil {
+		l.close()
+	}
+}
+
+// hostChanged reports, once, that the address changed.
+func (a *Agent) hostChanged() bool {
+	a.hosts.mu.Lock()
+	defer a.hosts.mu.Unlock()
+	c := a.hosts.changed
+	a.hosts.changed = false
+	return c
+}
+
+// reached notes the server answered; failed notes it did not, and after
+// switchAfter of that moves to the other address.
+func (a *Agent) reached() {
+	a.hosts.mu.Lock()
+	a.hosts.downSince = time.Time{}
+	a.hosts.mu.Unlock()
+}
+
+func (a *Agent) failed() {
+	fb := a.fallback()
+	if fb == "" || fb == a.cfg.Host {
+		return
+	}
+	a.hosts.mu.Lock()
+	now := time.Now()
+	if a.hosts.downSince.IsZero() {
+		a.hosts.downSince = now
+		a.hosts.mu.Unlock()
+		return
+	}
+	long := now.Sub(a.hosts.downSince) >= switchAfter
+	cur := a.hosts.cur
+	a.hosts.mu.Unlock()
+	if !long {
+		return
+	}
+	next := fb
+	if cur == fb {
+		next = a.cfg.Host
+	}
+	log.Printf("server out of reach for %s, trying %s", switchAfter, next)
+	a.setHost(next)
+}
+
+// watchMain moves back to the main address once it answers again.
+func (a *Agent) watchMain(ctx context.Context) {
+	t := time.NewTicker(mainCheck)
+	defer t.Stop()
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case <-t.C:
+		}
+		if a.host() == a.cfg.Host {
+			continue
+		}
+		if a.reachableAt(ctx, a.cfg.Host) {
+			log.Printf("main address answers again")
+			a.setHost(a.cfg.Host)
+		}
+	}
+}
+
+// reachableAt reports whether the server answers a quick request at base.
+func (a *Agent) reachableAt(ctx context.Context, base string) bool {
+	ctx, cancel := context.WithTimeout(ctx, 10*time.Second)
+	defer cancel()
+	req, _ := http.NewRequestWithContext(ctx, http.MethodGet, base+"/api/agent/config", nil)
+	a.authHeaders(req)
+	resp, err := a.http.Do(req)
+	if err != nil {
+		return false
+	}
+	resp.Body.Close()
+	if resp.StatusCode < 300 {
+		a.learnAddrs(resp.Header.Get(proto.MainHeader), resp.Header.Get(proto.FallbackHeader))
+		return true
+	}
+	return false
+}
@@ -0,0 +1,45 @@
+package agent
+
+import (
+	"context"
+	"math/rand"
+	"sync/atomic"
+	"testing"
+	"time"
+)
+
+// Pieces fetched side by side are used in their order, never more than
+// depth at once in flight.
+func TestOrderedKeepsOrder(t *testing.T) {
+	var inFlight, most int32
+	var got []int
+	err := ordered(context.Background(), 20, 3, func(ctx context.Context, i int) ([]byte, error) {
+		n := atomic.AddInt32(&inFlight, 1)
+		for {
+			m := atomic.LoadInt32(&most)
+			if n <= m || atomic.CompareAndSwapInt32(&most, m, n) {
+				break
+			}
+		}
+		time.Sleep(time.Duration(rand.Intn(5)) * time.Millisecond)
+		atomic.AddInt32(&inFlight, -1)
+		return []byte{byte(i)}, nil
+	}, func(i int, b []byte) error {
+		if int(b[0]) != i {
+			t.Errorf("piece %d carries %d", i, b[0])
+		}
+		got = append(got, i)
+		return nil
+	})
+	if err != nil || len(got) != 20 {
+		t.Fatalf("got %v, %v", got, err)
+	}
+	for i, v := range got {
+		if v != i {
+			t.Fatalf("order: %v", got)
+		}
+	}
+	if most > 3 || most < 2 {
+		t.Fatalf("at most %d in flight", most)
+	}
+}
@@ -16,8 +16,8 @@ import (

 // runTerminal spawns a PTY and bridges it to the session.
 // user is the OS user to run the shell as ("" = the agent's own user).
-func (a *Agent) runTerminal(parent context.Context, sid, user string) {
-	term, err := StartPTY(user)
+func (a *Agent) runTerminal(parent context.Context, sid, user, dir string) {
+	term, err := StartPTY(user, dir)
 	if err != nil {
 		log.Printf("term %s: start pty: %v", sid, err)
 		// Show the reason in the browser terminal before closing it.
@@ -26,12 +26,15 @@ func (a *Agent) runTerminal(parent context.Context, sid, user string) {
 		return
 	}
 	log.Printf("term %s: shell started (user %q)", sid, user)
+	termsBySID.Store(sid, term)
+	defer termsBySID.Delete(sid)
 	a.bridgeStream(parent, sid, term, term.Resize)
 	log.Printf("term %s: ended", sid)
 }

 // runForward dials 127.0.0.1:port on the client and bridges it to the session,
-// giving the host a reverse TCP tunnel over the same long-poll transport.
+// giving the host a reverse TCP tunnel over the agent's link to the server:
+// the WebSocket, or the long polls without one.
 func (a *Agent) runForward(parent context.Context, sid string, port int) {
 	d := net.Dialer{Timeout: 10 * time.Second}
 	conn, err := d.DialContext(parent, "tcp", net.JoinHostPort("127.0.0.1", strconv.Itoa(port)))
@@ -54,6 +57,15 @@ func (a *Agent) bridgeStream(parent context.Context, sid string, rw io.ReadWrite
 	ctx, cancel := context.WithCancel(parent)
 	defer cancel()
 	defer rw.Close()
+	defer func() {
+		if l := a.link.Load(); l != nil {
+			l.unsubscribe(sid)
+		}
+	}()
+	// A session closed from the panel (a tab reloaded, a window shut) ends
+	// the stream at once, not on its next output: an idle shell would live
+	// on until the agent stopped.
+	go func() { <-ctx.Done(); rw.Close() }()

 	// Downstream: pull input frames and write them to the stream.
 	go func() {
@@ -81,10 +93,26 @@ func (a *Agent) bridgeStream(parent context.Context, sid string, rw io.ReadWrite
 	}
 }

-// pollIn performs one downstream long-poll and applies the frames.
+// pollIn takes the next input - pushed on the WebSocket, else by a long
+// poll - and applies the frames.
 // Returns false when the session is gone and the loop should stop.
 func (a *Agent) pollIn(ctx context.Context, sid string, w io.Writer, onResize func(cols, rows uint16)) bool {
-	req, _ := http.NewRequestWithContext(ctx, http.MethodGet, a.cfg.Host+"/api/agent/term/"+sid+"/in", nil)
+	// On the WebSocket the input comes pushed; if it drops, by a long poll.
+	if l := a.link.Load(); l != nil {
+		if ch := l.subscribe(sid); ch != nil {
+			select {
+			case in := <-ch:
+				if in.gone {
+					return false
+				}
+				return applyFrames(in.frames, w, onResize)
+			case <-l.done:
+			case <-ctx.Done():
+				return false
+			}
+		}
+	}
+	req, _ := http.NewRequestWithContext(ctx, http.MethodGet, a.host()+"/api/agent/term/"+sid+"/in", nil)
 	a.authHeaders(req)
 	resp, err := a.http.Do(req)
 	if err != nil {
@@ -101,7 +129,13 @@ func (a *Agent) pollIn(ctx context.Context, sid string, w io.Writer, onResize fu
 	if err := json.NewDecoder(resp.Body).Decode(&batch); err != nil {
 		return true
 	}
-	for _, f := range batch.Frames {
+	return applyFrames(batch.Frames, w, onResize)
+}
+
+// applyFrames writes a session's input to its stream; false once the panel
+// closed it.
+func applyFrames(frames []proto.InFrame, w io.Writer, onResize func(cols, rows uint16)) bool {
+	for _, f := range frames {
 		switch f.Type {
 		case proto.FrameStdin:
 			if data, err := b64.DecodeString(f.Data); err == nil {
@@ -120,8 +154,13 @@ func (a *Agent) pollIn(ctx context.Context, sid string, w io.Writer, onResize fu

 // postOut sends one upstream message. Returns false if the session is gone.
 func (a *Agent) postOut(ctx context.Context, sid string, msg proto.OutMessage) bool {
+	if l := a.link.Load(); l != nil {
+		if l.send(proto.WSMsg{T: "out", SID: sid, Out: &msg}) == nil {
+			return true
+		}
+	}
 	body, _ := json.Marshal(msg)
-	req, _ := http.NewRequestWithContext(ctx, http.MethodPost, a.cfg.Host+"/api/agent/term/"+sid+"/out", bytes.NewReader(body))
+	req, _ := http.NewRequestWithContext(ctx, http.MethodPost, a.host()+"/api/agent/term/"+sid+"/out", bytes.NewReader(body))
 	a.authHeaders(req)
 	req.Header.Set("Content-Type", "application/json")
 	resp, err := a.http.Do(req)
@@ -0,0 +1,675 @@
+package agent
+
+import (
+	"archive/tar"
+	"bytes"
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"io/fs"
+	"net/http"
+	"os"
+	"path"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"sync"
+	"sync/atomic"
+	"syscall"
+	"time"
+
+	"golang.org/x/crypto/ssh"
+
+	"github.com/x-grk/longpolling-remote-access/internal/proto"
+)
+
+// A file or folder goes to another machine as a tar stream: packed here on
+// the fly, then either posted in pieces to a relay on the server for the
+// other agent to unpack, or written by SSH straight into tar on that host.
+// Nothing is staged on disk on either side.
+
+// shipMeter counts what has gone out, for the panel's progress bar.
+type shipMeter struct {
+	total, done atomic.Int64
+	files       atomic.Int64
+	note        atomic.Value // string
+}
+
+func (m *shipMeter) snapshot() proto.ShipProgress {
+	n, _ := m.note.Load().(string)
+	return proto.ShipProgress{Total: m.total.Load(), Done: m.done.Load(), Files: int(m.files.Load()), Note: n}
+}
+
+// reportShip posts the progress to the job until ctx ends; the server
+// answering 410 means the job was cancelled, and cancel is called.
+func (a *Agent) reportShip(ctx context.Context, job string, m *shipMeter, cancel func()) {
+	if job == "" {
+		return
+	}
+	t := time.NewTicker(700 * time.Millisecond)
+	defer t.Stop()
+	for {
+		body, _ := json.Marshal(m.snapshot())
+		req, _ := http.NewRequestWithContext(ctx, http.MethodPost, a.host()+"/api/agent/fs/job/"+job+"/progress", bytes.NewReader(body))
+		a.authHeaders(req)
+		req.Header.Set("Content-Type", "application/json")
+		if resp, err := a.http.Do(req); err == nil {
+			io.Copy(io.Discard, resp.Body)
+			resp.Body.Close()
+			if resp.StatusCode == http.StatusGone {
+				cancel()
+				return
+			}
+		}
+		select {
+		case <-ctx.Done():
+			return
+		case <-t.C:
+		}
+	}
+}
+
+// shipName checks the name the thing gets at the other end.
+func shipName(name string) error {
+	if name == "" || name == "." || name == ".." || strings.ContainsAny(name, "/\x00") {
+		return errors.New("недопустимое имя")
+	}
+	return nil
+}
+
+// treeSize is how many bytes of files are under p.
+func treeSize(ctx context.Context, p string) int64 {
+	var n int64
+	_ = filepath.WalkDir(p, func(_ string, d fs.DirEntry, err error) error {
+		if err != nil || ctx.Err() != nil {
+			return nil
+		}
+		if d.Type().IsRegular() {
+			if info, err := d.Info(); err == nil {
+				n += info.Size()
+			}
+		}
+		return nil
+	})
+	return n
+}
+
+// packTar writes src as a tar stream whose entries start at name. Owners are
+// left out: the numbers mean other people on another machine.
+func packTar(ctx context.Context, w io.Writer, src, name string, m *shipMeter) error {
+	return packTars(ctx, w, []shipItem{{src, name}}, m)
+}
+
+// shipItem is one thing sent: where it is and the name it goes under.
+type shipItem struct{ src, name string }
+
+// packTars writes the items as one tar stream, each under its name.
+func packTars(ctx context.Context, w io.Writer, items []shipItem, m *shipMeter) error {
+	tw := tar.NewWriter(w)
+	for _, it := range items {
+		if err := packInto(ctx, tw, it.src, it.name, m); err != nil {
+			return err
+		}
+	}
+	return tw.Close()
+}
+
+func packInto(ctx context.Context, tw *tar.Writer, src, name string, m *shipMeter) error {
+	err := filepath.WalkDir(src, func(p string, d fs.DirEntry, err error) error {
+		if err != nil {
+			return err
+		}
+		if err := ctx.Err(); err != nil {
+			return err
+		}
+		info, err := os.Lstat(p)
+		if err != nil {
+			return err
+		}
+		link := ""
+		switch {
+		case info.Mode()&fs.ModeSymlink != 0:
+			if link, err = os.Readlink(p); err != nil {
+				return err
+			}
+		case info.IsDir(), info.Mode().IsRegular():
+		default:
+			return nil // sockets, devices, pipes: not sent
+		}
+		hdr, err := tar.FileInfoHeader(info, link)
+		if err != nil {
+			return err
+		}
+		rel, _ := filepath.Rel(src, p)
+		hdr.Name = name
+		if rel != "." {
+			hdr.Name = path.Join(name, filepath.ToSlash(rel))
+		}
+		if info.IsDir() {
+			hdr.Name += "/"
+		}
+		hdr.Uid, hdr.Gid, hdr.Uname, hdr.Gname = 0, 0, "", ""
+		hdr.Format = tar.FormatPAX
+		if err := tw.WriteHeader(hdr); err != nil {
+			return err
+		}
+		if info.Mode().IsRegular() {
+			f, err := os.Open(p)
+			if err != nil {
+				return err
+			}
+			_, err = io.CopyN(tw, &countReader{r: f, n: &m.done}, hdr.Size)
+			f.Close()
+			if err != nil {
+				return fmt.Errorf("%s: %v", p, err)
+			}
+		}
+		m.files.Add(1)
+		return nil
+	})
+	return err
+}
+
+type countReader struct {
+	r io.Reader
+	n *atomic.Int64
+}
+
+func (c *countReader) Read(p []byte) (int, error) {
+	n, err := c.r.Read(p)
+	c.n.Add(int64(n))
+	return n, err
+}
+
+// doShipOut sends Src to the other machine: by the relay, or by SSH.
+func (a *Agent) doShipOut(parent context.Context, env proto.TaskEnvelope) proto.TaskResult {
+	var args proto.FSShipArgs
+	if err := json.Unmarshal(env.Args, &args); err != nil {
+		return proto.TaskResult{Error: err.Error()}
+	}
+	names := args.ShipNames()
+	for _, n := range names {
+		if err := shipName(n); err != nil {
+			return proto.TaskResult{Error: err.Error()}
+		}
+	}
+	if len(args.More) > 0 && args.SSH != nil {
+		return proto.TaskResult{Error: "по SSH-адресу - по одному"}
+	}
+	src := filepath.Clean(args.Src)
+	srcs := []string{args.Src}
+	for _, p := range args.More {
+		// The others: of the same folder only.
+		if path.Dir(path.Clean(p)) != path.Dir(path.Clean(args.Src)) {
+			return proto.TaskResult{Error: "несколько - только из одной папки"}
+		}
+		srcs = append(srcs, p)
+	}
+	var conn *sshfsConn
+	if args.Conn != "" {
+		// The files are on an SSH host this agent holds a connection to.
+		c, err := sshfsGet(args.Conn)
+		if err != nil {
+			return proto.TaskResult{Error: err.Error()}
+		}
+		conn, src = c, path.Clean(args.Src)
+	} else if _, err := os.Lstat(src); err != nil {
+		return proto.TaskResult{Error: err.Error()}
+	}
+	ctx, cancel := context.WithCancel(parent)
+	defer cancel()
+	m := &shipMeter{}
+	m.note.Store("подсчёт")
+	go a.reportShip(ctx, args.Job, m, cancel)
+	var total int64
+	items := make([]shipItem, len(srcs))
+	for i, p := range srcs {
+		if conn != nil {
+			total += a.remoteSize(conn, path.Clean(p))
+		} else {
+			total += treeSize(ctx, filepath.Clean(p))
+		}
+		items[i] = shipItem{filepath.Clean(p), names[i]}
+	}
+	m.total.Store(total)
+	pack := func(w io.Writer) error { return packTars(ctx, w, items, m) }
+	if conn != nil {
+		pack = func(w io.Writer) error { return a.packRemote(ctx, w, conn, srcs, names, m) }
+	}
+
+	var err error
+	if args.SSH != nil {
+		err = a.shipSSH(ctx, args, src, m)
+	} else {
+		m.note.Store("")
+		err = a.shipRelay(ctx, args, pack)
+	}
+	if err != nil {
+		if ctx.Err() != nil && parent.Err() == nil {
+			err = errors.New("отменено")
+		}
+		return proto.TaskResult{Error: err.Error()}
+	}
+	res := map[string]any{"files": m.files.Load(), "bytes": m.done.Load()}
+	if args.Move && args.SSH != nil {
+		if err := os.RemoveAll(src); err != nil {
+			return proto.TaskResult{Error: "отправлено, но здесь не удалилось: " + err.Error()}
+		}
+	}
+	data, _ := json.Marshal(res)
+	return proto.TaskResult{OK: true, Data: data}
+}
+
+func (a *Agent) relayURL(id string, i int) string {
+	return a.host() + "/api/agent/fs/relay/" + id + "/" + strconv.Itoa(i)
+}
+
+// shipRelay posts the tar stream in pieces, a few at once; the last carries
+// X-Last.
+func (a *Agent) shipRelay(ctx context.Context, args proto.FSShipArgs, pack func(io.Writer) error) error {
+	if args.Relay == "" || args.Chunk <= 0 {
+		return errors.New("не задана передача")
+	}
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+	pr, pw := io.Pipe()
+	go func() { pw.CloseWithError(pack(pw)) }()
+	defer pr.Close()
+
+	type piece struct {
+		i    int
+		data []byte
+		last bool
+	}
+	ch := make(chan piece, 1)
+	var (
+		mu    sync.Mutex
+		first error
+		wg    sync.WaitGroup
+	)
+	setErr := func(err error) {
+		mu.Lock()
+		if first == nil {
+			first = err
+			cancel()
+		}
+		mu.Unlock()
+	}
+	for w := 0; w < xferWorkers; w++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			for p := range ch {
+				err := a.xferRequest(ctx, func(ctx context.Context) (*http.Request, error) {
+					req, err := http.NewRequestWithContext(ctx, http.MethodPost, a.relayURL(args.Relay, p.i), bytes.NewReader(p.data))
+					if err == nil {
+						req.Header.Set("Content-Type", "application/octet-stream")
+						if p.last {
+							req.Header.Set("X-Last", "1")
+						}
+					}
+					return req, err
+				}, func(*http.Response) error { return nil })
+				if err != nil {
+					setErr(err)
+				}
+			}
+		}()
+	}
+	for i := 0; ; i++ {
+		buf := make([]byte, args.Chunk)
+		n, err := io.ReadFull(pr, buf)
+		last := err == io.EOF || err == io.ErrUnexpectedEOF
+		if err != nil && !last {
+			setErr(err)
+			break
+		}
+		select {
+		case ch <- piece{i, buf[:n], last}:
+		case <-ctx.Done():
+		}
+		if last || ctx.Err() != nil {
+			break
+		}
+	}
+	close(ch)
+	wg.Wait()
+	if first != nil {
+		var gone errXferGone
+		if errors.As(first, &gone) {
+			return errors.New(string(gone))
+		}
+		return first
+	}
+	return ctx.Err()
+}
+
+// doShipIn takes the tar stream from the relay and unpacks it into Dir.
+func (a *Agent) doShipIn(ctx context.Context, env proto.TaskEnvelope) proto.TaskResult {
+	var args proto.FSShipArgs
+	if err := json.Unmarshal(env.Args, &args); err != nil {
+		return proto.TaskResult{Error: err.Error()}
+	}
+	names := args.ShipNames()
+	for _, n := range names {
+		if err := shipName(n); err != nil {
+			return proto.TaskResult{Error: err.Error()}
+		}
+	}
+	dir := filepath.Clean(args.Dir)
+	var conn *sshfsConn
+	if args.Conn != "" {
+		// Into an SSH host this agent holds a connection to.
+		c, err := sshfsGet(args.Conn)
+		if err != nil {
+			return proto.TaskResult{Error: err.Error()}
+		}
+		conn, dir = c, path.Clean(args.Dir)
+	} else {
+		for _, n := range names {
+			if _, err := os.Lstat(filepath.Join(dir, n)); err == nil && args.Conflict != "replace" && args.Conflict != "skip" {
+				return proto.TaskResult{Error: filepath.Join(dir, n) + " уже существует"}
+			}
+		}
+		if err := os.MkdirAll(dir, 0o755); err != nil {
+			return proto.TaskResult{Error: err.Error()}
+		}
+	}
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+	pr, pw := io.Pipe()
+	go func() {
+		for i := 0; ; i++ {
+			var data []byte
+			var last bool
+			err := a.xferRequest(ctx, func(ctx context.Context) (*http.Request, error) {
+				return http.NewRequestWithContext(ctx, http.MethodGet, a.relayURL(args.Relay, i), nil)
+			}, func(resp *http.Response) error {
+				b, err := io.ReadAll(io.LimitReader(resp.Body, int64(args.Chunk)+1))
+				data, last = b, resp.Header.Get("X-Last") != ""
+				return err
+			})
+			if err == nil {
+				_, err = pw.Write(data)
+			}
+			if err != nil {
+				pw.CloseWithError(err)
+				return
+			}
+			if last {
+				pw.Close()
+				return
+			}
+		}
+	}()
+	if conn != nil {
+		skipped, err := a.unpackRemote(conn, pr, dir, names, args.Conflict)
+		if err == nil {
+			_, _ = io.Copy(io.Discard, pr)
+		}
+		pr.CloseWithError(errors.New("распаковка закончена"))
+		if err != nil {
+			return proto.TaskResult{Error: err.Error()}
+		}
+		res := map[string]int{}
+		if skipped > 0 {
+			res["skipped"] = skipped
+		}
+		data, _ := json.Marshal(res)
+		return proto.TaskResult{OK: true, Data: data}
+	}
+	allowed := map[string]bool{}
+	for _, n := range names {
+		allowed[n] = true
+	}
+	u := &unpacker{dir: dir, names: allowed, conflict: args.Conflict}
+	if os.Geteuid() == 0 {
+		// New things belong to whoever owns the folder they land in.
+		if info, err := os.Stat(dir); err == nil {
+			if st, ok := info.Sys().(*syscall.Stat_t); ok {
+				u.uid, u.gid, u.chown = int(st.Uid), int(st.Gid), true
+			}
+		}
+	}
+	err := u.unpack(tar.NewReader(pr))
+	if err == nil {
+		// Whatever follows the archive's end is read off, so the sender
+		// finishes.
+		_, err = io.Copy(io.Discard, pr)
+	}
+	pr.CloseWithError(errors.New("распаковка закончена"))
+	if err != nil {
+		var gone errXferGone
+		if errors.As(err, &gone) {
+			err = errors.New(string(gone))
+		}
+		return proto.TaskResult{Error: err.Error()}
+	}
+	data, _ := json.Marshal(map[string]int{"done": u.done, "skipped": u.skipped})
+	return proto.TaskResult{OK: true, Data: data}
+}
+
+// unpacker writes a tar stream into dir, every entry under name, following
+// the conflict rule for what is there already: folders merge, and files are
+// replaced or kept.
+type unpacker struct {
+	dir, conflict string
+	names         map[string]bool // the top entries the stream may carry
+	uid, gid      int
+	chown         bool
+	done, skipped int
+}
+
+func (u *unpacker) unpack(tr *tar.Reader) error {
+	var skipUnder string
+	for {
+		hdr, err := tr.Next()
+		if err == io.EOF {
+			return nil
+		}
+		if err != nil {
+			return err
+		}
+		clean := path.Clean(hdr.Name)
+		top, _, _ := strings.Cut(clean, "/")
+		if !u.names[top] || clean == ".." || strings.HasPrefix(clean, "../") {
+			return fmt.Errorf("в архиве чужой путь %q", hdr.Name)
+		}
+		target := filepath.Join(u.dir, filepath.FromSlash(clean))
+		if skipUnder != "" && strings.HasPrefix(target, skipUnder) {
+			continue
+		}
+		have, err := os.Lstat(target)
+		exists := err == nil
+		if exists && !(hdr.Typeflag == tar.TypeDir && have.IsDir()) {
+			switch u.conflict {
+			case "skip":
+				u.skipped++
+				if hdr.Typeflag == tar.TypeDir {
+					skipUnder = target + string(filepath.Separator)
+				}
+				continue
+			case "replace":
+				if have.IsDir() || hdr.Typeflag != tar.TypeReg {
+					if err := os.RemoveAll(target); err != nil {
+						return err
+					}
+				}
+			default:
+				return fmt.Errorf("%s уже существует", target)
+			}
+		}
+		mode := os.FileMode(hdr.Mode).Perm()
+		switch hdr.Typeflag {
+		case tar.TypeDir:
+			if !exists || !have.IsDir() {
+				if err := os.MkdirAll(target, mode|0o700); err != nil {
+					return err
+				}
+				_ = os.Chmod(target, mode)
+				u.own(target)
+			}
+		case tar.TypeReg:
+			if err := u.writeFile(target, tr, mode, hdr.ModTime); err != nil {
+				return err
+			}
+		case tar.TypeSymlink:
+			if err := os.Symlink(hdr.Linkname, target); err != nil {
+				return err
+			}
+			u.own(target)
+		default:
+			continue
+		}
+		u.done++
+	}
+}
+
+// writeFile writes next to the target first and puts it in place when all of
+// it is there.
+func (u *unpacker) writeFile(target string, r io.Reader, mode os.FileMode, mtime time.Time) error {
+	tmp, err := os.CreateTemp(filepath.Dir(target), "."+filepath.Base(target)+".lpra-*")
+	if err != nil {
+		return err
+	}
+	if _, err := io.Copy(tmp, r); err != nil {
+		tmp.Close()
+		os.Remove(tmp.Name())
+		return err
+	}
+	if err := tmp.Close(); err != nil {
+		os.Remove(tmp.Name())
+		return err
+	}
+	_ = os.Chmod(tmp.Name(), mode)
+	_ = os.Chtimes(tmp.Name(), mtime, mtime)
+	u.own(tmp.Name())
+	if err := os.Rename(tmp.Name(), target); err != nil {
+		os.Remove(tmp.Name())
+		return err
+	}
+	return nil
+}
+
+func (u *unpacker) own(p string) {
+	if u.chown {
+		_ = os.Lchown(p, u.uid, u.gid)
+	}
+}
+
+// shq quotes s for a POSIX shell.
+func shq(s string) string { return "'" + strings.ReplaceAll(s, "'", `'\''`) + "'" }
+
+// posix wraps a command for the host's sh: the user's login shell gets one
+// word to hand on, so fish or csh there does not matter.
+func posix(cmd string) string {
+	// csh reads "!" as history even inside single quotes; '\!' is a plain
+	// "!" for it and for sh alike.
+	return "sh -c " + strings.ReplaceAll(shq(cmd), "!", `'\!'`)
+}
+
+// shipSSH writes the tar stream into tar on the SSH host, in Dir.
+func (a *Agent) shipSSH(ctx context.Context, args proto.FSShipArgs, src string, m *shipMeter) error {
+	client, _, err := a.sshConnect(ctx, *args.SSH, func(_, note string) { m.note.Store(note) })
+	if err != nil {
+		return err
+	}
+	defer client.Close()
+	go func() { <-ctx.Done(); client.Close() }()
+	dir := args.Dir
+	if dir == "" {
+		dir = "."
+	}
+	target := strings.TrimSuffix(dir, "/") + "/" + args.Name
+
+	// What tar is there, and whether the target is.
+	m.note.Store("проверка на той стороне")
+	out, err := sshRun(client, "command -v tar >/dev/null 2>&1 || echo LPRA_NOTAR; tar --version 2>/dev/null | head -n 1; test -e "+shq(target)+" -o -L "+shq(target)+" && echo LPRA_EXISTS")
+	if err != nil {
+		return err
+	}
+	if strings.Contains(out, "LPRA_NOTAR") {
+		return errors.New("на той стороне нет tar")
+	}
+	if strings.Contains(out, "LPRA_EXISTS") && args.Conflict != "replace" && args.Conflict != "skip" {
+		return errors.New(target + " там уже существует")
+	}
+	gnu := strings.Contains(out, "GNU tar")
+	flags := ""
+	switch args.Conflict {
+	case "skip":
+		if gnu {
+			flags = " --skip-old-files"
+		} else {
+			flags = " -k"
+		}
+	case "replace":
+		if gnu {
+			flags = " --overwrite"
+		}
+	}
+
+	sess, err := client.NewSession()
+	if err != nil {
+		return err
+	}
+	defer sess.Close()
+	var stderr bytes.Buffer
+	sess.Stderr = &limitBuf{b: &stderr, max: 4096}
+	stdin, err := sess.StdinPipe()
+	if err != nil {
+		return err
+	}
+	cmd := "mkdir -p -- " + shq(dir) + " && cd -- " + shq(dir) + " && tar -xf -" + flags
+	if err := sess.Start(posix(cmd)); err != nil {
+		return err
+	}
+	m.note.Store("")
+	packErr := packTar(ctx, stdin, src, args.Name, m)
+	stdin.Close()
+	waitErr := sess.Wait()
+	msg := strings.TrimSpace(stderr.String())
+	if packErr != nil {
+		if msg != "" {
+			return fmt.Errorf("%v (%s)", packErr, msg)
+		}
+		return packErr
+	}
+	if waitErr != nil {
+		var ee *ssh.ExitError
+		if errors.As(waitErr, &ee) && msg != "" {
+			return errors.New("tar на той стороне: " + msg)
+		}
+		return waitErr
+	}
+	return nil
+}
+
+// sshRun runs a command and returns its output.
+func sshRun(c *ssh.Client, cmd string) (string, error) {
+	s, err := c.NewSession()
+	if err != nil {
+		return "", err
+	}
+	defer s.Close()
+	out, err := s.Output(posix(cmd))
+	var ee *ssh.ExitError
+	if errors.As(err, &ee) {
+		err = nil // the checks may exit non-zero; what they print is the answer
+	}
+	return string(out), err
+}
+
+type limitBuf struct {
+	b   *bytes.Buffer
+	max int
+}
+
+func (l *limitBuf) Write(p []byte) (int, error) {
+	if room := l.max - l.b.Len(); room > 0 {
+		l.b.Write(p[:min(len(p), room)])
+	}
+	return len(p), nil
+}
@@ -0,0 +1,66 @@
+package agent
+
+import (
+	"archive/tar"
+	"bytes"
+	"context"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+// Several items of one folder go as one tar and land side by side; an entry
+// of none of them is refused.
+func TestShipSeveralInOneTar(t *testing.T) {
+	src, dst := t.TempDir(), t.TempDir()
+	_ = os.WriteFile(filepath.Join(src, "a.txt"), []byte("A"), 0o644)
+	_ = os.MkdirAll(filepath.Join(src, "b"), 0o755)
+	_ = os.WriteFile(filepath.Join(src, "b", "c.txt"), []byte("C"), 0o644)
+	var buf bytes.Buffer
+	items := []shipItem{{filepath.Join(src, "a.txt"), "a.txt"}, {filepath.Join(src, "b"), "b"}}
+	if err := packTars(context.Background(), &buf, items, &shipMeter{}); err != nil {
+		t.Fatal(err)
+	}
+	u := &unpacker{dir: dst, names: map[string]bool{"a.txt": true, "b": true}}
+	if err := u.unpack(tar.NewReader(&buf)); err != nil {
+		t.Fatal(err)
+	}
+	if b, _ := os.ReadFile(filepath.Join(dst, "b", "c.txt")); string(b) != "C" {
+		t.Fatalf("b/c.txt: %q", b)
+	}
+	if b, _ := os.ReadFile(filepath.Join(dst, "a.txt")); string(b) != "A" {
+		t.Fatalf("a.txt: %q", b)
+	}
+	buf.Reset()
+	_ = packTars(context.Background(), &buf, items, &shipMeter{})
+	u = &unpacker{dir: t.TempDir(), names: map[string]bool{"a.txt": true}}
+	if err := u.unpack(tar.NewReader(&buf)); err == nil || !strings.Contains(err.Error(), "чужой путь") {
+		t.Fatalf("b let in: %v", err)
+	}
+}
+
+func TestRenameTarSeveral(t *testing.T) {
+	var src bytes.Buffer
+	tw := tar.NewWriter(&src)
+	for _, n := range []string{"a", "b/x", "c", "._a"} {
+		_ = tw.WriteHeader(&tar.Header{Name: n, Mode: 0o644, Typeflag: tar.TypeReg})
+	}
+	_ = tw.Close()
+	var out bytes.Buffer
+	if err := renameTar(&out, &src, map[string]string{"a": "a", "b": "b2"}); err != nil {
+		t.Fatal(err)
+	}
+	tr := tar.NewReader(&out)
+	var got []string
+	for {
+		h, err := tr.Next()
+		if err != nil {
+			break
+		}
+		got = append(got, h.Name)
+	}
+	if strings.Join(got, ",") != "a,b2/x" {
+		t.Fatalf("entries: %v", got)
+	}
+}
@@ -0,0 +1,167 @@
+package agent
+
+import (
+	"context"
+	"crypto/rand"
+	"encoding/json"
+	"errors"
+	"io"
+	"net/http"
+	"time"
+
+	"github.com/x-grk/longpolling-remote-access/internal/proto"
+)
+
+const (
+	// speedWindow is how long each direction is measured for, unless the
+	// server asks for another window; speedWindowMax bounds what it may ask.
+	speedWindow    = 3 * time.Second
+	speedWindowMax = 30 * time.Second
+	// speedWait is how long the download may take to start: in a relayed test
+	// its bytes come from the browser.
+	speedWait = 10 * time.Second
+	// speedUpCap bounds the upload, whatever the link does in the window.
+	speedUpCap = 48 << 20
+)
+
+// doSpeed measures the agent's HTTP link to the server: round-trip time of an
+// empty request, then how much flows each way in the window. In a relayed
+// test the server pipes both streams to the browser, so they run end to end.
+func (a *Agent) doSpeed(ctx context.Context, env proto.TaskEnvelope) proto.TaskResult {
+	var args proto.SysSpeedArgs
+	if len(env.Args) > 0 {
+		_ = json.Unmarshal(env.Args, &args)
+	}
+	window := speedWindow
+	if args.WindowMs > 0 {
+		window = min(time.Duration(args.WindowMs)*time.Millisecond, speedWindowMax)
+	}
+	res, err := a.measureSpeed(ctx, args.Relay, window)
+	if err != nil {
+		return proto.TaskResult{Error: err.Error()}
+	}
+	data, _ := json.Marshal(res)
+	return proto.TaskResult{OK: true, Data: data}
+}
+
+func (a *Agent) measureSpeed(ctx context.Context, relay bool, window time.Duration) (proto.SysSpeedResult, error) {
+	res := proto.SysSpeedResult{Relay: relay}
+	streams := "/api/agent/speed"
+	if relay {
+		streams += "/relay"
+	}
+	// Ping: the first request may pay for a new connection, so keep the best.
+	for i := 0; i < 4; i++ {
+		start := time.Now()
+		resp, err := a.speedRequest(ctx, http.MethodGet, "/api/agent/speed/down?bytes=0", nil)
+		if err != nil {
+			return res, err
+		}
+		io.Copy(io.Discard, resp.Body)
+		resp.Body.Close()
+		ms := float64(time.Since(start).Microseconds()) / 1000
+		if i == 0 || ms < res.PingMs {
+			res.PingMs = ms
+		}
+	}
+
+	down, err := a.speedDown(ctx, streams+"/down", window)
+	if err != nil {
+		return res, err
+	}
+	res.DownBps = down
+
+	// Up: send until the window closes or the cap is hit.
+	body := &speedSource{deadline: time.Now().Add(window), left: speedUpCap}
+	start := time.Now()
+	resp, err := a.speedRequest(ctx, http.MethodPost, streams+"/up", body)
+	if err != nil {
+		return res, err
+	}
+	io.Copy(io.Discard, resp.Body)
+	resp.Body.Close()
+	res.UpBps = bps(int64(speedUpCap-body.left), time.Since(start))
+	return res, nil
+}
+
+// speedDown reads what the server streams for the window, counted from the
+// first byte, and returns the rate.
+func (a *Agent) speedDown(ctx context.Context, path string, window time.Duration) (float64, error) {
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+	t := time.AfterFunc(speedWait, cancel)
+	defer t.Stop()
+	resp, err := a.speedRequest(ctx, http.MethodGet, path, nil)
+	if err != nil {
+		return 0, err
+	}
+	defer resp.Body.Close()
+	var (
+		n     int64
+		start time.Time
+		buf   = make([]byte, 64<<10)
+	)
+	for {
+		k, err := resp.Body.Read(buf)
+		if k > 0 && start.IsZero() {
+			start = time.Now()
+			t.Reset(window)
+		}
+		n += int64(k)
+		if err != nil {
+			break
+		}
+	}
+	if start.IsZero() {
+		return 0, errors.New("нет данных для замера")
+	}
+	return bps(n, time.Since(start)), nil
+}
+
+func (a *Agent) speedRequest(ctx context.Context, method, path string, body io.Reader) (*http.Response, error) {
+	req, err := http.NewRequestWithContext(ctx, method, a.host()+path, body)
+	if err != nil {
+		return nil, err
+	}
+	a.authHeaders(req)
+	resp, err := a.http.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	if resp.StatusCode != http.StatusOK && resp.StatusCode != http.StatusNoContent {
+		resp.Body.Close()
+		return nil, errStatus(resp.StatusCode)
+	}
+	return resp, nil
+}
+
+func bps(n int64, d time.Duration) float64 {
+	if d <= 0 {
+		return 0
+	}
+	return float64(n) * 8 / d.Seconds()
+}
+
+// speedSource is an upload body of incompressible bytes that ends at the
+// deadline or after `left` bytes.
+type speedSource struct {
+	deadline time.Time
+	left     int
+	block    []byte
+}
+
+func (s *speedSource) Read(p []byte) (int, error) {
+	if s.left <= 0 || !time.Now().Before(s.deadline) {
+		return 0, io.EOF
+	}
+	if s.block == nil {
+		s.block = make([]byte, 64<<10)
+		rand.Read(s.block)
+	}
+	n := copy(p, s.block)
+	if n > s.left {
+		n = s.left
+	}
+	s.left -= n
+	return n, nil
+}
@@ -0,0 +1,512 @@
+package agent
+
+import (
+	"context"
+	"database/sql"
+	"encoding/hex"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net/url"
+	"os"
+	"strconv"
+	"strings"
+	"time"
+
+	_ "modernc.org/sqlite"
+
+	"github.com/x-grk/longpolling-remote-access/internal/proto"
+)
+
+// SQLite databases are read and changed here, through SQLite itself, so a
+// database that is in use keeps its locks and journal: a value is set with an
+// UPDATE, not by writing the file over.
+
+// dbCell is one value as the panel shows and sends it: t is "i" (integer),
+// "r" (real), "s" (text), "b" (blob, v its size, not editable) or "n" (NULL).
+type dbCell struct {
+	T string `json:"t"`
+	V string `json:"v,omitempty"`
+}
+
+func cellOf(v any) dbCell {
+	switch x := v.(type) {
+	case nil:
+		return dbCell{T: "n"}
+	case int64:
+		return dbCell{T: "i", V: strconv.FormatInt(x, 10)}
+	case float64:
+		return dbCell{T: "r", V: strconv.FormatFloat(x, 'g', -1, 64)}
+	case string:
+		return dbCell{T: "s", V: x}
+	case []byte:
+		return dbCell{T: "b", V: strconv.Itoa(len(x))}
+	case bool:
+		if x {
+			return dbCell{T: "i", V: "1"}
+		}
+		return dbCell{T: "i", V: "0"}
+	case time.Time:
+		return dbCell{T: "s", V: x.Format(time.RFC3339Nano)}
+	}
+	return dbCell{T: "s", V: fmt.Sprint(v)}
+}
+
+// value is what a cell becomes for SQLite.
+func (c dbCell) value() (any, error) {
+	switch c.T {
+	case "n":
+		return nil, nil
+	case "i":
+		n, err := strconv.ParseInt(strings.TrimSpace(c.V), 10, 64)
+		if err != nil {
+			return nil, fmt.Errorf("%q - не целое число", c.V)
+		}
+		return n, nil
+	case "r":
+		f, err := strconv.ParseFloat(strings.TrimSpace(c.V), 64)
+		if err != nil {
+			return nil, fmt.Errorf("%q - не число", c.V)
+		}
+		return f, nil
+	case "x":
+		b, err := hex.DecodeString(strings.ReplaceAll(c.V, " ", ""))
+		if err != nil {
+			return nil, errors.New("blob - нужны шестнадцатеричные байты")
+		}
+		return b, nil
+	}
+	return c.V, nil
+}
+
+type dbArgs struct {
+	Path   string            `json:"path"`
+	Table  string            `json:"table,omitempty"`
+	Offset int               `json:"offset,omitempty"`
+	Limit  int               `json:"limit,omitempty"`
+	Key    json.RawMessage   `json:"key,omitempty"`
+	Keys   []json.RawMessage `json:"keys,omitempty"`
+	Column string            `json:"column,omitempty"`
+	Value  *dbCell           `json:"value,omitempty"`
+	Values map[string]dbCell `json:"values,omitempty"`
+	SQL    string            `json:"sql,omitempty"`
+}
+
+func dbOpen(path string) (*sql.DB, error) {
+	info, err := os.Stat(path)
+	if err != nil {
+		return nil, err
+	}
+	if info.IsDir() {
+		return nil, errors.New("это каталог")
+	}
+	u := url.URL{Scheme: "file", Path: path}
+	db, err := sql.Open("sqlite", u.String()+"?mode=rw&_pragma=busy_timeout(5000)")
+	if err != nil {
+		return nil, err
+	}
+	db.SetMaxOpenConns(1)
+	return db, nil
+}
+
+func qid(name string) string { return `"` + strings.ReplaceAll(name, `"`, `""`) + `"` }
+
+// dbTable is a table's shape: its columns, and how a row is found again -
+// by rowid, by its primary key (a WITHOUT ROWID table), or not at all (a
+// view: shown, not changed).
+type dbTable struct {
+	Name    string     `json:"name"`
+	Type    string     `json:"type"`
+	Columns []dbColumn `json:"columns"`
+	Key     string     `json:"key"` // "rowid", "pk" or ""
+	// Alias is the INTEGER PRIMARY KEY column: another name for the rowid.
+	Alias string `json:"alias,omitempty"`
+	pk    []string
+}
+
+type dbColumn struct {
+	Name    string `json:"name"`
+	Type    string `json:"type"`
+	NotNull bool   `json:"notnull,omitempty"`
+	PK      bool   `json:"pk,omitempty"`
+	Default string `json:"default,omitempty"`
+}
+
+func dbTableInfo(ctx context.Context, db *sql.DB, name string) (*dbTable, error) {
+	t := &dbTable{Name: name}
+	if err := db.QueryRowContext(ctx, `SELECT type FROM sqlite_master WHERE name = ? AND type IN ('table','view')`, name).Scan(&t.Type); err != nil {
+		if errors.Is(err, sql.ErrNoRows) {
+			return nil, fmt.Errorf("нет таблицы %s", name)
+		}
+		return nil, err
+	}
+	rows, err := db.QueryContext(ctx, `SELECT name, type, "notnull", dflt_value, pk FROM pragma_table_info(?)`, name)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	type pkc struct {
+		n   int
+		col string
+	}
+	var pks []pkc
+	for rows.Next() {
+		var c dbColumn
+		var notnull, pk int
+		var dflt sql.NullString
+		if err := rows.Scan(&c.Name, &c.Type, &notnull, &dflt, &pk); err != nil {
+			return nil, err
+		}
+		c.NotNull, c.PK, c.Default = notnull == 1, pk > 0, dflt.String
+		if pk > 0 {
+			pks = append(pks, pkc{pk, c.Name})
+		}
+		t.Columns = append(t.Columns, c)
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	for i := 1; i <= len(pks); i++ {
+		for _, p := range pks {
+			if p.n == i {
+				t.pk = append(t.pk, p.col)
+			}
+		}
+	}
+	if t.Type == "table" {
+		if r, err := db.QueryContext(ctx, `SELECT rowid FROM `+qid(name)+` LIMIT 0`); err == nil {
+			r.Close()
+			t.Key = "rowid"
+			if len(t.pk) == 1 {
+				for _, c := range t.Columns {
+					if c.Name == t.pk[0] && strings.EqualFold(strings.TrimSpace(c.Type), "INTEGER") {
+						t.Alias = c.Name
+					}
+				}
+			}
+		} else if len(t.pk) > 0 {
+			t.Key = "pk"
+		}
+	}
+	return t, nil
+}
+
+// where is the condition that finds the row by its key: a rowid, or the
+// primary key's cells in order.
+func (t *dbTable) where(key json.RawMessage) (string, []any, error) {
+	switch t.Key {
+	case "rowid":
+		var id int64
+		if err := json.Unmarshal(key, &id); err != nil {
+			var s string
+			if json.Unmarshal(key, &s) != nil {
+				return "", nil, errors.New("плохой ключ строки")
+			}
+			if id, err = strconv.ParseInt(s, 10, 64); err != nil {
+				return "", nil, errors.New("плохой ключ строки")
+			}
+		}
+		return "rowid = ?", []any{id}, nil
+	case "pk":
+		var cells []dbCell
+		if err := json.Unmarshal(key, &cells); err != nil || len(cells) != len(t.pk) {
+			return "", nil, errors.New("плохой ключ строки")
+		}
+		parts, args := make([]string, len(t.pk)), make([]any, len(t.pk))
+		for i, col := range t.pk {
+			v, err := cells[i].value()
+			if err != nil {
+				return "", nil, err
+			}
+			parts[i], args[i] = qid(col)+" IS ?", v
+		}
+		return strings.Join(parts, " AND "), args, nil
+	}
+	return "", nil, errors.New("строки этой таблицы нельзя менять: нет ни rowid, ни первичного ключа")
+}
+
+func (t *dbTable) column(name string) bool {
+	for _, c := range t.Columns {
+		if c.Name == name {
+			return true
+		}
+	}
+	return false
+}
+
+// dbTask runs one database task.
+func dbTask(env proto.TaskEnvelope) (any, error) {
+	var a dbArgs
+	if err := json.Unmarshal(env.Args, &a); err != nil {
+		return nil, err
+	}
+	db, err := dbOpen(a.Path)
+	if err != nil {
+		return nil, err
+	}
+	defer db.Close()
+	ctx, cancel := context.WithTimeout(context.Background(), 50*time.Second)
+	defer cancel()
+
+	if env.Type == proto.TaskDBTables {
+		rows, err := db.QueryContext(ctx, `SELECT name, type FROM sqlite_master WHERE type IN ('table','view') AND name NOT LIKE 'sqlite_%' ORDER BY type, name`)
+		if err != nil {
+			return nil, dbErr(err)
+		}
+		defer rows.Close()
+		type item struct {
+			Name string `json:"name"`
+			Type string `json:"type"`
+		}
+		out := []item{}
+		for rows.Next() {
+			var it item
+			if err := rows.Scan(&it.Name, &it.Type); err != nil {
+				return nil, err
+			}
+			out = append(out, it)
+		}
+		return map[string]any{"tables": out}, rows.Err()
+	}
+	if env.Type == proto.TaskDBSQL {
+		return dbSQL(ctx, db, a.SQL)
+	}
+
+	t, err := dbTableInfo(ctx, db, a.Table)
+	if err != nil {
+		return nil, dbErr(err)
+	}
+	switch env.Type {
+	case proto.TaskDBRows:
+		return dbRows(ctx, db, t, a.Offset, a.Limit)
+	case proto.TaskDBSet:
+		if !t.column(a.Column) || a.Value == nil {
+			return nil, errors.New("нет такого столбца")
+		}
+		cond, args, err := t.where(a.Key)
+		if err != nil {
+			return nil, err
+		}
+		v, err := a.Value.value()
+		if err != nil {
+			return nil, err
+		}
+		res, err := db.ExecContext(ctx, `UPDATE `+qid(t.Name)+` SET `+qid(a.Column)+` = ? WHERE `+cond, append([]any{v}, args...)...)
+		if err != nil {
+			return nil, dbErr(err)
+		}
+		if n, _ := res.RowsAffected(); n != 1 {
+			return nil, fmt.Errorf("изменено строк: %d - строку могли удалить или поменять", n)
+		}
+		// A key column changed: the row is found by its new key now.
+		out := map[string]any{}
+		switch {
+		case t.Key == "rowid" && a.Column == t.Alias:
+			args = []any{v}
+			out["key"] = a.Value.V
+		case t.Key == "pk":
+			var cells []dbCell
+			_ = json.Unmarshal(a.Key, &cells)
+			for i, col := range t.pk {
+				if col == a.Column {
+					args[i], cells[i] = v, *a.Value
+					out["key"] = cells
+				}
+			}
+		}
+		// What SQLite stored, after its type affinity.
+		var got any
+		_ = db.QueryRowContext(ctx, `SELECT `+qid(a.Column)+` FROM `+qid(t.Name)+` WHERE `+cond, args...).Scan(&got)
+		out["value"] = cellOf(got)
+		if k, ok := out["key"].([]dbCell); ok {
+			for i, col := range t.pk {
+				if col == a.Column {
+					k[i] = cellOf(got)
+				}
+			}
+		}
+		return out, nil
+	case proto.TaskDBAdd:
+		if t.Type != "table" {
+			return nil, errors.New("в представление строки не добавляются")
+		}
+		var cols, marks []string
+		var vals []any
+		for name, c := range a.Values {
+			if !t.column(name) {
+				return nil, fmt.Errorf("нет столбца %s", name)
+			}
+			v, err := c.value()
+			if err != nil {
+				return nil, err
+			}
+			cols, marks, vals = append(cols, qid(name)), append(marks, "?"), append(vals, v)
+		}
+		q := `INSERT INTO ` + qid(t.Name) + ` DEFAULT VALUES`
+		if len(cols) > 0 {
+			q = `INSERT INTO ` + qid(t.Name) + ` (` + strings.Join(cols, ", ") + `) VALUES (` + strings.Join(marks, ", ") + `)`
+		}
+		res, err := db.ExecContext(ctx, q, vals...)
+		if err != nil {
+			return nil, dbErr(err)
+		}
+		id, _ := res.LastInsertId()
+		return map[string]any{"rowid": id}, nil
+	case proto.TaskDBDel:
+		tx, err := db.BeginTx(ctx, nil)
+		if err != nil {
+			return nil, dbErr(err)
+		}
+		defer tx.Rollback()
+		n := int64(0)
+		for _, k := range a.Keys {
+			cond, args, err := t.where(k)
+			if err != nil {
+				return nil, err
+			}
+			res, err := tx.ExecContext(ctx, `DELETE FROM `+qid(t.Name)+` WHERE `+cond, args...)
+			if err != nil {
+				return nil, dbErr(err)
+			}
+			c, _ := res.RowsAffected()
+			n += c
+		}
+		if err := tx.Commit(); err != nil {
+			return nil, dbErr(err)
+		}
+		return map[string]any{"deleted": n}, nil
+	}
+	return nil, errors.New("неизвестная операция")
+}
+
+// dbRows is a page of a table's rows, with each row's key.
+func dbRows(ctx context.Context, db *sql.DB, t *dbTable, offset, limit int) (any, error) {
+	if limit <= 0 || limit > 1000 {
+		limit = 200
+	}
+	var total int64
+	_ = db.QueryRowContext(ctx, `SELECT COUNT(*) FROM `+qid(t.Name)).Scan(&total)
+	sel := make([]string, 0, len(t.Columns)+1)
+	if t.Key == "rowid" {
+		sel = append(sel, "rowid")
+	}
+	for _, c := range t.Columns {
+		sel = append(sel, qid(c.Name))
+	}
+	order := ""
+	switch t.Key {
+	case "rowid":
+		order = " ORDER BY rowid"
+	case "pk":
+		parts := make([]string, len(t.pk))
+		for i, c := range t.pk {
+			parts[i] = qid(c)
+		}
+		order = " ORDER BY " + strings.Join(parts, ", ")
+	}
+	rows, err := db.QueryContext(ctx, `SELECT `+strings.Join(sel, ", ")+` FROM `+qid(t.Name)+order+` LIMIT ? OFFSET ?`, limit, offset)
+	if err != nil {
+		return nil, dbErr(err)
+	}
+	defer rows.Close()
+	type row struct {
+		K any      `json:"k,omitempty"`
+		V []dbCell `json:"v"`
+	}
+	out := []row{}
+	n := len(sel)
+	for rows.Next() {
+		vals := make([]any, n)
+		ptrs := make([]any, n)
+		for i := range vals {
+			ptrs[i] = &vals[i]
+		}
+		if err := rows.Scan(ptrs...); err != nil {
+			return nil, err
+		}
+		r := row{}
+		if t.Key == "rowid" {
+			r.K = cellOf(vals[0]).V
+			vals = vals[1:]
+		}
+		for _, v := range vals {
+			r.V = append(r.V, cellOf(v))
+		}
+		if t.Key == "pk" {
+			key := make([]dbCell, len(t.pk))
+			for i, pk := range t.pk {
+				for j, c := range t.Columns {
+					if c.Name == pk {
+						key[i] = r.V[j]
+					}
+				}
+			}
+			r.K = key
+		}
+		out = append(out, r)
+	}
+	return map[string]any{"table": t, "total": total, "offset": offset, "rows": out}, rows.Err()
+}
+
+// dbSQL runs what was typed: a query gives up to 500 rows, anything else
+// how many rows it changed.
+func dbSQL(ctx context.Context, db *sql.DB, q string) (any, error) {
+	q = strings.TrimSpace(q)
+	if q == "" {
+		return nil, errors.New("пустой запрос")
+	}
+	head := strings.ToLower(strings.Fields(q)[0])
+	if head == "select" || head == "pragma" || head == "with" || head == "explain" || head == "values" {
+		rows, err := db.QueryContext(ctx, q)
+		if err != nil {
+			return nil, dbErr(err)
+		}
+		defer rows.Close()
+		cols, _ := rows.Columns()
+		out := [][]dbCell{}
+		more := false
+		for rows.Next() {
+			if len(out) == 500 {
+				more = true
+				break
+			}
+			vals := make([]any, len(cols))
+			ptrs := make([]any, len(cols))
+			for i := range vals {
+				ptrs[i] = &vals[i]
+			}
+			if err := rows.Scan(ptrs...); err != nil {
+				return nil, err
+			}
+			r := make([]dbCell, len(cols))
+			for i, v := range vals {
+				r[i] = cellOf(v)
+			}
+			out = append(out, r)
+		}
+		return map[string]any{"columns": cols, "rows": out, "more": more}, dbErr(rows.Err())
+	}
+	res, err := db.ExecContext(ctx, q)
+	if err != nil {
+		return nil, dbErr(err)
+	}
+	n, _ := res.RowsAffected()
+	return map[string]any{"changed": n}, nil
+}
+
+// dbErr says the common SQLite troubles in words.
+func dbErr(err error) error {
+	if err == nil {
+		return nil
+	}
+	m := err.Error()
+	switch {
+	case strings.Contains(m, "file is not a database"):
+		return errors.New("это не база SQLite")
+	case strings.Contains(m, "database is locked"), strings.Contains(m, "SQLITE_BUSY"):
+		return errors.New("база занята другой программой - попробуйте ещё раз")
+	case strings.Contains(m, "readonly"):
+		return errors.New("база только для чтения (нет прав на файл или его папку)")
+	}
+	return err
+}
@@ -0,0 +1,250 @@
+package agent
+
+import (
+	"bufio"
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"log"
+	"net"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+
+	"golang.org/x/crypto/ssh"
+
+	"github.com/x-grk/longpolling-remote-access/internal/proto"
+)
+
+// An SSH terminal: the agent connects to another host by SSH and bridges the
+// remote shell to the session, as it does a local one. The panel is told how
+// the connection goes (connecting, signing in, in) to show it.
+
+// sshKnownHosts holds the host keys seen, next to the agent's state: a host
+// is trusted the first time, and a changed key is refused.
+func (a *Agent) sshKnownHosts() string {
+	return filepath.Join(filepath.Dir(a.cfg.StatePath), "ssh_known_hosts")
+}
+
+var knownHostsMu sync.Mutex
+
+// hostKeyCheck trusts a new host and remembers its key; a host whose key
+// has changed since is refused, as ssh would.
+func (a *Agent) hostKeyCheck(seen *string) ssh.HostKeyCallback {
+	return func(hostname string, _ net.Addr, key ssh.PublicKey) error {
+		knownHostsMu.Lock()
+		defer knownHostsMu.Unlock()
+		fp := ssh.FingerprintSHA256(key)
+		*seen = fp
+		path := a.sshKnownHosts()
+		line := hostname + " " + key.Type() + " "
+		if f, err := os.Open(path); err == nil {
+			sc := bufio.NewScanner(f)
+			for sc.Scan() {
+				fields := strings.Fields(sc.Text())
+				if len(fields) != 3 || fields[0] != hostname {
+					continue
+				}
+				if fields[1] == key.Type() && fields[2] == fp {
+					f.Close()
+					return nil
+				}
+				if fields[1] == key.Type() {
+					f.Close()
+					return fmt.Errorf("ключ хоста %s изменился: был %s, теперь %s. Если так и должно быть, удалите строку с этим хостом из %s на агенте",
+						hostname, fields[2], fp, path)
+				}
+			}
+			f.Close()
+		}
+		_ = os.MkdirAll(filepath.Dir(path), 0o700)
+		f, err := os.OpenFile(path, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0o600)
+		if err == nil {
+			_, _ = f.WriteString(line + fp + "\n")
+			f.Close()
+		}
+		return nil
+	}
+}
+
+// sshAuth is how to sign in: the key given, the password given (also
+// answered to keyboard-interactive prompts), or the agent user's own keys.
+func sshAuth(t proto.SSHTarget) ([]ssh.AuthMethod, error) {
+	var methods []ssh.AuthMethod
+	if t.Key != "" {
+		var signer ssh.Signer
+		var err error
+		if t.Passphrase != "" {
+			signer, err = ssh.ParsePrivateKeyWithPassphrase([]byte(t.Key), []byte(t.Passphrase))
+		} else {
+			signer, err = ssh.ParsePrivateKey([]byte(t.Key))
+		}
+		var missing *ssh.PassphraseMissingError
+		if errors.As(err, &missing) {
+			return nil, errors.New("ключ защищён фразой - введите её")
+		}
+		if err != nil {
+			return nil, fmt.Errorf("ключ не читается: %v", err)
+		}
+		methods = append(methods, ssh.PublicKeys(signer))
+	}
+	if t.Password != "" {
+		pw := t.Password
+		methods = append(methods, ssh.Password(pw),
+			ssh.KeyboardInteractive(func(_, _ string, qs []string, _ []bool) ([]string, error) {
+				ans := make([]string, len(qs))
+				for i := range ans {
+					ans[i] = pw
+				}
+				return ans, nil
+			}))
+	}
+	if len(methods) == 0 {
+		var signers []ssh.Signer
+		for _, n := range []string{"id_ed25519", "id_ecdsa", "id_rsa"} {
+			b, err := os.ReadFile(filepath.Join(homeDir(""), ".ssh", n))
+			if err != nil {
+				continue
+			}
+			if s, err := ssh.ParsePrivateKey(b); err == nil {
+				signers = append(signers, s)
+			}
+		}
+		if len(signers) == 0 {
+			return nil, errors.New("не задан ни пароль, ни ключ, и в ~/.ssh агента нет ключей без фразы")
+		}
+		methods = append(methods, ssh.PublicKeys(signers...))
+	}
+	return methods, nil
+}
+
+// sshShell is the remote shell as a stream: its output (stdout and stderr,
+// one on a PTY) to read, keystrokes to write.
+type sshShell struct {
+	client *ssh.Client
+	sess   *ssh.Session
+	stdin  io.WriteCloser
+	out    *io.PipeReader
+	once   sync.Once
+}
+
+func (s *sshShell) Read(b []byte) (int, error)  { return s.out.Read(b) }
+func (s *sshShell) Write(b []byte) (int, error) { return s.stdin.Write(b) }
+func (s *sshShell) Resize(cols, rows uint16) {
+	if cols > 0 && rows > 0 {
+		_ = s.sess.WindowChange(int(rows), int(cols))
+	}
+}
+func (s *sshShell) Close() error {
+	s.once.Do(func() {
+		_ = s.sess.Close()
+		_ = s.client.Close()
+		_ = s.out.Close()
+	})
+	return nil
+}
+
+// sshConnect connects and signs in to t, saying how it goes by status (the
+// SSHStatus steps). It returns the client and the host key's fingerprint.
+func (a *Agent) sshConnect(ctx context.Context, t proto.SSHTarget, status func(st, note string)) (*ssh.Client, string, error) {
+	if t.Port == 0 {
+		t.Port = 22
+	}
+	addr := net.JoinHostPort(t.Host, strconv.Itoa(t.Port))
+	auth, err := sshAuth(t)
+	if err != nil {
+		return nil, "", err
+	}
+	status(proto.SSHDial, "подключение к "+addr)
+	d := net.Dialer{Timeout: 15 * time.Second, KeepAlive: 30 * time.Second}
+	conn, err := d.DialContext(ctx, "tcp", addr)
+	if err != nil {
+		return nil, "", fmt.Errorf("не подключиться к %s: %v", addr, err)
+	}
+	status(proto.SSHAuth, "вход как "+t.User)
+	var fp string
+	_ = conn.SetDeadline(time.Now().Add(30 * time.Second))
+	c, chans, reqs, err := ssh.NewClientConn(conn, addr, &ssh.ClientConfig{
+		User:            t.User,
+		Auth:            auth,
+		HostKeyCallback: a.hostKeyCheck(&fp),
+		Timeout:         15 * time.Second,
+	})
+	if err != nil {
+		conn.Close()
+		msg := strings.TrimPrefix(err.Error(), "ssh: handshake failed: ")
+		if strings.Contains(msg, "unable to authenticate") {
+			msg = "сервер не принял вход как " + t.User + " - проверьте пароль или ключ"
+		}
+		return nil, "", errors.New(msg)
+	}
+	_ = conn.SetDeadline(time.Time{})
+	return ssh.NewClient(c, chans, reqs), fp, nil
+}
+
+// runSSH connects to the target and bridges its shell to the session.
+func (a *Agent) runSSH(parent context.Context, sid string, t proto.SSHTarget) {
+	status := func(st, note string) {
+		a.postOut(context.Background(), sid, proto.OutMessage{Status: st, Note: note})
+	}
+	fail := func(err error) {
+		log.Printf("ssh %s: %v", sid, err)
+		status(proto.SSHErr, err.Error())
+		a.postOut(context.Background(), sid, proto.OutMessage{Data: b64.EncodeToString([]byte("\x1b[31m" + err.Error() + "\x1b[0m\r\n"))})
+		a.postOut(context.Background(), sid, proto.OutMessage{Exit: true})
+	}
+	client, fp, err := a.sshConnect(parent, t, status)
+	if err != nil {
+		fail(err)
+		return
+	}
+	port := t.Port
+	if port == 0 {
+		port = 22
+	}
+	addr := net.JoinHostPort(t.Host, strconv.Itoa(port))
+	sess, err := client.NewSession()
+	if err != nil {
+		client.Close()
+		fail(fmt.Errorf("сессия не открылась: %v", err))
+		return
+	}
+	modes := ssh.TerminalModes{ssh.ECHO: 1, ssh.TTY_OP_ISPEED: 115200, ssh.TTY_OP_OSPEED: 115200}
+	if err := sess.RequestPty("xterm-256color", 24, 80, modes); err != nil {
+		sess.Close()
+		client.Close()
+		fail(fmt.Errorf("терминал не выделен: %v", err))
+		return
+	}
+	stdin, _ := sess.StdinPipe()
+	pr, pw := io.Pipe()
+	sess.Stdout = pw
+	sess.Stderr = pw
+	if err := sess.Shell(); err != nil {
+		sess.Close()
+		client.Close()
+		fail(fmt.Errorf("оболочка не запустилась: %v", err))
+		return
+	}
+	sh := &sshShell{client: client, sess: sess, stdin: stdin, out: pr}
+	go func() { _ = sess.Wait(); pw.Close() }()
+	// Keep-alives, so a dead host is noticed and the session ends.
+	go func() {
+		tk := time.NewTicker(30 * time.Second)
+		defer tk.Stop()
+		for range tk.C {
+			if _, _, err := client.SendRequest("keepalive@openssh.com", true, nil); err != nil {
+				sh.Close()
+				return
+			}
+		}
+	}()
+	log.Printf("ssh %s: %s@%s up (host key %s)", sid, t.User, addr, fp)
+	status(proto.SSHOK, t.User+"@"+addr)
+	a.bridgeStream(parent, sid, sh, sh.Resize)
+	log.Printf("ssh %s: ended", sid)
+}
@@ -0,0 +1,794 @@
+package agent
+
+// Files on an SSH host, for the panel's file panes: the agent keeps one SSH
+// connection per pane and runs plain commands there - stat, cat, mv, rm - as
+// the tar transfer does. No SFTP is needed on the host. A connection that
+// dropped is opened again once with what it was opened with; one left alone
+// for sshfsIdle is closed.
+
+import (
+	"archive/tar"
+	"bytes"
+	"context"
+	"crypto/rand"
+	"encoding/base64"
+	"encoding/hex"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"path"
+	"strconv"
+	"strings"
+	"sync"
+	"sync/atomic"
+	"time"
+	"unicode/utf8"
+
+	"golang.org/x/crypto/ssh"
+
+	"github.com/x-grk/longpolling-remote-access/internal/proto"
+)
+
+const sshfsIdle = 10 * time.Minute
+
+type sshfsConn struct {
+	mu      sync.Mutex
+	client  *ssh.Client
+	target  proto.SSHTarget // kept in the agent's memory to reconnect once after a drop
+	statFmt string          // "gnu", "bsd" or "ls"
+	home    string
+	last    time.Time
+	busy    int // transfers under way: the sweep leaves the connection be
+}
+
+// hold marks the connection busy for a long transfer; the returned func ends
+// it and starts the idle clock again.
+func (c *sshfsConn) hold() func() {
+	c.mu.Lock()
+	c.busy++
+	c.mu.Unlock()
+	return func() {
+		c.mu.Lock()
+		c.busy--
+		c.last = time.Now()
+		c.mu.Unlock()
+	}
+}
+
+// idle: nothing under way and unused for sshfsIdle by now.
+func (c *sshfsConn) idle(now time.Time) bool {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	return c.busy == 0 && now.Sub(c.last) > sshfsIdle
+}
+
+var (
+	sshfsConns   sync.Map // id -> *sshfsConn
+	sshfsJanitor sync.Once
+)
+
+// statCommand lists dir's entries as "type|size|mtime|mode|name" lines.
+func statCommand(flavour, dir string) string {
+	d := shq(strings.TrimSuffix(dir, "/") + "/")
+	// Each line starts with LD for a link to a folder, so it opens like one.
+	loop := "cd " + d + " && for f in .[!.]* ..?* *; do [ -e \"$f\" ] || [ -L \"$f\" ] || continue; " +
+		"t=; [ -L \"$f\" ] && [ -d \"$f\" ] && t=LD; printf '%s|' \"$t\"; "
+	switch flavour {
+	case "bsd":
+		return loop + "stat -f '%HT|%z|%m|%Sp|%N' -- \"$f\"; done"
+	case "ls":
+		return "cd " + d + " && LC_ALL=C ls -la"
+	}
+	return loop + "stat -c '%F|%s|%Y|%A|%n' -- \"$f\"; done"
+}
+
+// parseStatLine reads one line of statCommand's output.
+func parseStatLine(line string) (proto.FSEntry, bool) {
+	// The LD mark of statCommand: empty, or LD for a link to a folder.
+	mark := ""
+	if i := strings.IndexByte(line, '|'); i >= 0 && (line[:i] == "" || line[:i] == "LD") {
+		mark, line = line[:i], line[i+1:]
+	}
+	p := strings.SplitN(line, "|", 5)
+	if len(p) != 5 {
+		return proto.FSEntry{}, false
+	}
+	size, err1 := strconv.ParseInt(p[1], 10, 64)
+	mt, err2 := strconv.ParseInt(p[2], 10, 64)
+	if err1 != nil || err2 != nil {
+		return proto.FSEntry{}, false
+	}
+	t := strings.ToLower(p[0])
+	return proto.FSEntry{Name: p[4], IsDir: strings.Contains(t, "directory") || mark == "LD", Size: size, MTime: mt, Mode: p[3],
+		Link: strings.Contains(t, "link")}, true
+}
+
+// parseLsLine reads a line of "ls -la" for a host with no stat: no times.
+func parseLsLine(line string) (proto.FSEntry, bool) {
+	f := strings.Fields(line)
+	if len(f) < 9 || len(f[0]) < 10 {
+		return proto.FSEntry{}, false
+	}
+	size, err := strconv.ParseInt(f[4], 10, 64)
+	if err != nil {
+		return proto.FSEntry{}, false
+	}
+	// The name is what follows the eighth field, spaces and all.
+	rest := line
+	for i := 0; i < 8; i++ {
+		rest = strings.TrimLeft(rest, " ")
+		rest = rest[strings.IndexByte(rest, ' ')+1:]
+	}
+	name := strings.TrimLeft(rest, " ")
+	if f[0][0] == 'l' {
+		if i := strings.Index(name, " -> "); i >= 0 {
+			name = name[:i]
+		}
+	}
+	if name == "." || name == ".." {
+		return proto.FSEntry{}, false
+	}
+	return proto.FSEntry{Name: name, IsDir: f[0][0] == 'd', Size: size, Mode: f[0]}, true
+}
+
+func randHex(n int) string {
+	b := make([]byte, n)
+	_, _ = rand.Read(b)
+	return hex.EncodeToString(b)
+}
+
+// sshfsOpen connects for a file pane and tells the host's home.
+func (a *Agent) sshfsOpen(ctx context.Context, t proto.SSHTarget) (any, error) {
+	client, _, err := a.sshConnect(ctx, t, func(string, string) {})
+	if err != nil {
+		return nil, err
+	}
+	c := &sshfsConn{client: client, target: t, last: time.Now()}
+	out, _ := sshRun(client, "stat -c %F / >/dev/null 2>&1 && echo GNU; stat -f %HT / >/dev/null 2>&1 && echo BSD; "+
+		"command -v zip >/dev/null 2>&1 && echo ZIP; command -v unzip >/dev/null 2>&1 && echo UNZIP; "+
+		"command -v python3 >/dev/null 2>&1 && echo PY; echo \"$HOME\"")
+	lines := strings.Split(strings.TrimSpace(out), "\n")
+	switch {
+	case strings.Contains(out, "GNU"):
+		c.statFmt = "gnu"
+	case strings.Contains(out, "BSD"):
+		c.statFmt = "bsd"
+	default:
+		c.statFmt = "ls"
+	}
+	c.home = strings.TrimSpace(lines[len(lines)-1])
+	if !strings.HasPrefix(c.home, "/") {
+		c.home = "/"
+	}
+	id := randHex(12)
+	sshfsConns.Store(id, c)
+	sshfsJanitor.Do(func() { go sshfsSweep() })
+	// zip and unzip, where the host has them, for the pane's buttons.
+	return map[string]any{"id": id, "home": c.home,
+		"zip": hasLine(lines, "ZIP") || hasLine(lines, "PY"), "unzip": hasLine(lines, "UNZIP") || hasLine(lines, "PY")}, nil
+}
+
+func hasLine(lines []string, w string) bool {
+	for _, l := range lines {
+		if strings.TrimSpace(l) == w {
+			return true
+		}
+	}
+	return false
+}
+
+// sshfsSweep closes connections nobody used for sshfsIdle.
+func sshfsSweep() {
+	for range time.Tick(time.Minute) {
+		sshfsConns.Range(func(k, v any) bool {
+			if v.(*sshfsConn).idle(time.Now()) {
+				sshfsClose(k.(string))
+			}
+			return true
+		})
+	}
+}
+
+func sshfsClose(id string) {
+	if v, ok := sshfsConns.LoadAndDelete(id); ok {
+		_ = v.(*sshfsConn).client.Close()
+	}
+}
+
+func sshfsGet(id string) (*sshfsConn, error) {
+	v, ok := sshfsConns.Load(id)
+	if !ok {
+		return nil, errors.New("подключение закрыто - откройте файлы по SSH снова")
+	}
+	c := v.(*sshfsConn)
+	c.mu.Lock()
+	c.last = time.Now()
+	c.mu.Unlock()
+	return c, nil
+}
+
+// session opens an SSH session on the connection; a connection that dropped
+// is opened again once.
+func (a *Agent) sshfsSession(c *sshfsConn) (*ssh.Session, error) {
+	c.mu.Lock()
+	client := c.client
+	c.mu.Unlock()
+	s, err := client.NewSession()
+	if err == nil {
+		return s, nil
+	}
+	ctx, cancel := context.WithTimeout(context.Background(), 40*time.Second)
+	defer cancel()
+	nc, _, cerr := a.sshConnect(ctx, c.target, func(string, string) {})
+	if cerr != nil {
+		return nil, fmt.Errorf("подключение к хосту потеряно: %v", cerr)
+	}
+	c.mu.Lock()
+	_ = c.client.Close()
+	c.client = nc
+	c.mu.Unlock()
+	return nc.NewSession()
+}
+
+// run runs cmd on the host with stdin, returning its output; a failure
+// carries what the command said on stderr.
+func (a *Agent) sshfsRun(c *sshfsConn, cmd string, stdin io.Reader) ([]byte, error) {
+	s, err := a.sshfsSession(c)
+	if err != nil {
+		return nil, err
+	}
+	defer s.Close()
+	var out, errb bytes.Buffer
+	s.Stdout = &out
+	s.Stderr = &limitBuf{b: &errb, max: 4096}
+	if stdin != nil {
+		s.Stdin = stdin
+	}
+	if err := s.Run(posix(cmd)); err != nil {
+		msg := strings.TrimSpace(errb.String())
+		if msg == "" {
+			msg = err.Error()
+		}
+		if len(msg) > 300 {
+			msg = msg[:300]
+		}
+		return out.Bytes(), errors.New(msg)
+	}
+	return out.Bytes(), nil
+}
+
+// sshfsTask runs one sshfs.* task.
+func (a *Agent) sshfsTask(ctx context.Context, env proto.TaskEnvelope) (any, error) {
+	var args proto.SSHFSArgs
+	if err := json.Unmarshal(env.Args, &args); err != nil {
+		return nil, err
+	}
+	switch env.Type {
+	case proto.TaskSSHFSOpen:
+		if args.SSH == nil {
+			return nil, errors.New("не указан хост")
+		}
+		return a.sshfsOpen(ctx, *args.SSH)
+	case proto.TaskSSHFSClose:
+		sshfsClose(args.Conn)
+		return nil, nil
+	}
+	c, err := sshfsGet(args.Conn)
+	if err != nil {
+		return nil, err
+	}
+	return a.sshfsOp(c, args.Op, args.Args)
+}
+
+func (a *Agent) sshfsOp(c *sshfsConn, op string, raw json.RawMessage) (any, error) {
+	switch op {
+	case "list":
+		var p proto.FSPathArgs
+		_ = json.Unmarshal(raw, &p)
+		dir := p.Path
+		if dir == "" || strings.HasPrefix(dir, "~") {
+			dir = c.home
+		}
+		out, err := a.sshfsRun(c, statCommand(c.statFmt, dir), nil)
+		if err != nil && len(out) == 0 {
+			return nil, err
+		}
+		entries := []proto.FSEntry{}
+		for _, line := range strings.Split(string(out), "\n") {
+			var e proto.FSEntry
+			var ok bool
+			if c.statFmt == "ls" {
+				e, ok = parseLsLine(line)
+			} else {
+				e, ok = parseStatLine(line)
+			}
+			if ok {
+				entries = append(entries, e)
+			}
+		}
+		return proto.FSListResult{Path: path.Clean(dir), Entries: entries}, nil
+	case "read":
+		var p proto.FSPathArgs
+		_ = json.Unmarshal(raw, &p)
+		size, _ := a.sshfsSize(c, p.Path)
+		out, err := a.sshfsRun(c, "head -c "+strconv.Itoa(proto.FSReadCap+1)+" -- "+shq(p.Path), nil)
+		if err != nil {
+			return nil, err
+		}
+		truncated := len(out) > proto.FSReadCap
+		if truncated {
+			out = out[:proto.FSReadCap]
+		}
+		return proto.FSReadResult{Path: p.Path, Size: size, Content: base64.StdEncoding.EncodeToString(out),
+			Truncated: truncated, Binary: !utf8.Valid(out) || bytes.IndexByte(out, 0) >= 0}, nil
+	case "write":
+		var p proto.FSWriteArgs
+		_ = json.Unmarshal(raw, &p)
+		data, err := base64.StdEncoding.DecodeString(p.Data)
+		if err != nil {
+			return nil, err
+		}
+		_, err = a.sshfsRun(c, writeCommand(p.Path), bytes.NewReader(data))
+		return map[string]string{"path": p.Path}, err
+	case "mkdir":
+		var p proto.FSPathArgs
+		_ = json.Unmarshal(raw, &p)
+		_, err := a.sshfsRun(c, "mkdir -p -- "+shq(p.Path), nil)
+		return map[string]string{"path": p.Path}, err
+	case "delete", "deltree":
+		var p proto.FSPathArgs
+		_ = json.Unmarshal(raw, &p)
+		if p.Path == "" || path.Clean(p.Path) == "/" {
+			return nil, errors.New("отказ: удаление корня запрещено")
+		}
+		flag := "-f"
+		if op == "deltree" {
+			flag = "-rf"
+		}
+		_, err := a.sshfsRun(c, "rm "+flag+" -- "+shq(p.Path), nil)
+		return map[string]string{"path": p.Path}, err
+	case "move":
+		var p proto.FSMoveArgs
+		_ = json.Unmarshal(raw, &p)
+		_, err := a.sshfsRun(c, "mv -- "+shq(p.Src)+" "+shq(p.Dst), nil)
+		return map[string]string{"src": p.Src, "dst": p.Dst}, err
+	case "copy":
+		var p proto.FSCopyArgs
+		_ = json.Unmarshal(raw, &p)
+		return nil, a.sshfsCopy(c, p)
+	case "zip":
+		var p proto.FSZipArgs
+		_ = json.Unmarshal(raw, &p)
+		cmd, err := zipCommand(p.Paths, p.Dest)
+		if err != nil {
+			return nil, err
+		}
+		_, err = a.sshfsRun(c, cmd, nil)
+		return map[string]string{"dest": p.Dest}, err
+	case "unzip":
+		var p proto.FSUnzipArgs
+		_ = json.Unmarshal(raw, &p)
+		_, err := a.sshfsRun(c, unzipCommand(p.Path, p.Dest), nil)
+		return map[string]string{"dest": p.Dest}, err
+	case "stat":
+		var p proto.FSPathArgs
+		_ = json.Unmarshal(raw, &p)
+		return a.sshfsStat(c, p.Path)
+	case "chmod":
+		var p proto.FSChmodArgs
+		_ = json.Unmarshal(raw, &p)
+		rec := ""
+		if p.Recursive {
+			rec = "-R "
+		}
+		var cmds []string
+		if p.Mode != nil {
+			cmds = append(cmds, "chmod "+rec+fmt.Sprintf("%o", *p.Mode)+" -- "+shq(p.Path))
+		}
+		if p.Owner != "" || p.Group != "" {
+			who := p.Owner
+			if p.Group != "" {
+				who += ":" + p.Group
+			}
+			cmds = append(cmds, "chown "+rec+shq(who)+" -- "+shq(p.Path))
+		}
+		if len(cmds) == 0 {
+			return nil, nil
+		}
+		_, err := a.sshfsRun(c, strings.Join(cmds, " && "), nil)
+		return map[string]string{"path": p.Path}, err
+	}
+	return nil, errors.New("неизвестная операция")
+}
+
+// zipCommand packs paths - items of one folder - into the archive dest, from
+// that folder, under their own names. Paths are absolute and names start
+// with "./", so none reads as an option.
+func zipCommand(paths []string, dest string) (string, error) {
+	if len(paths) == 0 {
+		return "", errors.New("не выбраны файлы")
+	}
+	dir := path.Dir(path.Clean(paths[0]))
+	names := make([]string, len(paths))
+	for i, p := range paths {
+		p = path.Clean(p)
+		if path.Dir(p) != dir {
+			return "", errors.New("в архив - только из одной папки")
+		}
+		names[i] = shq("./" + path.Base(p))
+	}
+	// zip where the host has it, else Python's zipfile, which most have.
+	items := strings.Join(names, " ")
+	return "cd -- " + shq(dir) + " && if command -v zip >/dev/null 2>&1; then zip -r -q -y " + shq(path.Clean(dest)) + " " + items + "; " +
+		"else python3 -m zipfile -c " + shq(path.Clean(dest)) + " " + items + "; fi", nil
+}
+
+// unzipCommand unpacks the archive p into dest (its own folder if empty),
+// replacing what is there, as on a machine.
+func unzipCommand(p, dest string) string {
+	if dest == "" {
+		dest = path.Dir(path.Clean(p))
+	}
+	return "if command -v unzip >/dev/null 2>&1; then unzip -o -q " + shq(path.Clean(p)) + " -d " + shq(path.Clean(dest)) + "; " +
+		"else python3 -m zipfile -e " + shq(path.Clean(p)) + " " + shq(path.Clean(dest)) + "; fi"
+}
+
+// writeCommand writes stdin to p through a file beside it, so a broken
+// transfer leaves the old file as it was.
+func writeCommand(p string) string {
+	tmp := path.Join(path.Dir(p), "."+path.Base(p)+".lpra-"+randHex(4))
+	return "cat > " + shq(tmp) + " && mv -f -- " + shq(tmp) + " " + shq(p) + " || { rm -f -- " + shq(tmp) + "; exit 1; }"
+}
+
+// sizeCommand tells the size of p - of its target, if a link: what cat
+// reads.
+func sizeCommand(statFmt, p string) string {
+	switch statFmt {
+	case "bsd":
+		return "stat -L -f %z -- " + shq(p)
+	case "ls":
+		return "wc -c < " + shq(p)
+	}
+	return "stat -L -c %s -- " + shq(p)
+}
+
+func (a *Agent) sshfsSize(c *sshfsConn, p string) (int64, error) {
+	out, err := a.sshfsRun(c, sizeCommand(c.statFmt, p), nil)
+	if err != nil {
+		return 0, err
+	}
+	return strconv.ParseInt(strings.TrimSpace(string(out)), 10, 64)
+}
+
+func (a *Agent) sshfsStat(c *sshfsConn, p string) (any, error) {
+	cmd := "stat -c '%F|%s|%Y|%a|%u|%g|%U|%G' -- " + shq(p)
+	if c.statFmt == "bsd" {
+		cmd = "stat -f '%HT|%z|%m|%Lp|%u|%g|%Su|%Sg' -- " + shq(p)
+	}
+	out, err := a.sshfsRun(c, cmd, nil)
+	if err != nil {
+		return nil, err
+	}
+	f := strings.Split(strings.TrimSpace(string(out)), "|")
+	if len(f) != 8 {
+		return nil, errors.New("не удалось прочитать свойства")
+	}
+	size, _ := strconv.ParseInt(f[1], 10, 64)
+	mt, _ := strconv.ParseInt(f[2], 10, 64)
+	mode, _ := strconv.ParseUint(f[3], 8, 32)
+	uid, _ := strconv.Atoi(f[4])
+	gid, _ := strconv.Atoi(f[5])
+	return proto.FSStatResult{Path: p, IsDir: strings.Contains(strings.ToLower(f[0]), "directory"), Size: size, MTime: mt,
+		Mode: uint32(mode), UID: uid, GID: gid, Owner: f[6], Group: f[7], Users: []string{}, Groups: []string{}}, nil
+}
+
+// sshfsCopy copies or moves on the host, by the conflict rule for what is
+// there already.
+func (a *Agent) sshfsCopy(c *sshfsConn, p proto.FSCopyArgs) error {
+	src, dst := shq(p.Src), shq(p.Dst)
+	exists, _ := a.sshfsRun(c, "test -e "+dst+" -o -L "+dst+" && echo EXISTS", nil)
+	there := strings.Contains(string(exists), "EXISTS")
+	if there {
+		switch p.Conflict {
+		case "replace":
+			if _, err := a.sshfsRun(c, "rm -rf -- "+dst, nil); err != nil {
+				return err
+			}
+		case "skip":
+			return nil
+		default:
+			return fmt.Errorf("%s уже существует", p.Dst)
+		}
+	}
+	cmd := "cp -a -- " + src + " " + dst
+	if p.Move {
+		cmd = "mv -- " + src + " " + dst
+	}
+	_, err := a.sshfsRun(c, cmd, nil)
+	return err
+}
+
+// doSSHFSSend sends a file of the host to the browser in pieces, as
+// doFSSend does with a local one: cat's output, piece after piece.
+func (a *Agent) doSSHFSSend(ctx context.Context, env proto.TaskEnvelope) proto.TaskResult {
+	var args proto.FSXferArgs
+	if err := json.Unmarshal(env.Args, &args); err != nil || args.Chunk <= 0 {
+		return proto.TaskResult{Error: "плохой запрос"}
+	}
+	c, err := sshfsGet(args.Conn)
+	if err != nil {
+		return proto.TaskResult{Error: err.Error()}
+	}
+	defer c.hold()()
+	size, err := a.sshfsSize(c, args.Path)
+	if err != nil {
+		return proto.TaskResult{Error: err.Error()}
+	}
+	if size > proto.FSFileCap {
+		return proto.TaskResult{Error: "файл больше 512 МБ"}
+	}
+	s, err := a.sshfsSession(c)
+	if err != nil {
+		return proto.TaskResult{Error: err.Error()}
+	}
+	defer s.Close()
+	out, _ := s.StdoutPipe()
+	if err := s.Start(posix("cat -- " + shq(args.Path))); err != nil {
+		return proto.TaskResult{Error: err.Error()}
+	}
+	// Read in order from cat, posted to the server a few at a time.
+	sizeHdr := strconv.FormatInt(size, 10)
+	n := pieceCount(size, args.Chunk)
+	pctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+	var (
+		wg    sync.WaitGroup
+		once  sync.Once
+		first error
+	)
+	fail := func(err error) { once.Do(func() { first = err; cancel() }) }
+	sem := make(chan struct{}, xferWorkers)
+	for i := 0; i < n && pctx.Err() == nil; i++ {
+		buf := make([]byte, min(int64(args.Chunk), size-int64(i)*int64(args.Chunk)))
+		if _, err := io.ReadFull(out, buf); err != nil {
+			fail(errors.New("файл изменился во время чтения: " + err.Error()))
+			break
+		}
+		select {
+		case sem <- struct{}{}:
+		case <-pctx.Done():
+		}
+		if pctx.Err() != nil {
+			break
+		}
+		wg.Add(1)
+		go func(i int, buf []byte) {
+			defer func() { <-sem; wg.Done() }()
+			err := a.xferRequest(pctx, func(ctx context.Context) (*http.Request, error) {
+				req, err := http.NewRequestWithContext(ctx, http.MethodPost, a.xferURL(args.Xfer, i), bytes.NewReader(buf))
+				if err == nil {
+					req.Header.Set("X-Size", sizeHdr)
+					req.Header.Set("Content-Type", "application/octet-stream")
+				}
+				return req, err
+			}, func(*http.Response) error { return nil })
+			if err != nil {
+				fail(errors.New("передача прервана: " + err.Error()))
+			}
+		}(i, buf)
+	}
+	wg.Wait()
+	if first == nil && ctx.Err() != nil {
+		first = ctx.Err()
+	}
+	if first != nil {
+		return proto.TaskResult{Error: first.Error()}
+	}
+	// All of it is read; the session closes (deferred) without waiting on a
+	// cat that may have more to say.
+	data, _ := json.Marshal(map[string]any{"path": args.Path, "size": size})
+	return proto.TaskResult{OK: true, Data: data}
+}
+
+// doSSHFSPut writes a file the browser uploads onto the host, through a file
+// beside it.
+func (a *Agent) doSSHFSPut(ctx context.Context, env proto.TaskEnvelope) proto.TaskResult {
+	var args proto.FSXferArgs
+	if err := json.Unmarshal(env.Args, &args); err != nil || args.Chunk <= 0 || args.Size < 0 || args.Size > proto.FSFileCap {
+		return proto.TaskResult{Error: "плохой запрос"}
+	}
+	c, err := sshfsGet(args.Conn)
+	if err != nil {
+		return proto.TaskResult{Error: err.Error()}
+	}
+	defer c.hold()()
+	s, err := a.sshfsSession(c)
+	if err != nil {
+		return proto.TaskResult{Error: err.Error()}
+	}
+	defer s.Close()
+	in, _ := s.StdinPipe()
+	var errb bytes.Buffer
+	s.Stderr = &limitBuf{b: &errb, max: 4096}
+	if err := s.Start(posix(writeCommand(args.Path))); err != nil {
+		return proto.TaskResult{Error: err.Error()}
+	}
+	// Pieces come in a few ahead; stdin takes them in order. ack: how many
+	// are written, for the server to let go.
+	n := pieceCount(args.Size, args.Chunk)
+	var written atomic.Int64
+	err = ordered(ctx, n, xferWorkers, func(ctx context.Context, i int) ([]byte, error) {
+		want := min(int64(args.Chunk), args.Size-int64(i)*int64(args.Chunk))
+		var data []byte
+		err := a.xferRequest(ctx, func(ctx context.Context) (*http.Request, error) {
+			return http.NewRequestWithContext(ctx, http.MethodGet, a.xferURL(args.Xfer, i)+"?ack="+strconv.FormatInt(written.Load(), 10), nil)
+		}, func(resp *http.Response) error {
+			b, err := io.ReadAll(io.LimitReader(resp.Body, int64(args.Chunk)+1))
+			if err == nil && int64(len(b)) != want {
+				err = errors.New("кусок не той длины")
+			}
+			data = b
+			return err
+		})
+		return data, err
+	}, func(i int, b []byte) error {
+		_, err := in.Write(b)
+		written.Store(int64(i + 1))
+		return err
+	})
+	if err != nil {
+		_ = s.Close()
+		return proto.TaskResult{Error: "загрузка прервана: " + err.Error()}
+	}
+	_ = in.Close()
+	if err := s.Wait(); err != nil {
+		msg := strings.TrimSpace(errb.String())
+		if msg == "" {
+			msg = err.Error()
+		}
+		return proto.TaskResult{Error: msg}
+	}
+	data, _ := json.Marshal(map[string]any{"path": args.Path, "size": args.Size})
+	return proto.TaskResult{OK: true, Data: data}
+}
+
+// renameTar copies a tar stream, giving each top entry named in names - and
+// everything under it - its new name: what the host's tar packs under the
+// file's own name arrives under the name chosen for it. Other entries (the
+// "._" companions a macOS tar adds) are left out.
+func renameTar(w io.Writer, r io.Reader, names map[string]string) error {
+	tr, tw := tar.NewReader(r), tar.NewWriter(w)
+	for {
+		h, err := tr.Next()
+		if err == io.EOF {
+			return tw.Close()
+		}
+		if err != nil {
+			return err
+		}
+		n := strings.TrimPrefix(h.Name, "./")
+		top, rest := n, ""
+		if i := strings.IndexByte(n, '/'); i >= 0 {
+			top, rest = n[:i], n[i:]
+		}
+		// Only base and what is under it - nothing that climbs out by "..".
+		name, ok := names[top]
+		if !ok || strings.Contains("/"+rest+"/", "/../") {
+			continue
+		}
+		h.Name = name + rest
+		h.Uid, h.Gid, h.Uname, h.Gname = 0, 0, "", ""
+		if err := tw.WriteHeader(h); err != nil {
+			return err
+		}
+		if _, err := io.Copy(tw, tr); err != nil {
+			return err
+		}
+	}
+}
+
+// packRemote writes src on the connection's host as a tar stream named name,
+// counting what goes for the progress.
+func (a *Agent) packRemote(ctx context.Context, w io.Writer, c *sshfsConn, srcs, names []string, m *shipMeter) error {
+	defer c.hold()()
+	s, err := a.sshfsSession(c)
+	if err != nil {
+		return err
+	}
+	defer s.Close()
+	go func() { <-ctx.Done(); s.Close() }()
+	out, _ := s.StdoutPipe()
+	var errb bytes.Buffer
+	s.Stderr = &limitBuf{b: &errb, max: 4096}
+	// All from one folder: packed from there by their own names.
+	dir := path.Dir(path.Clean(srcs[0]))
+	rename := map[string]string{}
+	cmd := "COPYFILE_DISABLE=1 tar -cf - -C " + shq(dir) + " --"
+	for i, p := range srcs {
+		b := path.Base(path.Clean(p))
+		rename[b] = names[i]
+		cmd += " " + shq(b)
+	}
+	if err := s.Start(posix(cmd)); err != nil {
+		return err
+	}
+	if err := renameTar(w, &countReader{r: out, n: &m.done}, rename); err != nil {
+		return err
+	}
+	if err := s.Wait(); err != nil {
+		if msg := strings.TrimSpace(errb.String()); msg != "" {
+			return errors.New("tar на хосте: " + msg)
+		}
+		return err
+	}
+	return nil
+}
+
+// remoteSize is about how many bytes src takes on the host, for progress.
+func (a *Agent) remoteSize(c *sshfsConn, src string) int64 {
+	out, err := a.sshfsRun(c, "du -sk -- "+shq(src), nil)
+	if err != nil {
+		return 0
+	}
+	f := strings.Fields(string(out))
+	if len(f) == 0 {
+		return 0
+	}
+	kb, _ := strconv.ParseInt(f[0], 10, 64)
+	return kb * 1024
+}
+
+// unpackRemote puts a tar stream into dir on the connection's host, by the
+// conflict rule: tar keeps or replaces what is there, an "error" rule
+// refuses when name is there already.
+func (a *Agent) unpackRemote(c *sshfsConn, r io.Reader, dir string, names []string, conflict string) (skipped int, err error) {
+	defer c.hold()()
+	base := strings.TrimSuffix(dir, "/") + "/"
+	check := ""
+	for _, n := range names {
+		check += "test -e " + shq(base+n) + " -o -L " + shq(base+n) + " && echo " + shq("LPRA_EXISTS "+n) + "; "
+	}
+	out, _ := a.sshfsRun(c, check+"true", nil)
+	keep := map[string]string{}
+	var put []string
+	for _, n := range names {
+		if strings.Contains(string(out), "LPRA_EXISTS "+n+"\n") {
+			switch conflict {
+			case "skip":
+				// Left as it was, as on a machine.
+				skipped++
+				continue
+			case "replace":
+			default:
+				return 0, errors.New(base + n + " уже существует")
+			}
+		}
+		keep[n] = n
+		put = append(put, n)
+	}
+	if len(put) == 0 {
+		return skipped, nil
+	}
+	// Only the items sent (and not kept back) reach the host's tar.
+	pr, pw := io.Pipe()
+	go func() { pw.CloseWithError(renameTar(pw, r, keep)) }()
+	defer pr.Close()
+	_, err = a.sshfsRun(c, unpackCommand(dir, put, conflict), pr)
+	return skipped, err
+}
+
+// unpackCommand unpacks a tar stream of names into dir; "replace" removes
+// what is there first, so each thing is replaced whole as on a machine.
+func unpackCommand(dir string, names []string, conflict string) string {
+	cmd := "mkdir -p -- " + shq(dir) + " && cd -- " + shq(dir) + " && tar -xf -"
+	if conflict == "replace" {
+		rm := "rm -rf --"
+		for _, n := range names {
+			rm += " " + shq(strings.TrimSuffix(dir, "/")+"/"+n)
+		}
+		cmd = rm + " && " + cmd
+	}
+	return cmd
+}
@@ -0,0 +1,242 @@
+package agent
+
+import (
+	"archive/tar"
+	"bytes"
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+	"time"
+)
+
+func TestParseStatLine(t *testing.T) {
+	// statCommand prints: type|size|mtime|mode|name
+	e, ok := parseStatLine("directory|4096|1760000000|drwxr-xr-x|my dir")
+	if !ok || !e.IsDir || e.Name != "my dir" || e.MTime != 1760000000 || e.Mode != "drwxr-xr-x" {
+		t.Fatalf("dir: %+v %v", e, ok)
+	}
+	e, ok = parseStatLine("regular file|12|1760000001|-rw-r--r--|a|b.txt")
+	if !ok || e.IsDir || e.Size != 12 || e.Name != "a|b.txt" {
+		t.Fatalf("file with | in name: %+v %v", e, ok)
+	}
+	if _, ok := parseStatLine("garbage"); ok {
+		t.Fatal("garbage parsed")
+	}
+}
+
+func TestStatCommandQuotes(t *testing.T) {
+	for _, fl := range []string{"gnu", "bsd"} {
+		c := statCommand(fl, "/srv/it's here")
+		if !strings.Contains(c, `'/srv/it'\''s here/'`) {
+			t.Errorf("%s: dir not quoted: %s", fl, c)
+		}
+	}
+}
+
+func TestParseLsLine(t *testing.T) {
+	e, ok := parseLsLine("-rw-r--r--  1 root root  1234 Oct 15 10:00 my file.txt")
+	if !ok || e.Name != "my file.txt" || e.Size != 1234 || e.IsDir {
+		t.Fatalf("file: %+v %v", e, ok)
+	}
+	e, ok = parseLsLine("lrwxrwxrwx  1 root root     7 Oct 15 10:00 link -> target")
+	if !ok || e.Name != "link" {
+		t.Fatalf("link: %+v %v", e, ok)
+	}
+	if _, ok := parseLsLine("drwxr-xr-x  2 root root  4096 Oct 15 10:00 .."); ok {
+		t.Fatal(".. listed")
+	}
+	if _, ok := parseLsLine("total 8"); ok {
+		t.Fatal("total parsed")
+	}
+}
+
+func TestRenameTarEntries(t *testing.T) {
+	var src bytes.Buffer
+	tw := tar.NewWriter(&src)
+	for _, n := range []string{"old/", "old/a.txt", "old/sub/b"} {
+		typ := byte(tar.TypeReg)
+		if strings.HasSuffix(n, "/") {
+			typ = tar.TypeDir
+		}
+		_ = tw.WriteHeader(&tar.Header{Name: n, Mode: 0o644, Typeflag: typ})
+	}
+	_ = tw.Close()
+	var out bytes.Buffer
+	if err := renameTar(&out, &src, map[string]string{"old": "new"}); err != nil {
+		t.Fatal(err)
+	}
+	tr := tar.NewReader(&out)
+	var names []string
+	for {
+		h, err := tr.Next()
+		if err != nil {
+			break
+		}
+		names = append(names, h.Name)
+	}
+	if strings.Join(names, ",") != "new/,new/a.txt,new/sub/b" {
+		t.Fatalf("names: %v", names)
+	}
+}
+
+// A macOS host's tar packs "._name" companions with the file's attributes;
+// they are not the file and must not land under its name.
+func TestRenameTarDropsOtherEntries(t *testing.T) {
+	var src bytes.Buffer
+	tw := tar.NewWriter(&src)
+	for _, e := range []struct{ n, body string }{{"./._r.txt", "attrs"}, {"./r.txt", "data"}} {
+		_ = tw.WriteHeader(&tar.Header{Name: e.n, Mode: 0o644, Typeflag: tar.TypeReg, Size: int64(len(e.body))})
+		_, _ = tw.Write([]byte(e.body))
+	}
+	_ = tw.Close()
+	var out bytes.Buffer
+	if err := renameTar(&out, &src, map[string]string{"r.txt": "new.txt"}); err != nil {
+		t.Fatal(err)
+	}
+	tr := tar.NewReader(&out)
+	var got []string
+	for {
+		h, err := tr.Next()
+		if err != nil {
+			break
+		}
+		b, _ := io.ReadAll(tr)
+		got = append(got, h.Name+"="+string(b))
+	}
+	if strings.Join(got, ",") != "new.txt=data" {
+		t.Fatalf("entries: %v", got)
+	}
+}
+
+// zip on an SSH host: from the items' folder, by their own names, quoted.
+func TestZipCommand(t *testing.T) {
+	cmd, err := zipCommand([]string{"/srv/a b", "/srv/it's"}, "/tmp/x.zip")
+	if err != nil {
+		t.Fatal(err)
+	}
+	want := `cd -- '/srv' && if command -v zip >/dev/null 2>&1; then zip -r -q -y '/tmp/x.zip' './a b' './it'\''s'; ` +
+		`else python3 -m zipfile -c '/tmp/x.zip' './a b' './it'\''s'; fi`
+	if cmd != want {
+		t.Fatalf("got  %s\nwant %s", cmd, want)
+	}
+	if _, err := zipCommand([]string{"/a/x", "/b/y"}, "/t.zip"); err == nil {
+		t.Fatal("items of two folders: want an error")
+	}
+	if _, err := zipCommand(nil, "/t.zip"); err == nil {
+		t.Fatal("no items: want an error")
+	}
+	if got := unzipCommand("/srv/a.zip", ""); got != `if command -v unzip >/dev/null 2>&1; then unzip -o -q '/srv/a.zip' -d '/srv'; else python3 -m zipfile -e '/srv/a.zip' '/srv'; fi` {
+		t.Fatalf("unzip: %s", got)
+	}
+}
+
+// A connection busy with a long transfer is not idle, however long ago it
+// was opened; once the transfer ends the idle clock starts again.
+func TestSweepSparesBusyConn(t *testing.T) {
+	c := &sshfsConn{last: time.Now().Add(-2 * sshfsIdle)}
+	release := c.hold()
+	if c.idle(time.Now()) {
+		t.Fatal("a busy connection was taken for idle")
+	}
+	release()
+	if c.idle(time.Now()) {
+		t.Fatal("just released: not idle yet")
+	}
+	if !c.idle(time.Now().Add(2 * sshfsIdle)) {
+		t.Fatal("unused for long: idle")
+	}
+}
+
+// A file's size is its target's when it is a link: what cat will read.
+func TestSizeCommandFollowsLinks(t *testing.T) {
+	for _, f := range []string{"gnu", "bsd"} {
+		if cmd := sizeCommand(f, "/x"); !strings.Contains(cmd, "stat -L ") {
+			t.Fatalf("%s: %s", f, cmd)
+		}
+	}
+}
+
+// Nothing of a tar stream lands outside name: other entries and ".." paths
+// are dropped.
+func TestRenameTarKeepsInsideName(t *testing.T) {
+	var src bytes.Buffer
+	tw := tar.NewWriter(&src)
+	for _, n := range []string{"d/a", "d/../../etc/x", ".ssh/authorized_keys", "d/b"} {
+		_ = tw.WriteHeader(&tar.Header{Name: n, Mode: 0o644, Typeflag: tar.TypeReg})
+	}
+	_ = tw.Close()
+	var out bytes.Buffer
+	if err := renameTar(&out, &src, map[string]string{"d": "d"}); err != nil {
+		t.Fatal(err)
+	}
+	tr := tar.NewReader(&out)
+	var got []string
+	for {
+		h, err := tr.Next()
+		if err != nil {
+			break
+		}
+		got = append(got, h.Name)
+	}
+	if strings.Join(got, ",") != "d/a,d/b" {
+		t.Fatalf("entries: %v", got)
+	}
+}
+
+// Into an SSH host, "replace" replaces the thing whole, as on a machine.
+func TestUnpackCommandReplaces(t *testing.T) {
+	cmd := unpackCommand("/srv", []string{"d"}, "replace")
+	if !strings.HasPrefix(cmd, "rm -rf -- '/srv/d' && ") || strings.Contains(cmd, "--overwrite") {
+		t.Fatalf("replace: %s", cmd)
+	}
+	if cmd := unpackCommand("/srv", []string{"d"}, "error"); cmd != "mkdir -p -- '/srv' && cd -- '/srv' && tar -xf -" {
+		t.Fatalf("error: %s", cmd)
+	}
+}
+
+// A link to a folder lists as a folder (marked as a link), so it opens.
+func TestParseStatLineFolderLink(t *testing.T) {
+	e, ok := parseStatLine("LD|symbolic link|7|1700000000|lrwxrwxrwx|www")
+	if !ok || !e.IsDir || !e.Link || e.Name != "www" {
+		t.Fatalf("%+v %v", e, ok)
+	}
+	e, ok = parseStatLine("|regular file|5|1700000000|-rw-r--r--|a|b")
+	if !ok || e.IsDir || e.Name != "a|b" {
+		t.Fatalf("plain: %+v %v", e, ok)
+	}
+	if !strings.Contains(statCommand("gnu", "/x"), `[ -L "$f" ] && [ -d "$f" ]`) {
+		t.Fatal("the command does not mark folder links")
+	}
+}
+
+func TestListFolderLink(t *testing.T) {
+	d := t.TempDir()
+	_ = os.Mkdir(filepath.Join(d, "real"), 0o755)
+	_ = os.Symlink(filepath.Join(d, "real"), filepath.Join(d, "ln"))
+	r, err := fsList(d)
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, e := range r.Entries {
+		if e.Name == "ln" && (!e.IsDir || !e.Link) {
+			t.Fatalf("link: %+v", e)
+		}
+	}
+}
+
+// Commands go to the host as one argument of sh -c, so the user's own login
+// shell (fish, csh) cannot read them its way.
+func TestPosixCommand(t *testing.T) {
+	if got := posix(`if [ -d '/x' ]; then echo ok; fi`); got != `sh -c 'if [ -d '\''/x'\'' ]; then echo ok; fi'` {
+		t.Fatalf("%s", got)
+	}
+}
+
+// csh expands "!" even inside single quotes: it goes out as '\!'.
+func TestPosixCommandBang(t *testing.T) {
+	if got := posix(`ls .[!.]*`); got != `sh -c 'ls .['\!'.]*'` {
+		t.Fatalf("%s", got)
+	}
+}
@@ -0,0 +1,45 @@
+package agent
+
+import (
+	"runtime"
+	"sync"
+	"syscall"
+
+	"github.com/x-grk/longpolling-remote-access/internal/proto"
+)
+
+// statMu serializes samples: the CPU figure is a delta against the last one.
+var statMu sync.Mutex
+
+// sysStat samples the machine's load. It costs nothing while nobody asks: the
+// panel requests it only for an open status page.
+func sysStat() (proto.SysStatResult, error) {
+	statMu.Lock()
+	defer statMu.Unlock()
+	res := proto.SysStatResult{NCPU: runtime.NumCPU()}
+	cpu, err := cpuPercent()
+	if err != nil {
+		return res, err
+	}
+	res.CPU = cpu
+	if res.MemTotal, res.MemUsed, err = memUsage(); err != nil {
+		return res, err
+	}
+	var fs syscall.Statfs_t
+	if err := syscall.Statfs("/", &fs); err != nil {
+		return res, err
+	}
+	res.DiskTotal = uint64(fs.Blocks) * uint64(fs.Bsize)
+	res.DiskFree = uint64(fs.Bavail) * uint64(fs.Bsize)
+	return res, nil
+}
+
+func clampPercent(v float64) float64 {
+	if v < 0 {
+		return 0
+	}
+	if v > 100 {
+		return 100
+	}
+	return v
+}
@@ -0,0 +1,43 @@
+package agent
+
+import (
+	"bytes"
+	"os/exec"
+	"runtime"
+	"strconv"
+
+	"golang.org/x/sys/unix"
+)
+
+// cpuPercent sums the per-process CPU shares ps reports. macOS exposes the
+// host CPU ticks only through Mach calls, which need cgo.
+func cpuPercent() (float64, error) {
+	out, err := exec.Command("/bin/ps", "-A", "-o", "%cpu=").Output()
+	if err != nil {
+		return 0, err
+	}
+	var sum float64
+	for _, f := range bytes.Fields(out) {
+		// Some locales print a decimal comma.
+		v, _ := strconv.ParseFloat(string(bytes.Replace(f, []byte(","), []byte("."), 1)), 64)
+		sum += v
+	}
+	return clampPercent(sum / float64(runtime.NumCPU())), nil
+}
+
+// memUsage takes the kernel's own share of memory still available
+// (kern.memorystatus_level, what `memory_pressure` prints).
+func memUsage() (total, used uint64, err error) {
+	total, err = unix.SysctlUint64("hw.memsize")
+	if err != nil {
+		return 0, 0, err
+	}
+	level, err := unix.SysctlUint32("kern.memorystatus_level")
+	if err != nil {
+		return 0, 0, err
+	}
+	if level > 100 {
+		level = 100
+	}
+	return total, total / 100 * uint64(100-level), nil
+}
@@ -0,0 +1,121 @@
+package agent
+
+import (
+	"bytes"
+	"errors"
+	"os"
+	"strconv"
+	"time"
+)
+
+// Previous /proc/stat reading; the load is the busy share of the ticks since.
+var (
+	cpuPrevIdle, cpuPrevTotal uint64
+	cpuPrevAt                 time.Time
+)
+
+// cpuStaleAfter is how old the previous reading may be: past it the delta
+// would average over a stretch nobody was watching, so take a fresh pair.
+const cpuStaleAfter = 15 * time.Second
+
+func cpuPercent() (float64, error) {
+	if time.Since(cpuPrevAt) > cpuStaleAfter {
+		idle, total, err := readCPUTicks()
+		if err != nil {
+			return 0, err
+		}
+		cpuPrevIdle, cpuPrevTotal = idle, total
+		time.Sleep(200 * time.Millisecond)
+	}
+	idle, total, err := readCPUTicks()
+	if err != nil {
+		return 0, err
+	}
+	dIdle, dTotal := idle-cpuPrevIdle, total-cpuPrevTotal
+	cpuPrevIdle, cpuPrevTotal, cpuPrevAt = idle, total, time.Now()
+	if dTotal == 0 || dIdle > dTotal {
+		return 0, nil
+	}
+	return clampPercent(100 * float64(dTotal-dIdle) / float64(dTotal)), nil
+}
+
+// readCPUTicks parses the aggregate "cpu" line of /proc/stat:
+// user nice system idle iowait irq softirq steal ...
+func readCPUTicks() (idle, total uint64, err error) {
+	var buf [512]byte
+	f, err := os.Open("/proc/stat")
+	if err != nil {
+		return 0, 0, err
+	}
+	n, _ := f.Read(buf[:])
+	f.Close()
+	line := buf[:n]
+	if i := bytes.IndexByte(line, '\n'); i >= 0 {
+		line = line[:i]
+	}
+	fields := bytes.Fields(line)
+	if len(fields) < 5 || string(fields[0]) != "cpu" {
+		return 0, 0, errors.New("unexpected /proc/stat")
+	}
+	for i, f := range fields[1:] {
+		if i >= 8 { // guest time is already counted in user/nice
+			break
+		}
+		v, _ := strconv.ParseUint(string(f), 10, 64)
+		total += v
+		if i == 3 || i == 4 { // idle, iowait
+			idle += v
+		}
+	}
+	return idle, total, nil
+}
+
+// memUsage reads /proc/meminfo; used is everything not available to new
+// processes (so page cache does not count as used).
+func memUsage() (total, used uint64, err error) {
+	data, err := os.ReadFile("/proc/meminfo")
+	if err != nil {
+		return 0, 0, err
+	}
+	var avail, free uint64
+	var haveAvail bool
+	for len(data) > 0 {
+		line := data
+		if i := bytes.IndexByte(data, '\n'); i >= 0 {
+			line, data = data[:i], data[i+1:]
+		} else {
+			data = nil
+		}
+		switch {
+		case bytes.HasPrefix(line, []byte("MemTotal:")):
+			total = meminfoKB(line)
+		case bytes.HasPrefix(line, []byte("MemFree:")):
+			free = meminfoKB(line)
+		case bytes.HasPrefix(line, []byte("MemAvailable:")):
+			avail, haveAvail = meminfoKB(line), true
+		}
+		if haveAvail && total > 0 {
+			break
+		}
+	}
+	if total == 0 {
+		return 0, 0, errors.New("unexpected /proc/meminfo")
+	}
+	if !haveAvail {
+		avail = free
+	}
+	if avail > total {
+		avail = total
+	}
+	return total, total - avail, nil
+}
+
+// meminfoKB returns the value of a "Key:   123 kB" line in bytes.
+func meminfoKB(line []byte) uint64 {
+	f := bytes.Fields(line)
+	if len(f) < 2 {
+		return 0
+	}
+	v, _ := strconv.ParseUint(string(f[1]), 10, 64)
+	return v * 1024
+}
@@ -17,9 +17,26 @@ func (a *Agent) runTask(ctx context.Context, taskID string) {
 		return
 	}
 	var res proto.TaskResult
-	if env.Type == proto.TaskSysUpdate {
+	switch env.Type {
+	case proto.TaskSysUpdate:
 		res = a.doUpdate()
-	} else {
+	case proto.TaskSysSpeed:
+		res = a.doSpeed(ctx, env)
+	case proto.TaskFSPut:
+		res = a.doFSPut(ctx, env)
+	case proto.TaskFSSend:
+		res = a.doFSSend(ctx, env)
+	case proto.TaskSSHFSSend:
+		res = a.doSSHFSSend(ctx, env)
+	case proto.TaskSSHFSPut:
+		res = a.doSSHFSPut(ctx, env)
+	case proto.TaskSSHFSOpen, proto.TaskSSHFSClose, proto.TaskSSHFSOp:
+		res = resultOf(a.sshfsTask(ctx, env))
+	case proto.TaskFSShipOut:
+		res = a.doShipOut(ctx, env)
+	case proto.TaskFSShipIn:
+		res = a.doShipIn(ctx, env)
+	default:
 		res = a.execTask(env)
 	}
 	a.postResult(ctx, taskID, res)
@@ -27,7 +44,7 @@ func (a *Agent) runTask(ctx context.Context, taskID string) {

 func (a *Agent) fetchTask(ctx context.Context, taskID string) (proto.TaskEnvelope, error) {
 	var env proto.TaskEnvelope
-	req, _ := http.NewRequestWithContext(ctx, http.MethodGet, a.cfg.Host+"/api/agent/task/"+taskID, nil)
+	req, _ := http.NewRequestWithContext(ctx, http.MethodGet, a.host()+"/api/agent/task/"+taskID, nil)
 	a.authHeaders(req)
 	resp, err := a.http.Do(req)
 	if err != nil {
@@ -43,7 +60,7 @@ func (a *Agent) fetchTask(ctx context.Context, taskID string) (proto.TaskEnvelop

 func (a *Agent) postResult(ctx context.Context, taskID string, res proto.TaskResult) {
 	body, _ := json.Marshal(res)
-	req, _ := http.NewRequestWithContext(ctx, http.MethodPost, a.cfg.Host+"/api/agent/task/"+taskID+"/result", bytes.NewReader(body))
+	req, _ := http.NewRequestWithContext(ctx, http.MethodPost, a.host()+"/api/agent/task/"+taskID+"/result", bytes.NewReader(body))
 	a.authHeaders(req)
 	req.Header.Set("Content-Type", "application/json")
 	resp, err := a.http.Do(req)
@@ -96,3 +113,15 @@ func itoa64(n int64) string {
 	}
 	return string(b[i:])
 }
+
+// resultOf makes a task's result of what it returned.
+func resultOf(data any, err error) proto.TaskResult {
+	if err != nil {
+		return proto.TaskResult{Error: err.Error()}
+	}
+	raw, err := json.Marshal(data)
+	if err != nil {
+		return proto.TaskResult{Error: err.Error()}
+	}
+	return proto.TaskResult{OK: true, Data: raw}
+}
@@ -0,0 +1,62 @@
+package agent
+
+import (
+	"errors"
+	"os"
+	"os/exec"
+	"runtime"
+	"strconv"
+	"strings"
+	"sync"
+
+	"golang.org/x/sys/unix"
+)
+
+// termsBySID are the running terminals by their session, so the panel can
+// ask where one of them is.
+var termsBySID sync.Map // sid -> *PTY
+
+// Cwd is the folder the terminal is in now: that of the program in front
+// (the shell, or what it runs), else of the shell itself.
+func (p *PTY) Cwd() (string, error) {
+	pid := 0
+	if g, err := unix.IoctlGetInt(int(p.f.Fd()), unix.TIOCGPGRP); err == nil && g > 0 {
+		pid = g
+	}
+	if pid > 0 {
+		if d, err := procCwd(pid); err == nil {
+			return d, nil
+		}
+	}
+	return procCwd(p.cmd.Process.Pid)
+}
+
+// procCwd is a process's working folder: /proc on Linux, lsof elsewhere.
+func procCwd(pid int) (string, error) {
+	if runtime.GOOS == "linux" {
+		return os.Readlink("/proc/" + strconv.Itoa(pid) + "/cwd")
+	}
+	out, err := exec.Command("lsof", "-a", "-p", strconv.Itoa(pid), "-d", "cwd", "-Fn").Output()
+	if err != nil {
+		return "", err
+	}
+	for _, l := range strings.Split(string(out), "\n") {
+		if strings.HasPrefix(l, "n/") {
+			return l[1:], nil
+		}
+	}
+	return "", errors.New("папка терминала не найдена")
+}
+
+// termCwd answers the panel: where the terminal of session sid is now.
+func termCwd(sid string) (any, error) {
+	v, ok := termsBySID.Load(sid)
+	if !ok {
+		return nil, errors.New("терминал не найден")
+	}
+	d, err := v.(*PTY).Cwd()
+	if err != nil {
+		return nil, err
+	}
+	return map[string]string{"path": d}, nil
+}
@@ -4,24 +4,65 @@ import (
 	"fmt"
 	"os"
 	"os/exec"
+	"path/filepath"
+	"strings"
+	"sync"
+	"syscall"
+	"time"

 	"github.com/creack/pty"
 )

 // PTY is a pseudo-terminal running an interactive login shell.
 type PTY struct {
-	cmd *exec.Cmd
-	f   *os.File
+	cmd    *exec.Cmd
+	f      *os.File
+	exited chan struct{} // closed once the shell has exited
+	once   sync.Once
+}
+
+// hangupGrace is how long a shell gets after the hangup to save its history
+// and exit before it is killed.
+const hangupGrace = 3 * time.Second
+
+// openPTYs are the terminals running now, to close on shutdown.
+var openPTYs sync.Map // *PTY -> struct{}
+
+// CloseTerminals hangs up every open terminal and waits for them, so the
+// shells save their history before the agent exits.
+func CloseTerminals() {
+	var wg sync.WaitGroup
+	openPTYs.Range(func(k, _ any) bool {
+		wg.Add(1)
+		go func() { defer wg.Done(); k.(*PTY).Close() }()
+		return true
+	})
+	wg.Wait()
 }

 // StartPTY launches a login shell attached to a new PTY. With user empty (or
-// equal to the agent's own user) it is the agent's shell — root by default,
+// equal to the agent's own user) it is the agent's shell - root by default,
 // since the agent runs as a root systemd service. Any other user is entered via
-// `su -l`, which only a root agent can do without a password.
-func StartPTY(user string) (*PTY, error) {
+// `su -l`, which only a root agent can do without a password. dir, when it
+// is a folder, is where the shell starts instead of home.
+func StartPTY(user, dir string) (*PTY, error) {
+	if dir != "" && (!filepath.IsAbs(dir) || strings.ContainsAny(dir, "\x00\r\n") || !isDir(dir)) {
+		dir = ""
+	}
 	var cmd *exec.Cmd
+	env := append(os.Environ(), "TERM=xterm-256color")
 	if user == "" || user == currentUser() {
 		cmd = exec.Command(defaultShell(), "-l")
+		// A login shell does not change directory by itself: it would start
+		// where the service runs, "/". Start it at home, and say where home
+		// is, as a root service often has no $HOME.
+		if home := homeDir(""); isDir(home) {
+			cmd.Dir = home
+			env = append(env, "HOME="+home)
+		}
+		if dir != "" {
+			cmd.Dir = dir
+		}
 	} else {
 		if !validUserName(user) {
 			return nil, fmt.Errorf("недопустимое имя пользователя %q", user)
@@ -37,13 +78,31 @@ func StartPTY(user string) (*PTY, error) {
 			return nil, fmt.Errorf("su не найден: %w", err)
 		}
 		cmd = exec.Command(su, "-l", user)
+		// su -l always goes home; to start elsewhere, its shell changes
+		// directory first and becomes the login shell (sh and csh alike).
+		if dir != "" {
+			cmd = exec.Command(su, "-l", user, "-c", "cd "+shQuote(dir)+"; exec \"$SHELL\" -l")
+		}
+		// su -l goes to the user's home; starting there too keeps the shell
+		// out of "/" should it not.
+		if home := homeDir(user); isDir(home) {
+			cmd.Dir = home
+		}
 	}
-	cmd.Env = append(os.Environ(), "TERM=xterm-256color")
+	cmd.Env = env
 	f, err := pty.Start(cmd)
 	if err != nil {
 		return nil, err
 	}
-	return &PTY{cmd: cmd, f: f}, nil
+	p := &PTY{cmd: cmd, f: f, exited: make(chan struct{})}
+	go func() { _ = cmd.Wait(); close(p.exited) }()
+	openPTYs.Store(p, struct{}{})
+	return p, nil
+}
+
+func isDir(p string) bool {
+	info, err := os.Stat(p)
+	return err == nil && info.IsDir()
 }

 // Read reads terminal output.
@@ -60,12 +119,30 @@ func (p *PTY) Resize(cols, rows uint16) {
 	_ = pty.Setsize(p.f, &pty.Winsize{Rows: rows, Cols: cols})
 }

-// Close terminates the shell and releases the PTY.
+// Close hangs the terminal up as a closed window would: the shell gets
+// SIGHUP, saves its history and exits. One that does not within hangupGrace
+// is killed. Safe to call more than once.
 func (p *PTY) Close() error {
-	err := p.f.Close()
-	if p.cmd.Process != nil {
-		_ = p.cmd.Process.Kill()
-	}
-	_ = p.cmd.Wait()
+	var err error
+	p.once.Do(func() {
+		// Closing the master hangs up the session; the signal to the
+		// shell's process group makes sure it hears, through su as well.
+		err = p.f.Close()
+		pid := p.cmd.Process.Pid
+		_ = syscall.Kill(-pid, syscall.SIGHUP)
+		select {
+		case <-p.exited:
+		case <-time.After(hangupGrace):
+			_ = syscall.Kill(-pid, syscall.SIGKILL)
+			<-p.exited
+		}
+		openPTYs.Delete(p)
+	})
 	return err
 }
+
+// shQuote puts s in single quotes for sh and csh alike, closing and
+// reopening them around each quote inside.
+func shQuote(s string) string {
+	return "'" + strings.ReplaceAll(s, "'", `'\''`) + "'"
+}
@@ -0,0 +1,115 @@
+package agent
+
+import (
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/x-grk/longpolling-remote-access/internal/proto"
+)
+
+// A terminal opened with a folder starts its shell there; a folder that is
+// not there leaves it at home.
+func TestStartPTYDir(t *testing.T) {
+	dir, err := filepath.EvalSymlinks(t.TempDir())
+	if err != nil {
+		t.Fatal(err)
+	}
+	sub := filepath.Join(dir, "sub dir")
+	if err := os.Mkdir(sub, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if got := ptyPwd(t, sub); got != sub {
+		t.Fatalf("pwd = %q, want %q", got, sub)
+	}
+	home, _ := filepath.EvalSymlinks(homeDir(""))
+	if got := ptyPwd(t, filepath.Join(dir, "missing")); got != home {
+		t.Fatalf("pwd for a missing folder = %q, want home %q", got, home)
+	}
+}
+
+// ptyPwd opens a terminal at dir and returns where its shell is.
+func ptyPwd(t *testing.T, dir string) string {
+	t.Helper()
+	t.Setenv("SHELL", "/bin/sh")
+	p, err := StartPTY("", dir)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer p.Close()
+	if _, err := p.Write([]byte("echo \"@@$(pwd -P)@@\"\n")); err != nil {
+		t.Fatal(err)
+	}
+	var out strings.Builder
+	buf := make([]byte, 4096)
+	deadline := time.Now().Add(5 * time.Second)
+	for time.Now().Before(deadline) {
+		n, err := p.Read(buf)
+		out.Write(buf[:n])
+		s := out.String()
+		// The echoed command line has "@@$(pwd" in it; the answer does not.
+		for _, part := range strings.Split(s, "@@") {
+			if strings.HasPrefix(part, "/") && strings.Contains(s, part+"@@") {
+				return part
+			}
+		}
+		if err != nil {
+			break
+		}
+	}
+	t.Fatalf("no pwd in %q", out.String())
+	return ""
+}
+
+// A terminal tells the folder its shell is in now, after a cd.
+func TestPTYCwd(t *testing.T) {
+	dir, err := filepath.EvalSymlinks(t.TempDir())
+	if err != nil {
+		t.Fatal(err)
+	}
+	sub := filepath.Join(dir, "next one")
+	if err := os.Mkdir(sub, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	t.Setenv("SHELL", "/bin/sh")
+	p, err := StartPTY("", dir)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer p.Close()
+	go func() { _, _ = io.Copy(io.Discard, p) }()
+	if _, err := p.Write([]byte("cd 'next one'\n")); err != nil {
+		t.Fatal(err)
+	}
+	var got string
+	for i := 0; i < 50; i++ {
+		if got, err = p.Cwd(); err == nil && got == sub {
+			return
+		}
+		time.Sleep(100 * time.Millisecond)
+	}
+	t.Fatalf("Cwd = %q, %v; want %q", got, err, sub)
+}
+
+// The panel asks for a terminal's folder by its session.
+func TestTermCwdTask(t *testing.T) {
+	dir, _ := filepath.EvalSymlinks(t.TempDir())
+	t.Setenv("SHELL", "/bin/sh")
+	p, err := StartPTY("", dir)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer p.Close()
+	termsBySID.Store("s1", p)
+	defer termsBySID.Delete("s1")
+	res, err := dispatchTask(proto.TaskEnvelope{Type: proto.TaskTermCwd, Args: []byte(`{"session":"s1"}`)})
+	if err != nil || res.(map[string]string)["path"] != dir {
+		t.Fatalf("term.cwd = %v, %v; want %q", res, err, dir)
+	}
+	if _, err := dispatchTask(proto.TaskEnvelope{Type: proto.TaskTermCwd, Args: []byte(`{"session":"nope"}`)}); err == nil {
+		t.Fatal("an unknown session has a folder")
+	}
+}
@@ -15,33 +15,33 @@ import (

 // --- direct TCP mux tunnel ---

-// runTunnel keeps a persistent connection to the host's 8446 tunnel, dialing
-// client-side ports on demand for "tcp" forward rules.
-func (a *Agent) runTunnel(ctx context.Context) {
+// runTunnel keeps a persistent connection to the host's tunnel at addr, dialing
+// client-side ports on demand for "tcp" forward rules, until ctx is cancelled.
+func (a *Agent) runTunnel(ctx context.Context, addr string) {
 	backoff := time.Second
 	for ctx.Err() == nil {
-		if err := a.tunnelOnce(ctx); err != nil {
+		if err := a.tunnelOnce(ctx, addr); err != nil {
 			select {
 			case <-time.After(backoff):
 			case <-ctx.Done():
 				return
 			}
-			if backoff < 15*time.Second {
-				backoff *= 2
-			}
+			backoff = min(backoff*2, retryCap)
 			continue
 		}
 		backoff = time.Second
 	}
 }

-func (a *Agent) tunnelOnce(ctx context.Context) error {
+func (a *Agent) tunnelOnce(ctx context.Context, addr string) error {
 	d := net.Dialer{Timeout: 10 * time.Second}
-	conn, err := d.DialContext(ctx, "tcp", a.cfg.TunnelAddr)
+	conn, err := d.DialContext(ctx, "tcp", addr)
 	if err != nil {
 		return err
 	}
 	defer conn.Close()
+	// Unblock the read loop when the tunnel is stopped or moved.
+	defer context.AfterFunc(ctx, func() { conn.Close() })()
 	if tc, ok := conn.(*net.TCPConn); ok {
 		_ = tc.SetNoDelay(true)
 	}
@@ -65,7 +65,7 @@ func (a *Agent) tunnelOnce(ctx context.Context) error {
 		return err
 	}
 	_ = conn.SetDeadline(time.Time{})
-	log.Printf("tunnel: connected to %s", a.cfg.TunnelAddr)
+	log.Printf("tunnel: connected to %s", addr)

 	tc := &tunClient{conn: conn, streams: map[uint32]*agentStream{}}
 	return tc.readLoop()
@@ -94,8 +94,14 @@ func (t *tunClient) write(f tunnel.Frame) error {
 	return tunnel.WriteFrame(t.conn, f)
 }

+// tunnelSilence is how long the tunnel may say nothing before it is taken
+// for dead: the server pings every 20 s, so this is three missed pings - a
+// connection a NAT forgot while the machine slept, say.
+const tunnelSilence = 65 * time.Second
+
 func (t *tunClient) readLoop() error {
 	for {
+		_ = t.conn.SetReadDeadline(time.Now().Add(tunnelSilence))
 		f, err := tunnel.ReadFrame(t.conn)
 		if err != nil {
 			t.shutdown()
@@ -194,28 +200,26 @@ func (t *tunClient) shutdown() {

 // --- direct UDP forwarding ---

-// runUDP maintains the agent's UDP endpoint on the host's 8446 channel and
+// runUDP maintains the agent's UDP endpoint on the host's tunnel at addr and
 // relays datagrams to/from client-side UDP ports for "udp" forward rules.
-func (a *Agent) runUDP(ctx context.Context) {
+func (a *Agent) runUDP(ctx context.Context, addr string) {
 	backoff := time.Second
 	for ctx.Err() == nil {
-		if err := a.udpOnce(ctx); err != nil {
+		if err := a.udpOnce(ctx, addr); err != nil {
 			select {
 			case <-time.After(backoff):
 			case <-ctx.Done():
 				return
 			}
-			if backoff < 15*time.Second {
-				backoff *= 2
-			}
+			backoff = min(backoff*2, retryCap)
 			continue
 		}
 		backoff = time.Second
 	}
 }

-func (a *Agent) udpOnce(ctx context.Context) error {
-	raddr, err := net.ResolveUDPAddr("udp", a.cfg.TunnelAddr)
+func (a *Agent) udpOnce(ctx context.Context, addr string) error {
+	raddr, err := net.ResolveUDPAddr("udp", addr)
 	if err != nil {
 		return err
 	}
@@ -224,6 +228,8 @@ func (a *Agent) udpOnce(ctx context.Context) error {
 		return err
 	}
 	defer conn.Close()
+	// Unblock the read loop when the tunnel is stopped or moved.
+	defer context.AfterFunc(ctx, func() { conn.Close() })()

 	key := tunnel.AuthKey(a.state.Token)
 	register := func() {
@@ -268,7 +274,7 @@ func (a *Agent) udpOnce(ctx context.Context) error {
 }

 type udpClient struct {
-	server *net.UDPConn // connection back to host:8446
+	server *net.UDPConn // connection back to the host tunnel
 	mu     sync.Mutex
 	dials  map[uint32]*net.UDPConn // sid -> client-side socket
 }
@@ -3,31 +3,40 @@ package agent
 import (
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
+	"log"
 	"net/http"
 	"os"
 	"os/exec"
 	"path/filepath"
 	"runtime"
+	"strings"
+	"syscall"
 	"time"

 	"github.com/x-grk/longpolling-remote-access/internal/proto"
 )

-// doUpdate downloads the latest agent binary for this platform, atomically
-// replaces the running executable, and schedules a service restart. It never
-// uninstalls — only updates.
+// doUpdate downloads the latest agent binary for this platform, replaces the
+// running executable and restarts the service. It runs as root when it can:
+// the agent's own user if that is root, otherwise sudo when it needs no
+// password. It never uninstalls - only updates.
 func (a *Agent) doUpdate() proto.TaskResult {
 	exe, err := os.Executable()
 	if err != nil {
 		return proto.TaskResult{Error: "не удалось определить путь бинарника: " + err.Error()}
 	}
 	exe, _ = filepath.EvalSymlinks(exe)
+	sudo := ""
+	if os.Geteuid() != 0 {
+		sudo = sudoPath()
+	}

-	url := fmt.Sprintf("%s/download/agent-%s-%s", a.cfg.Host, runtime.GOOS, runtime.GOARCH)
+	url := fmt.Sprintf("%s/download/agent-%s-%s", a.host(), runtime.GOOS, runtime.GOARCH)
 	req, _ := http.NewRequestWithContext(context.Background(), http.MethodGet, url, nil)
-	resp, err := a.http.Do(req)
+	resp, err := a.stream.Do(req)
 	if err != nil {
 		return proto.TaskResult{Error: "скачивание: " + err.Error()}
 	}
@@ -36,41 +45,125 @@ func (a *Agent) doUpdate() proto.TaskResult {
 		return proto.TaskResult{Error: "скачивание: сервер вернул " + resp.Status}
 	}

-	tmp := exe + ".new"
-	f, err := os.OpenFile(tmp, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0o755)
-	if err != nil {
-		return proto.TaskResult{Error: "создание файла: " + err.Error()}
+	// The new binary lands next to the old one, or, when root's hand is
+	// needed to put it there, in a temporary folder first.
+	dir := filepath.Dir(exe)
+	if sudo != "" {
+		dir = ""
 	}
-	if _, err := io.Copy(f, resp.Body); err != nil {
-		f.Close()
-		os.Remove(tmp)
+	f, err := os.CreateTemp(dir, ".lpagent-new-*")
+	if err != nil {
+		return proto.TaskResult{Error: "создание файла: " + err.Error() + userNote()}
+	}
+	tmp := f.Name()
+	defer os.Remove(tmp)
+	n, err := io.Copy(f, io.LimitReader(resp.Body, 256<<20))
+	if cerr := f.Close(); err == nil {
+		err = cerr
+	}
+	if err != nil {
 		return proto.TaskResult{Error: "запись: " + err.Error()}
 	}
-	f.Close()
+	if err := checkBinary(tmp, n); err != nil {
+		return proto.TaskResult{Error: err.Error()}
+	}
+	if err := os.Chmod(tmp, 0o755); err != nil {
+		return proto.TaskResult{Error: err.Error()}
+	}

-	// Atomic replace: renaming over a running executable is allowed on Linux;
-	// the live process keeps the old inode until it restarts.
-	if err := os.Rename(tmp, exe); err != nil {
-		os.Remove(tmp)
-		return proto.TaskResult{Error: "замена бинарника: " + err.Error()}
+	how := "от " + currentUser()
+	if sudo != "" {
+		// install copies it in place under a new inode, as a rename would.
+		if out, err := exec.Command(sudo, "-n", "install", "-m", "0755", tmp, exe).CombinedOutput(); err != nil {
+			return proto.TaskResult{Error: "замена бинарника через sudo: " + strings.TrimSpace(string(out)+" "+err.Error())}
+		}
+		how = "через sudo"
+	} else if err := os.Rename(tmp, exe); err != nil {
+		// Renaming over a running executable is allowed; the live process
+		// keeps the old inode until it restarts.
+		return proto.TaskResult{Error: "замена бинарника: " + err.Error() + userNote()}
 	}

 	// Restart shortly, after the result has been reported.
 	go func() {
 		time.Sleep(1500 * time.Millisecond)
-		restartSelf()
+		restartSelf(exe, sudo)
 	}()

-	data, _ := json.Marshal(map[string]string{"status": "обновлено, перезапуск"})
+	data, _ := json.Marshal(map[string]string{"status": "обновлено " + how + ", перезапуск"})
 	return proto.TaskResult{OK: true, Data: data}
 }

-// restartSelf restarts the agent so the new binary takes effect.
-func restartSelf() {
-	if path, err := exec.LookPath("systemctl"); err == nil {
-		_ = exec.Command(path, "restart", "lpagent").Start()
-		return
+// sudoPath is sudo when it lets this user run commands without a password.
+func sudoPath() string {
+	p, err := exec.LookPath("sudo")
+	if err != nil {
+		return ""
+	}
+	if exec.Command(p, "-n", "true").Run() != nil {
+		return ""
+	}
+	return p
+}
+
+func userNote() string {
+	if os.Geteuid() == 0 {
+		return ""
+	}
+	return " (агент запущен от " + currentUser() + ", без root и sudo без пароля - обновите установщиком)"
+}
+
+// checkBinary makes sure what came is a program for this system, not an
+// error page: a binary of a sensible size with the right header.
+func checkBinary(path string, size int64) error {
+	if size < 1<<20 {
+		return fmt.Errorf("скачанный файл слишком мал (%d байт) - не похоже на агента", size)
+	}
+	f, err := os.Open(path)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+	var magic [4]byte
+	if _, err := io.ReadFull(f, magic[:]); err != nil {
+		return err
+	}
+	ok := false
+	switch runtime.GOOS {
+	case "linux":
+		ok = string(magic[:]) == "\x7fELF"
+	case "darwin":
+		ok = magic == [4]byte{0xcf, 0xfa, 0xed, 0xfe} || magic == [4]byte{0xca, 0xfe, 0xba, 0xbe}
+	default:
+		ok = true
+	}
+	if !ok {
+		return errors.New("скачанный файл - не программа для " + runtime.GOOS)
+	}
+	return nil
+}
+
+// restartSelf starts the new binary. Under systemd the service is restarted
+// (queued, so it goes on after this process is stopped); otherwise the
+// process replaces itself with the new binary.
+func restartSelf(exe, sudo string) {
+	if os.Getenv("INVOCATION_ID") != "" {
+		if path, err := exec.LookPath("systemctl"); err == nil {
+			args := []string{"--no-block", "restart", "lpagent"}
+			cmd := exec.Command(path, args...)
+			if sudo != "" {
+				cmd = exec.Command(sudo, append([]string{"-n", path}, args...)...)
+			}
+			if cmd.Run() == nil {
+				return
+			}
+		}
+		// systemd brings a service that stopped back up (Restart=always).
+		os.Exit(0)
+	}
+	CloseTerminals()
+	if err := syscall.Exec(exe, os.Args, os.Environ()); err != nil {
+		log.Printf("update: restart: %v", err)
+		os.Exit(0)
 	}
-	// No systemd (e.g. launchd/manual run): exit so the supervisor restarts us.
-	os.Exit(0)
 }
@@ -33,10 +33,18 @@ func dispatchTask(env proto.TaskEnvelope) (any, error) {
 	switch env.Type {
 	case proto.TaskSysUsers:
 		return sysUsers(), nil
+	case proto.TaskSysStat:
+		return sysStat()
 	case proto.TaskSysUserAdd:
 		var a proto.SysUserAddArgs
 		_ = json.Unmarshal(env.Args, &a)
 		return nil, addUser(a)
+	case proto.TaskDBTables, proto.TaskDBRows, proto.TaskDBSet, proto.TaskDBAdd, proto.TaskDBDel, proto.TaskDBSQL:
+		return dbTask(env)
+	case proto.TaskTermCwd:
+		var a proto.TermCwdArgs
+		_ = json.Unmarshal(env.Args, &a)
+		return termCwd(a.Session)
 	}
 	return dispatchFS(env)
 }
@@ -0,0 +1,180 @@
+package agent
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"log"
+	"net/http"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/coder/websocket"
+	"github.com/coder/websocket/wsjson"
+
+	"github.com/x-grk/longpolling-remote-access/internal/proto"
+)
+
+// The WebSocket to the server: control messages arrive on it as soon as they
+// are queued, and terminal and http-forward sessions send and take their
+// bytes over it instead of a request each. When it drops, sessions carry on
+// over plain requests.
+
+const wsPing = 20 * time.Second
+
+type wsLink struct {
+	c     *websocket.Conn
+	ctx   context.Context
+	mu    sync.Mutex
+	subs  map[string]chan wsIn
+	asked map[string]bool // sessions whose input was asked for
+	done  chan struct{}
+	stop  context.CancelFunc
+}
+
+// close drops the link: the agent then connects again, to the address in
+// use by then.
+func (l *wsLink) close() { l.stop() }
+
+// wsIn is what the server sent for a session: its input, or that it is over.
+type wsIn struct {
+	frames []proto.InFrame
+	gone   bool
+}
+
+func (l *wsLink) send(m proto.WSMsg) error {
+	ctx, cancel := context.WithTimeout(l.ctx, 30*time.Second)
+	defer cancel()
+	return wsjson.Write(ctx, l.c, m)
+}
+
+// subscribe asks the server for a session's input on this link, once, and
+// returns where it arrives; nil when the link cannot take it.
+func (l *wsLink) subscribe(sid string) chan wsIn {
+	l.mu.Lock()
+	ch := l.subs[sid]
+	if ch == nil {
+		ch = make(chan wsIn, 64)
+		l.subs[sid] = ch
+	}
+	fresh := !l.subscribed(sid)
+	l.mu.Unlock()
+	if fresh && l.send(proto.WSMsg{T: "sub", SID: sid}) != nil {
+		return nil
+	}
+	return ch
+}
+
+// subscribed marks a session as asked for; l.mu is held.
+func (l *wsLink) subscribed(sid string) bool {
+	if l.asked == nil {
+		l.asked = map[string]bool{}
+	}
+	if l.asked[sid] {
+		return true
+	}
+	l.asked[sid] = true
+	return false
+}
+
+func (l *wsLink) unsubscribe(sid string) {
+	l.mu.Lock()
+	delete(l.subs, sid)
+	delete(l.asked, sid)
+	l.mu.Unlock()
+}
+
+func (l *wsLink) deliver(sid string, in wsIn) {
+	l.mu.Lock()
+	ch := l.subs[sid]
+	l.mu.Unlock()
+	if ch == nil {
+		return
+	}
+	select {
+	case ch <- in:
+	case <-l.done:
+	}
+}
+
+// runWS holds the WebSocket until it ends, dispatching what comes on it.
+func (a *Agent) runWS(ctx context.Context) error {
+	u := a.host() + "/api/agent/ws"
+	u = "ws" + strings.TrimPrefix(u, "http")
+	hdr := http.Header{}
+	hdr.Set("X-Agent-Id", a.state.AgentID)
+	hdr.Set("Authorization", "Bearer "+a.state.Token)
+	hdr.Set("X-Agent-Version", Version)
+	hdr.Set("X-Agent-User", currentUser())
+	dctx, dcancel := context.WithTimeout(ctx, 15*time.Second)
+	c, resp, err := websocket.Dial(dctx, u, &websocket.DialOptions{
+		HTTPClient: a.stream, HTTPHeader: hdr, CompressionMode: websocket.CompressionDisabled,
+	})
+	dcancel()
+	if err != nil {
+		if resp != nil {
+			a.applyTransport(resp.Header.Get(proto.TransportHeader))
+			return fmt.Errorf("server answered %s", resp.Status)
+		}
+		return err
+	}
+	c.SetReadLimit(8 << 20)
+	lctx, lcancel := context.WithCancel(ctx)
+	l := &wsLink{c: c, ctx: lctx, subs: map[string]chan wsIn{}, done: make(chan struct{}), stop: lcancel}
+	a.link.Store(l)
+	defer func() {
+		a.link.CompareAndSwap(l, nil)
+		close(l.done)
+		lcancel()
+		c.CloseNow()
+	}()
+	log.Printf("connected by websocket")
+	a.reached()
+	go func() {
+		t := time.NewTicker(wsPing)
+		defer t.Stop()
+		for {
+			select {
+			case <-lctx.Done():
+				return
+			case <-t.C:
+				pctx, pcancel := context.WithTimeout(lctx, 15*time.Second)
+				err := c.Ping(pctx)
+				pcancel()
+				if err != nil {
+					lcancel()
+					return
+				}
+			}
+		}
+	}()
+	for {
+		var m proto.WSMsg
+		if err := wsjson.Read(lctx, c, &m); err != nil {
+			if errors.Is(err, context.Canceled) && ctx.Err() == nil {
+				return errors.New("no answer to ping")
+			}
+			return err
+		}
+		switch m.T {
+		case "ctrl":
+			if m.Ctrl != nil {
+				// Sessions live on the agent's context: they outlast the link.
+				a.dispatch(ctx, *m.Ctrl)
+			}
+		case "cfg":
+			a.applyTunnelAddr(ctx, m.Tunnel)
+			a.learnAddrs(m.Main, m.Fallback)
+			a.applyTransport(m.Transport)
+			a.applyUpdateInfo(m.AutoUpdate, m.ServerVersion)
+			if a.mode() == proto.TransportLP {
+				return errors.New("set to long polling")
+			}
+		case "in":
+			l.deliver(m.SID, wsIn{frames: m.Frames})
+		case "gone":
+			l.deliver(m.SID, wsIn{gone: true})
+		}
+	}
+}
@@ -1,15 +1,17 @@
 // Package proto describes the wire messages shared by the server and the agent.
 //
-// All agent<->server traffic is plain JSON over HTTP(S) long-polling so it
-// survives NAT and restrictive egress firewalls: the agent only ever makes
-// outbound requests.
+// All agent<->server traffic is plain JSON, on a WebSocket the agent opens or,
+// where that does not get through, over HTTP(S) long polls, so it survives
+// NAT and restrictive egress firewalls: the agent only ever connects out.
 package proto

+import "strings"
+
 import "encoding/json"

 // Control poll message types (server -> agent, returned from /api/agent/poll).
 const (
-	// CtrlIdle is returned when the long-poll times out with nothing to do.
+	// CtrlIdle is returned when the control poll times out with nothing to do.
 	CtrlIdle = "idle"
 	// CtrlOpenTerminal tells the agent to spawn a PTY for the session id.
 	CtrlOpenTerminal = "open_terminal"
@@ -18,8 +20,26 @@ const (
 	CtrlOpenForward = "open_forward"
 	// CtrlTask tells the agent to fetch and run the one-shot task TaskID.
 	CtrlTask = "task"
+	// CtrlOpenSSH tells the agent to open an SSH connection to SSH and bridge
+	// its shell to the session id, as a terminal.
+	CtrlOpenSSH = "open_ssh"
 )

+// SSHTarget is where an SSH terminal connects and how it signs in: a
+// password, a private key (PEM or OpenSSH, with its passphrase if it has
+// one), or, with neither, the agent user's own keys in ~/.ssh.
+type SSHTarget struct {
+	Host       string `json:"host"`
+	Port       int    `json:"port,omitempty"`
+	User       string `json:"user"`
+	Password   string `json:"password,omitempty"`
+	Key        string `json:"key,omitempty"`
+	Passphrase string `json:"passphrase,omitempty"`
+	// Saved: a host the user saved on the server; it fills the rest there and
+	// never reaches an agent.
+	Saved int64 `json:"saved,omitempty"`
+}
+
 // EnrollRequest is sent once by a freshly installed agent.
 type EnrollRequest struct {
 	Name     string `json:"name"`
@@ -36,15 +56,66 @@ type EnrollResponse struct {
 	Token   string `json:"token"`
 }

-// ControlMessage is the body returned by the control long-poll.
+// ControlMessage is a command for the agent: on the WebSocket, or the body of
+// the control long poll.
 type ControlMessage struct {
-	Type      string `json:"type"`
-	SessionID string `json:"session_id,omitempty"`
-	Port      int    `json:"port,omitempty"`    // CtrlOpenForward: client-side port to dial
-	TaskID    string `json:"task_id,omitempty"` // CtrlTask
-	User      string `json:"user,omitempty"`    // CtrlOpenTerminal: OS user for the shell ("" = the agent's own)
+	Type      string     `json:"type"`
+	SessionID string     `json:"session_id,omitempty"`
+	Port      int        `json:"port,omitempty"`    // CtrlOpenForward: client-side port to dial
+	TaskID    string     `json:"task_id,omitempty"` // CtrlTask
+	User      string     `json:"user,omitempty"`    // CtrlOpenTerminal: OS user for the shell ("" = the agent's own)
+	Dir       string     `json:"dir,omitempty"`     // CtrlOpenTerminal: the folder to start in ("" or missing = home)
+	SSH       *SSHTarget `json:"ssh,omitempty"`     // CtrlOpenSSH
 }

+// Transports an agent can reach the server by.
+const (
+	TransportAuto = "auto" // WebSocket, long polling while it cannot connect
+	TransportWS   = "ws"   // WebSocket only
+	TransportLP   = "lp"   // long polling only
+)
+
+// TransportHeader carries the agent's transport setting on poll and config
+// answers.
+const TransportHeader = "X-Transport"
+
+// FallbackHeader carries the server's direct address (one not behind a
+// proxy like Cloudflare) on poll and config answers, for the agent to turn
+// to when the main one is out of reach.
+const FallbackHeader = "X-Fallback-Host"
+
+// MainHeader carries the server's main address beside FallbackHeader, for an
+// agent set to the direct one to fall back to the main one.
+const MainHeader = "X-Main-Host"
+
+// WSMsg is one message on an agent's WebSocket, either way. Server to agent:
+// "ctrl" (Ctrl, as a control poll would answer), "cfg" (Tunnel and
+// Transport, also a keep-alive), "in" (Frames for session SID), "gone"
+// (session SID is over). Agent to server: "sub" (send the input of session
+// SID here), "out" (Out of session SID).
+type WSMsg struct {
+	T         string          `json:"t"`
+	Ctrl      *ControlMessage `json:"ctrl,omitempty"`
+	SID       string          `json:"sid,omitempty"`
+	Frames    []InFrame       `json:"frames,omitempty"`
+	Out       *OutMessage     `json:"out,omitempty"`
+	Tunnel    string          `json:"tunnel,omitempty"`
+	Transport string          `json:"transport,omitempty"`
+	Fallback  string          `json:"fallback,omitempty"`
+	Main      string          `json:"main,omitempty"`
+	// Auto-update of agents: how often (minutes) an agent compares its
+	// version with the server's and updates itself if the server's is newer;
+	// 0 or missing - it does not. ServerVersion is the server's.
+	AutoUpdate    int    `json:"autoupdate,omitempty"`
+	ServerVersion string `json:"server_version,omitempty"`
+}
+
+// Headers with the same on the poll answer and on /api/agent/config.
+const (
+	AutoUpdateHeader    = "X-Auto-Update"    // minutes, "0" or missing: off
+	ServerVersionHeader = "X-Server-Version" // the server's release version
+)
+
 // Terminal / stream frame types on the session "in" channel (server -> agent).
 // Reused for both PTY terminals and raw TCP port-forward streams.
 const (
@@ -70,8 +141,20 @@ type InBatch struct {
 type OutMessage struct {
 	Data string `json:"data,omitempty"` // base64 bytes
 	Exit bool   `json:"exit,omitempty"`
+	// Status tells the panel how an SSH terminal's connection goes: one of
+	// the SSHStatus values, with Note to show.
+	Status string `json:"status,omitempty"`
+	Note   string `json:"note,omitempty"`
 }

+// The steps of an SSH terminal's connection, as OutMessage.Status.
+const (
+	SSHDial = "dial" // connecting to the host
+	SSHAuth = "auth" // the host answered, signing in
+	SSHOK   = "ok"   // signed in, the shell runs
+	SSHErr  = "err"  // it failed; Note says why
+)
+
 // --- one-shot tasks (file manager, native in the agent) ---

 const (
@@ -85,12 +168,62 @@ const (
 	TaskFSZip      = "fs.zip"      // zip selected paths (native archive/zip)
 	TaskFSMove     = "fs.move"     // move/rename
 	TaskFSDownload = "fs.download" // read a whole file (larger cap) for browser download
+	TaskFSStat     = "fs.stat"     // a file's properties: type, size, mode, owner
+	TaskFSChmod    = "fs.chmod"    // change mode and owner, of a folder's contents too
+	TaskFSCopy     = "fs.copy"     // copy or move, with a rule for what is already there
+	TaskFSPut      = "fs.put"      // write a file the browser sends in pieces
+	TaskFSSend     = "fs.send"     // send a file to the browser in pieces

 	TaskSysUpdate  = "sys.update"  // download the latest agent binary and restart
 	TaskSysUsers   = "sys.users"   // report the agent's user and the login-capable users
 	TaskSysUserAdd = "sys.useradd" // create a new OS user
+	TaskSysStat    = "sys.stat"    // CPU load, RAM and disk usage right now
+	TaskSysSpeed   = "sys.speed"   // measure the link to the server (ping, down, up)
+	TaskDBTables   = "db.tables"   // an SQLite database's tables and views
+	TaskDBRows     = "db.rows"     // a page of a table's rows, with each row's key
+	TaskDBSet      = "db.set"      // set one value of one row
+	TaskDBAdd      = "db.add"      // add a row
+	TaskDBDel      = "db.del"      // delete rows by their keys
+	TaskDBSQL      = "db.sql"      // run a statement typed in the panel
+	TaskTermCwd    = "term.cwd"    // the folder a terminal is in now (TermCwdArgs); result {path}
+	TaskSSHFSOpen  = "sshfs.open"  // connect to an SSH host for a file pane; result {id, home}
+	TaskSSHFSClose = "sshfs.close" // drop that connection
+	TaskSSHFSOp    = "sshfs.op"    // a file operation on the host: list, read, write, mkdir, delete, deltree, move, copy, stat, chmod
+	TaskSSHFSSend  = "sshfs.send"  // a file of the host to the browser in pieces (FSXferArgs with Conn)
+	TaskSSHFSPut   = "sshfs.put"   // a file from the browser to the host in pieces
+	TaskFSShipOut  = "fs.ship.out" // pack a file or folder and send it to another machine
+	TaskFSShipIn   = "fs.ship.in"  // unpack what another machine sends
 )

+// FSReadCap bounds how many bytes TaskFSRead returns (5 MiB). The panel lets a
+// file be edited only when it fits, so that a save never cuts it short.
+const FSReadCap = 5 * 1024 * 1024
+
+// FSFileCap bounds a file sent either way in pieces (TaskFSPut, TaskFSSend).
+const FSFileCap = 512 << 20
+
+// FSXferArgs are the arguments of TaskFSPut and TaskFSSend: the file, and the
+// transfer on the server whose pieces carry it - GET them for a put, POST them
+// for a send, Chunk bytes each. Size is a put's length; -1 for a send.
+type FSXferArgs struct {
+	Path  string `json:"path"`
+	Xfer  string `json:"xfer"`
+	Size  int64  `json:"size"`
+	Chunk int    `json:"chunk"`
+	// Conn is the SSH file connection the file is on (sshfs.send, sshfs.put).
+	Conn string `json:"conn,omitempty"`
+}
+
+// SSHFSArgs are the arguments of the sshfs.* tasks: the connection (Conn), or
+// where to connect (SSH, for open); for an operation its name (Op) and its
+// arguments (Args) in the shapes of the fs.* tasks.
+type SSHFSArgs struct {
+	Conn string          `json:"conn,omitempty"`
+	SSH  *SSHTarget      `json:"ssh,omitempty"`
+	Op   string          `json:"op,omitempty"`
+	Args json.RawMessage `json:"args,omitempty"`
+}
+
 // TaskEnvelope is what the agent fetches for a task id.
 type TaskEnvelope struct {
 	Type string          `json:"type"`
@@ -125,6 +258,47 @@ type FSMoveArgs struct {
 	Dst string `json:"dst"`
 }

+// FSStatResult is returned for TaskFSStat. Mode holds the permission bits
+// with setuid, setgid and sticky (07777). Users and Groups are the names on
+// the machine, offered when choosing an owner.
+type FSStatResult struct {
+	Path   string   `json:"path"`
+	IsDir  bool     `json:"is_dir"`
+	Link   string   `json:"link,omitempty"` // where a symlink points
+	Size   int64    `json:"size"`
+	MTime  int64    `json:"mtime"`
+	Mode   uint32   `json:"mode"`
+	UID    int      `json:"uid"`
+	GID    int      `json:"gid"`
+	Owner  string   `json:"owner"`
+	Group  string   `json:"group"`
+	Users  []string `json:"users"`
+	Groups []string `json:"groups"`
+}
+
+// FSChmodArgs are the arguments of TaskFSChmod. Mode nil, Owner or Group
+// empty leave that as it is. Recursive applies to everything inside a folder
+// as well, Only narrowing it to "files" or "dirs".
+type FSChmodArgs struct {
+	Path      string  `json:"path"`
+	Mode      *uint32 `json:"mode,omitempty"`
+	Owner     string  `json:"owner,omitempty"`
+	Group     string  `json:"group,omitempty"`
+	Recursive bool    `json:"recursive,omitempty"`
+	Only      string  `json:"only,omitempty"`
+}
+
+// FSCopyArgs are the arguments of TaskFSCopy: Src goes to Dst (the full new
+// path), copied or, with Move, moved. Conflict says what to do when Dst is
+// already there: "error" (the default) stops, "replace" puts Src in its place,
+// "skip" keeps it. Folders on both sides are merged under replace and skip.
+type FSCopyArgs struct {
+	Src      string `json:"src"`
+	Dst      string `json:"dst"`
+	Move     bool   `json:"move,omitempty"`
+	Conflict string `json:"conflict,omitempty"`
+}
+
 // FSEntry is one directory entry.
 type FSEntry struct {
 	Name  string `json:"name"`
@@ -132,6 +306,8 @@ type FSEntry struct {
 	Size  int64  `json:"size"`
 	Mode  string `json:"mode"`
 	MTime int64  `json:"mtime"`
+	// Link: a symbolic link (IsDir then says where it leads: a folder).
+	Link bool `json:"link,omitempty"`
 }

 // FSListResult is returned for TaskFSList.
@@ -162,3 +338,84 @@ type SysUserAddArgs struct {
 	Password string `json:"password,omitempty"` // empty leaves the account without a password
 	Sudo     bool   `json:"sudo"`               // add to the sudo/wheel group
 }
+
+// SysStatResult is returned for TaskSysStat. Sizes are in bytes.
+type SysStatResult struct {
+	CPU       float64 `json:"cpu"` // load across all cores, 0..100
+	NCPU      int     `json:"ncpu"`
+	MemTotal  uint64  `json:"mem_total"`
+	MemUsed   uint64  `json:"mem_used"`
+	DiskTotal uint64  `json:"disk_total"` // filesystem holding "/"
+	DiskFree  uint64  `json:"disk_free"`
+}
+
+// SysSpeedArgs are the arguments of TaskSysSpeed.
+type SysSpeedArgs struct {
+	// Relay makes the agent use the relayed streams, which the server pipes
+	// to and from the browser.
+	Relay bool `json:"relay,omitempty"`
+	// WindowMs is how long to measure each direction for; 0 leaves it to the
+	// agent (3 s, all an agent that predates this argument does).
+	WindowMs int `json:"window_ms,omitempty"`
+}
+
+// SysSpeedResult is returned for TaskSysSpeed: the agent's HTTP link to the
+// server as the agent measured it. Down is server -> agent.
+type SysSpeedResult struct {
+	PingMs  float64 `json:"ping_ms"`
+	DownBps float64 `json:"down_bps"` // bits per second
+	UpBps   float64 `json:"up_bps"`
+	Relay   bool    `json:"relay,omitempty"` // the streams went through the relay
+	// Partial marks a test the server cut short: the numbers are what it had
+	// counted on its own side by then.
+	Partial bool `json:"partial,omitempty"`
+}
+
+// FSShipArgs are the arguments of TaskFSShipOut and TaskFSShipIn: Src (on the
+// sending machine) lands in Dir as Name (on the receiving one), following
+// Conflict as FSCopyArgs does. The sender packs it as a tar stream and either
+// posts it in pieces of Chunk bytes to Relay on the server, for the receiver
+// to take, or with SSH set writes it to tar on that host itself, and with
+// Move then deletes Src. Both report to Job how far they are.
+type FSShipArgs struct {
+	Src      string     `json:"src,omitempty"`
+	Name     string     `json:"name"`
+	Dir      string     `json:"dir"`
+	Conflict string     `json:"conflict,omitempty"`
+	Move     bool       `json:"move,omitempty"`
+	Relay    string     `json:"relay,omitempty"`
+	Chunk    int        `json:"chunk,omitempty"`
+	Job      string     `json:"job,omitempty"`
+	SSH      *SSHTarget `json:"ssh,omitempty"`
+	// Conn: the files of this side are on the SSH host of this agent's file
+	// connection (an SSH file pane), not on the machine itself.
+	Conn string `json:"conn,omitempty"`
+	// More: other things of Src's folder sent in the same stream under their
+	// own names (several files dragged at once). Agents before 0.2.0 do not
+	// know it; the server sends to them one at a time.
+	More []string `json:"more,omitempty"`
+}
+
+// ShipNames is what lands at the other end: Name, then More by their names.
+func (a FSShipArgs) ShipNames() []string {
+	n := []string{a.Name}
+	for _, p := range a.More {
+		p = strings.TrimRight(p, "/")
+		n = append(n, p[strings.LastIndex(p, "/")+1:])
+	}
+	return n
+}
+
+// ShipProgress is what a sending machine reports: bytes of files sent out of
+// Total, and files done.
+type ShipProgress struct {
+	Total int64  `json:"total"`
+	Done  int64  `json:"done"`
+	Files int    `json:"files"`
+	Note  string `json:"note,omitempty"` // what is going on: connecting, signing in
+}
+
+// TermCwdArgs names the terminal session whose folder the panel asks for.
+type TermCwdArgs struct {
+	Session string `json:"session"`
+}
@@ -0,0 +1,50 @@
+package proto
+
+import (
+	"strconv"
+	"strings"
+)
+
+// versionParts reads "0.2.5" (a leading v and a "-suffix" are allowed) as
+// numbers; ok is false for anything that is not a dotted number.
+func versionParts(v string) (parts []int, ok bool) {
+	v = strings.TrimPrefix(strings.TrimSpace(v), "v")
+	if i := strings.IndexAny(v, "-+"); i >= 0 {
+		v = v[:i]
+	}
+	if v == "" {
+		return nil, false
+	}
+	for _, p := range strings.Split(v, ".") {
+		n, err := strconv.Atoi(p)
+		if err != nil || n < 0 {
+			return nil, false
+		}
+		parts = append(parts, n)
+	}
+	return parts, true
+}
+
+// VersionNewer reports whether version a is higher than b. Anything that is
+// not a dotted number (a build named "dev", an empty string) is never newer
+// and never older - so a program is never "updated" down, or from a guess.
+func VersionNewer(a, b string) bool {
+	pa, okA := versionParts(a)
+	pb, okB := versionParts(b)
+	if !okA || !okB {
+		return false
+	}
+	for i := 0; i < len(pa) || i < len(pb); i++ {
+		var x, y int
+		if i < len(pa) {
+			x = pa[i]
+		}
+		if i < len(pb) {
+			y = pb[i]
+		}
+		if x != y {
+			return x > y
+		}
+	}
+	return false
+}
@@ -0,0 +1,30 @@
+package proto
+
+import "testing"
+
+// A version is newer only when it is a higher dotted number: never for the
+// same, an older one, or what is not a version at all.
+func TestVersionNewer(t *testing.T) {
+	for _, c := range []struct {
+		a, b string
+		want bool
+	}{
+		{"0.2.5", "0.2.4", true},
+		{"0.2.10", "0.2.9", true},
+		{"0.3.0", "0.2.99", true},
+		{"1.0", "0.9.9", true},
+		{"0.2.4", "0.2.4", false},
+		{"0.2.3", "0.2.4", false},
+		{"0.2", "0.2.0", false},
+		{"v0.2.5", "0.2.4", true},
+		{"", "0.2.4", false},
+		{"dev", "0.2.4", false},
+		{"0.2.5", "dev", false},
+		{"0.2.5", "", false},
+		{"0.2.5-rc1", "0.2.4", true},
+	} {
+		if got := VersionNewer(c.a, c.b); got != c.want {
+			t.Errorf("VersionNewer(%q, %q) = %v, want %v", c.a, c.b, got, c.want)
+		}
+	}
+}
@@ -24,6 +24,16 @@ func (s *Server) authenticateAgent(r *http.Request) *Agent {
 	return a
 }

+// online reports whether the agent is connected right now: the hub knows from
+// its control polls. Right after a start it cannot tell yet, so the last poll
+// recorded in the database decides.
+func (s *Server) online(a *Agent) bool {
+	if on, ok := s.hub.Online(a.ID); ok {
+		return on
+	}
+	return a.recentlySeen()
+}
+
 func bearerToken(r *http.Request) string {
 	h := r.Header.Get("Authorization")
 	if strings.HasPrefix(h, "Bearer ") {
@@ -0,0 +1,435 @@
+package server
+
+import (
+	"context"
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"strconv"
+	"strings"
+	"testing"
+	"time"
+)
+
+func collect(t *testing.T, cfg aiConfig) (string, error) {
+	t.Helper()
+	var b strings.Builder
+	err := aiStream(context.Background(), cfg, "sys", []aiMsg{{Role: "user", Content: "раз"}, {Role: "assistant", Content: "два"}, {Role: "user", Content: "три"}}, func(s string) { b.WriteString(s) })
+	return b.String(), err
+}
+
+// Gradio (the Qwen space behind the proxy): history in, the answer streamed
+// as diffs of the chatbot, the key in X-Agent-Key.
+func TestAIGradio(t *testing.T) {
+	var joined map[string]any
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Header.Get("X-Agent-Key") != "k" {
+			http.Error(w, "no key", 403)
+			return
+		}
+		switch r.URL.Path {
+		case "/config":
+			fmt.Fprint(w, `{"dependencies":[{"id":3,"api_name":"other"},{"id":0,"api_name":"chat_predict","targets":[[21,"click"]]}]}`)
+		case "/gradio_api/queue/join":
+			_ = json.NewDecoder(r.Body).Decode(&joined)
+			fmt.Fprint(w, `{"event_id":"e"}`)
+		case "/gradio_api/queue/data":
+			w.Header().Set("Content-Type", "text/event-stream")
+			for _, m := range []string{
+				`{"msg":"process_starts"}`,
+				`{"msg":"process_generating","output":{"data":[null,null,null,null,[{"role":"user","content":"три"}],{},{}]}}`,
+				`{"msg":"process_generating","output":{"data":[[],[],[],[],[["add",[3],{"role":"assistant","content":"При"}]],[],[]]}}`,
+				`{"msg":"process_generating","output":{"data":[[],[],[],[],[["append",[3,"content"],"вет"]],[],[]]}}`,
+				`{"msg":"process_completed","success":true,"output":{"data":[{},{},{},{},[{"role":"user","content":"три"},{"role":"assistant","content":"Привет!"}],{},{}]}}`,
+			} {
+				fmt.Fprintf(w, "data: %s\n\n", m)
+			}
+		default:
+			http.NotFound(w, r)
+		}
+	}))
+	defer srv.Close()
+	got, err := collect(t, aiConfig{Type: "gradio", URL: srv.URL, Key: "k"})
+	if err != nil || got != "Привет!" {
+		t.Fatalf("got %q, %v", got, err)
+	}
+	d := joined["data"].([]any)
+	if joined["fn_index"].(float64) != 0 || d[0] != "три" || d[5] != "sys" || len(d[4].([]any)) != 2 {
+		t.Fatalf("join: %v", joined)
+	}
+}
+
+func TestAIGradioError(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		switch r.URL.Path {
+		case "/config":
+			fmt.Fprint(w, `{"dependencies":[{"id":0,"api_name":"chat_predict"}]}`)
+		case "/gradio_api/queue/join":
+			fmt.Fprint(w, `{"event_id":"e"}`)
+		default:
+			fmt.Fprint(w, "data: {\"msg\":\"process_completed\",\"success\":false,\"output\":{\"error\":\"GPU занят\"}}\n\n")
+		}
+	}))
+	defer srv.Close()
+	if _, err := collect(t, aiConfig{Type: "gradio", URL: srv.URL}); err == nil || !strings.Contains(err.Error(), "GPU занят") {
+		t.Fatalf("err: %v", err)
+	}
+}
+
+func TestAIOpenAI(t *testing.T) {
+	var body map[string]any
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path != "/v1/chat/completions" || r.Header.Get("Authorization") != "Bearer k" {
+			http.Error(w, "bad", 400)
+			return
+		}
+		_ = json.NewDecoder(r.Body).Decode(&body)
+		fmt.Fprint(w, "data: {\"choices\":[{\"delta\":{\"role\":\"assistant\"}}]}\n\ndata: {\"choices\":[{\"delta\":{\"content\":\"При\"}}]}\n\ndata: {\"choices\":[{\"delta\":{\"content\":\"вет\"}}]}\n\ndata: [DONE]\n\n")
+	}))
+	defer srv.Close()
+	got, err := collect(t, aiConfig{Type: "openai", URL: srv.URL + "/v1", Key: "k", Model: "m"})
+	if err != nil || got != "Привет" {
+		t.Fatalf("got %q, %v", got, err)
+	}
+	msgs := body["messages"].([]any)
+	if body["model"] != "m" || body["stream"] != true || len(msgs) != 4 || msgs[0].(map[string]any)["role"] != "system" {
+		t.Fatalf("body: %v", body)
+	}
+}
+
+func TestAIOpenAIAttachments(t *testing.T) {
+	var body map[string]any
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		_ = json.NewDecoder(r.Body).Decode(&body)
+		fmt.Fprint(w, "data: [DONE]\n\n")
+	}))
+	defer srv.Close()
+	msg := aiMsg{Role: "user", Content: "посмотри", Attachments: []aiAttachment{
+		{Name: "image.png", MIME: "image/png", Data: "AQID"},
+		{Name: "voice.wav", MIME: "audio/wav", Data: "BAUG"},
+		{Name: "clip.mp4", MIME: "video/mp4", Data: "BwgJ"},
+	}}
+	if err := aiOpenAI(context.Background(), aiConfig{Type: "openai", URL: srv.URL, Model: "m"}, "sys", []aiMsg{msg}, func(string) {}); err != nil {
+		t.Fatal(err)
+	}
+	messages := body["messages"].([]any)
+	content := messages[1].(map[string]any)["content"].([]any)
+	if len(content) != 4 || content[3].(map[string]any)["text"] != "посмотри" {
+		t.Fatalf("content: %#v", content)
+	}
+	if got := content[0].(map[string]any)["image_url"].(map[string]any)["url"].(string); !strings.HasPrefix(got, "data:image/png;base64,") {
+		t.Fatalf("image: %q", got)
+	}
+	if got := content[1].(map[string]any)["input_audio"].(map[string]any)["format"]; got != "wav" {
+		t.Fatalf("audio: %#v", content[1])
+	}
+	video := content[2].(map[string]any)
+	if video["type"] != "video_url" || video["fps"] != float64(1) || !strings.HasPrefix(video["video_url"].(map[string]any)["url"].(string), "data:video/mp4;base64,") {
+		t.Fatalf("video: %#v", video)
+	}
+}
+
+func TestAIAnthropic(t *testing.T) {
+	var body map[string]any
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path != "/v1/messages" || r.Header.Get("x-api-key") != "k" || r.Header.Get("anthropic-version") == "" {
+			http.Error(w, "bad", 400)
+			return
+		}
+		_ = json.NewDecoder(r.Body).Decode(&body)
+		fmt.Fprint(w, "event: message_start\ndata: {\"type\":\"message_start\"}\n\n"+
+			"event: content_block_delta\ndata: {\"type\":\"content_block_delta\",\"delta\":{\"type\":\"text_delta\",\"text\":\"При\"}}\n\n"+
+			"event: content_block_delta\ndata: {\"type\":\"content_block_delta\",\"delta\":{\"type\":\"text_delta\",\"text\":\"вет\"}}\n\n"+
+			"event: message_stop\ndata: {\"type\":\"message_stop\"}\n\n")
+	}))
+	defer srv.Close()
+	got, err := collect(t, aiConfig{Type: "anthropic", URL: srv.URL, Key: "k", Model: "m"})
+	if err != nil || got != "Привет" {
+		t.Fatalf("got %q, %v", got, err)
+	}
+	if body["system"] != "sys" || len(body["messages"].([]any)) != 3 {
+		t.Fatalf("body: %v", body)
+	}
+}
+
+// The chat is on by default, and an explicit user preference can still turn it off.
+func TestAIChatDefaultOnAndCanBeDisabled(t *testing.T) {
+	s, c := newTestServer(t)
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		fmt.Fprint(w, "data: {\"choices\":[{\"delta\":{\"content\":\"ok\"}}]}\n\ndata: [DONE]\n\n")
+	}))
+	defer srv.Close()
+	_ = s.db.SetConfig(cfgAIType, "openai")
+	_ = s.db.SetConfig(cfgAIURL, srv.URL)
+	post := func() *httptest.ResponseRecorder {
+		req := httptest.NewRequest(http.MethodPost, "/api/panel/ai/chat", strings.NewReader(`{"message":"hi","context":"x"}`))
+		req.AddCookie(c)
+		w := httptest.NewRecorder()
+		s.Handler().ServeHTTP(w, req)
+		return w
+	}
+	a, _ := s.db.AdminByUsername("adm")
+	state := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodGet, "/api/panel/ai", nil)
+	req.AddCookie(c)
+	s.handleAIState(state, req)
+	var got struct {
+		On bool `json:"on"`
+	}
+	if err := json.Unmarshal(state.Body.Bytes(), &got); err != nil || !got.On {
+		t.Fatalf("default state: %s (%v)", state.Body.String(), err)
+	}
+	w := post()
+	b, _ := io.ReadAll(w.Body)
+	if w.Code != 200 || string(b) != "ok" {
+		t.Fatalf("on: %d %q", w.Code, b)
+	}
+	// The talk is kept: the question and the answer.
+	cs := s.aiChats(a.ID)
+	// Named by the question at once (the model may rename it a moment later).
+	if len(cs) != 1 || cs[0].Title == "" || w.Header().Get("X-Chat-Id") != strconv.FormatInt(cs[0].ID, 10) {
+		t.Fatalf("chats: %+v %q", cs, w.Header().Get("X-Chat-Id"))
+	}
+	if h := s.aiHistoryOf(a.ID, cs[0].ID, 10); len(h) != 2 || h[0].Content != "hi" || h[1].Content != "ok" {
+		t.Fatalf("history: %+v", h)
+	}
+	off := httptest.NewRecorder()
+	req = httptest.NewRequest(http.MethodPost, "/api/panel/ai/toggle", strings.NewReader(`{"on":false}`))
+	req.AddCookie(c)
+	s.handleAIToggle(off, req)
+	state = httptest.NewRecorder()
+	req = httptest.NewRequest(http.MethodGet, "/api/panel/ai", nil)
+	req.AddCookie(c)
+	s.handleAIState(state, req)
+	var after struct {
+		On bool `json:"on"`
+	}
+	if err := json.Unmarshal(state.Body.Bytes(), &after); err != nil || after.On {
+		t.Fatalf("disabled state: %s (%v)", state.Body.String(), err)
+	}
+	if w := post(); w.Code != http.StatusForbidden {
+		t.Fatalf("explicit off: %d %s", w.Code, w.Body.String())
+	}
+}
+
+func TestAIChatKeepsAttachmentTextOnly(t *testing.T) {
+	s, c := newTestServer(t)
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		var in struct {
+			Messages []map[string]any `json:"messages"`
+		}
+		_ = json.NewDecoder(r.Body).Decode(&in)
+		content := in.Messages[len(in.Messages)-1]["content"].([]any)
+		if content[0].(map[string]any)["type"] != "image_url" {
+			http.Error(w, "image missing", http.StatusBadRequest)
+			return
+		}
+		fmt.Fprint(w, "data: [DONE]\n\n")
+	}))
+	defer srv.Close()
+	_ = s.db.SetConfig(cfgAIType, "openai")
+	_ = s.db.SetConfig(cfgAIURL, srv.URL)
+	a, _ := s.db.AdminByUsername("adm")
+	_ = s.db.SetConfig(aiUserKey(a.ID), "1")
+	chatID := s.aiNewChat(a.ID)
+	s.aiAppendTo(a.ID, chatID, "user", "предыдущий вопрос")
+	s.aiAppendTo(a.ID, chatID, "assistant", "ответ")
+	body := fmt.Sprintf(`{"message":"посмотри","chat":%d,"attachments":[{"name":"x.png","mime":"image/png","data":"AQID"}]}`, chatID)
+	req := httptest.NewRequest(http.MethodPost, "/api/panel/ai/chat", strings.NewReader(body))
+	req.AddCookie(c)
+	w := httptest.NewRecorder()
+	s.Handler().ServeHTTP(w, req)
+	if w.Code != http.StatusOK {
+		t.Fatalf("response: %d %s", w.Code, w.Body.String())
+	}
+	chat, _ := strconv.ParseInt(w.Header().Get("X-Chat-Id"), 10, 64)
+	history := s.aiHistoryOf(a.ID, chat, 10)
+	if chat != chatID || len(history) != 3 || !strings.Contains(history[2].Content, "x.png") || strings.Contains(history[2].Content, "AQID") {
+		t.Fatalf("history contains wrong attachment data: %+v", history)
+	}
+}
+
+func TestVersionAtLeast(t *testing.T) {
+	for _, c := range []struct {
+		v    string
+		want bool
+	}{{"0.2.0", true}, {"0.10.1", true}, {"0.1.9", false}, {"", false}, {"dev", false}, {"1.0", true}} {
+		if got := versionAtLeast(c.v, "0.2.0"); got != c.want {
+			t.Errorf("%q: %v", c.v, got)
+		}
+	}
+}
+
+// The window the model sees: newest first within the budget, old results
+// and answers cut down, results as the user's words, same roles merged.
+func TestAIWindow(t *testing.T) {
+	big := strings.Repeat("x", 5000)
+	rows := []aiMsg{
+		{Role: "user", Content: "старое"},
+		{Role: "assistant", Content: big},
+		{Role: "result", Content: big},
+		{Role: "user", Content: "дальше"},
+		{Role: "assistant", Content: "ок"},
+		{Role: "result", Content: "вывод"},
+	}
+	w := aiWindow(rows, 100000)
+	if len(w) != 5 || w[0].Role != "user" || w[len(w)-1].Role != "user" {
+		t.Fatalf("roles: %+v", w)
+	}
+	if len(w[1].Content) > 3200 || len(w[2].Content) > 1700+len("дальше")+40 {
+		t.Fatalf("old not cut: %d %d", len(w[1].Content), len(w[2].Content))
+	}
+	if !strings.Contains(w[4].Content, "вывод") || !strings.HasPrefix(w[4].Content, "Результат") {
+		t.Fatalf("last result: %q", w[4].Content)
+	}
+	// A small budget keeps the newest, starting with the user.
+	w = aiWindow(rows, 60)
+	if len(w) == 0 || w[0].Role != "user" || !strings.Contains(w[len(w)-1].Content, "вывод") {
+		t.Fatalf("small: %+v", w)
+	}
+}
+
+func TestStripThink(t *testing.T) {
+	if got := stripThink("::думаю::\nхм\n::ответ::\n391"); got != "391" {
+		t.Fatalf("%q", got)
+	}
+	if got := stripThink("просто"); got != "просто" {
+		t.Fatalf("%q", got)
+	}
+}
+
+// Several talks: each its own messages; a new one is named by its first
+// question; deleting one leaves the others.
+func TestAIChats(t *testing.T) {
+	s, _ := newTestServer(t)
+	a, _ := s.db.AdminByUsername("adm")
+	one := s.aiNewChat(a.ID)
+	two := s.aiNewChat(a.ID)
+	s.aiAppendTo(a.ID, one, "user", "первый вопрос про nginx и его настройки, длинный-длинный")
+	s.aiAppendTo(a.ID, two, "user", "второй")
+	if h := s.aiHistoryOf(a.ID, one, 10); len(h) != 1 || h[0].Content[:5] != "перв"[:5] {
+		t.Fatalf("one: %+v", h)
+	}
+	list := s.aiChats(a.ID)
+	if len(list) != 2 || list[0].ID != two || !strings.HasPrefix(list[1].Title, "первый вопрос") || len([]rune(list[1].Title)) > 41 {
+		t.Fatalf("list: %+v", list)
+	}
+	s.aiDeleteChat(a.ID, one)
+	if list = s.aiChats(a.ID); len(list) != 1 || len(s.aiHistoryOf(a.ID, one, 10)) != 0 {
+		t.Fatalf("after delete: %+v", list)
+	}
+	// Another user sees none of them and cannot write into them.
+	if len(s.aiChats(a.ID+1)) != 0 {
+		t.Fatal("another user sees the talks")
+	}
+	s.aiAppendTo(a.ID+1, two, "user", "чужое")
+	if len(s.aiHistoryOf(a.ID, two, 10)) != 1 {
+		t.Fatal("another user wrote into the talk")
+	}
+}
+
+// The thinking is kept with the answer (and how long it took), so it shows
+// again later; the model never gets it back.
+func TestAIThinkingKept(t *testing.T) {
+	s, c := newTestServer(t)
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		fl := w.(http.Flusher)
+		fmt.Fprint(w, "data: {\"choices\":[{\"delta\":{\"content\":\"::думаю::\\nхм\\n\"}}]}\n\n")
+		fl.Flush()
+		time.Sleep(1100 * time.Millisecond)
+		fmt.Fprint(w, "data: {\"choices\":[{\"delta\":{\"content\":\"::ответ::\\n391\"}}]}\n\ndata: [DONE]\n\n")
+	}))
+	defer srv.Close()
+	_ = s.db.SetConfig(cfgAIType, "openai")
+	_ = s.db.SetConfig(cfgAIURL, srv.URL)
+	a, _ := s.db.AdminByUsername("adm")
+	_ = s.db.SetConfig(aiUserKey(a.ID), "1")
+	req := httptest.NewRequest(http.MethodPost, "/api/panel/ai/chat", strings.NewReader(`{"message":"17*23","think":true}`))
+	req.AddCookie(c)
+	w := httptest.NewRecorder()
+	s.Handler().ServeHTTP(w, req)
+	chat, _ := strconv.ParseInt(w.Header().Get("X-Chat-Id"), 10, 64)
+	h := s.aiHistoryOf(a.ID, chat, 10)
+	if len(h) != 2 || !strings.Contains(h[1].Content, "::думаю::") || h[1].ThinkMS < 1000 {
+		t.Fatalf("kept: %+v", h)
+	}
+	if win := aiWindow(h, 10000); strings.Contains(win[len(win)-1].Content, "хм") {
+		t.Fatalf("the model gets the thinking back: %+v", win)
+	}
+}
+
+// A new chat is named by the model: its first question in two or three
+// words, asked aside so the answer does not wait.
+func TestAIChatTitle(t *testing.T) {
+	s, c := newTestServer(t)
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		var in struct {
+			Messages []aiMsg `json:"messages"`
+		}
+		_ = json.NewDecoder(r.Body).Decode(&in)
+		reply := "ok"
+		if strings.Contains(in.Messages[0].Content, "название") {
+			reply = "«Выбор поисковика.»"
+		}
+		b, _ := json.Marshal(reply)
+		fmt.Fprintf(w, "data: {\"choices\":[{\"delta\":{\"content\":%s}}]}\n\ndata: [DONE]\n\n", b)
+	}))
+	defer srv.Close()
+	_ = s.db.SetConfig(cfgAIType, "openai")
+	_ = s.db.SetConfig(cfgAIURL, srv.URL)
+	a, _ := s.db.AdminByUsername("adm")
+	_ = s.db.SetConfig(aiUserKey(a.ID), "1")
+	req := httptest.NewRequest(http.MethodPost, "/api/panel/ai/chat", strings.NewReader(`{"message":"какой поисковик ты используешь сейчас"}`))
+	req.AddCookie(c)
+	w := httptest.NewRecorder()
+	s.Handler().ServeHTTP(w, req)
+	for i := 0; i < 50; i++ {
+		if cs := s.aiChats(a.ID); len(cs) == 1 && cs[0].Title == "Выбор поисковика" {
+			return
+		}
+		time.Sleep(50 * time.Millisecond)
+	}
+	t.Fatalf("title: %+v", s.aiChats(a.ID))
+}
+
+// Qwen Omni's files go where its inputs are (audio before image there), and
+// a video as Gradio 5 takes one: {video, subtitles}.
+func TestAIGradioMediaSlots(t *testing.T) {
+	var joined map[string]any
+	n := 0
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		switch r.URL.Path {
+		case "/config":
+			fmt.Fprint(w, `{"components":[{"id":20,"type":"textbox"},{"id":16,"type":"audio"},{"id":17,"type":"image"},{"id":18,"type":"video"},`+
+				`{"id":13,"type":"chatbot"},{"id":7,"type":"textbox"},{"id":8,"type":"slider"},{"id":9,"type":"slider"},{"id":10,"type":"slider"}],`+
+				`"dependencies":[{"id":0,"api_name":"chat_predict","targets":[[21,"click"]],"inputs":[20,16,17,18,13,7,8,9,10]}]}`)
+		case "/gradio_api/upload":
+			n++
+			fmt.Fprintf(w, `["/tmp/f%d"]`, n)
+		case "/gradio_api/queue/join":
+			_ = json.NewDecoder(r.Body).Decode(&joined)
+			fmt.Fprint(w, `{"event_id":"e"}`)
+		case "/gradio_api/queue/data":
+			fmt.Fprint(w, "data: {\"msg\":\"process_completed\",\"success\":true,\"output\":{\"data\":[{},{},{},{},[{\"role\":\"assistant\",\"content\":\"ok\"}],{},{}]}}\n\n")
+		}
+	}))
+	defer srv.Close()
+	enc := base64.StdEncoding.EncodeToString([]byte("x"))
+	msgs := []aiMsg{{Role: "user", Content: "что тут", Attachments: []aiAttachment{
+		{Name: "a.png", MIME: "image/png", Data: enc},
+		{Name: "b.mp3", MIME: "audio/mpeg", Data: enc},
+		{Name: "c.mp4", MIME: "video/mp4", Data: enc},
+	}}}
+	if err := aiStream(context.Background(), aiConfig{Type: "gradio", URL: srv.URL}, "sys", msgs, func(string) {}); err != nil {
+		t.Fatal(err)
+	}
+	d := joined["data"].([]any)
+	path := func(v any) string { m, _ := v.(map[string]any); p, _ := m["path"].(string); return p }
+	video, _ := d[3].(map[string]any)
+	if path(d[1]) != "/tmp/f2" || path(d[2]) != "/tmp/f1" || path(video["video"]) != "/tmp/f3" || video["subtitles"] != nil || d[5] != "sys" {
+		t.Fatalf("data: %v", d)
+	}
+}
@@ -0,0 +1,110 @@
+package server
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"strings"
+	"testing"
+)
+
+// The model set before there could be several is the first of the list.
+func TestAIModelsFromLegacy(t *testing.T) {
+	s, _ := newTestServer(t)
+	_ = s.db.SetConfig(cfgAIType, "openai")
+	_ = s.db.SetConfig(cfgAIURL, "https://api.example/v1/")
+	_ = s.db.SetConfig(cfgAIModel, "gpt-x")
+	_ = s.db.SetConfig(cfgAIKey, "k1")
+	ms := s.aiModels()
+	if len(ms) != 1 || ms[0].Type != "openai" || ms[0].URL != "https://api.example/v1" || ms[0].Model != "gpt-x" || ms[0].Key != "k1" || ms[0].ID == "" {
+		t.Fatalf("models: %+v", ms)
+	}
+	if got := s.aiModel("nope"); got.ID != ms[0].ID {
+		t.Fatalf("an unknown id is not the first model: %+v", got)
+	}
+}
+
+// postAIModels sends the settings form with the given models.
+func postAIModels(t *testing.T, s *Server, c *http.Cookie, models [][7]string) {
+	t.Helper()
+	f := url.Values{"csrf": {"tok"}}
+	for _, m := range models {
+		f.Add("m_id", m[0])
+		f.Add("m_name", m[1])
+		f.Add("m_type", m[2])
+		f.Add("m_url", m[3])
+		f.Add("m_model", m[4])
+		f.Add("m_key", m[5])
+		f.Add("m_short", m[6])
+	}
+	req := httptest.NewRequest(http.MethodPost, "/settings/ai", strings.NewReader(f.Encode()))
+	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+	req.AddCookie(c)
+	req.AddCookie(&http.Cookie{Name: csrfCookie, Value: "tok"})
+	w := httptest.NewRecorder()
+	s.Handler().ServeHTTP(w, req)
+	if w.Code != http.StatusSeeOther {
+		t.Fatalf("save: %d %s", w.Code, w.Body)
+	}
+}
+
+// Настройки keep several models with their names; the chat learns the
+// names and ids only, never a key.
+func TestAIModelsSaveAndList(t *testing.T) {
+	s, c := newTestServer(t)
+	postAIModels(t, s, c, [][7]string{
+		{"", "Qwen", "gradio", "", "", "", ""},
+		{"", "Claude", "anthropic", "https://api.anthropic.com", "claude-x", "secret-key", "Сонет 4.5 длинно"},
+		{"", "", "", "", "", "", ""}, // an empty card is dropped
+	})
+	ms := s.aiModels()
+	if len(ms) != 2 || ms[0].Name != "Qwen" || ms[1].Name != "Claude" || ms[1].Key != "secret-key" || ms[0].ID == "" || ms[0].ID == ms[1].ID || ms[1].Short != "Сонет 4.5 дл" {
+		t.Fatalf("models: %+v", ms)
+	}
+	body := get(t, s, c, "/api/panel/ai").Body.String()
+	if strings.Contains(body, "secret-key") || !strings.Contains(body, `"name":"Claude"`) || !strings.Contains(body, `"short":"Сонет 4.5 дл"`) || !strings.Contains(body, ms[1].ID) {
+		t.Fatalf("state: %s", body)
+	}
+	// Saved again with its id, a model keeps it.
+	postAIModels(t, s, c, [][7]string{{ms[1].ID, "Claude 2", "anthropic", "https://api.anthropic.com", "claude-x", "secret-key", ""}})
+	if got := s.aiModels(); len(got) != 1 || got[0].ID != ms[1].ID || got[0].Name != "Claude 2" {
+		t.Fatalf("after resave: %+v", got)
+	}
+	if !strings.Contains(get(t, s, c, "/settings?frag=1").Body.String(), `value="Claude 2"`) {
+		t.Fatal("the settings page does not show the model's name")
+	}
+}
+
+// The chat asks the model it names.
+func TestAIChatUsesChosenModel(t *testing.T) {
+	s, c := newTestServer(t)
+	srv := func(word string) *httptest.Server {
+		return httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			fmt.Fprintf(w, "data: {\"choices\":[{\"delta\":{\"content\":\"%s\"}}]}\n\ndata: [DONE]\n\n", word)
+		}))
+	}
+	one, two := srv("first"), srv("second")
+	defer one.Close()
+	defer two.Close()
+	postAIModels(t, s, c, [][7]string{
+		{"", "One", "openai", one.URL, "m", "", ""},
+		{"", "Two", "openai", two.URL, "m", "", ""},
+	})
+	ms := s.aiModels()
+	ask := func(model string) string {
+		b, _ := json.Marshal(map[string]any{"message": "hi", "context": "x", "model": model})
+		req := httptest.NewRequest(http.MethodPost, "/api/panel/ai/chat", strings.NewReader(string(b)))
+		req.AddCookie(c)
+		w := httptest.NewRecorder()
+		s.Handler().ServeHTTP(w, req)
+		return w.Body.String()
+	}
+	if got := ask(ms[1].ID); !strings.Contains(got, "second") {
+		t.Fatalf("model Two: %q", got)
+	}
+	if got := ask(""); !strings.Contains(got, "first") {
+		t.Fatalf("no model named - the first: %q", got)
+	}
+}
@@ -0,0 +1,42 @@
+package server
+
+import (
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+)
+
+// The assistant is on unless the user turned it off - for the web search
+// and page reading as for the chat (a user who never touched the switch
+// has no setting at all).
+func TestAISearchAndFetchOnByDefault(t *testing.T) {
+	s, c := newTestServer(t)
+	sx := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		fmt.Fprint(w, `{"results":[{"title":"Intel","url":"https://example.com/intel","content":"процессоры"}]}`)
+	}))
+	defer sx.Close()
+	_ = s.db.SetConfig(cfgSearchEngine, "searxng")
+	_ = s.db.SetConfig(cfgSearchURL, sx.URL)
+	post := func(path, body string) string {
+		req := httptest.NewRequest(http.MethodPost, path, strings.NewReader(body))
+		req.AddCookie(c)
+		w := httptest.NewRecorder()
+		s.Handler().ServeHTTP(w, req)
+		return w.Body.String()
+	}
+	if got := post("/api/panel/ai/search", `{"q":"intel"}`); !strings.Contains(got, `"ok":true`) {
+		t.Fatalf("search by default: %s", got)
+	}
+	if got := post("/api/panel/ai/fetch", `{"url":"не адрес"}`); strings.Contains(got, "выключен") {
+		t.Fatalf("fetch by default: %s", got)
+	}
+	a, _ := s.db.AdminByUsername("adm")
+	_ = s.db.SetConfig(aiUserKey(a.ID), "0")
+	for _, p := range []string{"/api/panel/ai/search", "/api/panel/ai/fetch"} {
+		if got := post(p, `{"q":"intel","url":"https://example.com"}`); !strings.Contains(got, "выключен") {
+			t.Fatalf("%s with the assistant off: %s", p, got)
+		}
+	}
+}
@@ -0,0 +1,144 @@
+package server
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"sync"
+	"testing"
+)
+
+// openAIChunk is one streamed delta of an OpenAI-compatible server.
+func openAIChunk(field, text string) string {
+	b, _ := json.Marshal(map[string]any{"choices": []any{map[string]any{"delta": map[string]string{field: text}}}})
+	return "data: " + string(b) + "\n\n"
+}
+
+// A model that thinks by itself (llama.cpp, vLLM: reasoning_content) has its
+// thinking shown as the chat's own: between ::думаю:: and ::ответ::.
+func TestAIOpenAINativeReasoning(t *testing.T) {
+	var body map[string]any
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		_ = json.NewDecoder(r.Body).Decode(&body)
+		fmt.Fprint(w, openAIChunk("reasoning_content", "17*23")+openAIChunk("reasoning_content", " = 391")+
+			openAIChunk("content", "391")+"data: [DONE]\n\n")
+	}))
+	defer srv.Close()
+	got, err := collect(t, aiConfig{Type: "openai", URL: srv.URL, Model: "m", think: "on"})
+	if err != nil || got != "::думаю::\n17*23 = 391\n::ответ::\n391" {
+		t.Fatalf("got %q, %v", got, err)
+	}
+	kw, _ := body["chat_template_kwargs"].(map[string]any)
+	if kw["enable_thinking"] != true {
+		t.Fatalf("thinking not asked for: %v", body)
+	}
+}
+
+// A server that does not know the thinking switch (400 on it) is asked again
+// without it.
+func TestAIOpenAIRetriesWithoutThinkSwitch(t *testing.T) {
+	var mu sync.Mutex
+	var calls []map[string]any
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		var b map[string]any
+		_ = json.NewDecoder(r.Body).Decode(&b)
+		mu.Lock()
+		calls = append(calls, b)
+		mu.Unlock()
+		if _, ok := b["chat_template_kwargs"]; ok {
+			http.Error(w, `{"error":{"message":"Unrecognized request argument supplied: chat_template_kwargs"}}`, 400)
+			return
+		}
+		fmt.Fprint(w, openAIChunk("content", "ok")+"data: [DONE]\n\n")
+	}))
+	defer srv.Close()
+	got, err := collect(t, aiConfig{Type: "openai", URL: srv.URL, Model: "m", think: "off"})
+	if err != nil || got != "ok" || len(calls) != 2 {
+		t.Fatalf("got %q, %v, %d calls", got, err, len(calls))
+	}
+}
+
+// Anthropic: «Думать» turns on extended thinking; its thinking_delta is the
+// thinking shown.
+func TestAIAnthropicThinking(t *testing.T) {
+	var body map[string]any
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		_ = json.NewDecoder(r.Body).Decode(&body)
+		fmt.Fprint(w, "data: {\"type\":\"content_block_delta\",\"delta\":{\"type\":\"thinking_delta\",\"thinking\":\"хм\"}}\n\n"+
+			"data: {\"type\":\"content_block_delta\",\"delta\":{\"type\":\"text_delta\",\"text\":\"Да\"}}\n\n"+
+			"data: {\"type\":\"message_stop\"}\n\n")
+	}))
+	defer srv.Close()
+	got, err := collect(t, aiConfig{Type: "anthropic", URL: srv.URL, Key: "k", Model: "m", think: "on"})
+	if err != nil || got != "::думаю::\nхм\n::ответ::\nДа" {
+		t.Fatalf("got %q, %v", got, err)
+	}
+	th, _ := body["thinking"].(map[string]any)
+	if th["type"] != "enabled" || body["max_tokens"].(float64) <= th["budget_tokens"].(float64) {
+		t.Fatalf("thinking not asked for: %v", body)
+	}
+}
+
+// askThink sends one «Думать» question to the chat and gives the answer and
+// the system prompts the model got, in order.
+func askThink(t *testing.T, reply func(system string, body map[string]any) string) (string, []string) {
+	t.Helper()
+	s, c := newTestServer(t)
+	var mu sync.Mutex
+	var systems []string
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		var b map[string]any
+		_ = json.NewDecoder(r.Body).Decode(&b)
+		sys := b["messages"].([]any)[0].(map[string]any)["content"].(string)
+		if strings.Contains(fmt.Sprint(b["messages"]), "название чата") || strings.Contains(sys, "название чата") {
+			fmt.Fprint(w, openAIChunk("content", "Чат")+"data: [DONE]\n\n")
+			return
+		}
+		mu.Lock()
+		systems = append(systems, sys)
+		mu.Unlock()
+		fmt.Fprint(w, reply(sys, b)+"data: [DONE]\n\n")
+	}))
+	t.Cleanup(srv.Close)
+	postAIModels(t, s, c, [][7]string{{"", "M", "openai", srv.URL, "m", "", ""}})
+	req := httptest.NewRequest(http.MethodPost, "/api/panel/ai/chat", strings.NewReader(`{"message":"сколько 17*23","context":"x","think":true}`))
+	req.AddCookie(c)
+	w := httptest.NewRecorder()
+	s.Handler().ServeHTTP(w, req)
+	mu.Lock()
+	defer mu.Unlock()
+	return w.Body.String(), append([]string(nil), systems...)
+}
+
+// A model with thinking of its own thinks once, by itself: no "think in
+// words" prompt on top.
+func TestAIChatThinkNative(t *testing.T) {
+	got, systems := askThink(t, func(sys string, b map[string]any) string {
+		return openAIChunk("reasoning_content", "считаю") + openAIChunk("content", "391")
+	})
+	if len(systems) != 1 || strings.Contains(systems[0], "Режим размышления") {
+		t.Fatalf("systems: %q", systems)
+	}
+	if !strings.Contains(got, "::думаю::\nсчитаю\n::ответ::\n391") {
+		t.Fatalf("answer: %q", got)
+	}
+}
+
+// A model without it is asked again with the prompt, its first answer
+// dropped unseen.
+func TestAIChatThinkPromptFallback(t *testing.T) {
+	got, systems := askThink(t, func(sys string, b map[string]any) string {
+		if strings.Contains(sys, "Режим размышления") {
+			return openAIChunk("content", "::думаю::\nсчитаю\n::ответ::\n391")
+		}
+		return openAIChunk("content", "сразу ответ")
+	})
+	if len(systems) != 2 || strings.Contains(systems[0], "Режим размышления") || !strings.Contains(systems[1], "Режим размышления") {
+		t.Fatalf("systems: %q", systems)
+	}
+	if strings.Contains(got, "сразу ответ") || !strings.Contains(got, "::ответ::\n391") {
+		t.Fatalf("answer: %q", got)
+	}
+}
@@ -0,0 +1,389 @@
+package server
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/x-grk/longpolling-remote-access/internal/proto"
+)
+
+// Auto-update, two kinds, each off until asked for (Настройки › Автообновление):
+//   - of the agents: they are told how often to compare their version with
+//     the server's and, if the server's is newer, to take the agent from it
+//     (as the panel's «Обновить» does);
+//   - of the server: it compares itself with the latest release on GitLab;
+//     when that is newer, an administrator is offered it at login (after the
+//     PIN), and on «Обновить» the install script is run (the same one as
+//     `wget -qO- …/server-install.sh | sudo sh`). Nothing runs unasked.
+
+const (
+	cfgAgentAuto     = "agent_autoupdate"
+	cfgAgentAutoMin  = "agent_autoupdate_min"
+	cfgServerAuto    = "server_autoupdate"
+	cfgServerAutoMin = "server_autoupdate_min"
+
+	// Where releases are. Not in the settings: for tests.
+	cfgUpdateRepo = "update_repo"
+	cfgUpdateBase = "update_base"
+
+	DefaultUpdateRepo = "itzredtea/lpra"
+	DefaultUpdateBase = "https://gitlab.com"
+
+	defaultAutoMin = 360          // 6 hours
+	maxAutoMin     = 60 * 24 * 30 // 30 days
+)
+
+// autoSetting reads an "on" flag and its interval in minutes.
+func (s *Server) autoSetting(onKey, minKey string) (bool, int) {
+	on, _ := s.db.GetConfig(onKey)
+	m, _ := strconv.Atoi(func() string { v, _ := s.db.GetConfig(minKey); return v }())
+	if m < 1 || m > maxAutoMin {
+		m = defaultAutoMin
+	}
+	return on == "1", m
+}
+
+func (s *Server) agentAuto() (bool, int)  { return s.autoSetting(cfgAgentAuto, cfgAgentAutoMin) }
+func (s *Server) serverAuto() (bool, int) { return s.autoSetting(cfgServerAuto, cfgServerAutoMin) }
+
+// setUpdateHeaders tells an agent the server's version and how often to
+// compare ("0": never).
+func (s *Server) setUpdateHeaders(w http.ResponseWriter) {
+	w.Header().Set(proto.ServerVersionHeader, Version)
+	w.Header().Set(proto.AutoUpdateHeader, strconv.Itoa(s.agentAutoMinutes()))
+}
+
+// agentAutoMinutes is the interval agents are given, 0 when off.
+func (s *Server) agentAutoMinutes() int {
+	if on, m := s.agentAuto(); on {
+		return m
+	}
+	return 0
+}
+
+// minutesOf turns "2" and "h" into 120: min, h, d.
+func minutesOf(n, unit string) int {
+	v, err := strconv.Atoi(strings.TrimSpace(n))
+	if err != nil || v < 1 {
+		return defaultAutoMin
+	}
+	switch unit {
+	case "h":
+		v *= 60
+	case "d":
+		v *= 60 * 24
+	}
+	if v > maxAutoMin {
+		v = maxAutoMin
+	}
+	return v
+}
+
+// POST /settings/autoupdate - both settings.
+func (s *Server) handleSetAutoUpdate(w http.ResponseWriter, r *http.Request) {
+	if !checkCSRF(r) {
+		http.Error(w, "bad csrf", http.StatusForbidden)
+		return
+	}
+	flag := func(v string) string {
+		if v == "1" {
+			return "1"
+		}
+		return ""
+	}
+	_ = s.db.SetConfig(cfgAgentAuto, flag(r.FormValue("agent_auto")))
+	_ = s.db.SetConfig(cfgAgentAutoMin, strconv.Itoa(minutesOf(r.FormValue("agent_every"), r.FormValue("agent_unit"))))
+	_ = s.db.SetConfig(cfgServerAuto, flag(r.FormValue("server_auto")))
+	_ = s.db.SetConfig(cfgServerAutoMin, strconv.Itoa(minutesOf(r.FormValue("server_every"), r.FormValue("server_unit"))))
+	// A server that was told to look again looks at once.
+	s.upd.mu.Lock()
+	s.upd.last = time.Time{}
+	s.upd.mu.Unlock()
+	http.Redirect(w, r, "/settings#autoupdate", http.StatusSeeOther)
+}
+
+// intervalParts is a number of minutes as the form shows it: 120 - 2 h.
+func intervalParts(min int) (int, string) {
+	switch {
+	case min%(60*24) == 0:
+		return min / (60 * 24), "d"
+	case min%60 == 0:
+		return min / 60, "h"
+	}
+	return min, "min"
+}
+
+// autoView is what Настройки show of the settings.
+type autoView struct {
+	AgentOn, ServerOn       bool
+	AgentEvery, ServerEvery int
+	AgentUnit, ServerUnit   string
+	Status                  updStatus
+}
+
+func (s *Server) autoView() autoView {
+	var v autoView
+	var am, sm int
+	v.AgentOn, am = s.agentAuto()
+	v.ServerOn, sm = s.serverAuto()
+	v.AgentEvery, v.AgentUnit = intervalParts(am)
+	v.ServerEvery, v.ServerUnit = intervalParts(sm)
+	v.Status = s.updateStatus()
+	return v
+}
+
+// updState is what the updating of the server remembers.
+type updState struct {
+	mu      sync.Mutex
+	last    time.Time // when it last looked
+	latest  string
+	checked time.Time
+	err     string
+}
+
+// updStatus is that, for the settings page.
+type updStatus struct {
+	Current, Latest string
+	Checked         string
+	Error           string
+	Newer           bool
+}
+
+func (s *Server) updateStatus() updStatus {
+	s.upd.mu.Lock()
+	defer s.upd.mu.Unlock()
+	st := updStatus{Current: Version, Latest: s.upd.latest, Error: s.upd.err, Newer: proto.VersionNewer(s.upd.latest, Version)}
+	if !s.upd.checked.IsZero() {
+		st.Checked = s.upd.checked.Format("02.01.2006 15:04")
+	}
+	return st
+}
+
+func (s *Server) updateRepoBase() (base, repo string) {
+	base, _ = s.db.GetConfig(cfgUpdateBase)
+	if base == "" {
+		base = DefaultUpdateBase
+	}
+	repo, _ = s.db.GetConfig(cfgUpdateRepo)
+	if repo == "" {
+		repo = DefaultUpdateRepo
+	}
+	return strings.TrimRight(base, "/"), repo
+}
+
+var updateClient = &http.Client{Timeout: 30 * time.Second}
+
+// latestRelease is the tag of the project's latest release on GitLab.
+func (s *Server) latestRelease(ctx context.Context) (string, error) {
+	base, repo := s.updateRepoBase()
+	req, _ := http.NewRequestWithContext(ctx, http.MethodGet, base+"/api/v4/projects/"+url.PathEscape(repo)+"/releases/permalink/latest", nil)
+	req.Header.Set("Accept", "application/json")
+	resp, err := updateClient.Do(req)
+	if err != nil {
+		return "", errors.New("GitLab не отвечает: " + err.Error())
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode/100 != 2 {
+		return "", errors.New("GitLab ответил " + resp.Status)
+	}
+	var out struct {
+		Tag string `json:"tag_name"`
+	}
+	if err := json.NewDecoder(io.LimitReader(resp.Body, 1<<20)).Decode(&out); err != nil || out.Tag == "" {
+		return "", errors.New("не прочиталась версия последнего релиза")
+	}
+	return strings.TrimPrefix(out.Tag, "v"), nil
+}
+
+// checkRelease looks at GitLab and keeps what it found for the page.
+func (s *Server) checkRelease(ctx context.Context) (string, error) {
+	tag, err := s.latestRelease(ctx)
+	s.upd.mu.Lock()
+	defer s.upd.mu.Unlock()
+	s.upd.checked = time.Now()
+	if err != nil {
+		s.upd.err = err.Error()
+		return "", err
+	}
+	s.upd.latest, s.upd.err = tag, ""
+	return tag, nil
+}
+
+// installScript is the install script on the project's main branch.
+func (s *Server) installScript(ctx context.Context) ([]byte, error) {
+	base, repo := s.updateRepoBase()
+	req, _ := http.NewRequestWithContext(ctx, http.MethodGet, base+"/"+repo+"/-/raw/main/server-install.sh", nil)
+	resp, err := updateClient.Do(req)
+	if err != nil {
+		return nil, errors.New("скрипт установки не скачался: " + err.Error())
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode/100 != 2 {
+		return nil, errors.New("скрипт установки: GitLab ответил " + resp.Status)
+	}
+	b, _ := io.ReadAll(io.LimitReader(resp.Body, 1<<20))
+	// What is run as root must be the script, not a page of an error.
+	if !strings.HasPrefix(string(b), "#!/bin/sh\n") || !strings.Contains(string(b), "LPRA server") {
+		return nil, errors.New("по адресу скрипта установки лежит не он")
+	}
+	return b, nil
+}
+
+// startServerUpdate takes the install script and has it run, apart from
+// this process: it stops the service, and a script in the service's own
+// control group would go with it.
+func (s *Server) startServerUpdate(ctx context.Context) error {
+	script, err := s.installScript(ctx)
+	if err != nil {
+		return err
+	}
+	run := s.updRun
+	if run == nil {
+		run = runServerUpdate
+	}
+	return run(script)
+}
+
+// runServerUpdate runs the script as a transient systemd unit of its own,
+// in the folder this server lives in. Needs root and systemd.
+func runServerUpdate(script []byte) error {
+	if os.Geteuid() != 0 {
+		return errors.New("сервер запущен не от root - обновить его самому нельзя, запустите server-install.sh")
+	}
+	sr, err := exec.LookPath("systemd-run")
+	if err != nil {
+		return errors.New("нет systemd-run - автообновление сервера работает только под systemd")
+	}
+	exe, err := os.Executable()
+	if err != nil {
+		return err
+	}
+	dir := filepath.Dir(exe)
+	path := filepath.Join(dir, ".server-update.sh")
+	if err := os.WriteFile(path, script, 0o700); err != nil {
+		return errors.New("скрипт не записался: " + err.Error())
+	}
+	out, err := exec.Command(sr, "--unit=lpra-self-update", "--collect", "--setenv=LPRA_DIR="+dir,
+		"/bin/sh", "-c", "sh '"+path+"'; rm -f '"+path+"'").CombinedOutput()
+	if err != nil {
+		_ = os.Remove(path)
+		return fmt.Errorf("systemd-run: %s", strings.TrimSpace(string(out)))
+	}
+	return nil
+}
+
+// autoUpdateTick: one look at the clock. When the server is to look at
+// GitLab (on, and the interval is out) it does, and keeps what it found.
+func (s *Server) autoUpdateTick(now time.Time) {
+	on, min := s.serverAuto()
+	if !on {
+		return
+	}
+	s.upd.mu.Lock()
+	if !s.upd.last.IsZero() && now.Sub(s.upd.last) < time.Duration(min)*time.Minute {
+		s.upd.mu.Unlock()
+		return
+	}
+	s.upd.last = now
+	s.upd.mu.Unlock()
+
+	ctx, cancel := context.WithTimeout(context.Background(), time.Minute)
+	defer cancel()
+	_, _ = s.checkRelease(ctx)
+}
+
+// RunAutoUpdate watches the clock until ctx ends.
+func (s *Server) RunAutoUpdate(ctx context.Context) {
+	t := time.NewTicker(30 * time.Second)
+	defer t.Stop()
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case now := <-t.C:
+			s.autoUpdateTick(now)
+		}
+	}
+}
+
+// POST /api/panel/update/check - looks at GitLab now.
+func (s *Server) handleUpdateCheck(w http.ResponseWriter, r *http.Request) {
+	tag, err := s.checkRelease(r.Context())
+	if err != nil {
+		writeJSON(w, map[string]any{"ok": false, "error": err.Error(), "current": Version})
+		return
+	}
+	writeJSON(w, map[string]any{"ok": true, "current": Version, "latest": tag, "newer": proto.VersionNewer(tag, Version)})
+}
+
+// POST /api/panel/update/run - updates the server now, to a newer release.
+func (s *Server) handleUpdateRun(w http.ResponseWriter, r *http.Request) {
+	tag, err := s.checkRelease(r.Context())
+	if err != nil {
+		writeJSON(w, map[string]any{"ok": false, "error": err.Error()})
+		return
+	}
+	if !proto.VersionNewer(tag, Version) {
+		writeJSON(w, map[string]any{"ok": false, "error": "уже последняя версия (" + Version + ")"})
+		return
+	}
+	if err := s.startServerUpdate(r.Context()); err != nil {
+		writeJSON(w, map[string]any{"ok": false, "error": err.Error()})
+		return
+	}
+	writeJSON(w, map[string]any{"ok": true, "latest": tag})
+}
+
+func declinedKey(id int64) string { return "update_declined_" + strconv.FormatInt(id, 10) }
+
+// GET /api/panel/update/offer - whether this administrator is to be offered
+// an update now: auto-update on, a release newer than this one, and not one
+// they declined.
+func (s *Server) handleUpdateOffer(w http.ResponseWriter, r *http.Request) {
+	no := func() { writeJSON(w, map[string]any{"offer": false}) }
+	on, min := s.serverAuto()
+	if !on {
+		no()
+		return
+	}
+	// Not looked at lately (just started, or the interval is out): look now.
+	s.upd.mu.Lock()
+	stale := s.upd.checked.IsZero() || time.Since(s.upd.checked) >= time.Duration(min)*time.Minute
+	s.upd.mu.Unlock()
+	if stale {
+		ctx, cancel := context.WithTimeout(r.Context(), 10*time.Second)
+		_, _ = s.checkRelease(ctx)
+		cancel()
+	}
+	st := s.updateStatus()
+	declined, _ := s.db.GetConfig(declinedKey(s.currentAdmin(r).ID))
+	if !st.Newer || declined == st.Latest {
+		no()
+		return
+	}
+	writeJSON(w, map[string]any{"offer": true, "current": st.Current, "latest": st.Latest})
+}
+
+// POST /api/panel/update/decline - {version}: this administrator is not to
+// be asked about that release again.
+func (s *Server) handleUpdateDecline(w http.ResponseWriter, r *http.Request) {
+	var in struct {
+		Version string `json:"version"`
+	}
+	if json.NewDecoder(http.MaxBytesReader(w, r.Body, 1<<10)).Decode(&in) == nil && len(in.Version) <= 32 {
+		_ = s.db.SetConfig(declinedKey(s.currentAdmin(r).ID), in.Version)
+	}
+	writeJSON(w, map[string]any{"ok": true})
+}
@@ -0,0 +1,272 @@
+package server
+
+import (
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"strings"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/x-grk/longpolling-remote-access/internal/proto"
+)
+
+// fakeGitLab is the place releases come from: the latest release's tag and
+// the install script on main.
+type fakeGitLab struct {
+	srv    *httptest.Server
+	mu     sync.Mutex
+	tag    string
+	script string
+	hits   int
+}
+
+func newFakeGitLab(t *testing.T, tag string) *fakeGitLab {
+	g := &fakeGitLab{tag: tag, script: "#!/bin/sh\n# LPRA server: install or update in one command.\necho updating\n"}
+	g.srv = httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		g.mu.Lock()
+		defer g.mu.Unlock()
+		g.hits++
+		switch r.URL.EscapedPath() {
+		case "/api/v4/projects/itzredtea%2Flpra/releases/permalink/latest":
+			// The real one sends the caller on to the release itself.
+			http.Redirect(w, r, "/api/v4/projects/1/releases/"+g.tag, http.StatusFound)
+		case "/api/v4/projects/1/releases/" + g.tag:
+			fmt.Fprintf(w, `{"tag_name":%q}`, g.tag)
+		case "/itzredtea/lpra/-/raw/main/server-install.sh":
+			fmt.Fprint(w, g.script)
+		default:
+			http.NotFound(w, r)
+		}
+	}))
+	t.Cleanup(g.srv.Close)
+	return g
+}
+
+func useFakeGitLab(s *Server, g *fakeGitLab) {
+	_ = s.db.SetConfig(cfgUpdateBase, g.srv.URL)
+}
+
+// A runner that only notes what it was given, in place of a real update.
+type runs struct {
+	mu      sync.Mutex
+	scripts []string
+	err     error
+}
+
+func (r *runs) run(script []byte) error {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	r.scripts = append(r.scripts, string(script))
+	return r.err
+}
+
+func (r *runs) n() int { r.mu.Lock(); defer r.mu.Unlock(); return len(r.scripts) }
+
+// postAuto sends the form of Настройки › Автообновление.
+func postAuto(t *testing.T, s *Server, c *http.Cookie, f url.Values) {
+	t.Helper()
+	f.Set("csrf", "tok")
+	req := httptest.NewRequest(http.MethodPost, "/settings/autoupdate", strings.NewReader(f.Encode()))
+	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+	req.AddCookie(c)
+	req.AddCookie(&http.Cookie{Name: csrfCookie, Value: "tok"})
+	w := httptest.NewRecorder()
+	s.Handler().ServeHTTP(w, req)
+	if w.Code != http.StatusSeeOther {
+		t.Fatalf("save: %d %s", w.Code, w.Body)
+	}
+}
+
+// The settings are kept in minutes whatever unit they were given in, and
+// off unless asked for.
+func TestAutoUpdateSettings(t *testing.T) {
+	s, c := newTestServer(t)
+	if on, _ := s.agentAuto(); on {
+		t.Fatal("agents update by themselves with nothing set")
+	}
+	postAuto(t, s, c, url.Values{"agent_auto": {"1"}, "agent_every": {"2"}, "agent_unit": {"h"}, "server_auto": {"1"}, "server_every": {"1"}, "server_unit": {"d"}})
+	if on, m := s.agentAuto(); !on || m != 120 {
+		t.Fatalf("agents: %v %d", on, m)
+	}
+	if on, m := s.serverAuto(); !on || m != 1440 {
+		t.Fatalf("server: %v %d", on, m)
+	}
+	// Out of range or not a number: the default, or the largest.
+	postAuto(t, s, c, url.Values{"agent_auto": {"1"}, "agent_every": {"x"}, "agent_unit": {"min"}, "server_every": {"999"}, "server_unit": {"d"}})
+	if _, m := s.agentAuto(); m != defaultAutoMin {
+		t.Fatalf("a bad number: %d", m)
+	}
+	if on, m := s.serverAuto(); on || m != maxAutoMin {
+		t.Fatalf("server off, a large number: %v %d", on, m)
+	}
+	body := get(t, s, c, "/settings?frag=1").Body.String()
+	if !strings.Contains(body, `id="autoupdate"`) || !strings.Contains(body, "Автообновление клиентов") || !strings.Contains(body, "Автообновление сервера") {
+		t.Fatal("the settings page has no auto-update card")
+	}
+}
+
+// Agents are told of it - on the config they fetch, and with their poll -
+// together with the server's own version.
+func TestAgentsToldOfAutoUpdate(t *testing.T) {
+	s, c := newTestServer(t)
+	if err := s.db.CreateAgent(Agent{ID: "a2", Name: "n", Hostname: "h", OS: "linux", Arch: "amd64", TokenHash: hashToken("tok2")}); err != nil {
+		t.Fatal(err)
+	}
+	cfg := func() http.Header {
+		req := httptest.NewRequest(http.MethodGet, "/api/agent/config", nil)
+		req.Header.Set("X-Agent-Id", "a2")
+		req.Header.Set("Authorization", "Bearer tok2")
+		w := httptest.NewRecorder()
+		s.Handler().ServeHTTP(w, req)
+		if w.Code != http.StatusNoContent {
+			t.Fatalf("config: %d", w.Code)
+		}
+		return w.Header()
+	}
+	h := cfg()
+	if h.Get(proto.AutoUpdateHeader) != "0" || h.Get(proto.ServerVersionHeader) != Version {
+		t.Fatalf("off: %v", h)
+	}
+	postAuto(t, s, c, url.Values{"agent_auto": {"1"}, "agent_every": {"90"}, "agent_unit": {"min"}})
+	if h := cfg(); h.Get(proto.AutoUpdateHeader) != "90" {
+		t.Fatalf("on: %v", h)
+	}
+}
+
+// The latest release is read from GitLab, through its redirect.
+func TestLatestRelease(t *testing.T) {
+	s, _ := newTestServer(t)
+	g := newFakeGitLab(t, "9.9.9")
+	useFakeGitLab(s, g)
+	tag, err := s.latestRelease(t.Context())
+	if err != nil || tag != "9.9.9" {
+		t.Fatalf("latest: %q %v", tag, err)
+	}
+	g.srv.Close()
+	if _, err := s.latestRelease(t.Context()); err == nil {
+		t.Fatal("no error with GitLab out of reach")
+	}
+}
+
+// With auto-update on the server looks at GitLab by itself, at the interval,
+// and only looks: updating is the administrator's to say yes to.
+func TestServerAutoUpdateTick(t *testing.T) {
+	s, c := newTestServer(t)
+	g := newFakeGitLab(t, "99.0.0")
+	useFakeGitLab(s, g)
+	r := &runs{}
+	s.updRun = r.run
+	now := time.Now()
+
+	s.autoUpdateTick(now)
+	if g.hits != 0 {
+		t.Fatalf("off, yet it looked: %d hits", g.hits)
+	}
+	postAuto(t, s, c, url.Values{"server_auto": {"1"}, "server_every": {"60"}, "server_unit": {"min"}})
+	s.autoUpdateTick(now)
+	if st := s.updateStatus(); st.Latest != "99.0.0" || !st.Newer {
+		t.Fatalf("it did not learn of the release: %+v", st)
+	}
+	hits := g.hits
+	s.autoUpdateTick(now.Add(10 * time.Minute))
+	if g.hits != hits {
+		t.Fatal("it looked again before the interval was out")
+	}
+	s.autoUpdateTick(now.Add(61 * time.Minute))
+	if g.hits == hits {
+		t.Fatal("it did not look when the interval was out")
+	}
+	if r.n() != 0 {
+		t.Fatalf("it updated by itself: %d runs", r.n())
+	}
+	// GitLab out of reach: told on the page, kept until it answers.
+	g.srv.Close()
+	s.autoUpdateTick(now.Add(130 * time.Minute))
+	if st := s.updateStatus(); st.Error == "" {
+		t.Fatalf("the failure is not kept: %+v", st)
+	}
+}
+
+// What an administrator is offered at login: a newer release, with
+// auto-update on, not one they said no to - and again when a newer one comes.
+func TestUpdateOffer(t *testing.T) {
+	s, c := newTestServer(t)
+	g := newFakeGitLab(t, "99.0.0")
+	useFakeGitLab(s, g)
+	offer := func() string { return apiCall(t, s, c, "GET", "/api/panel/update/offer", "") }
+	if got := offer(); !strings.Contains(got, `"offer":false`) {
+		t.Fatalf("auto-update off: %s", got)
+	}
+	postAuto(t, s, c, url.Values{"server_auto": {"1"}, "server_every": {"60"}, "server_unit": {"min"}})
+	got := offer()
+	if !strings.Contains(got, `"offer":true`) || !strings.Contains(got, `"latest":"99.0.0"`) || !strings.Contains(got, `"current":"`+Version+`"`) {
+		t.Fatalf("a newer release: %s", got)
+	}
+	apiCall(t, s, c, "POST", "/api/panel/update/decline", `{"version":"99.0.0"}`)
+	if got := offer(); !strings.Contains(got, `"offer":false`) {
+		t.Fatalf("after saying no: %s", got)
+	}
+	g.tag = "99.1.0"
+	s.upd.mu.Lock()
+	s.upd.checked = time.Time{}
+	s.upd.mu.Unlock()
+	if got := offer(); !strings.Contains(got, `"offer":true`) || !strings.Contains(got, `"latest":"99.1.0"`) {
+		t.Fatalf("a still newer release: %s", got)
+	}
+	g.tag = Version
+	s.upd.mu.Lock()
+	s.upd.checked = time.Time{}
+	s.upd.mu.Unlock()
+	if got := offer(); !strings.Contains(got, `"offer":false`) {
+		t.Fatalf("nothing newer: %s", got)
+	}
+}
+
+// Anything but the install script is not run: a page of GitLab's, say.
+func TestUpdateScriptChecked(t *testing.T) {
+	s, _ := newTestServer(t)
+	g := newFakeGitLab(t, "99.0.0")
+	g.script = "<html>502 Bad Gateway</html>"
+	useFakeGitLab(s, g)
+	r := &runs{}
+	s.updRun = r.run
+	if err := s.startServerUpdate(t.Context()); err == nil || r.n() != 0 {
+		t.Fatalf("a page was run as a script: %v, %d runs", err, r.n())
+	}
+}
+
+// From the panel: check now, and update now - only to a newer release.
+func TestUpdatePanelButtons(t *testing.T) {
+	s, c := newTestServer(t)
+	g := newFakeGitLab(t, "99.0.0")
+	useFakeGitLab(s, g)
+	r := &runs{}
+	s.updRun = r.run
+	got := apiCall(t, s, c, "POST", "/api/panel/update/check", "")
+	if !strings.Contains(got, `"newer":true`) || !strings.Contains(got, `"latest":"99.0.0"`) || !strings.Contains(got, `"current":"`+Version+`"`) {
+		t.Fatalf("check: %s", got)
+	}
+	if got := apiCall(t, s, c, "POST", "/api/panel/update/run", ""); !strings.Contains(got, `"ok":true`) || r.n() != 1 {
+		t.Fatalf("run: %s, %d runs", got, r.n())
+	}
+	g.tag = Version
+	if got := apiCall(t, s, c, "POST", "/api/panel/update/run", ""); !strings.Contains(got, `"ok":false`) || r.n() != 1 {
+		t.Fatalf("run with nothing newer: %s, %d runs", got, r.n())
+	}
+}
+
+// Not for everybody: only an administrator updates the server.
+func TestUpdateOnlyForAdmins(t *testing.T) {
+	s, c := newTestServer(t)
+	a, _ := s.db.AdminByUsername("adm")
+	if a == nil {
+		t.Fatal("no admin")
+	}
+	// The test's user is an administrator; the guard is the route's own.
+	if got := apiCall(t, s, c, "POST", "/api/panel/update/check", ""); strings.Contains(got, "только для администраторов") {
+		t.Fatalf("an administrator was refused: %s", got)
+	}
+}
@@ -0,0 +1,89 @@
+package server
+
+import (
+	"bytes"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+// A chat deleted takes with it what the user attached to it: the text of
+// its files lives in the messages, and must be gone from the database
+// files too - not just from the tables (SQLite leaves deleted rows in its
+// free pages and in the write-ahead log).
+func TestDeleteChatWipesAttachments(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "t.db")
+	db, err := OpenDB(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	s, err := New(Options{DB: db, DistDir: t.TempDir()})
+	if err != nil {
+		t.Fatal(err)
+	}
+	hash, _ := hashPassword("Passw0rd12345")
+	if err := db.CreateAdmin("adm", hash); err != nil {
+		t.Fatal(err)
+	}
+	adm, _ := db.AdminByUsername("adm")
+	me := adm.ID
+	const secret = "TOP-SECRET-CONTENT-OF-AN-ATTACHED-FILE-7731"
+	chat := s.aiNewChat(me)
+	other := s.aiNewChat(me)
+	s.aiAppendTo(me, chat, "user", "посмотри\n\n[Вложение: notes.txt]\nСодержимое файла:\n"+secret)
+	s.aiAppendTo(me, chat, "result", "Картинка готова [картинка: https://s2.x-grk.com/uploads/userphoto/ai/zzz-7731.png]")
+	s.aiAppendTo(me, other, "user", "другой чат, остаётся")
+
+	s.aiDeleteChat(me, chat)
+
+	var n int
+	_ = db.sql.QueryRow(`SELECT COUNT(*) FROM ai_messages WHERE chat_id = ?`, chat).Scan(&n)
+	if n != 0 {
+		t.Fatalf("%d messages of the deleted chat remain", n)
+	}
+	_ = db.sql.QueryRow(`SELECT COUNT(*) FROM ai_messages WHERE chat_id = ?`, other).Scan(&n)
+	if n != 1 {
+		t.Fatalf("the other chat has %d messages, want 1", n)
+	}
+	for _, f := range []string{path, path + "-wal"} {
+		b, _ := os.ReadFile(f)
+		if bytes.Contains(b, []byte(secret)) || bytes.Contains(b, []byte("zzz-7731")) {
+			t.Fatalf("the deleted chat's content is still in %s", filepath.Base(f))
+		}
+	}
+}
+
+// The oldest chats go past the limit the same way: nothing of them is kept.
+func TestOldChatsWipedToo(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "t.db")
+	db, err := OpenDB(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	s, err := New(Options{DB: db, DistDir: t.TempDir()})
+	if err != nil {
+		t.Fatal(err)
+	}
+	hash, _ := hashPassword("Passw0rd12345")
+	if err := db.CreateAdmin("adm", hash); err != nil {
+		t.Fatal(err)
+	}
+	adm, _ := db.AdminByUsername("adm")
+	me := adm.ID
+	first := s.aiNewChat(me)
+	s.aiAppendTo(me, first, "user", "[Вложение: a.txt]\nСодержимое файла:\nOLD-ATTACHMENT-TEXT-5512")
+	for i := 0; i < aiChatsKeep; i++ {
+		s.aiNewChat(me)
+	}
+	if s.aiOwns(me, first) {
+		t.Fatal("the oldest chat is kept past the limit")
+	}
+	for _, f := range []string{path, path + "-wal"} {
+		b, _ := os.ReadFile(f)
+		if bytes.Contains(b, []byte("OLD-ATTACHMENT-TEXT-5512")) {
+			t.Fatalf("the old chat's content is still in %s", filepath.Base(f))
+		}
+	}
+}
@@ -3,6 +3,10 @@ package server
 import (
 	"crypto/rand"
 	"encoding/hex"
+	"net/url"
+	"strconv"
+
+	lpra "github.com/x-grk/longpolling-remote-access"
 )

 // Config keys stored in the config table.
@@ -11,16 +15,20 @@ const (
 	cfgEnrollSecret = "enroll_secret"
 	cfgSetupDone    = "setup_done"
 	cfgInstallCode  = "install_code"
+	cfgInstallLen   = "install_code_len"
 	cfgUfwEnabled   = "ufw_enabled"
+	cfgTunnelHost   = "tunnel_host"
+	cfgTunnelPort   = "tunnel_port"
+	cfgDirectAddr   = "direct_address"
 )

 // DefaultHostAddress is the public URL agents dial by default. It is baked into
 // the rendered install.sh and can be changed from the settings page.
 const DefaultHostAddress = "https://REDACTED:8445"

-// Version is the server build version, injected at compile time via -ldflags
-// (-X .../internal/server.Version=...). It is the newest version agents update to.
-var Version = "dev"
+// Version is the server build version (see VERSION.txt). It is the newest
+// version agents update to.
+var Version = lpra.Version

 // ensureDefaults seeds the host address and a random enroll secret on first boot.
 func (db *DB) ensureDefaults() error {
@@ -47,7 +55,7 @@ func (db *DB) ensureDefaults() error {
 		return err
 	}
 	if code == "" {
-		if err := db.SetConfig(cfgInstallCode, shortCode()); err != nil {
+		if err := db.SetConfig(cfgInstallCode, shortCode(db.InstallCodeLen())); err != nil {
 			return err
 		}
 	}
@@ -62,6 +70,23 @@ func (db *DB) HostAddress() string {
 	return v
 }

+// DirectAddress is the server's direct URL, one that is not behind a proxy
+// like Cloudflare: the agents' fallback, and a way to install when the main
+// address is out of reach. Empty when not set.
+func (db *DB) DirectAddress() string {
+	v, _ := db.GetConfig(cfgDirectAddr)
+	return v
+}
+
+// directHost is the direct address's host name, without scheme and port.
+func directHost(addr string) string {
+	u, err := url.Parse(addr)
+	if err != nil {
+		return ""
+	}
+	return u.Hostname()
+}
+
 func (db *DB) EnrollSecret() string {
 	v, _ := db.GetConfig(cfgEnrollSecret)
 	return v
@@ -86,6 +111,24 @@ func (db *DB) SetUfwEnabled(on bool) error {
 	return db.SetConfig(cfgUfwEnabled, "0")
 }

+// TunnelHost is the host agents dial for the direct tunnel. Empty means the
+// host of the URL they already reach the panel on.
+func (db *DB) TunnelHost() string {
+	v, _ := db.GetConfig(cfgTunnelHost)
+	return v
+}
+
+// TunnelPort is the direct-tunnel port set in Settings, or 0 when it is left
+// at the port of the server's -tunnel address.
+func (db *DB) TunnelPort() int {
+	v, _ := db.GetConfig(cfgTunnelPort)
+	n, _ := strconv.Atoi(v)
+	if n < 1 || n > 65535 {
+		return 0
+	}
+	return n
+}
+
 func (db *DB) SetupDone() bool {
 	v, _ := db.GetConfig(cfgSetupDone)
 	return v == "1"
@@ -102,16 +145,36 @@ func randToken() string {
 	return hex.EncodeToString(b)
 }

-// shortCode returns a short, URL-safe, typo-resistant code for install links.
-// It avoids ambiguous characters (0/O, 1/l/I) so it is easy to read and type.
-func shortCode() string {
-	const alphabet = "abcdefghjkmnpqrstuvwxyz23456789"
-	b := make([]byte, 7)
-	if _, err := rand.Read(b); err != nil {
-		panic("crypto/rand failed: " + err.Error())
+// Install code length: 3 by default, up to 24.
+const (
+	installCodeMin = 3
+	installCodeMax = 24
+	installCodeDef = 3
+)
+
+// InstallCodeLen is how many characters a new install code has.
+func (db *DB) InstallCodeLen() int {
+	v, _ := db.GetConfig(cfgInstallLen)
+	if n, err := strconv.Atoi(v); err == nil && n >= installCodeMin && n <= installCodeMax {
+		return n
 	}
-	for i := range b {
-		b[i] = alphabet[int(b[i])%len(alphabet)]
+	return installCodeDef
+}
+
+// shortCode returns a random code of n English letters and digits for the
+// /i/<code> install link. Every character is equally likely.
+func shortCode(n int) string {
+	const alphabet = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
+	out := make([]byte, 0, n)
+	b := make([]byte, 1)
+	for len(out) < n {
+		if _, err := rand.Read(b); err != nil {
+			panic("crypto/rand failed: " + err.Error())
+		}
+		// 248 = 4 * 62: drop the rest, so no character comes up more often.
+		if b[0] < 248 {
+			out = append(out, alphabet[int(b[0])%len(alphabet)])
+		}
 	}
-	return string(b)
+	return string(out)
 }
@@ -11,7 +11,8 @@ import (

 // DB wraps the SQLite connection and all queries used by the server.
 type DB struct {
-	sql *sql.DB
+	sql  *dbx
+	path string // the file; the key of saved secrets sits beside it
 }

 // OpenDB opens (creating if needed) the SQLite database at path and runs
@@ -19,7 +20,7 @@ type DB struct {
 func OpenDB(path string) (*DB, error) {
 	// _pragma busy_timeout avoids "database is locked" under the concurrent
 	// long-poll load; foreign_keys keeps the schema honest.
-	dsn := fmt.Sprintf("file:%s?_pragma=busy_timeout(5000)&_pragma=foreign_keys(1)&_pragma=journal_mode(WAL)", path)
+	dsn := fmt.Sprintf("file:%s?_pragma=busy_timeout(5000)&_pragma=foreign_keys(1)&_pragma=journal_mode(WAL)&_pragma=secure_delete(1)", path)
 	sdb, err := sql.Open("sqlite", dsn)
 	if err != nil {
 		return nil, err
@@ -30,7 +31,7 @@ func OpenDB(path string) (*DB, error) {
 	if err := sdb.Ping(); err != nil {
 		return nil, err
 	}
-	db := &DB{sql: sdb}
+	db := &DB{sql: &dbx{DB: sdb}, path: path}
 	if err := db.migrate(); err != nil {
 		return nil, err
 	}
@@ -85,6 +86,16 @@ CREATE TABLE IF NOT EXISTS ufw_rules (
    created_at INTEGER NOT NULL,
    UNIQUE(port, proto)
 );
+CREATE TABLE IF NOT EXISTS admin_keys (
+    id          INTEGER PRIMARY KEY AUTOINCREMENT,
+    admin_id    INTEGER NOT NULL REFERENCES admins(id) ON DELETE CASCADE,
+    cred_id     BLOB UNIQUE NOT NULL,
+    public_key  BLOB NOT NULL,
+    sign_count  INTEGER NOT NULL DEFAULT 0,
+    name        TEXT NOT NULL DEFAULT '',
+    created_at  INTEGER NOT NULL,
+    last_used   INTEGER NOT NULL DEFAULT 0
+);
 CREATE TABLE IF NOT EXISTS forward_rules (
    id          INTEGER PRIMARY KEY AUTOINCREMENT,
    agent_id    TEXT NOT NULL,
@@ -105,11 +116,43 @@ CREATE TABLE IF NOT EXISTS forward_rules (
 		`ALTER TABLE ufw_rules ADD COLUMN rule_id INTEGER NOT NULL DEFAULT 0`,
 		`ALTER TABLE agents ADD COLUMN run_user TEXT NOT NULL DEFAULT ''`,
 		`ALTER TABLE agents ADD COLUMN login_user TEXT NOT NULL DEFAULT ''`,
+		`ALTER TABLE forward_rules ADD COLUMN no_ufw INTEGER NOT NULL DEFAULT 0`,
+		`ALTER TABLE forward_rules ADD COLUMN label TEXT NOT NULL DEFAULT ''`,
+		`ALTER TABLE admins ADD COLUMN password_off INTEGER NOT NULL DEFAULT 0`,
+		`ALTER TABLE agents ADD COLUMN transport TEXT NOT NULL DEFAULT 'auto'`,
+		`ALTER TABLE admins ADD COLUMN pin_hash TEXT NOT NULL DEFAULT ''`,
+		`ALTER TABLE admins ADD COLUMN role TEXT NOT NULL DEFAULT 'admin'`,
+		`ALTER TABLE admins ADD COLUMN pw_locked INTEGER NOT NULL DEFAULT 0`,
+		`CREATE TABLE IF NOT EXISTS ai_messages (
+		    id INTEGER PRIMARY KEY AUTOINCREMENT,
+		    admin_id INTEGER NOT NULL REFERENCES admins(id) ON DELETE CASCADE,
+		    role TEXT NOT NULL, content TEXT NOT NULL, at INTEGER NOT NULL)`,
+		`CREATE INDEX IF NOT EXISTS ai_messages_admin ON ai_messages(admin_id, id)`,
+		`ALTER TABLE ai_messages ADD COLUMN chat_id INTEGER NOT NULL DEFAULT 0`,
+		`ALTER TABLE ai_messages ADD COLUMN think_ms INTEGER NOT NULL DEFAULT 0`,
+		`CREATE TABLE IF NOT EXISTS ai_chats (
+		    id INTEGER PRIMARY KEY AUTOINCREMENT,
+		    admin_id INTEGER NOT NULL REFERENCES admins(id) ON DELETE CASCADE,
+		    title TEXT NOT NULL, created INTEGER NOT NULL, updated INTEGER NOT NULL)`,
+		`CREATE INDEX IF NOT EXISTS ai_messages_chat ON ai_messages(chat_id, id)`,
+		`CREATE TABLE IF NOT EXISTS ssh_hosts (
+		    id INTEGER PRIMARY KEY AUTOINCREMENT,
+		    admin_id INTEGER NOT NULL REFERENCES admins(id) ON DELETE CASCADE,
+		    label TEXT NOT NULL, host TEXT NOT NULL, port INTEGER NOT NULL, login TEXT NOT NULL,
+		    auth TEXT NOT NULL, secret TEXT NOT NULL)`,
+		`CREATE TABLE IF NOT EXISTS admin_agents (
+		    admin_id INTEGER NOT NULL REFERENCES admins(id) ON DELETE CASCADE,
+		    agent_id TEXT NOT NULL,
+		    PRIMARY KEY (admin_id, agent_id))`,
 	} {
 		if _, err := db.sql.Exec(alter); err != nil && !strings.Contains(err.Error(), "duplicate column") {
 			return err
 		}
 	}
+	// ssh_hosts.user (a word PostgreSQL keeps for itself) became login.
+	if !db.sql.pg {
+		_, _ = db.sql.Exec(`ALTER TABLE ssh_hosts RENAME COLUMN user TO login`)
+	}
 	return nil
 }

@@ -140,24 +183,52 @@ func (db *DB) CountAdmins() (int, error) {
 }

 func (db *DB) CreateAdmin(username, passHash string) error {
-	_, err := db.sql.Exec(
-		`INSERT INTO admins(username, pass_hash, created_at) VALUES(?, ?, ?)`,
-		username, passHash, time.Now().Unix())
+	_, err := db.CreateUser(username, passHash, RoleAdmin)
 	return err
 }

-// Admin is one row of the admins table.
+// CreateUser adds a panel user with the role given and returns its id.
+func (db *DB) CreateUser(username, passHash, role string) (int64, error) {
+	return db.sql.insert(
+		`INSERT INTO admins(username, pass_hash, created_at, role) VALUES(?, ?, ?, ?)`,
+		username, passHash, time.Now().Unix(), role)
+}
+
+// Roles of panel users: an admin sees and runs everything; a user only the
+// machines given to them, and none of the settings.
+const (
+	RoleAdmin = "admin"
+	RoleUser  = "user"
+)
+
+// Admin is one row of the admins table: a panel user, an admin or not.
 type Admin struct {
 	ID       int64
 	Username string
 	PassHash string
+	Role     string
+	// PwLocked keeps the user from turning the password sign-in on or off
+	// themselves: an admin set it.
+	PwLocked bool
+}
+
+// IsAdmin reports whether the user has the run of the whole panel.
+func (a *Admin) IsAdmin() bool { return a != nil && a.Role != RoleUser }
+
+const adminCols = `id, username, pass_hash, role, pw_locked`
+
+func scanAdmin(row interface{ Scan(...any) error }) (*Admin, error) {
+	a := &Admin{}
+	var locked int
+	if err := row.Scan(&a.ID, &a.Username, &a.PassHash, &a.Role, &locked); err != nil {
+		return nil, err
+	}
+	a.PwLocked = locked == 1
+	return a, nil
 }

 func (db *DB) AdminByUsername(username string) (*Admin, error) {
-	a := &Admin{}
-	err := db.sql.QueryRow(
-		`SELECT id, username, pass_hash FROM admins WHERE username = ?`, username).
-		Scan(&a.ID, &a.Username, &a.PassHash)
+	a, err := scanAdmin(db.sql.QueryRow(`SELECT `+adminCols+` FROM admins WHERE username = ?`, username))
 	if err == sql.ErrNoRows {
 		return nil, nil
 	}
@@ -165,27 +236,215 @@ func (db *DB) AdminByUsername(username string) (*Admin, error) {
 }

 func (db *DB) ListAdmins() ([]Admin, error) {
-	rows, err := db.sql.Query(`SELECT id, username FROM admins ORDER BY username`)
+	rows, err := db.sql.Query(`SELECT ` + adminCols + ` FROM admins ORDER BY role, username`)
 	if err != nil {
 		return nil, err
 	}
 	defer rows.Close()
 	var out []Admin
 	for rows.Next() {
-		var a Admin
-		if err := rows.Scan(&a.ID, &a.Username); err != nil {
+		a, err := scanAdmin(rows)
+		if err != nil {
 			return nil, err
 		}
-		out = append(out, a)
+		out = append(out, *a)
 	}
 	return out, rows.Err()
 }

+// CountRole is how many users have the role.
+func (db *DB) CountRole(role string) int {
+	var n int
+	_ = db.sql.QueryRow(`SELECT COUNT(*) FROM admins WHERE role = ?`, role).Scan(&n)
+	return n
+}
+
+func (db *DB) SetUserRole(id int64, role string) error {
+	_, err := db.sql.Exec(`UPDATE admins SET role = ? WHERE id = ?`, role, id)
+	return err
+}
+
+func (db *DB) SetPwLocked(id int64, locked bool) error {
+	_, err := db.sql.Exec(`UPDATE admins SET pw_locked = ? WHERE id = ?`, boolInt(locked), id)
+	return err
+}
+
+// UserAgents are the machines a user may use.
+func (db *DB) UserAgents(adminID int64) map[string]bool {
+	out := map[string]bool{}
+	rows, err := db.sql.Query(`SELECT agent_id FROM admin_agents WHERE admin_id = ?`, adminID)
+	if err != nil {
+		return out
+	}
+	defer rows.Close()
+	for rows.Next() {
+		var id string
+		if rows.Scan(&id) == nil {
+			out[id] = true
+		}
+	}
+	return out
+}
+
+// SetUserAgents gives the user exactly these machines.
+func (db *DB) SetUserAgents(adminID int64, agentIDs []string) error {
+	tx, err := db.sql.Begin()
+	if err != nil {
+		return err
+	}
+	defer tx.Rollback()
+	if _, err := tx.Exec(`DELETE FROM admin_agents WHERE admin_id = ?`, adminID); err != nil {
+		return err
+	}
+	for _, id := range agentIDs {
+		if _, err := tx.Exec(`INSERT OR IGNORE INTO admin_agents(admin_id, agent_id) VALUES(?, ?)`, adminID, id); err != nil {
+			return err
+		}
+	}
+	return tx.Commit()
+}
+
+// CanUseAgent reports whether the user may use the machine.
+func (db *DB) CanUseAgent(a *Admin, agentID string) bool {
+	if a == nil {
+		return false
+	}
+	if a.IsAdmin() {
+		return true
+	}
+	var n int
+	_ = db.sql.QueryRow(`SELECT COUNT(*) FROM admin_agents WHERE admin_id = ? AND agent_id = ?`, a.ID, agentID).Scan(&n)
+	return n > 0
+}
+
 func (db *DB) DeleteAdmin(id int64) error {
 	_, err := db.sql.Exec(`DELETE FROM admins WHERE id = ?`, id)
 	return err
 }

+// AdminKey is a passkey an admin signs in with.
+type AdminKey struct {
+	ID        int64
+	AdminID   int64
+	CredID    []byte
+	PublicKey []byte // PKIX DER
+	SignCount uint32
+	Name      string
+	CreatedAt int64
+	LastUsed  int64
+}
+
+func (db *DB) AdminByID(id int64) (*Admin, error) {
+	a, err := scanAdmin(db.sql.QueryRow(`SELECT `+adminCols+` FROM admins WHERE id = ?`, id))
+	if err == sql.ErrNoRows {
+		return nil, nil
+	}
+	return a, err
+}
+
+func (db *DB) AddAdminKey(k AdminKey) error {
+	_, err := db.sql.Exec(
+		`INSERT INTO admin_keys(admin_id, cred_id, public_key, sign_count, name, created_at) VALUES(?, ?, ?, ?, ?, ?)`,
+		k.AdminID, k.CredID, k.PublicKey, k.SignCount, k.Name, time.Now().Unix())
+	return err
+}
+
+func (db *DB) ListAdminKeys(adminID int64) ([]AdminKey, error) {
+	rows, err := db.sql.Query(
+		`SELECT id, admin_id, cred_id, public_key, sign_count, name, created_at, last_used
+		   FROM admin_keys WHERE admin_id = ? ORDER BY id`, adminID)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var out []AdminKey
+	for rows.Next() {
+		var k AdminKey
+		if err := rows.Scan(&k.ID, &k.AdminID, &k.CredID, &k.PublicKey, &k.SignCount, &k.Name, &k.CreatedAt, &k.LastUsed); err != nil {
+			return nil, err
+		}
+		out = append(out, k)
+	}
+	return out, rows.Err()
+}
+
+// PasswordOff tells an admin who turned the password off: then only a
+// passkey signs them in. It holds only while they have one.
+func (db *DB) PasswordOff(adminID int64) bool {
+	var off int
+	_ = db.sql.QueryRow(`SELECT password_off FROM admins WHERE id = ?`, adminID).Scan(&off)
+	return off == 1 && db.CountAdminKeys(adminID) > 0
+}
+
+// AdminPin is the hash of the admin's PIN, "" when there is none.
+func (db *DB) AdminPin(adminID int64) string {
+	var h string
+	_ = db.sql.QueryRow(`SELECT pin_hash FROM admins WHERE id = ?`, adminID).Scan(&h)
+	return h
+}
+
+func (db *DB) SetAdminPin(adminID int64, pinHash string) error {
+	_, err := db.sql.Exec(`UPDATE admins SET pin_hash = ? WHERE id = ?`, pinHash, adminID)
+	return err
+}
+
+func (db *DB) SetAdminPassword(adminID int64, passHash string) error {
+	_, err := db.sql.Exec(`UPDATE admins SET pass_hash = ? WHERE id = ?`, passHash, adminID)
+	return err
+}
+
+func (db *DB) SetPasswordOff(adminID int64, off bool) error {
+	v := 0
+	if off {
+		v = 1
+	}
+	_, err := db.sql.Exec(`UPDATE admins SET password_off = ? WHERE id = ?`, v, adminID)
+	return err
+}
+
+// CountAdminKeys is how many passkeys an admin has.
+func (db *DB) CountAdminKeys(adminID int64) int {
+	var n int
+	_ = db.sql.QueryRow(`SELECT COUNT(*) FROM admin_keys WHERE admin_id = ?`, adminID).Scan(&n)
+	return n
+}
+
+func (db *DB) AdminKeyByCredID(credID []byte) (*AdminKey, error) {
+	k := &AdminKey{}
+	err := db.sql.QueryRow(
+		`SELECT id, admin_id, cred_id, public_key, sign_count, name, created_at, last_used
+		   FROM admin_keys WHERE cred_id = ?`, credID).
+		Scan(&k.ID, &k.AdminID, &k.CredID, &k.PublicKey, &k.SignCount, &k.Name, &k.CreatedAt, &k.LastUsed)
+	if err == sql.ErrNoRows {
+		return nil, nil
+	}
+	return k, err
+}
+
+func (db *DB) UseAdminKey(id int64, signCount uint32) error {
+	_, err := db.sql.Exec(`UPDATE admin_keys SET sign_count = ?, last_used = ? WHERE id = ?`, signCount, time.Now().Unix(), id)
+	return err
+}
+
+// DeleteAdminKey removes a passkey; with the last one gone, the password
+// signs the admin in again.
+func (db *DB) DeleteAdminKey(adminID, id int64) error {
+	if _, err := db.sql.Exec(`DELETE FROM admin_keys WHERE admin_id = ? AND id = ?`, adminID, id); err != nil {
+		return err
+	}
+	if db.CountAdminKeys(adminID) == 0 {
+		return db.SetPasswordOff(adminID, false)
+	}
+	return nil
+}
+
+func (db *DB) DeleteAdminKeys(adminID int64) error {
+	if _, err := db.sql.Exec(`DELETE FROM admin_keys WHERE admin_id = ?`, adminID); err != nil {
+		return err
+	}
+	return db.SetPasswordOff(adminID, false)
+}
+
 // --- admin sessions ---

 func (db *DB) CreateSession(id string, adminID int64, ttl time.Duration) error {
@@ -198,12 +457,10 @@ func (db *DB) CreateSession(id string, adminID int64, ttl time.Duration) error {

 // SessionAdmin returns the admin for a live (non-expired) session, or nil.
 func (db *DB) SessionAdmin(sessionID string) (*Admin, error) {
-	a := &Admin{}
-	err := db.sql.QueryRow(
-		`SELECT a.id, a.username, a.pass_hash
+	a, err := scanAdmin(db.sql.QueryRow(
+		`SELECT a.id, a.username, a.pass_hash, a.role, a.pw_locked
 		   FROM admin_sessions s JOIN admins a ON a.id = s.admin_id
-		  WHERE s.id = ? AND s.expires_at > ?`, sessionID, time.Now().Unix()).
-		Scan(&a.ID, &a.Username, &a.PassHash)
+		  WHERE s.id = ? AND s.expires_at > ?`, sessionID, time.Now().Unix()))
 	if err == sql.ErrNoRows {
 		return nil, nil
 	}
@@ -228,6 +485,7 @@ type Agent struct {
 	Version   string
 	RunUser   string // OS user the agent process runs as (reported by the agent)
 	LoginUser string // OS user terminals are opened as; "" = RunUser
+	Transport string // auto, ws or lp: how the agent is to reach us
 	LastSeen  time.Time
 }

@@ -238,8 +496,9 @@ func (a Agent) TerminalUser() string {
 	return firstNonEmpty(a.LoginUser, a.RunUser, "root")
 }

-// Online reports whether the agent polled recently enough to be considered up.
-func (a Agent) Online() bool {
+// recentlySeen is the fallback for "online" right after a server start, while
+// the hub has not seen the agents' polls yet (see Server.online).
+func (a Agent) recentlySeen() bool {
 	return time.Since(a.LastSeen) < 45*time.Second
 }

@@ -256,8 +515,8 @@ func (db *DB) GetAgent(id string) (*Agent, error) {
 	a := &Agent{}
 	var last int64
 	err := db.sql.QueryRow(
-		`SELECT id, name, hostname, os, arch, token_hash, version, run_user, login_user, last_seen FROM agents WHERE id = ?`, id).
-		Scan(&a.ID, &a.Name, &a.Hostname, &a.OS, &a.Arch, &a.TokenHash, &a.Version, &a.RunUser, &a.LoginUser, &last)
+		`SELECT id, name, hostname, os, arch, token_hash, version, run_user, login_user, transport, last_seen FROM agents WHERE id = ?`, id).
+		Scan(&a.ID, &a.Name, &a.Hostname, &a.OS, &a.Arch, &a.TokenHash, &a.Version, &a.RunUser, &a.LoginUser, &a.Transport, &last)
 	if err == sql.ErrNoRows {
 		return nil, nil
 	}
@@ -288,6 +547,11 @@ func (db *DB) ListAgents() ([]Agent, error) {
 	return out, rows.Err()
 }

+func (db *DB) SetAgentTransport(id, transport string) error {
+	_, err := db.sql.Exec(`UPDATE agents SET transport = ? WHERE id = ?`, transport, id)
+	return err
+}
+
 func (db *DB) TouchAgent(id string) error {
 	_, err := db.sql.Exec(`UPDATE agents SET last_seen = ? WHERE id = ?`, time.Now().Unix(), id)
 	return err
@@ -308,6 +572,9 @@ func (db *DB) SetAgentLoginUser(id, user string) error {

 func (db *DB) DeleteAgent(id string) error {
 	_, err := db.sql.Exec(`DELETE FROM agents WHERE id = ?`, id)
+	if err == nil {
+		_, _ = db.sql.Exec(`DELETE FROM admin_agents WHERE agent_id = ?`, id)
+	}
 	return err
 }

@@ -327,25 +594,23 @@ type ForwardRule struct {
 	HostPort   int
 	ListenAddr string
 	Proto      string
+	NoUfw      bool   // the panel opens no ufw rule for this forward
+	Label      string // optional note shown next to the rule
 }

 func (db *DB) CreateForwardRule(r ForwardRule) (int64, error) {
 	if r.Proto == "" {
 		r.Proto = "http"
 	}
-	res, err := db.sql.Exec(
-		`INSERT INTO forward_rules(agent_id, client_port, host_port, listen_addr, proto, created_at)
-		 VALUES(?, ?, ?, ?, ?, ?)`,
-		r.AgentID, r.ClientPort, r.HostPort, r.ListenAddr, r.Proto, time.Now().Unix())
-	if err != nil {
-		return 0, err
-	}
-	return res.LastInsertId()
+	return db.sql.insert(
+		`INSERT INTO forward_rules(agent_id, client_port, host_port, listen_addr, proto, no_ufw, label, created_at)
+		 VALUES(?, ?, ?, ?, ?, ?, ?, ?)`,
+		r.AgentID, r.ClientPort, r.HostPort, r.ListenAddr, r.Proto, boolInt(r.NoUfw), r.Label, time.Now().Unix())
 }

 func (db *DB) ListForwardRules() ([]ForwardRule, error) {
 	rows, err := db.sql.Query(
-		`SELECT id, agent_id, client_port, host_port, listen_addr, proto FROM forward_rules ORDER BY id`)
+		`SELECT id, agent_id, client_port, host_port, listen_addr, proto, no_ufw, label FROM forward_rules ORDER BY id`)
 	if err != nil {
 		return nil, err
 	}
@@ -353,7 +618,7 @@ func (db *DB) ListForwardRules() ([]ForwardRule, error) {
 	var out []ForwardRule
 	for rows.Next() {
 		var r ForwardRule
-		if err := rows.Scan(&r.ID, &r.AgentID, &r.ClientPort, &r.HostPort, &r.ListenAddr, &r.Proto); err != nil {
+		if err := rows.Scan(&r.ID, &r.AgentID, &r.ClientPort, &r.HostPort, &r.ListenAddr, &r.Proto, &r.NoUfw, &r.Label); err != nil {
 			return nil, err
 		}
 		out = append(out, r)
@@ -378,8 +643,8 @@ func (db *DB) ListForwardRulesByAgent(agentID string) ([]ForwardRule, error) {
 func (db *DB) GetForwardRule(id int64) (*ForwardRule, error) {
 	r := &ForwardRule{}
 	err := db.sql.QueryRow(
-		`SELECT id, agent_id, client_port, host_port, listen_addr, proto FROM forward_rules WHERE id = ?`, id).
-		Scan(&r.ID, &r.AgentID, &r.ClientPort, &r.HostPort, &r.ListenAddr, &r.Proto)
+		`SELECT id, agent_id, client_port, host_port, listen_addr, proto, no_ufw, label FROM forward_rules WHERE id = ?`, id).
+		Scan(&r.ID, &r.AgentID, &r.ClientPort, &r.HostPort, &r.ListenAddr, &r.Proto, &r.NoUfw, &r.Label)
 	if err == sql.ErrNoRows {
 		return nil, nil
 	}
@@ -397,7 +662,20 @@ type UfwRule struct {
 	ID     int64
 	Port   int
 	Proto  string
-	RuleID int64 // bound forward rule id, or 0 for shared/manual (e.g. tunnel 8446)
+	RuleID int64 // bound forward rule id, 0 for shared (the tunnel port), ufwManual for one added in Settings
+}
+
+// ufwManual is the RuleID of a ufw rule the admin added by hand: no forward
+// owns it, so only the admin removes it.
+const ufwManual = -1
+
+// Manual reports whether the admin added the rule by hand.
+func (r UfwRule) Manual() bool { return r.RuleID == ufwManual }
+
+// SetUfwRuleManual hands a tracked rule over to the admin.
+func (db *DB) SetUfwRuleManual(port int, proto string) error {
+	_, err := db.sql.Exec(`UPDATE ufw_rules SET rule_id = ? WHERE port = ? AND proto = ?`, ufwManual, port, proto)
+	return err
 }

 func (db *DB) AddUfwRule(port int, proto string, ruleID int64) error {
@@ -469,3 +747,22 @@ func (db *DB) Audit(adminID int64, agentID, action string) {
 		`INSERT INTO audit(admin_id, agent_id, action, at) VALUES(?, ?, ?, ?)`,
 		adminID, agentID, action, time.Now().Unix())
 }
+
+func boolInt(b bool) int {
+	if b {
+		return 1
+	}
+	return 0
+}
+
+// wipeDeleted makes what was deleted leave the database's files: with
+// secure_delete the freed pages are overwritten, and the write-ahead log,
+// which still holds the rows as they were written, is emptied (SQLite only;
+// PostgreSQL cleans up for itself). The attachments of a chat deleted are
+// among that.
+func (db *DB) wipeDeleted() {
+	if db.sql.pg {
+		return
+	}
+	_, _ = db.sql.Exec(`PRAGMA wal_checkpoint(TRUNCATE)`)
+}
@@ -0,0 +1,251 @@
+package server
+
+import (
+	"context"
+	"database/sql"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"log"
+	"net/http"
+	"net/url"
+	"os"
+	"strconv"
+	"strings"
+	"time"
+
+	_ "github.com/jackc/pgx/v5/stdlib"
+)
+
+// The panel keeps its data in SQLite by default, or in PostgreSQL when the
+// admins choose so in Настройки. The choice lives in a small file beside the
+// SQLite database (<db>.backend.json, readable by the server only) and
+// takes effect on the next start; the first start on an empty PostgreSQL
+// copies everything over from the SQLite file, which stays as it was.
+
+type PGConf struct {
+	Host     string `json:"host"`
+	Port     int    `json:"port"`
+	Name     string `json:"name"`
+	User     string `json:"user"`
+	Password string `json:"password"`
+	SSLMode  string `json:"sslmode"`
+}
+
+type backendConf struct {
+	Type string  `json:"type"` // sqlite or postgres
+	PG   *PGConf `json:"pg,omitempty"`
+}
+
+func (c PGConf) DSN() string {
+	port := c.Port
+	if port == 0 {
+		port = 5432
+	}
+	ssl := c.SSLMode
+	if ssl == "" {
+		ssl = "prefer"
+	}
+	u := url.URL{Scheme: "postgres", User: url.UserPassword(c.User, c.Password), Host: c.Host + ":" + strconv.Itoa(port), Path: "/" + c.Name}
+	u.RawQuery = url.Values{"sslmode": {ssl}, "connect_timeout": {"10"}}.Encode()
+	return u.String()
+}
+
+func backendPath(dbPath string) string { return dbPath + ".backend.json" }
+
+func readBackend(dbPath string) backendConf {
+	var c backendConf
+	if b, err := os.ReadFile(backendPath(dbPath)); err == nil {
+		_ = json.Unmarshal(b, &c)
+	}
+	if c.Type != "postgres" || c.PG == nil {
+		c = backendConf{Type: "sqlite"}
+	}
+	return c
+}
+
+func writeBackend(dbPath string, c backendConf) error {
+	b, _ := json.MarshalIndent(c, "", "  ")
+	return os.WriteFile(backendPath(dbPath), b, 0o600)
+}
+
+// OpenStore opens the database the admins chose: SQLite at path, or the
+// PostgreSQL named beside it.
+func OpenStore(path string) (*DB, error) {
+	c := readBackend(path)
+	if c.Type == "postgres" {
+		return OpenPostgres(*c.PG, path)
+	}
+	return OpenDB(path)
+}
+
+// pingPG checks that PostgreSQL c answers.
+func pingPG(c PGConf) error {
+	d, err := sql.Open("pgx", c.DSN())
+	if err != nil {
+		return err
+	}
+	defer d.Close()
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+	return d.PingContext(ctx)
+}
+
+// OpenPostgres opens PostgreSQL c, brings its tables up to date and, when it
+// has no users yet, copies over the SQLite database at sqlitePath.
+func OpenPostgres(c PGConf, sqlitePath string) (*DB, error) {
+	d, err := sql.Open("pgx", c.DSN())
+	if err != nil {
+		return nil, err
+	}
+	d.SetMaxOpenConns(16)
+	d.SetMaxIdleConns(4)
+	d.SetConnMaxIdleTime(5 * time.Minute)
+	if err := d.Ping(); err != nil {
+		return nil, fmt.Errorf("PostgreSQL: %w", err)
+	}
+	db := &DB{sql: &dbx{DB: d, pg: true}, path: sqlitePath}
+	if err := db.migrate(); err != nil {
+		return nil, fmt.Errorf("PostgreSQL: %w", err)
+	}
+	var n int
+	_ = db.sql.QueryRow(`SELECT COUNT(*) FROM admins`).Scan(&n)
+	if _, err := os.Stat(sqlitePath); n == 0 && err == nil {
+		src, err := OpenDB(sqlitePath)
+		if err != nil {
+			return nil, err
+		}
+		defer src.Close()
+		if err := copyDB(src, db); err != nil {
+			return nil, fmt.Errorf("перенос из SQLite: %w", err)
+		}
+		log.Printf("db: data copied from %s to PostgreSQL", sqlitePath)
+	}
+	return db, nil
+}
+
+// copyTables are copied parents first, for the foreign keys.
+var copyTables = []string{"config", "admins", "agents", "admin_sessions", "audit", "ufw_rules", "admin_keys",
+	"forward_rules", "admin_agents", "ssh_hosts", "ai_chats", "ai_messages"}
+
+// copyDB copies every row of src into dst (an empty PostgreSQL), in one
+// transaction, then moves the id counters past the copied ids.
+func copyDB(src, dst *DB) error {
+	tx, err := dst.sql.DB.Begin()
+	if err != nil {
+		return err
+	}
+	defer tx.Rollback()
+	for _, t := range copyTables {
+		rows, err := src.sql.Query(`SELECT * FROM ` + t)
+		if err != nil {
+			return err
+		}
+		cols, _ := rows.Columns()
+		ph := make([]string, len(cols))
+		for i := range ph {
+			ph[i] = "$" + strconv.Itoa(i+1)
+		}
+		ins := `INSERT INTO ` + t + ` (` + strings.Join(cols, ", ") + `) VALUES (` + strings.Join(ph, ", ") + `)`
+		for rows.Next() {
+			vals := make([]any, len(cols))
+			ptrs := make([]any, len(cols))
+			for i := range vals {
+				ptrs[i] = &vals[i]
+			}
+			if err := rows.Scan(ptrs...); err != nil {
+				rows.Close()
+				return err
+			}
+			if _, err := tx.Exec(ins, vals...); err != nil {
+				rows.Close()
+				return fmt.Errorf("%s: %w", t, err)
+			}
+		}
+		rows.Close()
+		if err := rows.Err(); err != nil {
+			return err
+		}
+	}
+	if err := tx.Commit(); err != nil {
+		return err
+	}
+	// The id counters past the copied ids, where a table has one.
+	for _, t := range copyTables {
+		var seq sql.NullString
+		err := dst.sql.DB.QueryRow(`SELECT pg_get_serial_sequence($1, column_name) FROM information_schema.columns
+			WHERE table_name = $1 AND column_name = 'id' AND column_default LIKE 'nextval%'`, t).Scan(&seq)
+		if err != nil || !seq.Valid {
+			continue
+		}
+		if _, err := dst.sql.DB.Exec(`SELECT setval($1, COALESCE((SELECT MAX(id) FROM `+t+`), 0) + 1, false)`, seq.String); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// Backend tells which database is in use and which is chosen for the next
+// start.
+func (db *DB) Backend() (now string, chosen backendConf) {
+	now = "sqlite"
+	if db.sql.pg {
+		now = "postgres"
+	}
+	return now, readBackend(db.path)
+}
+
+var errNoPGHost = errors.New("укажите хост, базу и пользователя PostgreSQL")
+
+// POST /settings/db - the database for the next start; PostgreSQL is tried
+// first and kept only if it answers.
+func (s *Server) handleSetDB(w http.ResponseWriter, r *http.Request) {
+	if !checkCSRF(r) {
+		http.Error(w, "bad csrf", http.StatusForbidden)
+		return
+	}
+	back := func(q string) { http.Redirect(w, r, "/settings?"+q+"#db", http.StatusSeeOther) }
+	if r.FormValue("db_type") != "postgres" {
+		if err := writeBackend(s.db.path, backendConf{Type: "sqlite"}); err != nil {
+			back("err=" + url.QueryEscape(err.Error()))
+			return
+		}
+		back("db=saved")
+		return
+	}
+	old := readBackend(s.db.path).PG
+	c := PGConf{Host: strings.TrimSpace(r.FormValue("pg_host")), Name: strings.TrimSpace(r.FormValue("pg_name")),
+		User: strings.TrimSpace(r.FormValue("pg_user")), Password: r.FormValue("pg_password"), SSLMode: r.FormValue("pg_sslmode")}
+	c.Port, _ = strconv.Atoi(r.FormValue("pg_port"))
+	if c.Password == "" && old != nil {
+		c.Password = old.Password
+	}
+	if c.Host == "" || c.Name == "" || c.User == "" {
+		back("err=" + url.QueryEscape(errNoPGHost.Error()))
+		return
+	}
+	if err := pingPG(c); err != nil {
+		back("err=" + url.QueryEscape("PostgreSQL не отвечает: "+err.Error()))
+		return
+	}
+	if err := writeBackend(s.db.path, backendConf{Type: "postgres", PG: &c}); err != nil {
+		back("err=" + url.QueryEscape(err.Error()))
+		return
+	}
+	back("db=saved")
+}
+
+// POST /settings/db/restart - the server ends; its service (systemd,
+// Restart=always) starts it again on the database chosen.
+func (s *Server) handleRestart(w http.ResponseWriter, r *http.Request) {
+	if !checkCSRF(r) {
+		http.Error(w, "bad csrf", http.StatusForbidden)
+		return
+	}
+	log.Printf("restart asked from the panel")
+	http.Redirect(w, r, "/settings?restarted=1#db", http.StatusSeeOther)
+	go func() {
+		time.Sleep(700 * time.Millisecond)
+		os.Exit(0)
+	}()
+}
@@ -0,0 +1,130 @@
+package server
+
+import (
+	"database/sql"
+	"encoding/json"
+	"os"
+	"testing"
+
+	"github.com/x-grk/longpolling-remote-access/internal/proto"
+)
+
+// On a real PostgreSQL (LPRA_TEST_PG: {"host","port","name","user","password",
+// "sslmode"} of an empty database): the first start copies the SQLite data
+// over, and the panel's queries work there.
+func TestPostgres(t *testing.T) {
+	raw := os.Getenv("LPRA_TEST_PG")
+	if raw == "" {
+		t.Skip("LPRA_TEST_PG not set")
+	}
+	var c PGConf
+	if err := json.Unmarshal([]byte(raw), &c); err != nil {
+		t.Fatal(err)
+	}
+	// SQLite with a user, a machine, a rule, a saved host and some talk.
+	s, _ := newTestServer(t)
+	a, _ := s.db.AdminByUsername("adm")
+	if _, err := s.db.CreateForwardRule(ForwardRule{AgentID: "x1", ClientPort: 80, HostPort: 18080, ListenAddr: "0.0.0.0", Proto: "tcp", NoUfw: true}); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := s.saveSSHHost(a.ID, savedHost{Label: "web", Host: "h", Port: 22, User: "root", Auth: "password"}, sshSecret{Password: "pw"}); err != nil {
+		t.Fatal(err)
+	}
+	chat := s.aiNewChat(a.ID)
+	s.aiAppendTo(a.ID, chat, "user", "привет")
+	_ = s.db.SetUserAgents(a.ID, []string{"x1"})
+
+	pgReset(t, c)
+	pg, err := OpenPostgres(c, s.db.path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer pg.Close()
+	// Clean up for the next run.
+	defer func() {
+		for i := len(copyTables) - 1; i >= 0; i-- {
+			_, _ = pg.sql.Exec(`DROP TABLE IF EXISTS ` + copyTables[i] + ` CASCADE`)
+		}
+	}()
+	p := &Server{db: pg}
+	if got, _ := pg.AdminByUsername("adm"); got == nil || got.ID != a.ID {
+		t.Fatalf("admin not copied: %+v", got)
+	}
+	if ag, _ := pg.GetAgent("x1"); ag == nil {
+		t.Fatal("agent not copied")
+	}
+	rules, _ := pg.ListForwardRules()
+	if len(rules) != 1 || !rules[0].NoUfw {
+		t.Fatalf("rules: %+v", rules)
+	}
+	tg := &proto.SSHTarget{Saved: p.listSSHHosts(a.ID)[0].ID}
+	if err := p.fillSaved(a.ID, tg); err != nil || tg.Password != "pw" {
+		t.Fatalf("saved host: %+v %v", tg, err)
+	}
+	if h := p.aiHistoryOf(a.ID, chat, 10); len(h) != 1 || h[0].Content != "привет" {
+		t.Fatalf("talk: %+v", h)
+	}
+	// New rows go on after the copied ids.
+	id, err := pg.CreateUser("bob", "x", RoleUser)
+	if err != nil || id <= a.ID {
+		t.Fatalf("new user id %d, %v", id, err)
+	}
+	if err := pg.SetConfig("k", "v1"); err != nil {
+		t.Fatal(err)
+	}
+	if err := pg.SetConfig("k", "v2"); err != nil {
+		t.Fatal(err)
+	}
+	if v, _ := pg.GetConfig("k"); v != "v2" {
+		t.Fatalf("config upsert: %q", v)
+	}
+	if err := pg.SetUserAgents(id, []string{"x1", "x1"}); err != nil {
+		t.Fatalf("grants: %v", err)
+	}
+	p.aiAppendTo(a.ID, chat, "assistant", "ответ")
+	if h := p.aiHistoryOf(a.ID, chat, 10); len(h) != 2 {
+		t.Fatalf("talk after: %+v", h)
+	}
+}
+
+// Chats on PostgreSQL: past the limit the oldest go.
+func TestPostgresChats(t *testing.T) {
+	raw := os.Getenv("LPRA_TEST_PG")
+	if raw == "" {
+		t.Skip("LPRA_TEST_PG not set")
+	}
+	var c PGConf
+	_ = json.Unmarshal([]byte(raw), &c)
+	s, _ := newTestServer(t)
+	pgReset(t, c)
+	pg, err := OpenPostgres(c, s.db.path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer pg.Close()
+	defer func() {
+		for i := len(copyTables) - 1; i >= 0; i-- {
+			_, _ = pg.sql.Exec(`DROP TABLE IF EXISTS ` + copyTables[i] + ` CASCADE`)
+		}
+	}()
+	p := &Server{db: pg}
+	a, _ := pg.AdminByUsername("adm")
+	for i := 0; i < aiChatsKeep+3; i++ {
+		p.aiAppendTo(a.ID, p.aiNewChat(a.ID), "user", "q")
+	}
+	if n := len(p.aiChats(a.ID)); n != aiChatsKeep {
+		t.Fatalf("chats kept: %d", n)
+	}
+}
+
+// pgReset empties the test database: the copy runs only into an empty one.
+func pgReset(t *testing.T, c PGConf) {
+	d, err := sql.Open("pgx", c.DSN())
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer d.Close()
+	for i := len(copyTables) - 1; i >= 0; i-- {
+		_, _ = d.Exec(`DROP TABLE IF EXISTS ` + copyTables[i] + ` CASCADE`)
+	}
+}
@@ -0,0 +1,93 @@
+package server
+
+import (
+	"database/sql"
+	"strconv"
+	"strings"
+)
+
+// dbx is the database the server talks to: SQLite, or PostgreSQL. The
+// queries are written once, for SQLite; on PostgreSQL each is rewritten
+// (pgSQL) on its way.
+type dbx struct {
+	*sql.DB
+	pg bool
+}
+
+func (d *dbx) q(query string) string {
+	if d.pg {
+		return pgSQL(query)
+	}
+	return query
+}
+
+func (d *dbx) Exec(query string, args ...any) (sql.Result, error) {
+	return d.DB.Exec(d.q(query), args...)
+}
+func (d *dbx) Query(query string, args ...any) (*sql.Rows, error) {
+	return d.DB.Query(d.q(query), args...)
+}
+func (d *dbx) QueryRow(query string, args ...any) *sql.Row {
+	return d.DB.QueryRow(d.q(query), args...)
+}
+func (d *dbx) Begin() (*txx, error) {
+	tx, err := d.DB.Begin()
+	return &txx{Tx: tx, pg: d.pg}, err
+}
+
+// insert runs an INSERT and gives the new row's id (LastInsertId on SQLite,
+// RETURNING id on PostgreSQL, which has no LastInsertId).
+func (d *dbx) insert(query string, args ...any) (int64, error) {
+	if d.pg {
+		var id int64
+		err := d.DB.QueryRow(pgSQL(query)+" RETURNING id", args...).Scan(&id)
+		return id, err
+	}
+	res, err := d.DB.Exec(query, args...)
+	if err != nil {
+		return 0, err
+	}
+	return res.LastInsertId()
+}
+
+type txx struct {
+	*sql.Tx
+	pg bool
+}
+
+func (t *txx) Exec(query string, args ...any) (sql.Result, error) {
+	if t.pg {
+		query = pgSQL(query)
+	}
+	return t.Tx.Exec(query, args...)
+}
+
+// pgSQL rewrites a query for SQLite into PostgreSQL's: $n placeholders,
+// INSERT OR IGNORE as ON CONFLICT DO NOTHING, and in table definitions
+// BIGSERIAL keys, BIGINT numbers (times are Unix seconds), BYTEA blobs and
+// ADD COLUMN IF NOT EXISTS.
+func pgSQL(q string) string {
+	if strings.HasPrefix(q, "INSERT OR IGNORE ") {
+		q = "INSERT " + strings.TrimPrefix(q, "INSERT OR IGNORE ") + " ON CONFLICT DO NOTHING"
+	}
+	if strings.Contains(q, "CREATE TABLE") || strings.Contains(q, "ALTER TABLE") {
+		q = strings.ReplaceAll(q, "INTEGER PRIMARY KEY AUTOINCREMENT", "BIGSERIAL PRIMARY KEY")
+		q = strings.ReplaceAll(q, "INTEGER", "BIGINT")
+		q = strings.ReplaceAll(q, "BLOB", "BYTEA")
+		q = strings.ReplaceAll(q, "ADD COLUMN ", "ADD COLUMN IF NOT EXISTS ")
+	}
+	var b strings.Builder
+	n, quoted := 0, false
+	for _, r := range q {
+		switch {
+		case r == '\'':
+			quoted = !quoted
+		case r == '?' && !quoted:
+			n++
+			b.WriteString("$" + strconv.Itoa(n))
+			continue
+		}
+		b.WriteRune(r)
+	}
+	return b.String()
+}
@@ -0,0 +1,19 @@
+package server
+
+import "testing"
+
+// Queries written for SQLite, as PostgreSQL takes them.
+func TestPGRebind(t *testing.T) {
+	for _, c := range [][2]string{
+		{`SELECT a FROM t WHERE x = ? AND y = ?`, `SELECT a FROM t WHERE x = $1 AND y = $2`},
+		{`INSERT OR IGNORE INTO admin_agents(admin_id, agent_id) VALUES(?, ?)`, `INSERT INTO admin_agents(admin_id, agent_id) VALUES($1, $2) ON CONFLICT DO NOTHING`},
+		{`SELECT '?' , ?`, `SELECT '?' , $1`},
+		{"CREATE TABLE IF NOT EXISTS x (\n id INTEGER PRIMARY KEY AUTOINCREMENT,\n n INTEGER NOT NULL,\n b BLOB NOT NULL)",
+			"CREATE TABLE IF NOT EXISTS x (\n id BIGSERIAL PRIMARY KEY,\n n BIGINT NOT NULL,\n b BYTEA NOT NULL)"},
+		{`ALTER TABLE agents ADD COLUMN run_user TEXT NOT NULL DEFAULT ''`, `ALTER TABLE agents ADD COLUMN IF NOT EXISTS run_user TEXT NOT NULL DEFAULT ''`},
+	} {
+		if got := pgSQL(c[0]); got != c[1] {
+			t.Errorf("\n got %s\nwant %s", got, c[1])
+		}
+	}
+}
@@ -0,0 +1,199 @@
+package server
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"html"
+	"io"
+	"mime"
+	"net"
+	"net/http"
+	"net/url"
+	"regexp"
+	"strconv"
+	"strings"
+	"time"
+	"unicode/utf8"
+)
+
+// fetch: one page by its address, for the assistant with «Поиск» on - to
+// read what a search found. The page comes back as the model wants it: its
+// title and main text, headings and lists kept, scripts, styles and menus
+// gone, cut to fetchMaxChars. Only http(s), and never the server's own
+// network: loopback, private and link-local addresses are refused at the
+// moment of connecting, redirects included.
+
+const fetchMaxChars = 12000
+
+// fetchAllowPrivate lets tests reach their own server.
+var fetchAllowPrivate = false
+
+type fetchedPage struct {
+	URL       string `json:"url"`
+	Title     string `json:"title"`
+	Type      string `json:"type"`
+	Text      string `json:"text"`
+	Truncated bool   `json:"truncated"`
+}
+
+func privateIP(ip net.IP) bool {
+	return ip.IsLoopback() || ip.IsPrivate() || ip.IsLinkLocalUnicast() || ip.IsLinkLocalMulticast() ||
+		ip.IsUnspecified() || ip.IsMulticast() || ip.IsInterfaceLocalMulticast()
+}
+
+var fetchClient = &http.Client{
+	Timeout: 20 * time.Second,
+	Transport: &http.Transport{
+		Proxy: nil,
+		DialContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
+			host, port, err := net.SplitHostPort(addr)
+			if err != nil {
+				return nil, err
+			}
+			ips, err := net.DefaultResolver.LookupIP(ctx, "ip", host)
+			if err != nil {
+				return nil, err
+			}
+			for _, ip := range ips {
+				if privateIP(ip) && !fetchAllowPrivate {
+					continue
+				}
+				var d net.Dialer
+				return d.DialContext(ctx, network, net.JoinHostPort(ip.String(), port))
+			}
+			return nil, errors.New("адрес во внутренней сети - не открываю")
+		},
+		TLSHandshakeTimeout:   10 * time.Second,
+		ResponseHeaderTimeout: 15 * time.Second,
+	},
+	CheckRedirect: func(req *http.Request, via []*http.Request) error {
+		if len(via) >= 5 {
+			return errors.New("слишком много переадресаций")
+		}
+		if req.URL.Scheme != "http" && req.URL.Scheme != "https" {
+			return errors.New("переадресация не на http(s)")
+		}
+		return nil
+	},
+}
+
+func fetchPage(ctx context.Context, raw string) (fetchedPage, error) {
+	u, err := url.Parse(strings.TrimSpace(raw))
+	if err != nil || (u.Scheme != "http" && u.Scheme != "https") || u.Host == "" {
+		return fetchedPage{}, errors.New("нужен адрес http(s)://…")
+	}
+	req, _ := http.NewRequestWithContext(ctx, http.MethodGet, u.String(), nil)
+	req.Header.Set("User-Agent", "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/124.0 Safari/537.36")
+	req.Header.Set("Accept", "text/html,text/plain,application/json;q=0.9,*/*;q=0.5")
+	req.Header.Set("Accept-Language", "ru,en;q=0.8")
+	resp, err := fetchClient.Do(req)
+	if err != nil {
+		return fetchedPage{}, err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode/100 != 2 {
+		return fetchedPage{}, errors.New("страница ответила " + resp.Status)
+	}
+	ct, _, _ := mime.ParseMediaType(resp.Header.Get("Content-Type"))
+	p := fetchedPage{URL: resp.Request.URL.String(), Type: ct}
+	b, _ := io.ReadAll(io.LimitReader(resp.Body, 3<<20))
+	switch {
+	case ct == "text/html" || ct == "application/xhtml+xml" || (ct == "" && strings.Contains(strings.ToLower(string(b[:min(len(b), 512)])), "<html")):
+		p.Title, p.Text = pageText(string(b))
+	case strings.HasPrefix(ct, "text/") || strings.Contains(ct, "json") || strings.Contains(ct, "xml") || strings.Contains(ct, "javascript"):
+		p.Text = strings.TrimSpace(string(b))
+	default:
+		p.Text = "(двоичный файл " + ct + ", " + strconv.Itoa(len(b)) + " байт - текста нет)"
+	}
+	if !utf8.ValidString(p.Text) {
+		p.Text = strings.ToValidUTF8(p.Text, "")
+	}
+	if r := []rune(p.Text); len(r) > fetchMaxChars {
+		p.Text, p.Truncated = string(r[:fetchMaxChars]), true
+	}
+	return p, nil
+}
+
+var (
+	reTitle   = regexp.MustCompile(`(?is)<title[^>]*>(.*?)</title>`)
+	reDrop    = regexp.MustCompile(`(?is)<(script|style|noscript|svg|nav|footer|header|aside|form|iframe|template|button|select)\b[^>]*>.*?</(script|style|noscript|svg|nav|footer|header|aside|form|iframe|template|button|select)>`)
+	reComment = regexp.MustCompile(`(?s)<!--.*?-->`)
+	reMain    = regexp.MustCompile(`(?is)<(main|article)\b[^>]*>(.*)</(main|article)>`)
+	reHead    = regexp.MustCompile(`(?is)<h([1-6])\b[^>]*>`)
+	reLi      = regexp.MustCompile(`(?is)<li\b[^>]*>`)
+	reBlock   = regexp.MustCompile(`(?is)</?(p|div|section|br|tr|table|ul|ol|pre|blockquote|h[1-6]|dd|dt|figcaption)\b[^>]*>`)
+	reCell    = regexp.MustCompile(`(?is)</t[dh]>`)
+	reSpaces  = regexp.MustCompile(`[ \t\x{00a0}]+`)
+	reBlanks  = regexp.MustCompile(`\n{3,}`)
+	rePre     = regexp.MustCompile(`(?is)<pre\b[^>]*>.*?</pre>`)
+	rePreMark = regexp.MustCompile("\x00pre[0-9]+\x00")
+	reWS      = regexp.MustCompile(`\s+`)
+)
+
+// pageText is a page's title and its text, in Markdown-ish lines.
+func pageText(page string) (string, string) {
+	title := ""
+	if m := reTitle.FindStringSubmatch(page); m != nil {
+		title = strings.TrimSpace(html.UnescapeString(reTags.ReplaceAllString(m[1], "")))
+	}
+	s := reComment.ReplaceAllString(page, "")
+	s = reDrop.ReplaceAllString(s, " ")
+	// Line breaks of the source mean nothing outside <pre>: one space. The
+	// <pre> blocks keep theirs (held aside meanwhile).
+	var pres []string
+	s = rePre.ReplaceAllStringFunc(s, func(p string) string {
+		pres = append(pres, p)
+		return "\x00pre" + strconv.Itoa(len(pres)-1) + "\x00"
+	})
+	s = reWS.ReplaceAllString(s, " ")
+	s = rePreMark.ReplaceAllStringFunc(s, func(m string) string {
+		i, _ := strconv.Atoi(strings.Trim(m, "\x00pre"))
+		return pres[i]
+	})
+	// The page's main part, when it marks one.
+	if m := reMain.FindStringSubmatch(s); m != nil && len(m[2]) > 200 {
+		s = m[2]
+	}
+	s = reHead.ReplaceAllStringFunc(s, func(t string) string {
+		n, _ := strconv.Atoi(reHead.FindStringSubmatch(t)[1])
+		return "\n\n" + strings.Repeat("#", n) + " "
+	})
+	s = reLi.ReplaceAllString(s, "\n- ")
+	s = reCell.ReplaceAllString(s, " | ")
+	s = reBlock.ReplaceAllString(s, "\n")
+	s = html.UnescapeString(reTags.ReplaceAllString(s, ""))
+	var lines []string
+	for _, l := range strings.Split(s, "\n") {
+		l = strings.TrimSpace(reSpaces.ReplaceAllString(l, " "))
+		if l == "-" || l == "|" {
+			continue
+		}
+		lines = append(lines, l)
+	}
+	text := reBlanks.ReplaceAllString(strings.Join(lines, "\n"), "\n\n")
+	return title, strings.TrimSpace(text)
+}
+
+// POST /api/panel/ai/fetch - {url}: the page as text, for a user with the
+// assistant on.
+func (s *Server) handleAIFetch(w http.ResponseWriter, r *http.Request) {
+	a := s.currentAdmin(r)
+	if !s.aiOn(a.ID) {
+		writeJSON(w, map[string]any{"ok": false, "error": "ассистент выключен в профиле"})
+		return
+	}
+	var in struct {
+		URL string `json:"url"`
+	}
+	if err := json.NewDecoder(http.MaxBytesReader(w, r.Body, 8<<10)).Decode(&in); err != nil {
+		writeJSON(w, map[string]any{"ok": false, "error": "плохой запрос"})
+		return
+	}
+	p, err := fetchPage(r.Context(), in.URL)
+	if err != nil {
+		writeJSON(w, map[string]any{"ok": false, "error": err.Error()})
+		return
+	}
+	writeJSON(w, map[string]any{"ok": true, "data": p})
+}
@@ -0,0 +1,78 @@
+package server
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+)
+
+// A page as the model wants it: title, the main text with headings and
+// lists, no scripts, styles or menus.
+func TestPageText(t *testing.T) {
+	page := `<html><head><title>Go 1.24 &amp; more</title><style>p{color:red}</style>
+<meta name="description" content="Release notes"></head><body>
+<nav><a href="/">Home</a> <a href="/doc">Docs</a></nav>
+<main><h1>Go 1.24</h1><p>Generic <b>type aliases</b> are here.</p><script>track()</script>
+<ul><li>Swiss tables</li><li>weak pointers</li></ul></main><footer>© Google</footer></body></html>`
+	title, text := pageText(page)
+	if title != "Go 1.24 & more" {
+		t.Fatalf("title %q", title)
+	}
+	for _, want := range []string{"# Go 1.24", "Generic type aliases are here.", "- Swiss tables", "- weak pointers"} {
+		if !strings.Contains(text, want) {
+			t.Fatalf("no %q in:\n%s", want, text)
+		}
+	}
+	for _, not := range []string{"track()", "color:red", "Home", "© Google"} {
+		if strings.Contains(text, not) {
+			t.Fatalf("%q left in:\n%s", not, text)
+		}
+	}
+}
+
+// The server's own network is out of reach: no loopback, private or local
+// addresses, whatever the name says.
+func TestFetchRefusesPrivate(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { fmt.Fprint(w, "secret") }))
+	defer srv.Close()
+	for _, u := range []string{srv.URL, "http://localhost:1/", "http://10.0.0.1/", "http://169.254.169.254/latest/meta-data/", "file:///etc/passwd", "ftp://x/"} {
+		if _, err := fetchPage(context.Background(), u); err == nil {
+			t.Errorf("%s: fetched", u)
+		}
+	}
+}
+
+func TestFetchPage(t *testing.T) {
+	old := fetchAllowPrivate
+	fetchAllowPrivate = true
+	defer func() { fetchAllowPrivate = old }()
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path == "/json" {
+			w.Header().Set("Content-Type", "application/json")
+			fmt.Fprint(w, `{"a":1}`)
+			return
+		}
+		w.Header().Set("Content-Type", "text/html; charset=utf-8")
+		fmt.Fprint(w, "<title>T</title><p>"+strings.Repeat("слово ", 5000)+"</p>")
+	}))
+	defer srv.Close()
+	p, err := fetchPage(context.Background(), srv.URL+"/page")
+	if err != nil || p.Title != "T" || !p.Truncated || len([]rune(p.Text)) > fetchMaxChars+10 {
+		t.Fatalf("page: %v %q %v %d", err, p.Title, p.Truncated, len(p.Text))
+	}
+	p, err = fetchPage(context.Background(), srv.URL+"/json")
+	if err != nil || p.Text != `{"a":1}` {
+		t.Fatalf("json: %+v %v", p, err)
+	}
+}
+
+// Lines broken in the page's source are one paragraph; code keeps its lines.
+func TestPageTextJoinsWrapped(t *testing.T) {
+	_, text := pageText("<p>The latest Go release,\n   version 1.24,\narrives in February.</p><pre>a\nb</pre>")
+	if !strings.Contains(text, "The latest Go release, version 1.24, arrives in February.") || !strings.Contains(text, "a\nb") {
+		t.Fatalf("%q", text)
+	}
+}
@@ -12,10 +12,11 @@ import (

 // forwardManager owns the host-side listeners for port-forward rules. It
 // supports three transports:
-//   - "http": tunneled over the HTTP long-poll channel (works anywhere nginx
-//     reaches, highest latency);
-//   - "tcp":  direct TCP multiplexed over the 8446 tunnel (low latency);
-//   - "udp":  direct UDP over the 8446 channel.
+//   - "http": over the agent's own link to the panel - its WebSocket, or the
+//     HTTP long polls while there is none (works anywhere nginx reaches,
+//     highest latency);
+//   - "tcp":  direct TCP multiplexed over the tunnel port (low latency);
+//   - "udp":  direct UDP over the tunnel port.
 type forwardManager struct {
 	hub *Hub
 	tun *tunnelHub
@@ -92,18 +93,19 @@ func (m *forwardManager) acceptTCP(rule ForwardRule, ln net.Listener) {
 	}
 }

-// bridgeDirect wires a connection to the agent's low-latency 8446 tunnel.
+// bridgeDirect wires a connection to the agent's low-latency direct tunnel.
 func (m *forwardManager) bridgeDirect(rule ForwardRule, conn net.Conn) {
 	at := m.tun.get(rule.AgentID)
 	if at == nil {
-		// No direct tunnel (agent offline or 8446 unreachable).
+		// No direct tunnel (agent offline or the tunnel port unreachable).
 		conn.Close()
 		return
 	}
 	at.openStream(rule.ClientPort, conn)
 }

-// bridgeHTTP wires a connection through the HTTP long-poll hub session.
+// bridgeHTTP wires a connection through a hub session: the agent carries it
+// over its WebSocket, or by long polls while it has none.
 func (m *forwardManager) bridgeHTTP(rule ForwardRule, conn net.Conn) {
 	sess := m.hub.CreateForward(rule.AgentID, rule.ClientPort)
 	defer m.hub.CloseSession(sess.ID)
@@ -127,20 +129,39 @@ func (m *forwardManager) bridgeHTTP(rule ForwardRule, conn net.Conn) {
 		}
 	}()

+	// write passes one message on; false: the stream is over.
+	write := func(out proto.OutMessage) bool {
+		if out.Exit {
+			return false
+		}
+		if out.Data != "" {
+			b, err := base64.StdEncoding.DecodeString(out.Data)
+			if err != nil {
+				return false
+			}
+			if _, err := conn.Write(b); err != nil {
+				return false
+			}
+		}
+		return true
+	}
 	for {
 		select {
-		case <-sess.Done():
-			return
 		case out, ok := <-sess.Out():
-			if !ok || out.Exit {
+			if !ok || !write(out) {
 				return
 			}
-			if out.Data != "" {
-				b, err := base64.StdEncoding.DecodeString(out.Data)
-				if err != nil {
-					return
-				}
-				if _, err := conn.Write(b); err != nil {
+		case <-sess.Done():
+			// The agent's end of stream closes the session at once, while
+			// what it sent before may still be queued (a download read
+			// faster than the browser takes it): that goes out first.
+			for {
+				select {
+				case out := <-sess.Out():
+					if !write(out) {
+						return
+					}
+				default:
 					return
 				}
 			}
@@ -0,0 +1,49 @@
+package server
+
+import (
+	"bytes"
+	"encoding/base64"
+	"io"
+	"net"
+	"testing"
+	"time"
+
+	"github.com/x-grk/longpolling-remote-access/internal/proto"
+)
+
+// An http-lp download the agent has finished (its last chunk, then the end)
+// reaches the browser whole: the session closing does not cut off what is
+// still queued for it.
+func TestForwardHTTPDrainsAfterClose(t *testing.T) {
+	hub := NewHub()
+	m := &forwardManager{hub: hub}
+	user, host := net.Pipe()
+	go m.bridgeHTTP(ForwardRule{AgentID: "a1", ClientPort: 80, Proto: "http"}, host)
+
+	var sess *Session
+	for i := 0; i < 100 && sess == nil; i++ {
+		hub.mu.Lock()
+		for _, s := range hub.sessions {
+			sess = s
+		}
+		hub.mu.Unlock()
+		time.Sleep(10 * time.Millisecond)
+	}
+	if sess == nil {
+		t.Fatal("no session")
+	}
+	want := bytes.Repeat([]byte("0123456789abcdef"), 4096) // 64 KiB in 64 chunks
+	go func() {
+		for i := 0; i < len(want); i += 1024 {
+			sess.PushOut(proto.OutMessage{Data: base64.StdEncoding.EncodeToString(want[i : i+1024])})
+		}
+		sess.PushOut(proto.OutMessage{Exit: true})
+		sess.close() // as the server does on the agent's end of stream
+	}()
+	time.Sleep(50 * time.Millisecond) // all of it queued, the session closed, before the browser reads
+	_ = user.SetReadDeadline(time.Now().Add(5 * time.Second))
+	got, _ := io.ReadAll(user)
+	if !bytes.Equal(got, want) {
+		t.Fatalf("got %d of %d bytes", len(got), len(want))
+	}
+}
@@ -0,0 +1,94 @@
+package server
+
+import (
+	"bytes"
+	"html/template"
+	"log"
+	"net/http"
+
+	"github.com/x-grk/longpolling-remote-access/internal/proto"
+)
+
+// A panel page is either a fragment - its content alone, for the shell to put
+// in place without reloading - or the shell with that content already in it.
+
+func isFrag(r *http.Request) bool { return r.URL.Query().Get("frag") == "1" }
+
+// pageView is the shell's view a page is shown in; the machine pages (Порты,
+// Статус, Изменить) open as a dialog over the machines view.
+var pageView = map[string]string{"dashboard": "dashboard", "settings": "settings"}
+
+func (s *Server) renderPage(w http.ResponseWriter, r *http.Request, name string, data map[string]any) {
+	w.Header().Set("Content-Type", "text/html; charset=utf-8")
+	w.Header().Set("Cache-Control", "no-store")
+	if data == nil {
+		data = map[string]any{}
+	}
+	data["IsAdmin"] = s.currentAdmin(r).IsAdmin()
+	if !isFrag(r) {
+		if _, ok := pageView[name]; !ok {
+			// A machine page asked for whole: the machines view with it in
+			// a dialog.
+			s.shell(w, r, map[string]any{"View": "dashboard", "Dialog": r.URL.Path})
+			return
+		}
+	}
+	var body bytes.Buffer
+	if err := s.tmpl.ExecuteTemplate(&body, name+"-body", data); err != nil {
+		log.Printf("template %s: %v", name, err)
+		http.Error(w, "internal error", http.StatusInternalServerError)
+		return
+	}
+	if isFrag(r) {
+		_, _ = w.Write(body.Bytes())
+		return
+	}
+	data["View"] = pageView[name]
+	data["Body"] = template.HTML(body.String())
+	s.shell(w, r, data)
+}
+
+// shell writes the shell page with data (View, Body, Open, Dialog).
+func (s *Server) shell(w http.ResponseWriter, r *http.Request, data map[string]any) {
+	data["IsAdmin"] = s.currentAdmin(r).IsAdmin()
+	data["EditLimit"] = proto.FSReadCap
+	if a := s.currentAdmin(r); a != nil {
+		data["Prefs"] = s.prefs(a.ID)
+	}
+	if data["View"] == "dashboard" && data["Body"] == nil {
+		// The machines list under a dialog: draw it too.
+		var body bytes.Buffer
+		if err := s.tmpl.ExecuteTemplate(&body, "dashboard-body", s.dashboardData(r)); err == nil {
+			data["Body"] = template.HTML(body.String())
+		}
+	}
+	w.Header().Set("Content-Type", "text/html; charset=utf-8")
+	w.Header().Set("Cache-Control", "no-store")
+	if err := s.tmpl.ExecuteTemplate(w, "app.html", data); err != nil {
+		log.Printf("template app.html: %v", err)
+	}
+}
+
+// handleShell serves the shell alone: the terminal view, or with a pane of
+// a machine opened at once (/agents/{id}/terminal, /agents/{id}/files).
+func (s *Server) handleShell(w http.ResponseWriter, r *http.Request) {
+	data := map[string]any{"View": "terminal"}
+	if id := r.PathValue("id"); id != "" {
+		a, _ := s.db.GetAgent(id)
+		if a == nil {
+			http.NotFound(w, r)
+			return
+		}
+		kind := "term"
+		switch r.PathValue("kind") {
+		case "", "terminal":
+		case "files":
+			kind = "files"
+		default:
+			http.NotFound(w, r)
+			return
+		}
+		data["Open"] = map[string]any{"kind": kind, "agent": map[string]string{"id": a.ID, "name": a.Name, "host": a.Hostname, "user": a.TerminalUser()}}
+	}
+	s.shell(w, r, data)
+}
@@ -0,0 +1,159 @@
+package server
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+)
+
+// newTestServer is a server on a fresh database with an admin signed in (the
+// cookie) and one machine, x1.
+func newTestServer(t *testing.T) (*Server, *http.Cookie) {
+	t.Helper()
+	db, err := OpenDB(t.TempDir() + "/t.db")
+	if err != nil {
+		t.Fatal(err)
+	}
+	s, err := New(Options{DB: db, DistDir: t.TempDir()})
+	if err != nil {
+		t.Fatal(err)
+	}
+	hash, _ := hashPassword("Passw0rd12345")
+	if err := db.CreateAdmin("adm", hash); err != nil {
+		t.Fatal(err)
+	}
+	_ = db.SetConfig(cfgSetupDone, "1")
+	a, _ := db.AdminByUsername("adm")
+	if err := db.CreateSession("sid-test", a.ID, sessionTTL); err != nil {
+		t.Fatal(err)
+	}
+	if err := db.CreateAgent(Agent{ID: "x1", Name: "t", Hostname: "h", OS: "linux", Arch: "amd64", TokenHash: "x"}); err != nil {
+		t.Fatal(err)
+	}
+	return s, &http.Cookie{Name: sessionCookie, Value: "sid-test"}
+}
+
+func get(t *testing.T, s *Server, c *http.Cookie, path string) *httptest.ResponseRecorder {
+	t.Helper()
+	req := httptest.NewRequest(http.MethodGet, path, nil)
+	req.AddCookie(c)
+	w := httptest.NewRecorder()
+	s.Handler().ServeHTTP(w, req)
+	return w
+}
+
+func TestFragmentHasNoChrome(t *testing.T) {
+	s, cookie := newTestServer(t)
+	w := get(t, s, cookie, "/settings?frag=1")
+	body := w.Body.String()
+	if w.Code != 200 || strings.Contains(body, "<html") || strings.Contains(body, "topbar") {
+		t.Fatalf("fragment: code %d, has chrome: %q", w.Code, body[:min(200, len(body))])
+	}
+	if !strings.Contains(body, `data-module="settings"`) {
+		t.Fatalf("fragment has no module root")
+	}
+}
+
+func TestShellRoutes(t *testing.T) {
+	s, cookie := newTestServer(t)
+	for _, p := range []string{"/", "/workspace", "/terminal", "/settings", "/agents/x1/files", "/agents/x1/terminal"} {
+		if w := get(t, s, cookie, p); !strings.Contains(w.Body.String(), `id="app"`) {
+			t.Errorf("%s: not the shell (code %d)", p, w.Code)
+		}
+	}
+}
+
+func TestSSHFSOpen(t *testing.T) {
+	s, admin := newTestServer(t)
+	// Long gone: the machine is offline.
+	if _, err := s.db.sql.Exec(`UPDATE agents SET last_seen = 0`); err != nil {
+		t.Fatal(err)
+	}
+	post := func(c *http.Cookie) *httptest.ResponseRecorder {
+		req := httptest.NewRequest(http.MethodPost, "/api/panel/agents/x1/sshfs/open", strings.NewReader(`{"ssh":{"host":"h","user":"u","password":"p"}}`))
+		req.AddCookie(c)
+		w := httptest.NewRecorder()
+		s.Handler().ServeHTTP(w, req)
+		return w
+	}
+	// The machine exists but is offline: the route answers in JSON.
+	if w := post(admin); w.Code != 200 || !strings.Contains(w.Body.String(), "офлайн") {
+		t.Fatalf("admin: %d %s", w.Code, w.Body.String())
+	}
+	// A user without the machine does not reach it.
+	hash, _ := hashPassword("userpass123")
+	id, _ := s.db.CreateUser("bob", hash, RoleUser)
+	_ = s.db.CreateSession("sid-bob", id, sessionTTL)
+	if w := post(&http.Cookie{Name: sessionCookie, Value: "sid-bob"}); w.Code != http.StatusNotFound {
+		t.Fatalf("a user without the machine got %d", w.Code)
+	}
+}
+
+// Renaming from the machine dialog keeps it open on «Изменить».
+func TestRenameStaysOnEdit(t *testing.T) {
+	s, c := newTestServer(t)
+	tok := "tok-test"
+	var req *http.Request
+	req = httptest.NewRequest(http.MethodPost, "/agents/x1/rename", strings.NewReader("csrf="+tok+"&name=new"))
+	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+	req.AddCookie(c)
+	req.AddCookie(&http.Cookie{Name: csrfCookie, Value: tok})
+	w := httptest.NewRecorder()
+	s.Handler().ServeHTTP(w, req)
+	if loc := w.Header().Get("Location"); w.Code != http.StatusSeeOther || loc != "/agents/x1/edit" {
+		t.Fatalf("rename: %d to %q", w.Code, loc)
+	}
+}
+
+// Настройки show the assistant's model as it is set, key included.
+func TestSettingsShowAI(t *testing.T) {
+	s, c := newTestServer(t)
+	_ = s.db.SetConfig(cfgAIKey, "key-123")
+	body := get(t, s, c, "/settings?frag=1").Body.String()
+	if !strings.Contains(body, `value="key-123"`) || !strings.Contains(body, `value="`+DefaultAIURL+`"`) {
+		t.Fatal("the AI card is empty")
+	}
+}
+
+// The look of the panel is each user's: kept on the server, only known
+// settings with known values, and given to the page at once.
+func TestViewPrefs(t *testing.T) {
+	s, c := newTestServer(t)
+	post := func(body string) string {
+		req := httptest.NewRequest(http.MethodPost, "/api/panel/account/prefs", strings.NewReader(body))
+		req.AddCookie(c)
+		w := httptest.NewRecorder()
+		s.Handler().ServeHTTP(w, req)
+		return w.Body.String()
+	}
+	if got := post(`{"tabIcons":"right","termFont":16,"compact":true,"motion":"off","evil":"<x>","fileTime":"maybe"}`); !strings.Contains(got, `"ok":true`) {
+		t.Fatal(got)
+	}
+	got := get(t, s, c, "/api/panel/account/prefs").Body.String()
+	if !strings.Contains(got, `"tabIcons":"right"`) || !strings.Contains(got, `"termFont":16`) || strings.Contains(got, "evil") || strings.Contains(got, "maybe") {
+		t.Fatalf("prefs: %s", got)
+	}
+	if body := get(t, s, c, "/workspace").Body.String(); !strings.Contains(body, `"tabIcons":"right"`) {
+		t.Fatal("the page does not get the prefs")
+	}
+	if got := post(`{"termFont":99}`); !strings.Contains(got, `"ok":true`) || strings.Contains(get(t, s, c, "/api/panel/account/prefs").Body.String(), "99") {
+		t.Fatal("a font size out of range was kept")
+	}
+	post(`{"openHere":"off"}`)
+	if got := get(t, s, c, "/api/panel/account/prefs").Body.String(); !strings.Contains(got, `"openHere":"off"`) {
+		t.Fatalf("openHere off not kept: %s", got)
+	}
+	post(`{"aiModelPick":"always","aiModel":"a1b2c3"}`)
+	if got := get(t, s, c, "/api/panel/account/prefs").Body.String(); !strings.Contains(got, `"aiModelPick":"always"`) || !strings.Contains(got, `"aiModel":"a1b2c3"`) {
+		t.Fatalf("the model choice not kept: %s", got)
+	}
+	post(`{"aiModelPick":"often","aiModel":"<x>"}`)
+	if got := get(t, s, c, "/api/panel/account/prefs").Body.String(); strings.Contains(got, "aiModel") {
+		t.Fatalf("an unknown model choice was kept: %s", got)
+	}
+	post(`{"openHere":"sometimes"}`)
+	if got := get(t, s, c, "/api/panel/account/prefs").Body.String(); strings.Contains(got, "openHere") {
+		t.Fatalf("an unknown openHere was kept: %s", got)
+	}
+}
@@ -0,0 +1,642 @@
+package server
+
+import (
+	"context"
+	"encoding/base64"
+	"encoding/json"
+	"errors"
+	"io"
+	"net/http"
+	"path"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/x-grk/longpolling-remote-access/internal/proto"
+)
+
+// Files go between the browser and the agent in pieces. Each piece is a
+// request of its own, small enough for any proxy in front (Cloudflare takes
+// 100 MB a request at most), and one that fails is sent again instead of the
+// whole file. Several pieces are in flight at once, so a good link stays as
+// busy as it would with one long stream. The server holds only a few pieces
+// of a transfer: whoever sends waits while they wait to be taken.
+//
+// A download keeps one plain response towards the browser, which a proxy
+// passes on whatever its size: links, previews and the hex editor read it.
+
+const (
+	// xferChunk is the size of a piece.
+	xferChunk = 4 << 20
+	// xferBuffer is how many pieces of a transfer the server holds.
+	xferBuffer = 8
+	// xferWait is how long a request waits for its piece, or for room for it,
+	// before it is told to ask again: well under a proxy's timeout.
+	xferWait = 50 * time.Second
+	// xferIdle ends a transfer nobody has touched for this long.
+	xferIdle = 10 * time.Minute
+	// xferTimeout bounds one transfer, however slow the links.
+	xferTimeout = 2 * time.Hour
+)
+
+// fsLegacyCap is the most an agent that predates the pieces can take in or
+// hand over: the file goes base64 inside a task then.
+const fsLegacyCap = 32 << 20
+
+// xfer is one file on its way.
+type xfer struct {
+	id, agentID string
+
+	mu      sync.Mutex
+	changed chan struct{} // closed and replaced on every change
+	size    int64         // -1 until known
+	n       int           // pieces in all, once the size is known
+	chunks  map[int][]byte
+	// low is the first piece still to go: the ones below it were written by
+	// the agent (upload) or to the browser (download).
+	low    int
+	sized  chan struct{} // closed once the size is known
+	err    string        // why the transfer failed
+	done   bool
+	result proto.TaskResult
+	last   time.Time
+}
+
+func pieces(size int64) int {
+	if size <= 0 {
+		return 1 // an empty file is one empty piece
+	}
+	return int((size + xferChunk - 1) / xferChunk)
+}
+
+// pieceLen is how long piece i of the file is.
+func (x *xfer) pieceLen(i int) int64 {
+	return min(int64(xferChunk), x.size-int64(i)*xferChunk)
+}
+
+// notify wakes whoever waits on the transfer; x.mu is held.
+func (x *xfer) notify() {
+	x.last = time.Now()
+	close(x.changed)
+	x.changed = make(chan struct{})
+}
+
+// await waits until ready() holds and returns true with x.mu held; false,
+// with it free, when the wait ran out or ctx ended.
+func (x *xfer) await(ctx context.Context, d time.Duration, ready func() bool) bool {
+	t := time.NewTimer(d)
+	defer t.Stop()
+	for {
+		x.mu.Lock()
+		if ready() {
+			return true
+		}
+		ch := x.changed
+		x.mu.Unlock()
+		select {
+		case <-ch:
+		case <-t.C:
+			return false
+		case <-ctx.Done():
+			return false
+		}
+	}
+}
+
+func (x *xfer) fail(msg string) {
+	x.mu.Lock()
+	if x.err == "" && !x.done {
+		x.err = msg
+		x.chunks = nil
+		x.notify()
+	}
+	x.mu.Unlock()
+}
+
+func (x *xfer) finish(res proto.TaskResult) {
+	x.mu.Lock()
+	x.done, x.result, x.chunks = true, res, nil
+	x.notify()
+	x.mu.Unlock()
+}
+
+// setSize records the file's size; false when it differs from the one known.
+func (x *xfer) setSize(size int64) bool {
+	x.mu.Lock()
+	defer x.mu.Unlock()
+	if x.size >= 0 {
+		return x.size == size
+	}
+	x.size, x.n = size, pieces(size)
+	close(x.sized)
+	x.notify()
+	return true
+}
+
+// put stores piece i once there is room for it, and answers with the HTTP
+// status for its sender. A piece already taken or held is accepted again: it
+// is a retry.
+func (x *xfer) put(ctx context.Context, i int, data []byte) (int, string) {
+	if !x.await(ctx, xferWait, func() bool { return x.err != "" || x.done || i < x.low+xferBuffer }) {
+		return http.StatusServiceUnavailable, "нет места, повторите"
+	}
+	defer x.mu.Unlock()
+	if x.err != "" || x.done {
+		return http.StatusGone, x.gone()
+	}
+	if i < 0 || i >= x.n || int64(len(data)) != x.pieceLen(i) {
+		return http.StatusBadRequest, "не тот кусок"
+	}
+	if i >= x.low && x.chunks[i] == nil {
+		x.chunks[i] = data
+		x.notify()
+	}
+	return http.StatusNoContent, ""
+}
+
+// take hands over piece i, the next one in order, and lets it go.
+func (x *xfer) take(ctx context.Context, i int, d time.Duration) ([]byte, error) {
+	if !x.await(ctx, d, func() bool { return x.err != "" || x.chunks[i] != nil }) {
+		return nil, errors.New("кусок не пришёл вовремя")
+	}
+	defer x.mu.Unlock()
+	if x.err != "" {
+		return nil, errors.New(x.err)
+	}
+	data := x.chunks[i]
+	delete(x.chunks, i)
+	x.low = i + 1
+	x.notify()
+	return data, nil
+}
+
+func (x *xfer) gone() string {
+	if x.err != "" {
+		return x.err
+	}
+	return "передача закончена"
+}
+
+// Read makes an upload a plain reader, for an agent that takes a file whole.
+type xferReader struct {
+	ctx context.Context
+	x   *xfer
+	i   int
+	buf []byte
+}
+
+func (r *xferReader) Read(p []byte) (int, error) {
+	for len(r.buf) == 0 {
+		if r.i >= r.x.n {
+			return 0, io.EOF
+		}
+		data, err := r.x.take(r.ctx, r.i, xferIdle)
+		if err != nil {
+			return 0, err
+		}
+		r.buf, r.i = data, r.i+1
+	}
+	n := copy(p, r.buf)
+	r.buf = r.buf[n:]
+	return n, nil
+}
+
+type xfers struct {
+	mu sync.Mutex
+	m  map[string]*xfer
+}
+
+func (c *xfers) open(agentID string, size int64) *xfer {
+	x := &xfer{
+		id: randToken()[:24], agentID: agentID, size: -1,
+		changed: make(chan struct{}), chunks: map[int][]byte{},
+		sized: make(chan struct{}), last: time.Now(),
+	}
+	if size >= 0 {
+		x.size, x.n = size, pieces(size)
+		close(x.sized)
+	}
+	c.mu.Lock()
+	if c.m == nil {
+		c.m = map[string]*xfer{}
+	}
+	// Forget the ones left behind: a closed tab, a client gone for good.
+	for id, old := range c.m {
+		old.mu.Lock()
+		stale := time.Since(old.last) > xferIdle
+		old.mu.Unlock()
+		if stale {
+			old.fail("передача брошена")
+			delete(c.m, id)
+		}
+	}
+	c.m[x.id] = x
+	c.mu.Unlock()
+	return x
+}
+
+func (c *xfers) get(id string) *xfer {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	return c.m[id]
+}
+
+// forAgent returns the transfer if it is the asking agent's.
+func (c *xfers) forAgent(id, agentID string) *xfer {
+	if x := c.get(id); x != nil && x.agentID == agentID {
+		return x
+	}
+	return nil
+}
+
+func (c *xfers) drop(id string) {
+	c.mu.Lock()
+	delete(c.m, id)
+	c.mu.Unlock()
+}
+
+// waitTask runs a task on the agent and waits for its result, or for ctx to
+// end.
+func (s *Server) waitTask(ctx context.Context, agentID, typ string, args any, timeout time.Duration) (proto.TaskResult, error) {
+	raw, _ := json.Marshal(args)
+	taskID, ch := s.hub.CreateTask(agentID, typ, raw)
+	defer s.hub.DiscardTask(taskID)
+	t := time.NewTimer(timeout)
+	defer t.Stop()
+	select {
+	case res := <-ch:
+		return res, nil
+	case <-ctx.Done():
+		return proto.TaskResult{}, ctx.Err()
+	case <-t.C:
+		return proto.TaskResult{}, errors.New("таймаут ожидания агента")
+	}
+}
+
+// unknownOp tells an agent that predates the task.
+func unknownOp(res proto.TaskResult) bool {
+	return !res.OK && strings.Contains(res.Error, "неизвестная операция")
+}
+
+// fsAgent answers the request itself and returns false when the agent is
+// unknown or offline.
+func (s *Server) fsAgent(w http.ResponseWriter, agentID string, asJSON bool) bool {
+	a, err := s.db.GetAgent(agentID)
+	if err != nil || a == nil {
+		http.Error(w, "not found", http.StatusNotFound)
+		return false
+	}
+	if !s.online(a) {
+		if asJSON {
+			writeJSON(w, proto.TaskResult{Error: "машина офлайн"})
+		} else {
+			http.Error(w, "машина офлайн", http.StatusServiceUnavailable)
+		}
+		return false
+	}
+	return true
+}
+
+// readPiece reads a piece's body into a buffer of its own size, so pieces
+// leave no trail of grown buffers behind.
+func readPiece(w http.ResponseWriter, r *http.Request) ([]byte, error) {
+	if r.ContentLength >= 0 && r.ContentLength <= xferChunk {
+		data := make([]byte, r.ContentLength)
+		_, err := io.ReadFull(r.Body, data)
+		return data, err
+	}
+	return io.ReadAll(http.MaxBytesReader(w, r.Body, xferChunk))
+}
+
+// ---------- upload: browser -> agent ----------
+
+// POST /api/panel/agents/{id}/fs/upload?path=...&size=N - start writing a
+// file. The answer names the transfer and the piece size; the browser then
+// PUTs the pieces and asks for the result.
+func (s *Server) handleFSUploadStart(w http.ResponseWriter, r *http.Request) {
+	s.uploadStart(w, r, proto.TaskFSPut, "")
+}
+
+// uploadStart starts a file upload to the agent's task (fs.put on the
+// machine, sshfs.put onto an SSH host through it, conn naming the
+// connection).
+func (s *Server) uploadStart(w http.ResponseWriter, r *http.Request, task, conn string) {
+	agentID, p := r.PathValue("id"), r.URL.Query().Get("path")
+	if !s.fsAgent(w, agentID, true) {
+		return
+	}
+	size, err := strconv.ParseInt(r.URL.Query().Get("size"), 10, 64)
+	if p == "" || err != nil || size < 0 {
+		writeJSON(w, proto.TaskResult{Error: "не указан путь или размер"})
+		return
+	}
+	if size > proto.FSFileCap {
+		writeJSON(w, proto.TaskResult{Error: "файл больше 512 МБ"})
+		return
+	}
+	x := s.xfers.open(agentID, size)
+	go s.runUpload(x, p, task, conn)
+	data, _ := json.Marshal(map[string]any{"id": x.id, "chunk": xferChunk})
+	writeJSON(w, proto.TaskResult{OK: true, Data: data})
+}
+
+// runUpload has the agent write the file and keeps the result for the
+// browser to collect.
+func (s *Server) runUpload(x *xfer, p, task, conn string) {
+	ctx, cancel := context.WithTimeout(context.Background(), xferTimeout)
+	defer cancel()
+	args := proto.FSXferArgs{Path: p, Xfer: x.id, Size: x.size, Chunk: xferChunk, Conn: conn}
+	res, err := s.waitTask(ctx, x.agentID, task, args, xferTimeout)
+	if err == nil && unknownOp(res) && task != proto.TaskFSPut {
+		res = proto.TaskResult{Error: "агент не умеет файлы по SSH - обновите его"}
+	} else if err == nil && unknownOp(res) {
+		res = s.legacyUpload(ctx, x, p)
+	}
+	if err != nil {
+		res = proto.TaskResult{Error: err.Error()}
+	}
+	if !res.OK {
+		x.fail(res.Error)
+	}
+	x.finish(res)
+	// The result waits a while for the browser to come for it.
+	time.AfterFunc(xferIdle, func() { s.xfers.drop(x.id) })
+}
+
+// legacyUpload writes a file through an agent that predates the pieces.
+func (s *Server) legacyUpload(ctx context.Context, x *xfer, p string) proto.TaskResult {
+	if x.size > fsLegacyCap {
+		return proto.TaskResult{Error: "клиент принимает файлы до 32 МБ - обновите его"}
+	}
+	data, err := io.ReadAll(&xferReader{ctx: ctx, x: x})
+	if err != nil {
+		return proto.TaskResult{Error: err.Error()}
+	}
+	args := proto.FSWriteArgs{Path: p, Data: base64.StdEncoding.EncodeToString(data)}
+	res, err := s.waitTask(ctx, x.agentID, proto.TaskFSWrite, args, fsTaskTimeout)
+	if err != nil {
+		return proto.TaskResult{Error: err.Error()}
+	}
+	return res
+}
+
+// PUT /api/panel/fs/xfer/{xid}/{i} - piece i of a file being uploaded. 503:
+// no room yet, send it again; 410: the transfer is over.
+func (s *Server) handleXferPut(w http.ResponseWriter, r *http.Request) {
+	x := s.xfers.get(r.PathValue("xid"))
+	i, err := strconv.Atoi(r.PathValue("i"))
+	if x == nil || err != nil {
+		http.Error(w, "передача не найдена", http.StatusGone)
+		return
+	}
+	data, err := readPiece(w, r)
+	if err != nil {
+		http.Error(w, "кусок не дошёл", http.StatusBadRequest)
+		return
+	}
+	code, msg := x.put(r.Context(), i, data)
+	if code == http.StatusNoContent {
+		w.WriteHeader(code)
+		return
+	}
+	http.Error(w, msg, code)
+}
+
+// POST /api/panel/fs/xfer/{xid}/cancel - the browser gives the upload up.
+func (s *Server) handleXferCancel(w http.ResponseWriter, r *http.Request) {
+	if x := s.xfers.get(r.PathValue("xid")); x != nil {
+		x.fail("отменено")
+	}
+	w.WriteHeader(http.StatusNoContent)
+}
+
+// GET /api/panel/fs/xfer/{xid}/result - the upload's result, once the agent
+// has written the file; {"done":false} means ask again.
+func (s *Server) handleXferResult(w http.ResponseWriter, r *http.Request) {
+	x := s.xfers.get(r.PathValue("xid"))
+	if x == nil {
+		writeJSON(w, map[string]any{"done": true, "result": proto.TaskResult{Error: "передача не найдена"}})
+		return
+	}
+	if !x.await(r.Context(), xferWait, func() bool { return x.done }) {
+		writeJSON(w, map[string]any{"done": false})
+		return
+	}
+	res := x.result
+	x.mu.Unlock()
+	writeJSON(w, map[string]any{"done": true, "result": res})
+}
+
+// GET /api/agent/fs/xfer/{xid}/{i}?ack=K - piece i of the upload, for the
+// agent to write. K says the agent has written every piece below it, so
+// those are let go. 503: not here yet, ask again; 410: the transfer is over.
+func (s *Server) handleAgentXferGet(w http.ResponseWriter, r *http.Request) {
+	a := s.authenticateAgent(r)
+	if a == nil {
+		http.Error(w, "unauthorized", http.StatusUnauthorized)
+		return
+	}
+	x := s.xfers.forAgent(r.PathValue("xid"), a.ID)
+	i, err := strconv.Atoi(r.PathValue("i"))
+	if x == nil || err != nil {
+		http.Error(w, "передача не найдена", http.StatusGone)
+		return
+	}
+	if ack, err := strconv.Atoi(r.URL.Query().Get("ack")); err == nil {
+		x.mu.Lock()
+		if ack > x.low {
+			for k := x.low; k < ack; k++ {
+				delete(x.chunks, k)
+			}
+			x.low = ack
+			x.notify()
+		}
+		x.mu.Unlock()
+	}
+	if !x.await(r.Context(), xferWait, func() bool { return x.err != "" || x.chunks[i] != nil }) {
+		http.Error(w, "кусок ещё не пришёл", http.StatusServiceUnavailable)
+		return
+	}
+	if x.err != "" {
+		msg := x.err
+		x.mu.Unlock()
+		http.Error(w, msg, http.StatusGone)
+		return
+	}
+	data := x.chunks[i]
+	x.mu.Unlock()
+	w.Header().Set("Content-Type", "application/octet-stream")
+	w.Header().Set("Content-Length", strconv.Itoa(len(data)))
+	_, _ = w.Write(data)
+}
+
+// ---------- download: agent -> browser ----------
+
+// inlineTypes are the files the panel shows in place rather than downloads.
+var inlineTypes = map[string]string{
+	".png": "image/png", ".jpg": "image/jpeg", ".jpeg": "image/jpeg", ".gif": "image/gif",
+	".webp": "image/webp", ".bmp": "image/bmp", ".ico": "image/x-icon", ".avif": "image/avif",
+	".svg": "image/svg+xml",
+	".mp4": "video/mp4", ".m4v": "video/mp4", ".webm": "video/webm", ".ogv": "video/ogg", ".mov": "video/quicktime",
+	".mp3": "audio/mpeg", ".wav": "audio/wav", ".ogg": "audio/ogg", ".oga": "audio/ogg", ".m4a": "audio/mp4",
+	".aac": "audio/aac", ".flac": "audio/flac", ".opus": "audio/ogg",
+	".pdf": "application/pdf",
+}
+
+// fileHeaders sets what the browser needs to download or show the file. A
+// file shown in place runs nothing: no scripts in an SVG, whatever it holds.
+// A PDF is the exception, as the browser's viewer will not open in a sandbox;
+// it runs in that viewer, not in the panel's page.
+func fileHeaders(w http.ResponseWriter, p string, inline bool) {
+	name := path.Base(p)
+	ctype := "application/octet-stream"
+	if t, ok := inlineTypes[strings.ToLower(path.Ext(name))]; ok && inline {
+		ctype = t
+	}
+	disp := "attachment"
+	if inline {
+		disp = "inline"
+	}
+	w.Header().Set("Content-Type", ctype)
+	w.Header().Set("Content-Disposition", disp+"; filename=\""+strings.ReplaceAll(name, "\"", "")+"\"")
+	w.Header().Set("X-Content-Type-Options", "nosniff")
+	if ctype != "application/pdf" {
+		w.Header().Set("Content-Security-Policy", "sandbox; default-src 'none'; img-src data:; style-src 'unsafe-inline'")
+	}
+	w.Header().Set("Cache-Control", "no-store")
+}
+
+// GET /api/panel/agents/{id}/fs/download?path=...[&inline=1] - the file, as
+// one response fed by the pieces the agent sends. inline=1 serves pictures,
+// video and sound for the page to show.
+func (s *Server) handleFSDownload(w http.ResponseWriter, r *http.Request) {
+	s.download(w, r, proto.TaskFSSend, "")
+}
+
+// download sends a file from the agent's task (fs.send, or sshfs.send for
+// an SSH host through it) as one response.
+func (s *Server) download(w http.ResponseWriter, r *http.Request, task, conn string) {
+	agentID, p := r.PathValue("id"), r.URL.Query().Get("path")
+	inline := r.URL.Query().Get("inline") != ""
+	if !s.fsAgent(w, agentID, false) {
+		return
+	}
+	x := s.xfers.open(agentID, -1)
+	defer s.xfers.drop(x.id)
+	defer x.fail("браузер ушёл") // stops the agent if the response ends early
+
+	raw, _ := json.Marshal(proto.FSXferArgs{Path: p, Xfer: x.id, Size: -1, Chunk: xferChunk, Conn: conn})
+	taskID, ch := s.hub.CreateTask(agentID, task, raw)
+	defer s.hub.DiscardTask(taskID)
+	// The agent's result: an error ends the transfer wherever it stands.
+	results := make(chan proto.TaskResult, 1)
+	go func() {
+		select {
+		case res := <-ch:
+			if !res.OK && !unknownOp(res) {
+				x.fail(res.Error)
+			}
+			results <- res
+		case <-r.Context().Done():
+		}
+	}()
+
+	select {
+	case <-x.sized:
+	case res := <-results:
+		if unknownOp(res) && task != proto.TaskFSSend {
+			http.Error(w, "агент не умеет файлы по SSH - обновите его", http.StatusBadGateway)
+			return
+		}
+		if unknownOp(res) {
+			s.legacyDownload(w, r, agentID, p, inline)
+			return
+		}
+		msg := res.Error
+		if msg == "" {
+			msg = "агент не отдал файл"
+		}
+		http.Error(w, msg, http.StatusBadGateway)
+		return
+	case <-r.Context().Done():
+		return
+	case <-time.After(fsTaskTimeout):
+		http.Error(w, "таймаут ожидания агента", http.StatusGatewayTimeout)
+		return
+	}
+
+	fileHeaders(w, p, inline)
+	w.Header().Set("Content-Length", strconv.FormatInt(x.size, 10))
+	rc := http.NewResponseController(w)
+	for i := 0; i < x.n; i++ {
+		data, err := x.take(r.Context(), i, xferIdle)
+		if err == nil {
+			_, err = w.Write(data)
+		}
+		if err != nil {
+			// Cut the response off, so the browser does not take a part of
+			// the file for all of it.
+			x.fail(err.Error())
+			panic(http.ErrAbortHandler)
+		}
+		_ = rc.Flush()
+	}
+}
+
+// legacyDownload gets a file from an agent that predates the pieces.
+func (s *Server) legacyDownload(w http.ResponseWriter, r *http.Request, agentID, p string, inline bool) {
+	res, err := s.waitTask(r.Context(), agentID, proto.TaskFSDownload, proto.FSPathArgs{Path: p}, fsTaskTimeout)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusGatewayTimeout)
+		return
+	}
+	if !res.OK {
+		http.Error(w, res.Error, http.StatusBadGateway)
+		return
+	}
+	var rr proto.FSReadResult
+	if err := json.Unmarshal(res.Data, &rr); err != nil {
+		http.Error(w, "bad result", http.StatusBadGateway)
+		return
+	}
+	data, _ := base64.StdEncoding.DecodeString(rr.Content)
+	fileHeaders(w, p, inline)
+	if rr.Truncated {
+		w.Header().Set("X-Truncated", "1")
+	}
+	_, _ = w.Write(data)
+}
+
+// POST /api/agent/fs/xfer/{xid}/{i} - piece i of the file the browser asked
+// for, X-Size its whole size. 503: no room yet, send it again; 410: the
+// browser is gone.
+func (s *Server) handleAgentXferPost(w http.ResponseWriter, r *http.Request) {
+	a := s.authenticateAgent(r)
+	if a == nil {
+		http.Error(w, "unauthorized", http.StatusUnauthorized)
+		return
+	}
+	x := s.xfers.forAgent(r.PathValue("xid"), a.ID)
+	i, err := strconv.Atoi(r.PathValue("i"))
+	if x == nil || err != nil {
+		http.Error(w, "передача не найдена", http.StatusGone)
+		return
+	}
+	size, err := strconv.ParseInt(r.Header.Get("X-Size"), 10, 64)
+	if err != nil || size < 0 || size > proto.FSFileCap || !x.setSize(size) {
+		http.Error(w, "не тот размер", http.StatusBadRequest)
+		return
+	}
+	data, err := readPiece(w, r)
+	if err != nil {
+		http.Error(w, "кусок не дошёл", http.StatusBadRequest)
+		return
+	}
+	code, msg := x.put(r.Context(), i, data)
+	if code == http.StatusNoContent {
+		w.WriteHeader(code)
+		return
+	}
+	http.Error(w, msg, code)
+}
@@ -16,7 +16,7 @@ func writeJSON(w http.ResponseWriter, v any) {
 	_ = json.NewEncoder(w).Encode(v)
 }

-// POST /api/agent/enroll — exchange the shared enroll secret for a per-agent id+token.
+// POST /api/agent/enroll - exchange the shared enroll secret for a per-agent id+token.
 func (s *Server) handleEnroll(w http.ResponseWriter, r *http.Request) {
 	secret := r.Header.Get("X-Enroll-Secret")
 	if !constantTimeEqual(secret, s.db.EnrollSecret()) {
@@ -36,7 +36,7 @@ func (s *Server) handleEnroll(w http.ResponseWriter, r *http.Request) {
 	writeJSON(w, proto.EnrollResponse{AgentID: id, Token: token})
 }

-// GET /api/agent/poll — control channel. Held until a job is queued or timeout.
+// GET /api/agent/poll - control channel. Held until a job is queued or timeout.
 func (s *Server) handlePoll(w http.ResponseWriter, r *http.Request) {
 	a := s.authenticateAgent(r)
 	if a == nil {
@@ -45,6 +45,7 @@ func (s *Server) handlePoll(w http.ResponseWriter, r *http.Request) {
 	}
 	// The agent sends its version and OS user occasionally; record them when
 	// present. Agents older than 0.0.2 send no user, so keep what we have.
+	s.viaDirectA.Store(a.ID, s.viaDirect(r))
 	v := r.Header.Get("X-Agent-Version")
 	u := firstNonEmpty(r.Header.Get("X-Agent-User"), a.RunUser)
 	if v != "" && (v != a.Version || u != a.RunUser) {
@@ -52,10 +53,43 @@ func (s *Server) handlePoll(w http.ResponseWriter, r *http.Request) {
 	} else {
 		_ = s.db.TouchAgent(a.ID)
 	}
-	writeJSON(w, s.hub.WaitControl(a.ID, pollHold))
+	msg := s.hub.WaitControl(r.Context().Done(), a.ID, pollHold)
+	// Set after the hold so a setting changed meanwhile reaches the agent now.
+	s.setTunnelHeader(w)
+	s.setUpdateHeaders(w)
+	w.Header().Set(proto.TransportHeader, s.transportOf(a.ID))
+	writeJSON(w, msg)
 }

-// GET /api/agent/task/{id} — the agent fetches the task to run.
+// tunnelAddrHeader carries the direct-tunnel address ("host:port", host empty
+// = the panel's host) to agents, on every poll and on /api/agent/config.
+const tunnelAddrHeader = "X-Tunnel-Addr"
+
+func (s *Server) setTunnelHeader(w http.ResponseWriter) {
+	if addr := s.tunnelAdvert(); addr != "" {
+		w.Header().Set(tunnelAddrHeader, addr)
+	}
+	if d := s.db.DirectAddress(); d != "" {
+		w.Header().Set(proto.FallbackHeader, d)
+		w.Header().Set(proto.MainHeader, s.db.HostAddress())
+	}
+}
+
+// GET /api/agent/config - settings an agent picks up when it connects, without
+// waiting out a poll hold.
+func (s *Server) handleAgentConfig(w http.ResponseWriter, r *http.Request) {
+	a := s.authenticateAgent(r)
+	if a == nil {
+		http.Error(w, "unauthorized", http.StatusUnauthorized)
+		return
+	}
+	s.setTunnelHeader(w)
+	s.setUpdateHeaders(w)
+	w.Header().Set(proto.TransportHeader, s.transportOf(a.ID))
+	w.WriteHeader(http.StatusNoContent)
+}
+
+// GET /api/agent/task/{id} - the agent fetches the task to run.
 func (s *Server) handleTaskFetch(w http.ResponseWriter, r *http.Request) {
 	if s.authenticateAgent(r) == nil {
 		http.Error(w, "unauthorized", http.StatusUnauthorized)
@@ -69,7 +103,7 @@ func (s *Server) handleTaskFetch(w http.ResponseWriter, r *http.Request) {
 	writeJSON(w, env)
 }

-// POST /api/agent/task/{id}/result — the agent returns the task result.
+// POST /api/agent/task/{id}/result - the agent returns the task result.
 func (s *Server) handleTaskResult(w http.ResponseWriter, r *http.Request) {
 	if s.authenticateAgent(r) == nil {
 		http.Error(w, "unauthorized", http.StatusUnauthorized)
@@ -84,7 +118,7 @@ func (s *Server) handleTaskResult(w http.ResponseWriter, r *http.Request) {
 	w.WriteHeader(http.StatusNoContent)
 }

-// GET /api/agent/term/{sid}/in — downstream (panel -> agent) long-poll.
+// GET /api/agent/term/{sid}/in - downstream (panel -> agent) long-poll.
 func (s *Server) handleTermIn(w http.ResponseWriter, r *http.Request) {
 	if s.authenticateAgent(r) == nil {
 		http.Error(w, "unauthorized", http.StatusUnauthorized)
@@ -103,7 +137,7 @@ func (s *Server) handleTermIn(w http.ResponseWriter, r *http.Request) {
 	writeJSON(w, proto.InBatch{Frames: frames})
 }

-// POST /api/agent/term/{sid}/out — upstream (agent PTY -> panel).
+// POST /api/agent/term/{sid}/out - upstream (agent PTY -> panel).
 func (s *Server) handleTermOut(w http.ResponseWriter, r *http.Request) {
 	if s.authenticateAgent(r) == nil {
 		http.Error(w, "unauthorized", http.StatusUnauthorized)
@@ -5,11 +5,13 @@ import (
 	"errors"
 	"fmt"
 	"log"
+	"net"
 	"net/http"
 	"net/url"
 	"slices"
 	"strconv"
 	"strings"
+	"sync"
 	"time"

 	"github.com/x-grk/longpolling-remote-access/internal/proto"
@@ -86,7 +88,12 @@ func (s *Server) handleLoginSubmit(w http.ResponseWriter, r *http.Request) {
 	admin, _ := s.db.AdminByUsername(username)
 	if admin == nil || !checkPassword(admin.PassHash, pw) {
 		s.limiter.fin(ip, false)
-		s.render(w, "login.html", map[string]any{"Error": "Неверный логин или пароль."})
+		s.render(w, "login.html", map[string]any{"Error": "Неверный логин или пароль.", "Username": username})
+		return
+	}
+	// An admin who turned the password off signs in with a passkey only.
+	if s.db.PasswordOff(admin.ID) {
+		s.render(w, "login.html", map[string]any{"Error": "Для этого аккаунта вход только по ключу доступа.", "Username": username})
 		return
 	}
 	s.limiter.fin(ip, true)
@@ -105,38 +112,69 @@ func (s *Server) handleLogout(w http.ResponseWriter, r *http.Request) {
 // --- dashboard ---

 func (s *Server) handleDashboard(w http.ResponseWriter, r *http.Request) {
-	agents, err := s.db.ListAgents()
-	if err != nil {
-		http.Error(w, "internal error", http.StatusInternalServerError)
-		return
-	}
+	s.renderPage(w, r, "dashboard", s.dashboardData(r))
+}
+
+// dashboardData is the machines list as the user may see it.
+func (s *Server) dashboardData(r *http.Request) map[string]any {
+	agents, _ := s.db.ListAgents()
 	type row struct {
 		Agent
 		Online bool
 		Seen   string
 	}
+	me := s.currentAdmin(r)
 	rows := make([]row, 0, len(agents))
 	for _, a := range agents {
-		rows = append(rows, row{Agent: a, Online: a.Online(), Seen: humanSince(a.LastSeen)})
+		if !s.db.CanUseAgent(me, a.ID) {
+			continue
+		}
+		on := s.online(&a)
+		rows = append(rows, row{Agent: a, Online: on, Seen: seenText(on, a.LastSeen)})
+	}
+	return map[string]any{
+		"Admin":   me,
+		"IsAdmin": me.IsAdmin(),
+		"Agents":  rows,
+		"CSRF":    csrfToken(r),
 	}
-	s.render(w, "dashboard.html", map[string]any{
-		"Admin":  s.currentAdmin(r),
-		"Agents": rows,
-		"CSRF":   csrfToken(r),
-	})
 }

-func (s *Server) handleTerminalPage(w http.ResponseWriter, r *http.Request) {
-	id := r.PathValue("id")
-	a, err := s.db.GetAgent(id)
-	if err != nil || a == nil {
-		http.NotFound(w, r)
+// seenText is the "activity" cell: a connected agent is active now, whatever
+// the time of its last recorded poll.
+func seenText(online bool, lastSeen time.Time) string {
+	if online {
+		return "сейчас"
+	}
+	return humanSince(lastSeen)
+}
+
+// GET /api/panel/agents/presence - who is online, for the dashboard to keep
+// its status column live without reloading.
+func (s *Server) handlePresence(w http.ResponseWriter, r *http.Request) {
+	agents, err := s.db.ListAgents()
+	if err != nil {
+		http.Error(w, "internal error", http.StatusInternalServerError)
 		return
 	}
-	s.render(w, "terminal.html", map[string]any{
-		"Agent": a,
-		"CSRF":  csrfToken(r),
-	})
+	type item struct {
+		ID       string `json:"id"`
+		Name     string `json:"name"`
+		Hostname string `json:"hostname"`
+		User     string `json:"user"` // who a terminal opens as
+		Online   bool   `json:"online"`
+		Seen     string `json:"seen"`
+	}
+	me := s.currentAdmin(r)
+	out := make([]item, 0, len(agents))
+	for _, a := range agents {
+		if !s.db.CanUseAgent(me, a.ID) {
+			continue
+		}
+		on := s.online(&a)
+		out = append(out, item{ID: a.ID, Name: a.Name, Hostname: a.Hostname, User: a.TerminalUser(), Online: on, Seen: seenText(on, a.LastSeen)})
+	}
+	writeJSON(w, out)
 }

 func (s *Server) handleAgentDelete(w http.ResponseWriter, r *http.Request) {
@@ -145,7 +183,16 @@ func (s *Server) handleAgentDelete(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 	id := r.PathValue("id")
+	// Its forward rules go with it: left behind they would keep their host
+	// ports bound and busy with no page to remove them from.
+	rules, _ := s.db.ListForwardRulesByAgent(id)
+	for _, rule := range rules {
+		s.removeForward(rule.ID)
+	}
 	_ = s.db.DeleteAgent(id)
+	s.stats.drop(id)
+	s.relays.drop(id, nil)
+	s.hub.Forget(id)
 	http.Redirect(w, r, "/", http.StatusSeeOther)
 }

@@ -158,22 +205,44 @@ func (s *Server) handleAgentEdit(w http.ResponseWriter, r *http.Request) {
 	}
 	data := map[string]any{
 		"Agent":         a,
+		"IsAdmin":       s.currentAdmin(r).IsAdmin(),
 		"CSRF":          csrfToken(r),
 		"ServerVersion": Version,
 		"Outdated":      a.Version != "" && a.Version != Version,
 		"Updated":       r.URL.Query().Get("updated") == "1",
+		"UpdateMsg":     r.URL.Query().Get("umsg"),
+		"UpdateErr":     r.URL.Query().Get("uperr"),
 		"UserOK":        r.URL.Query().Get("uok"),
 		"UserErr":       r.URL.Query().Get("uerr"),
+		"Transport":     firstNonEmpty(a.Transport, proto.TransportAuto),
+		"OnWS":          s.wsAgents.On(a.ID),
+		"ViaDirect":     viaDirectOf(&s.viaDirectA, a.ID),
+		"Online":        s.online(a),
 	}
 	// The user list lives on the machine, so it is only known while it is online.
-	if a.Online() {
+	if s.online(a) {
 		if users, err := s.agentUsers(id); err == nil {
 			data["Users"] = users
 		} else {
 			data["UsersErr"] = err.Error()
 		}
 	}
-	s.render(w, "edit.html", data)
+	s.renderPage(w, r, "edit", data)
+}
+
+// POST /agents/{id}/transport - how the agent is to reach the server: auto,
+// ws or lp. A connected agent picks it up within a poll round.
+func (s *Server) handleAgentTransport(w http.ResponseWriter, r *http.Request) {
+	if !checkCSRF(r) {
+		http.Error(w, "bad csrf", http.StatusForbidden)
+		return
+	}
+	id, t := r.PathValue("id"), r.FormValue("transport")
+	switch t {
+	case proto.TransportAuto, proto.TransportWS, proto.TransportLP:
+		_ = s.db.SetAgentTransport(id, t)
+	}
+	http.Redirect(w, r, "/agents/"+id+"/edit", http.StatusSeeOther)
 }

 // usersTaskTimeout bounds how long the edit page waits for the agent.
@@ -187,7 +256,7 @@ func (s *Server) agentUsers(agentID string) (*proto.SysUsersResult, error) {
 	case res := <-ch:
 		if !res.OK {
 			// Agents older than 0.0.2 don't know this task.
-			return nil, errors.New("клиент не поддерживает выбор пользователя — обновите его")
+			return nil, errors.New("клиент не поддерживает выбор пользователя - обновите его")
 		}
 		var out proto.SysUsersResult
 		if err := json.Unmarshal(res.Data, &out); err != nil {
@@ -217,8 +286,8 @@ func (s *Server) handleAgentSetUser(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 	name := strings.TrimSpace(r.FormValue("user"))
-	if !a.Online() {
-		editUserRedirect(w, r, id, "uerr", "Машина офлайн — сменить пользователя нельзя.")
+	if !s.online(a) {
+		editUserRedirect(w, r, id, "uerr", "Машина офлайн - сменить пользователя нельзя.")
 		return
 	}
 	// Only accept a user the machine itself reports, so a typo (or an agent too
@@ -258,8 +327,8 @@ func (s *Server) handleAgentAddUser(w http.ResponseWriter, r *http.Request) {
 		http.NotFound(w, r)
 		return
 	}
-	if !a.Online() {
-		editUserRedirect(w, r, id, "uerr", "Машина офлайн — создать пользователя нельзя.")
+	if !s.online(a) {
+		editUserRedirect(w, r, id, "uerr", "Машина офлайн - создать пользователя нельзя.")
 		return
 	}
 	name := strings.TrimSpace(r.FormValue("name"))
@@ -299,17 +368,28 @@ func (s *Server) handleAgentUpdate(w http.ResponseWriter, r *http.Request) {
 		http.NotFound(w, r)
 		return
 	}
-	if !a.Online() {
-		http.Redirect(w, r, "/agents/"+id+"/edit?updated=0", http.StatusSeeOther)
+	back := func(q url.Values) { http.Redirect(w, r, "/agents/"+id+"/edit?"+q.Encode(), http.StatusSeeOther) }
+	if !s.online(a) {
+		back(url.Values{"uperr": {"машина не в сети"}})
 		return
 	}
-	taskID, ch := s.hub.CreateTask(id, proto.TaskSysUpdate, nil)
-	defer s.hub.DiscardTask(taskID)
-	select {
-	case <-ch:
-	case <-time.After(30 * time.Second):
+	if admin := s.currentAdmin(r); admin != nil {
+		s.db.Audit(admin.ID, id, "update:"+a.Version+" -> "+Version)
+	}
+	// The download can take a while on a slow link; under a proxy's timeout.
+	res, err := s.waitTask(r.Context(), id, proto.TaskSysUpdate, nil, 80*time.Second)
+	switch {
+	case err != nil:
+		back(url.Values{"uperr": {"агент не ответил: " + err.Error()}})
+	case !res.OK:
+		back(url.Values{"uperr": {res.Error}})
+	default:
+		var d struct {
+			Status string `json:"status"`
+		}
+		_ = json.Unmarshal(res.Data, &d)
+		back(url.Values{"updated": {"1"}, "umsg": {d.Status}})
 	}
-	http.Redirect(w, r, "/agents/"+id+"/edit?updated=1", http.StatusSeeOther)
 }

 func (s *Server) handleAgentRename(w http.ResponseWriter, r *http.Request) {
@@ -322,45 +402,153 @@ func (s *Server) handleAgentRename(w http.ResponseWriter, r *http.Request) {
 	if name != "" {
 		_ = s.db.RenameAgent(id, name)
 	}
-	http.Redirect(w, r, "/", http.StatusSeeOther)
+	// Back to «Изменить», with the new name: the machine dialog stays open.
+	http.Redirect(w, r, "/agents/"+id+"/edit", http.StatusSeeOther)
 }

 // --- settings ---

 func (s *Server) handleSettings(w http.ResponseWriter, r *http.Request) {
 	admins, _ := s.db.ListAdmins()
+	keyCounts, passOff, agentCounts := map[int64]int{}, map[int64]bool{}, map[int64]int{}
+	for _, a := range admins {
+		keyCounts[a.ID] = s.db.CountAdminKeys(a.ID)
+		passOff[a.ID] = s.db.PasswordOff(a.ID)
+		agentCounts[a.ID] = len(s.db.UserAgents(a.ID))
+	}
+	allAgents, _ := s.db.ListAgents()
 	host := s.db.HostAddress()
+	direct := s.db.DirectAddress()
 	secret := s.db.EnrollSecret()
 	code := s.db.InstallCode()
 	ufwInstalled, ufwActive, ufwRunnable := s.ufw.status()
 	ufwRules, _ := s.db.ListUfwRules()
-	s.render(w, "settings.html", map[string]any{
+	dbNow, dbChosen := s.db.Backend()
+	s.renderPage(w, r, "settings", map[string]any{
 		"Admin":         s.currentAdmin(r),
 		"Host":          host,
+		"Direct":        direct,
+		"DirectShort":   fmt.Sprintf("wget -qO- %s/i/%s | sudo sh", direct, code),
+		"DirectCurl":    fmt.Sprintf("curl -fsSL %s/install.sh | sudo HOST=%s FALLBACK_HOST=%s ENROLL_SECRET=%s sh", direct, direct, host, secret),
 		"Secret":        secret,
+		"CodeLen":       s.db.InstallCodeLen(),
 		"Admins":        admins,
+		"KeyCounts":     keyCounts,
+		"AgentCounts":   agentCounts,
+		"AllAgents":     allAgents,
+		"Me":            s.currentAdmin(r),
+		"PassOff":       passOff,
 		"CSRF":          csrfToken(r),
 		"InstallShort":  fmt.Sprintf("wget -qO- %s/i/%s | sudo sh", host, code),
 		"InstallCurl":   fmt.Sprintf("curl -fsSL %s/install.sh | sudo HOST=%s ENROLL_SECRET=%s sh", host, host, secret),
 		"InstallWget":   fmt.Sprintf("wget -qO- %s/install.sh | sudo HOST=%s ENROLL_SECRET=%s sh", host, host, secret),
 		"ServerVersion": Version,
+		"AIModels":      s.aiModels(),
+		"Search":        s.searchConf(),
+		"ImageKey":      func() string { _, k := s.imageConf(); return k }(),
+		"Auto":          s.autoView(),
+		"DBNow":         dbNow,
+		"DBChosen":      dbChosen,
 		"UfwInstalled":  ufwInstalled,
 		"UfwActive":     ufwActive,
 		"UfwRunnable":   ufwRunnable,
 		"UfwEnabled":    s.db.UfwEnabled(),
 		"UfwRules":      ufwRules,
+		"UfwError":      s.ufw.LastError(),
+		"TunnelPort":    s.TunnelPort(),
+		"TunnelDefault": s.tunnelDefault,
+		"TunnelHost":    s.db.TunnelHost(),
+		"TunnelCustom":  s.db.TunnelPort() > 0,
+		"Error": map[string]string{
+			"tunnel_host":   "Некорректный хост туннеля: нужен IP или имя без схемы и порта.",
+			"host":          "Некорректный адрес: нужен URL вида https://panel.example.com, без пути.",
+			"tunnel_port":   "Некорректный порт туннеля.",
+			"ufw_port":      "Некорректное правило ufw: нужен порт 1-65535 и протокол tcp или udp.",
+			"ufw_off":       "Правило ufw не добавлено: ufw выключен или интеграция с ним отключена.",
+			"ufw_failed":    "Правило ufw не добавлено: команда ufw завершилась ошибкой.",
+			"ufw_exists":    "Этот порт уже открыт в ufw не панелью - правило осталось как было, панель его не отслеживает.",
+			"tunnel_listen": "Не удалось занять новый порт туннеля на хосте (возможно, уже используется). Порт не изменён.",
+		}[r.URL.Query().Get("err")],
 	})
 }

+// POST /settings/tunnel - host and port agents use for the direct tunnel.
+func (s *Server) handleSetTunnel(w http.ResponseWriter, r *http.Request) {
+	if !checkCSRF(r) {
+		http.Error(w, "bad csrf", http.StatusForbidden)
+		return
+	}
+	if s.tunnelDefault == 0 {
+		http.Redirect(w, r, "/settings", http.StatusSeeOther)
+		return
+	}
+	host := strings.TrimSpace(r.FormValue("tunnel_host"))
+	host = strings.TrimSuffix(strings.TrimPrefix(host, "["), "]")
+	if !validTunnelHost(host) {
+		http.Redirect(w, r, "/settings?err=tunnel_host", http.StatusSeeOther)
+		return
+	}
+	// An empty port goes back to the one the server was started with.
+	port, custom := s.tunnelDefault, ""
+	if v := strings.TrimSpace(r.FormValue("tunnel_port")); v != "" {
+		n, err := strconv.Atoi(v)
+		if err != nil || n < 1 || n > 65535 {
+			http.Redirect(w, r, "/settings?err=tunnel_port", http.StatusSeeOther)
+			return
+		}
+		port = n
+		if n != s.tunnelDefault {
+			custom = v
+		}
+	}
+	if err := s.setTunnelPort(port); err != nil {
+		log.Printf("tunnel: move to port %d: %v", port, err)
+		http.Redirect(w, r, "/settings?err=tunnel_listen", http.StatusSeeOther)
+		return
+	}
+	_ = s.db.SetConfig(cfgTunnelPort, custom)
+	_ = s.db.SetConfig(cfgTunnelHost, host)
+	http.Redirect(w, r, "/settings", http.StatusSeeOther)
+}
+
+// validTunnelHost accepts an empty value, an IP, or a bare host name.
+func validTunnelHost(host string) bool {
+	if host == "" || net.ParseIP(host) != nil {
+		return true
+	}
+	if len(host) > 253 {
+		return false
+	}
+	for _, c := range host {
+		switch {
+		case c >= 'a' && c <= 'z', c >= 'A' && c <= 'Z', c >= '0' && c <= '9', c == '-', c == '.', c == '_':
+		default:
+			return false
+		}
+	}
+	return true
+}
+
 func (s *Server) handleSetHost(w http.ResponseWriter, r *http.Request) {
 	if !checkCSRF(r) {
 		http.Error(w, "bad csrf", http.StatusForbidden)
 		return
 	}
 	host := strings.TrimRight(strings.TrimSpace(r.FormValue("host")), "/")
+	direct := strings.TrimRight(strings.TrimSpace(r.FormValue("direct")), "/")
+	for _, v := range []string{host, direct} {
+		if v == "" {
+			continue
+		}
+		if u, err := url.Parse(v); err != nil || (u.Scheme != "http" && u.Scheme != "https") || u.Host == "" || (u.Path != "" && u.Path != "/") {
+			http.Redirect(w, r, "/settings?err=host", http.StatusSeeOther)
+			return
+		}
+	}
 	if host != "" {
 		_ = s.db.SetConfig(cfgHostAddress, host)
 	}
+	_ = s.db.SetConfig(cfgDirectAddr, direct)
 	http.Redirect(w, r, "/settings", http.StatusSeeOther)
 }

@@ -371,7 +559,22 @@ func (s *Server) handleRotateSecret(w http.ResponseWriter, r *http.Request) {
 	}
 	_ = s.db.SetConfig(cfgEnrollSecret, randToken())
 	// Rotate the short install code too so old /i/<code> links stop working.
-	_ = s.db.SetConfig(cfgInstallCode, shortCode())
+	_ = s.db.SetConfig(cfgInstallCode, shortCode(s.db.InstallCodeLen()))
+	http.Redirect(w, r, "/settings", http.StatusSeeOther)
+}
+
+// POST /settings/install/code - a new install code, of the length given:
+// the old /i/<code> link stops working.
+func (s *Server) handleInstallCode(w http.ResponseWriter, r *http.Request) {
+	if !checkCSRF(r) {
+		http.Error(w, "bad csrf", http.StatusForbidden)
+		return
+	}
+	if n, err := strconv.Atoi(r.FormValue("len")); err == nil {
+		n = min(installCodeMax, max(installCodeMin, n))
+		_ = s.db.SetConfig(cfgInstallLen, strconv.Itoa(n))
+	}
+	_ = s.db.SetConfig(cfgInstallCode, shortCode(s.db.InstallCodeLen()))
 	http.Redirect(w, r, "/settings", http.StatusSeeOther)
 }

@@ -382,12 +585,21 @@ func (s *Server) handleAddAdmin(w http.ResponseWriter, r *http.Request) {
 	}
 	username := strings.TrimSpace(r.FormValue("username"))
 	pw := r.FormValue("password")
+	role := RoleAdmin
+	if r.FormValue("role") == RoleUser {
+		role = RoleUser
+	}
 	if username != "" && len(pw) >= 8 {
 		if hash, err := hashPassword(pw); err == nil {
-			_ = s.db.CreateAdmin(username, hash)
+			if id, err := s.db.CreateUser(username, hash, role); err == nil && role == RoleUser {
+				_ = s.db.SetUserAgents(id, r.Form["agents"])
+			}
+			if me := s.currentAdmin(r); me != nil {
+				s.db.Audit(me.ID, "", "user_add:"+username+":"+role)
+			}
 		}
 	}
-	http.Redirect(w, r, "/settings", http.StatusSeeOther)
+	http.Redirect(w, r, "/settings#users", http.StatusSeeOther)
 }

 func (s *Server) handleDeleteAdmin(w http.ResponseWriter, r *http.Request) {
@@ -397,7 +609,7 @@ func (s *Server) handleDeleteAdmin(w http.ResponseWriter, r *http.Request) {
 	}
 	id, _ := strconv.ParseInt(r.FormValue("id"), 10, 64)
 	// Never delete the last admin.
-	if n, _ := s.db.CountAdmins(); n > 1 {
+	if u, _ := s.db.AdminByID(id); u != nil && (!u.IsAdmin() || s.db.CountRole(RoleAdmin) > 1) {
 		_ = s.db.DeleteAdmin(id)
 	}
 	http.Redirect(w, r, "/settings", http.StatusSeeOther)
@@ -408,10 +620,33 @@ func (s *Server) handleUfwToggle(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, "bad csrf", http.StatusForbidden)
 		return
 	}
-	_ = s.db.SetUfwEnabled(r.FormValue("enabled") == "1")
+	on := r.FormValue("enabled") == "1"
+	_ = s.db.SetUfwEnabled(on)
+	if on {
+		// Open what forwards created while the integration was off need.
+		s.ufw.sync()
+	}
 	http.Redirect(w, r, "/settings", http.StatusSeeOther)
 }

+func (s *Server) handleUfwAdd(w http.ResponseWriter, r *http.Request) {
+	if !checkCSRF(r) {
+		http.Error(w, "bad csrf", http.StatusForbidden)
+		return
+	}
+	port, _ := strconv.Atoi(strings.TrimSpace(r.FormValue("port")))
+	proto := r.FormValue("proto")
+	if port < 1 || port > 65535 || (proto != "tcp" && proto != "udp") {
+		http.Redirect(w, r, "/settings?err=ufw_port", http.StatusSeeOther)
+		return
+	}
+	target := "/settings"
+	if key := s.ufw.allowManual(port, proto); key != "" {
+		target += "?err=" + key
+	}
+	http.Redirect(w, r, target, http.StatusSeeOther)
+}
+
 func (s *Server) handleUfwRevoke(w http.ResponseWriter, r *http.Request) {
 	if !checkCSRF(r) {
 		http.Error(w, "bad csrf", http.StatusForbidden)
@@ -427,7 +662,7 @@ func (s *Server) handleUfwRevoke(w http.ResponseWriter, r *http.Request) {
 // handleInstallScript serves the generic installer; the secret is NOT baked in,
 // so it must be supplied via env or the interactive prompt.
 func (s *Server) handleInstallScript(w http.ResponseWriter, r *http.Request) {
-	s.renderInstall(w, "")
+	s.renderInstall(w, r, "")
 }

 // handleShortInstall serves the installer behind the short /i/<code> link with
@@ -435,21 +670,49 @@ func (s *Server) handleInstallScript(w http.ResponseWriter, r *http.Request) {
 //
 //	wget -qO- https://host/i/<code> | sudo sh
 func (s *Server) handleShortInstall(w http.ResponseWriter, r *http.Request) {
+	// A short code can be guessed: wrong ones count against the address
+	// like wrong passwords do.
+	ip := clientIP(r)
+	if s.limiter.blocked(ip) {
+		http.Error(w, "too many attempts", http.StatusTooManyRequests)
+		return
+	}
 	code := r.PathValue("code")
 	want := s.db.InstallCode()
 	if want == "" || !constantTimeEqual(code, want) {
+		s.limiter.fin(ip, false)
 		http.NotFound(w, r)
 		return
 	}
-	s.renderInstall(w, s.db.EnrollSecret())
+	s.renderInstall(w, r, s.db.EnrollSecret())
 }

-// renderInstall writes install.sh with the current host and an optional secret.
-func (s *Server) renderInstall(w http.ResponseWriter, secret string) {
+// viaDirect reports whether the request came to the direct address.
+func (s *Server) viaDirect(r *http.Request) bool {
+	d := directHost(s.db.DirectAddress())
+	if d == "" {
+		return false
+	}
+	host := r.Host
+	if h, _, err := net.SplitHostPort(host); err == nil {
+		host = h
+	}
+	return strings.EqualFold(host, d)
+}
+
+// renderInstall writes install.sh with the server's addresses and an
+// optional secret. Fetched from the direct address, it makes that the
+// agent's address and the main one its fallback; otherwise the other way.
+func (s *Server) renderInstall(w http.ResponseWriter, r *http.Request, secret string) {
+	host, fallback := s.db.HostAddress(), s.db.DirectAddress()
+	if s.viaDirect(r) {
+		host, fallback = fallback, host
+	}
 	w.Header().Set("Content-Type", "text/x-shellscript; charset=utf-8")
 	if err := s.installTmpl.Execute(w, map[string]any{
-		"Host":   s.db.HostAddress(),
-		"Secret": secret,
+		"Host":     host,
+		"Fallback": fallback,
+		"Secret":   secret,
 	}); err != nil {
 		log.Printf("install.sh render: %v", err)
 		http.Error(w, "internal error", http.StatusInternalServerError)
@@ -461,3 +724,11 @@ func (s *Server) downloadHandler() http.Handler {
 	// install one-liner works before the machine is enrolled.
 	return http.FileServer(http.Dir(s.distDir))
 }
+
+// viaDirectOf tells whether the agent last reached the server at the direct
+// address.
+func viaDirectOf(m *sync.Map, id string) bool {
+	v, _ := m.Load(id)
+	b, _ := v.(bool)
+	return b
+}
@@ -1,11 +1,9 @@
 package server

 import (
-	"encoding/base64"
 	"encoding/json"
 	"io"
 	"net/http"
-	"path"
 	"time"

 	"github.com/x-grk/longpolling-remote-access/internal/proto"
@@ -13,31 +11,31 @@ import (

 // fsOps maps the URL op segment to a proto task type.
 var fsOps = map[string]string{
-	"list":    proto.TaskFSList,
-	"read":    proto.TaskFSRead,
-	"write":   proto.TaskFSWrite,
-	"mkdir":   proto.TaskFSMkdir,
-	"delete":  proto.TaskFSDelete,
-	"deltree": proto.TaskFSDelTree,
-	"unzip":   proto.TaskFSUnzip,
-	"zip":     proto.TaskFSZip,
-	"move":    proto.TaskFSMove,
+	"list":      proto.TaskFSList,
+	"read":      proto.TaskFSRead,
+	"write":     proto.TaskFSWrite,
+	"mkdir":     proto.TaskFSMkdir,
+	"delete":    proto.TaskFSDelete,
+	"deltree":   proto.TaskFSDelTree,
+	"unzip":     proto.TaskFSUnzip,
+	"zip":       proto.TaskFSZip,
+	"move":      proto.TaskFSMove,
+	"stat":      proto.TaskFSStat,
+	"chmod":     proto.TaskFSChmod,
+	"copy":      proto.TaskFSCopy,
+	"db.tables": proto.TaskDBTables,
+	"db.rows":   proto.TaskDBRows,
+	"db.set":    proto.TaskDBSet,
+	"db.add":    proto.TaskDBAdd,
+	"db.del":    proto.TaskDBDel,
+	"db.sql":    proto.TaskDBSQL,
+	"termcwd":   proto.TaskTermCwd,
 }

 // fsTaskTimeout bounds how long we wait for an agent to answer a file op.
 const fsTaskTimeout = 60 * time.Second

-func (s *Server) handleFilesPage(w http.ResponseWriter, r *http.Request) {
-	id := r.PathValue("id")
-	a, err := s.db.GetAgent(id)
-	if err != nil || a == nil {
-		http.NotFound(w, r)
-		return
-	}
-	s.render(w, "files.html", map[string]any{"Agent": a})
-}
-
-// POST /api/panel/agents/{id}/fs/{op} — run a file-manager operation on the
+// POST /api/panel/agents/{id}/fs/{op} - run a file-manager operation on the
 // agent and return its result. The request body is the op's JSON args and is
 // forwarded verbatim to the agent.
 func (s *Server) handleFSOp(w http.ResponseWriter, r *http.Request) {
@@ -53,7 +51,7 @@ func (s *Server) handleFSOp(w http.ResponseWriter, r *http.Request) {
 		http.NotFound(w, r)
 		return
 	}
-	if !a.Online() {
+	if !s.online(a) {
 		writeJSON(w, proto.TaskResult{Error: "машина офлайн"})
 		return
 	}
@@ -63,6 +61,26 @@ func (s *Server) handleFSOp(w http.ResponseWriter, r *http.Request) {
 		return
 	}

+	// Changes to a database go to the audit log, with what was done.
+	if op == "db.set" || op == "db.add" || op == "db.del" || op == "db.sql" {
+		var d struct {
+			Path, Table, Column, SQL string
+		}
+		_ = json.Unmarshal(args, &d)
+		what := d.Path + " " + d.Table
+		if d.Column != "" {
+			what += "." + d.Column
+		}
+		if d.SQL != "" {
+			what += " " + d.SQL
+		}
+		if len(what) > 300 {
+			what = what[:300]
+		}
+		if admin := s.currentAdmin(r); admin != nil {
+			s.db.Audit(admin.ID, agentID, op+":"+what)
+		}
+	}
 	taskID, resultCh := s.hub.CreateTask(agentID, taskType, args)
 	defer s.hub.DiscardTask(taskID)

@@ -73,44 +91,3 @@ func (s *Server) handleFSOp(w http.ResponseWriter, r *http.Request) {
 		writeJSON(w, proto.TaskResult{Error: "таймаут ожидания агента"})
 	}
 }
-
-// GET /api/panel/agents/{id}/fs/download?path=... — stream a file as a download.
-func (s *Server) handleFSDownload(w http.ResponseWriter, r *http.Request) {
-	agentID := r.PathValue("id")
-	p := r.URL.Query().Get("path")
-	a, err := s.db.GetAgent(agentID)
-	if err != nil || a == nil {
-		http.NotFound(w, r)
-		return
-	}
-	if !a.Online() {
-		http.Error(w, "машина офлайн", http.StatusServiceUnavailable)
-		return
-	}
-	args, _ := json.Marshal(proto.FSPathArgs{Path: p})
-	taskID, ch := s.hub.CreateTask(agentID, proto.TaskFSDownload, args)
-	defer s.hub.DiscardTask(taskID)
-
-	select {
-	case res := <-ch:
-		if !res.OK {
-			http.Error(w, res.Error, http.StatusBadGateway)
-			return
-		}
-		var rr proto.FSReadResult
-		if err := json.Unmarshal(res.Data, &rr); err != nil {
-			http.Error(w, "bad result", http.StatusBadGateway)
-			return
-		}
-		data, _ := base64.StdEncoding.DecodeString(rr.Content)
-		name := path.Base(p)
-		w.Header().Set("Content-Type", "application/octet-stream")
-		w.Header().Set("Content-Disposition", "attachment; filename=\""+name+"\"")
-		if rr.Truncated {
-			w.Header().Set("X-Truncated", "1")
-		}
-		_, _ = w.Write(data)
-	case <-time.After(fsTaskTimeout):
-		http.Error(w, "таймаут ожидания агента", http.StatusGatewayTimeout)
-	}
-}
@@ -3,6 +3,7 @@ package server
 import (
 	"log"
 	"net/http"
+	"net/url"
 	"strconv"
 	"strings"
 )
@@ -17,18 +18,37 @@ func (s *Server) handleForwardsPage(w http.ResponseWriter, r *http.Request) {
 	rules, _ := s.db.ListForwardRulesByAgent(id)
 	errMsg := map[string]string{
 		"busy":   "Этот порт хоста уже занят другим правилом.",
+		"tunnel": "Этот порт занят прямым туннелем панели (см. Настройки).",
 		"port":   "Некорректный номер порта.",
 		"listen": "Не удалось занять порт на хосте (возможно, уже используется).",
 		"db":     "Ошибка базы данных.",
 	}[r.URL.Query().Get("err")]
-	s.render(w, "forwards.html", map[string]any{
-		"Agent": a,
-		"Rules": rules,
-		"CSRF":  csrfToken(r),
-		"Error": errMsg,
+	s.renderPage(w, r, "forwards", map[string]any{
+		"Agent":      a,
+		"Rules":      rules,
+		"CSRF":       csrfToken(r),
+		"Error":      errMsg,
+		"TunnelPort": s.TunnelPort(),
+		"PanelPort":  panelPort(s.db.HostAddress()),
+		"UfwEnabled": s.ufw.enabled(),
 	})
 }

+// panelPort is the port of the panel URL agents dial, for the mode hints.
+func panelPort(host string) string {
+	u, err := url.Parse(host)
+	if err != nil {
+		return ""
+	}
+	if p := u.Port(); p != "" {
+		return p
+	}
+	if u.Scheme == "http" {
+		return "80"
+	}
+	return "443"
+}
+
 // POST /agents/{id}/forwards/add
 func (s *Server) handleForwardAdd(w http.ResponseWriter, r *http.Request) {
 	if !checkCSRF(r) {
@@ -57,12 +77,17 @@ func (s *Server) handleForwardAdd(w http.ResponseWriter, r *http.Request) {
 		http.Redirect(w, r, "/agents/"+id+"/forwards?err=port", http.StatusSeeOther)
 		return
 	}
-	// Reject a host port already bound by another forward rule.
+	// Reject a host port already bound by another forward rule or the tunnel.
+	if hostPort == s.TunnelPort() {
+		http.Redirect(w, r, "/agents/"+id+"/forwards?err=tunnel", http.StatusSeeOther)
+		return
+	}
 	if s.db.HostPortUsed(hostPort) {
 		http.Redirect(w, r, "/agents/"+id+"/forwards?err=busy", http.StatusSeeOther)
 		return
 	}
-	rule := ForwardRule{AgentID: id, ClientPort: clientPort, HostPort: hostPort, ListenAddr: listenAddr, Proto: protoKind}
+	rule := ForwardRule{AgentID: id, ClientPort: clientPort, HostPort: hostPort, ListenAddr: listenAddr, Proto: protoKind,
+		NoUfw: r.FormValue("no_ufw") != "", Label: forwardLabel(r.FormValue("label"))}
 	ruleID, err := s.db.CreateForwardRule(rule)
 	if err != nil {
 		http.Redirect(w, r, "/agents/"+id+"/forwards?err=db", http.StatusSeeOther)
@@ -89,13 +114,35 @@ func (s *Server) handleForwardDelete(w http.ResponseWriter, r *http.Request) {
 	}
 	rid, _ := strconv.ParseInt(r.PathValue("rid"), 10, 64)
 	rule, _ := s.db.GetForwardRule(rid)
-	s.fwd.close(rid)
-	_ = s.db.DeleteForwardRule(rid)
-	// Remove the ufw rule bound to this forward rule (shared 8446 stays).
-	s.ufw.revokeForRule(rid)
+	if rule == nil || !s.db.CanUseAgent(s.currentAdmin(r), rule.AgentID) {
+		http.NotFound(w, r)
+		return
+	}
+	s.removeForward(rid)
 	dest := "/"
 	if rule != nil {
 		dest = "/agents/" + rule.AgentID + "/forwards"
 	}
 	http.Redirect(w, r, dest, http.StatusSeeOther)
 }
+
+// removeForward closes a forward rule's listener and deletes the rule, along
+// with the ufw rule bound to it (the shared tunnel port stays while another
+// direct forward needs it).
+func (s *Server) removeForward(rid int64) {
+	s.fwd.close(rid)
+	_ = s.db.DeleteForwardRule(rid)
+	s.ufw.revokeForRule(rid)
+}
+
+// forwardLabelMax bounds a rule's label, in characters.
+const forwardLabelMax = 80
+
+// forwardLabel tidies the optional note of a rule: one line, bounded length.
+func forwardLabel(v string) string {
+	v = strings.Join(strings.Fields(v), " ")
+	if r := []rune(v); len(r) > forwardLabelMax {
+		v = string(r[:forwardLabelMax])
+	}
+	return v
+}
@@ -0,0 +1,542 @@
+package server
+
+import (
+	"crypto/rand"
+	"encoding/json"
+	"errors"
+	"io"
+	"net/http"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/x-grk/longpolling-remote-access/internal/proto"
+)
+
+const (
+	// statTaskTimeout bounds how long a status request waits for the agent.
+	statTaskTimeout = 8 * time.Second
+	// statCacheFor is how long one sample answers every open status page, so
+	// several tabs cost the agent a single reading.
+	statCacheFor = 2 * time.Second
+	// speedWindow is how long the agent is asked to measure each direction
+	// for. An agent that predates the argument keeps to its own 3 s.
+	speedWindow = 7 * time.Second
+	// speedTaskTimeout is how long a speed test may take. One that is not done
+	// by then is answered with what the server has counted itself.
+	speedTaskTimeout = 35 * time.Second
+	// speedDownCap bounds one download stream; speedDownFor ends it if the
+	// agent does not hang up first.
+	speedDownCap = 1 << 30
+	speedDownFor = 2 * speedWindow
+	speedUpCap   = 64 << 20
+	// speedRelayUpFor is how long the agent's upload is passed on to the
+	// browser: the agent's own window with slack.
+	speedRelayUpFor = speedWindow + time.Second
+)
+
+// statCache holds the last sample per agent and serializes its refresh.
+type statCache struct {
+	mu sync.Mutex
+	m  map[string]*statEntry
+}
+
+type statEntry struct {
+	mu  sync.Mutex
+	at  time.Time
+	res proto.TaskResult
+}
+
+func (c *statCache) entry(agentID string) *statEntry {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	if c.m == nil {
+		c.m = map[string]*statEntry{}
+	}
+	e := c.m[agentID]
+	if e == nil {
+		e = &statEntry{}
+		c.m[agentID] = e
+	}
+	return e
+}
+
+func (c *statCache) drop(agentID string) {
+	c.mu.Lock()
+	delete(c.m, agentID)
+	c.mu.Unlock()
+}
+
+func (s *Server) handleStatusPage(w http.ResponseWriter, r *http.Request) {
+	a, err := s.db.GetAgent(r.PathValue("id"))
+	if err != nil || a == nil {
+		http.NotFound(w, r)
+		return
+	}
+	s.renderPage(w, r, "status", map[string]any{"Agent": a, "RelayUpMs": speedRelayUpFor.Milliseconds()})
+}
+
+// runTask runs a one-shot task on the agent and waits for its result.
+func (s *Server) runTask(agentID, typ string, args []byte, timeout time.Duration) (proto.TaskResult, error) {
+	taskID, ch := s.hub.CreateTask(agentID, typ, args)
+	defer s.hub.DiscardTask(taskID)
+	t := time.NewTimer(timeout)
+	defer t.Stop()
+	select {
+	case res := <-ch:
+		return res, nil
+	case <-t.C:
+		return proto.TaskResult{}, errors.New("таймаут ожидания клиента")
+	}
+}
+
+// onlineAgent answers the request itself and returns false when the agent is
+// unknown or offline.
+func (s *Server) onlineAgent(w http.ResponseWriter, r *http.Request) (string, bool) {
+	id := r.PathValue("id")
+	a, err := s.db.GetAgent(id)
+	if err != nil || a == nil {
+		http.NotFound(w, r)
+		return "", false
+	}
+	if !s.online(a) {
+		writeJSON(w, proto.TaskResult{Error: "машина офлайн"})
+		return "", false
+	}
+	return id, true
+}
+
+// oldAgentError replaces the "unknown task" answer of an agent that predates
+// the task.
+func oldAgentError(res proto.TaskResult) proto.TaskResult {
+	if !res.OK && strings.Contains(res.Error, "неизвестная операция") {
+		res.Error = "клиент не поддерживает эту функцию - обновите его (нужен 0.0.5+)"
+	}
+	return res
+}
+
+// GET /api/panel/agents/{id}/stat - CPU, RAM and disk of the machine right now.
+func (s *Server) handleAgentStat(w http.ResponseWriter, r *http.Request) {
+	id, ok := s.onlineAgent(w, r)
+	if !ok {
+		return
+	}
+	e := s.stats.entry(id)
+	e.mu.Lock()
+	defer e.mu.Unlock()
+	if time.Since(e.at) > statCacheFor {
+		res, err := s.runTask(id, proto.TaskSysStat, nil, statTaskTimeout)
+		if err != nil {
+			// Cached too, so pages queued behind this one don't each wait it out.
+			res = proto.TaskResult{Error: err.Error()}
+		}
+		e.res, e.at = oldAgentError(res), time.Now()
+	}
+	writeJSON(w, e.res)
+}
+
+// POST /api/panel/agents/{id}/speed - have the agent measure its link to us.
+// With relay=1 its streams run through the relay opened for it, to and from
+// the browser.
+func (s *Server) handleAgentSpeed(w http.ResponseWriter, r *http.Request) {
+	id, ok := s.onlineAgent(w, r)
+	if !ok {
+		return
+	}
+	relay := r.URL.Query().Get("relay") != ""
+	m := s.meters.start(id)
+	defer s.meters.stop(id, m)
+	if relay {
+		rl := s.relays.get(id)
+		if rl == nil {
+			writeJSON(w, proto.TaskResult{Error: "замер через браузер не открыт"})
+			return
+		}
+		defer s.relays.drop(id, rl)
+	}
+	args, _ := json.Marshal(proto.SysSpeedArgs{Relay: relay, WindowMs: int(speedWindow.Milliseconds())})
+	res, err := s.runTask(id, proto.TaskSysSpeed, args, speedTaskTimeout)
+	if err != nil {
+		part, ok := m.result()
+		if !ok {
+			writeJSON(w, proto.TaskResult{Error: err.Error()})
+			return
+		}
+		part.Relay = relay
+		data, _ := json.Marshal(part)
+		res = proto.TaskResult{OK: true, Data: data}
+	}
+	res = oldAgentError(res)
+	if relay && res.OK {
+		// An agent that predates the relay ignores the argument and measures
+		// its own link.
+		var d proto.SysSpeedResult
+		if json.Unmarshal(res.Data, &d) != nil || !d.Relay {
+			res = proto.TaskResult{Error: "клиент не умеет замер через браузер - обновите его (нужен 0.0.6+)"}
+		}
+	}
+	writeJSON(w, res)
+}
+
+// speedMeter counts what flows through the streams of one speed test as the
+// server sees it: for the live reading on the page, and for the result of a
+// test that ran out of time.
+type speedMeter struct {
+	mu     sync.Mutex
+	start  time.Time
+	phase  string // "ping", "down", "up"
+	pingAt time.Time
+	pingMs float64
+	down   speedCount
+	up     speedCount
+}
+
+// speedCount is the bytes of one direction and when they went through. The
+// first piece only starts the clock.
+type speedCount struct {
+	n, skip     int64
+	first, last time.Time
+}
+
+func (c *speedCount) add(n int) {
+	now := time.Now()
+	if c.first.IsZero() {
+		c.first, c.skip = now, int64(n)
+	}
+	c.n += int64(n)
+	c.last = now
+}
+
+func (c *speedCount) bps() float64 {
+	d := c.last.Sub(c.first).Seconds()
+	if d <= 0 {
+		return 0
+	}
+	return float64(c.n-c.skip) * 8 / d
+}
+
+// ping notes one of the agent's ping probes: they come one right after
+// another, so the gap between two is its round trip.
+func (m *speedMeter) ping() {
+	if m == nil {
+		return
+	}
+	m.mu.Lock()
+	now := time.Now()
+	if !m.pingAt.IsZero() {
+		if ms := float64(now.Sub(m.pingAt).Microseconds()) / 1000; m.pingMs == 0 || ms < m.pingMs {
+			m.pingMs = ms
+		}
+	}
+	m.pingAt = now
+	m.mu.Unlock()
+}
+
+func (m *speedMeter) add(up bool, n int) {
+	if m == nil || n <= 0 {
+		return
+	}
+	m.mu.Lock()
+	if up {
+		m.phase = "up"
+		m.up.add(n)
+	} else {
+		m.phase = "down"
+		m.down.add(n)
+	}
+	m.mu.Unlock()
+}
+
+// result is the test as counted so far; false with nothing measured yet.
+func (m *speedMeter) result() (proto.SysSpeedResult, bool) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	res := proto.SysSpeedResult{PingMs: m.pingMs, DownBps: m.down.bps(), UpBps: m.up.bps(), Partial: true}
+	return res, res.DownBps > 0
+}
+
+// meterWriter counts what it passes on; a nil meter counts nothing.
+type meterWriter struct {
+	w  io.Writer
+	m  *speedMeter
+	up bool
+}
+
+func (c meterWriter) Write(p []byte) (int, error) {
+	n, err := c.w.Write(p)
+	c.m.add(c.up, n)
+	return n, err
+}
+
+// speedMeters holds the meter of each agent under test.
+type speedMeters struct {
+	mu sync.Mutex
+	m  map[string]*speedMeter
+}
+
+func (c *speedMeters) start(agentID string) *speedMeter {
+	m := &speedMeter{start: time.Now(), phase: "ping"}
+	c.mu.Lock()
+	if c.m == nil {
+		c.m = map[string]*speedMeter{}
+	}
+	c.m[agentID] = m
+	c.mu.Unlock()
+	return m
+}
+
+func (c *speedMeters) get(agentID string) *speedMeter {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	return c.m[agentID]
+}
+
+// stop forgets the agent's meter if it is still m.
+func (c *speedMeters) stop(agentID string, m *speedMeter) {
+	c.mu.Lock()
+	if c.m[agentID] == m {
+		delete(c.m, agentID)
+	}
+	c.mu.Unlock()
+}
+
+// GET /api/panel/agents/{id}/speed/progress - the bytes counted so far in the
+// agent's running speed test, for the page to turn into a live rate. An empty
+// phase means no test is running.
+func (s *Server) handleSpeedProgress(w http.ResponseWriter, r *http.Request) {
+	var out struct {
+		Phase string `json:"phase"`
+		Down  int64  `json:"down"`
+		Up    int64  `json:"up"`
+		Ms    int64  `json:"ms"` // since the test began, by the server's clock
+	}
+	if m := s.meters.get(r.PathValue("id")); m != nil {
+		m.mu.Lock()
+		out.Phase, out.Down, out.Up = m.phase, m.down.n, m.up.n
+		out.Ms = time.Since(m.start).Milliseconds()
+		m.mu.Unlock()
+	}
+	w.Header().Set("Cache-Control", "no-store")
+	writeJSON(w, out)
+}
+
+// speedBlock is one chunk of incompressible bytes, made once and sent over and
+// over, so a speed test costs the server no CPU beyond the copy.
+var speedBlock = sync.OnceValue(func() []byte {
+	b := make([]byte, 64<<10)
+	rand.Read(b)
+	return b
+})
+
+func speedStreamHeaders(w http.ResponseWriter) {
+	w.Header().Set("Content-Type", "application/octet-stream")
+	w.Header().Set("Cache-Control", "no-store")
+	// Keep a proxy in front from buffering or compressing the stream.
+	w.Header().Set("X-Accel-Buffering", "no")
+}
+
+// GET /api/agent/speed/down?bytes=N - stream N bytes (default: as much as fits
+// in the time window) for the agent to time. bytes=0 is the ping probe.
+func (s *Server) handleSpeedDown(w http.ResponseWriter, r *http.Request) {
+	a := s.authenticateAgent(r)
+	if a == nil {
+		http.Error(w, "unauthorized", http.StatusUnauthorized)
+		return
+	}
+	m := s.meters.get(a.ID)
+	left := speedDownCap
+	if v := r.URL.Query().Get("bytes"); v != "" {
+		if n, err := strconv.Atoi(v); err == nil && n >= 0 && n < left {
+			left = n
+		}
+	}
+	if left == 0 {
+		m.ping()
+	}
+	speedStreamHeaders(w)
+	block := speedBlock()
+	deadline := time.Now().Add(speedDownFor)
+	for left > 0 && time.Now().Before(deadline) && r.Context().Err() == nil {
+		chunk := block
+		if len(chunk) > left {
+			chunk = chunk[:left]
+		}
+		n, err := w.Write(chunk)
+		if err != nil {
+			return
+		}
+		m.add(false, n)
+		left -= n
+	}
+}
+
+// POST /api/agent/speed/up - swallow the agent's upload.
+func (s *Server) handleSpeedUp(w http.ResponseWriter, r *http.Request) {
+	a := s.authenticateAgent(r)
+	if a == nil {
+		http.Error(w, "unauthorized", http.StatusUnauthorized)
+		return
+	}
+	sink := meterWriter{w: io.Discard, m: s.meters.get(a.ID), up: true}
+	_, _ = io.Copy(sink, http.MaxBytesReader(w, r.Body, speedUpCap))
+	w.WriteHeader(http.StatusNoContent)
+}
+
+// speedRelay joins the agent's speed test streams to the browser's, so the
+// bytes travel browser - panel - client. Both pipes are unbuffered: a slow
+// reader holds its writer back, and the rate is that of the whole path.
+type speedRelay struct {
+	downR *io.PipeReader // browser -> agent
+	downW *io.PipeWriter
+	upR   *io.PipeReader // agent -> browser
+	upW   *io.PipeWriter
+}
+
+func (rl *speedRelay) close() {
+	rl.downR.CloseWithError(io.ErrClosedPipe)
+	rl.downW.CloseWithError(io.ErrClosedPipe)
+	rl.upR.CloseWithError(io.ErrClosedPipe)
+	rl.upW.CloseWithError(io.ErrClosedPipe)
+}
+
+// speedRelays holds the relay of each agent under test, one per agent.
+type speedRelays struct {
+	mu sync.Mutex
+	m  map[string]*speedRelay
+}
+
+// open starts a fresh relay for the agent, ending the one it had.
+func (c *speedRelays) open(agentID string) {
+	rl := &speedRelay{}
+	rl.downR, rl.downW = io.Pipe()
+	rl.upR, rl.upW = io.Pipe()
+	c.mu.Lock()
+	if c.m == nil {
+		c.m = map[string]*speedRelay{}
+	}
+	old := c.m[agentID]
+	c.m[agentID] = rl
+	c.mu.Unlock()
+	if old != nil {
+		old.close()
+	}
+}
+
+func (c *speedRelays) get(agentID string) *speedRelay {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	return c.m[agentID]
+}
+
+// drop ends the agent's relay; with rl given, only if it is still that one.
+func (c *speedRelays) drop(agentID string, rl *speedRelay) {
+	c.mu.Lock()
+	cur := c.m[agentID]
+	if cur != nil && (rl == nil || rl == cur) {
+		delete(c.m, agentID)
+	} else {
+		cur = nil
+	}
+	c.mu.Unlock()
+	if cur != nil {
+		cur.close()
+	}
+}
+
+// GET /api/panel/ping - an empty answer for the browser to time.
+func (s *Server) handlePanelPing(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Cache-Control", "no-store")
+	w.WriteHeader(http.StatusNoContent)
+}
+
+// POST /api/panel/agents/{id}/speed/relay - open the relay of a speed test
+// that runs through the browser. The test itself ends it.
+func (s *Server) handleSpeedRelayOpen(w http.ResponseWriter, r *http.Request) {
+	id, ok := s.onlineAgent(w, r)
+	if !ok {
+		return
+	}
+	s.relays.open(id)
+	writeJSON(w, proto.TaskResult{OK: true})
+}
+
+// POST /api/panel/agents/{id}/speed/down - a piece of the browser's upload,
+// passed on to the agent. 204 asks for the next piece, 200 says the agent has
+// stopped reading.
+func (s *Server) handleSpeedRelayFeed(w http.ResponseWriter, r *http.Request) {
+	body := http.MaxBytesReader(w, r.Body, speedUpCap)
+	rl := s.relays.get(r.PathValue("id"))
+	if rl != nil {
+		if _, err := io.Copy(rl.downW, body); err == nil {
+			w.WriteHeader(http.StatusNoContent)
+			return
+		}
+	}
+	// Take the rest of the piece before answering: an answer sent over an
+	// unread body makes Go drop the connection, which a proxy in front turns
+	// into a 502.
+	_, _ = io.Copy(io.Discard, body)
+	w.Header().Set("Cache-Control", "no-store")
+	_, _ = io.WriteString(w, "done")
+}
+
+// GET /api/panel/agents/{id}/speed/up - the agent's upload, for the browser to
+// time. Ends when the agent is done sending.
+func (s *Server) handleSpeedRelayDrain(w http.ResponseWriter, r *http.Request) {
+	id := r.PathValue("id")
+	rl := s.relays.get(id)
+	if rl == nil {
+		http.Error(w, "gone", http.StatusGone)
+		return
+	}
+	speedStreamHeaders(w)
+	_, _ = io.Copy(meterWriter{w: w, m: s.meters.get(id), up: true}, rl.upR)
+	// The browser may have left: don't let the agent keep sending to nobody.
+	rl.upR.CloseWithError(io.ErrClosedPipe)
+}
+
+// GET /api/agent/speed/relay/down - what the browser uploads, for the agent to
+// time.
+func (s *Server) handleSpeedRelayDown(w http.ResponseWriter, r *http.Request) {
+	a := s.authenticateAgent(r)
+	if a == nil {
+		http.Error(w, "unauthorized", http.StatusUnauthorized)
+		return
+	}
+	rl := s.relays.get(a.ID)
+	if rl == nil {
+		http.NotFound(w, r)
+		return
+	}
+	speedStreamHeaders(w)
+	// The agent waits on the headers, the browser may not have sent a byte yet.
+	_ = http.NewResponseController(w).Flush()
+	_, _ = io.Copy(meterWriter{w: w, m: s.meters.get(a.ID)}, rl.downR)
+	// The agent hung up at the end of its window: stop the browser's upload.
+	rl.downR.CloseWithError(io.ErrClosedPipe)
+}
+
+// POST /api/agent/speed/relay/up - the agent's upload, passed on to the browser.
+func (s *Server) handleSpeedRelayUp(w http.ResponseWriter, r *http.Request) {
+	a := s.authenticateAgent(r)
+	if a == nil {
+		http.Error(w, "unauthorized", http.StatusUnauthorized)
+		return
+	}
+	rl := s.relays.get(a.ID)
+	if rl == nil {
+		http.NotFound(w, r)
+		return
+	}
+	body := http.MaxBytesReader(w, r.Body, speedUpCap)
+	// A proxy in front may hand over the whole upload at once: pass on only
+	// what the browser takes in the window, or the agent would wait for the
+	// rest to trickle through a slower link.
+	t := time.AfterFunc(speedRelayUpFor, func() { rl.upW.Close() })
+	_, _ = io.Copy(rl.upW, body)
+	t.Stop()
+	rl.upW.Close()
+	_, _ = io.Copy(io.Discard, body)
+	w.WriteHeader(http.StatusNoContent)
+}
@@ -1,9 +1,18 @@
 package server

 import (
+	"context"
 	"encoding/json"
+	"io"
 	"log"
+	"net"
 	"net/http"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/coder/websocket"
+	"github.com/coder/websocket/wsjson"

 	"github.com/x-grk/longpolling-remote-access/internal/proto"
 )
@@ -12,7 +21,10 @@ import (
 // same transport the agent uses), so it works through any reverse proxy without
 // WebSocket upgrade support.

-// POST /api/panel/term/{agentID}/open — create a terminal session.
+// POST /api/panel/term/{agentID}/open - create a terminal session: a shell
+// on the agent, or with {"ssh": {...}} in the body a shell the agent opens
+// by SSH on another host. {"dir": "/path"} starts the shell in that folder
+// (an older agent, or a folder not there: at home).
 func (s *Server) handlePanelOpen(w http.ResponseWriter, r *http.Request) {
 	agentID := r.PathValue("agentID")
 	agent, err := s.db.GetAgent(agentID)
@@ -21,14 +33,50 @@ func (s *Server) handlePanelOpen(w http.ResponseWriter, r *http.Request) {
 		http.NotFound(w, r)
 		return
 	}
-	sess := s.hub.CreateSession(agentID, agent.LoginUser)
+	var body struct {
+		SSH *proto.SSHTarget `json:"ssh"`
+		Dir string           `json:"dir"`
+	}
+	if r.ContentLength != 0 {
+		if err := json.NewDecoder(http.MaxBytesReader(w, r.Body, 64<<10)).Decode(&body); err != nil && err != io.EOF {
+			http.Error(w, "bad request", http.StatusBadRequest)
+			return
+		}
+	}
+	if err := s.fillSaved(s.currentAdmin(r).ID, body.SSH); err != nil {
+		writeJSON(w, map[string]any{"error": err.Error()})
+		return
+	}
+	if t := body.SSH; t != nil {
+		t.Host, t.User = strings.TrimSpace(t.Host), strings.TrimSpace(t.User)
+		if t.Port == 0 {
+			t.Port = 22
+		}
+		if t.Host == "" || t.User == "" || t.Port < 1 || t.Port > 65535 || strings.ContainsAny(t.Host+t.User, " \t\r\n/") {
+			w.Header().Set("Content-Type", "application/json")
+			w.WriteHeader(http.StatusBadRequest)
+			_ = json.NewEncoder(w).Encode(map[string]string{"error": "нужны хост, порт 1-65535 и пользователь"})
+			return
+		}
+		sess := s.hub.CreateSSH(agentID, *t)
+		if admin := s.currentAdmin(r); admin != nil {
+			s.db.Audit(admin.ID, agentID, "open_ssh:"+t.User+"@"+net.JoinHostPort(t.Host, strconv.Itoa(t.Port)))
+		}
+		writeJSON(w, map[string]string{"session_id": sess.ID})
+		return
+	}
+	dir := body.Dir
+	if !strings.HasPrefix(dir, "/") || strings.ContainsAny(dir, "\x00\r\n") || len(dir) > 4096 {
+		dir = ""
+	}
+	sess := s.hub.CreateSession(agentID, agent.LoginUser, dir)
 	if admin := s.currentAdmin(r); admin != nil {
 		s.db.Audit(admin.ID, agentID, "open_terminal:"+agent.TerminalUser())
 	}
 	writeJSON(w, map[string]string{"session_id": sess.ID})
 }

-// GET /api/panel/term/{sid}/out — long-poll for PTY output.
+// GET /api/panel/term/{sid}/out - long-poll for PTY output.
 func (s *Server) handlePanelOut(w http.ResponseWriter, r *http.Request) {
 	sess := s.hub.Session(r.PathValue("sid"))
 	if sess == nil {
@@ -49,9 +97,12 @@ type panelInMsg struct {
 	D    string `json:"d,omitempty"`
 	Cols uint16 `json:"cols,omitempty"`
 	Rows uint16 `json:"rows,omitempty"`
+	// Seq numbers the messages of a session from 1; 0 from a page that
+	// predates it.
+	Seq uint64 `json:"seq,omitempty"`
 }

-// POST /api/panel/term/{sid}/in — send keystrokes/resize to the agent PTY.
+// POST /api/panel/term/{sid}/in - send keystrokes/resize to the agent PTY.
 func (s *Server) handlePanelIn(w http.ResponseWriter, r *http.Request) {
 	sess := s.hub.Session(r.PathValue("sid"))
 	if sess == nil {
@@ -63,16 +114,91 @@ func (s *Server) handlePanelIn(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, "bad request", http.StatusBadRequest)
 		return
 	}
+	takePanelIn(sess, m)
+	w.WriteHeader(http.StatusNoContent)
+}
+
+// takePanelIn passes the browser's keystrokes or resize on to the agent; a
+// repeat of one already taken is dropped.
+func takePanelIn(sess *Session, m panelInMsg) {
+	if m.Seq > 0 && !sess.TakeSeq(m.Seq) {
+		return
+	}
 	switch m.T {
 	case "i":
 		sess.PushIn(proto.InFrame{Type: proto.FrameStdin, Data: m.D})
 	case "r":
 		sess.PushIn(proto.InFrame{Type: proto.FrameResize, Cols: m.Cols, Rows: m.Rows})
 	}
-	w.WriteHeader(http.StatusNoContent)
 }

-// POST /api/panel/term/{sid}/close — tear the session down.
+// GET /api/panel/term/{sid}/ws - the browser's terminal on a WebSocket: what
+// the "in" requests send comes as messages, and output goes out as soon as
+// it is there, in the "out" answers' shape. The page falls back to those
+// requests when this does not connect.
+func (s *Server) handlePanelTermWS(w http.ResponseWriter, r *http.Request) {
+	sess := s.hub.Session(r.PathValue("sid"))
+	if sess == nil {
+		http.Error(w, "closed", http.StatusGone)
+		return
+	}
+	// Terminal text packs well: deflate with the context kept between
+	// messages, for the larger ones (screens of output, not keystrokes).
+	conn, err := websocket.Accept(w, r, &websocket.AcceptOptions{CompressionMode: websocket.CompressionContextTakeover, CompressionThreshold: 256})
+	if err != nil {
+		return
+	}
+	conn.SetReadLimit(1 << 20)
+	defer conn.CloseNow()
+	ctx, cancel := context.WithCancel(r.Context())
+	defer cancel()
+	go func() {
+		defer cancel()
+		for ctx.Err() == nil {
+			msgs, alive := sess.PollOutUntil(ctx.Done(), pollHold)
+			if ctx.Err() != nil {
+				return
+			}
+			out := map[string]any{"frames": msgs}
+			if !alive {
+				out = map[string]any{"closed": true}
+			}
+			wctx, wcancel := context.WithTimeout(ctx, 30*time.Second)
+			err := wsjson.Write(wctx, conn, out)
+			wcancel()
+			if err != nil || !alive {
+				return
+			}
+		}
+	}()
+	go func() {
+		t := time.NewTicker(wsPing)
+		defer t.Stop()
+		for {
+			select {
+			case <-ctx.Done():
+				return
+			case <-t.C:
+				pctx, pcancel := context.WithTimeout(ctx, 15*time.Second)
+				err := conn.Ping(pctx)
+				pcancel()
+				if err != nil {
+					cancel()
+					return
+				}
+			}
+		}
+	}()
+	for {
+		var m panelInMsg
+		if err := wsjson.Read(ctx, conn, &m); err != nil {
+			return
+		}
+		takePanelIn(sess, m)
+	}
+}
+
+// POST /api/panel/term/{sid}/close - tear the session down.
 func (s *Server) handlePanelClose(w http.ResponseWriter, r *http.Request) {
 	s.hub.CloseSession(r.PathValue("sid"))
 	w.WriteHeader(http.StatusNoContent)
@@ -7,8 +7,9 @@ import (
 	"github.com/x-grk/longpolling-remote-access/internal/proto"
 )

-// Hub is the in-memory broker between agents (HTTP long-polling) and the panel.
-// It carries three kinds of work to an agent through its single control poll:
+// Hub is the in-memory broker between agents (on a WebSocket, or by HTTP
+// long polls) and the panel. It carries three kinds of work to an agent
+// through its single control channel:
 // terminal sessions, port-forward streams, and one-shot tasks (file manager).
 // Nothing here is persisted.
 type Hub struct {
@@ -22,6 +23,12 @@ type Hub struct {

 	sessions map[string]*Session
 	tasks    map[string]*taskEntry
+
+	// Presence: control polls held open right now per agent, and when each
+	// agent's last one ended. started is when this hub came up.
+	polls    map[string]int
+	lastPoll map[string]time.Time
+	started  time.Time
 }

 // taskEntry is a pending one-shot task awaiting the agent's result.
@@ -31,7 +38,7 @@ type taskEntry struct {
 }

 // Session is one live byte stream between the panel and an agent (a PTY terminal
-// or a raw TCP forward — the hub treats both identically).
+// or a raw TCP forward - the hub treats both identically).
 type Session struct {
 	ID      string
 	AgentID string
@@ -39,6 +46,7 @@ type Session struct {
 	mu       sync.Mutex
 	inBuf    []proto.InFrame
 	inSignal chan struct{} // size-1; pulsed when inBuf gains data
+	inSeq    uint64        // number of the last browser message taken

 	out chan proto.OutMessage // agent -> panel

@@ -52,6 +60,9 @@ func NewHub() *Hub {
 		ctrlWaiters: map[string]chan struct{}{},
 		sessions:    map[string]*Session{},
 		tasks:       map[string]*taskEntry{},
+		polls:       map[string]int{},
+		lastPoll:    map[string]time.Time{},
+		started:     time.Now(),
 	}
 }

@@ -84,9 +95,16 @@ func (h *Hub) newSession(agentID string) *Session {

 // CreateSession registers a terminal session and queues it for the agent. user
 // is the OS user to run the shell as ("" = the agent's own user).
-func (h *Hub) CreateSession(agentID, user string) *Session {
+func (h *Hub) CreateSession(agentID, user, dir string) *Session {
 	s := h.newSession(agentID)
-	h.enqueueJob(agentID, proto.ControlMessage{Type: proto.CtrlOpenTerminal, SessionID: s.ID, User: user})
+	h.enqueueJob(agentID, proto.ControlMessage{Type: proto.CtrlOpenTerminal, SessionID: s.ID, User: user, Dir: dir})
+	return s
+}
+
+// CreateSSH registers a terminal session the agent opens by SSH to t.
+func (h *Hub) CreateSSH(agentID string, t proto.SSHTarget) *Session {
+	s := h.newSession(agentID)
+	h.enqueueJob(agentID, proto.ControlMessage{Type: proto.CtrlOpenSSH, SessionID: s.ID, SSH: &t})
 	return s
 }

@@ -97,9 +115,56 @@ func (h *Hub) CreateForward(agentID string, port int) *Session {
 	return s
 }

-// WaitControl blocks until a job is queued for agentID or timeout elapses.
-func (h *Hub) WaitControl(agentID string, timeout time.Duration) proto.ControlMessage {
-	deadline := time.After(timeout)
+// pollGrace is how long an agent stays online between two control polls: it
+// re-polls at once, so this only has to cover a slow round trip or one retry.
+const pollGrace = 10 * time.Second
+
+// Online reports whether the agent is connected: it holds a control poll open
+// or has just finished one. ok is false while that cannot be told yet (right
+// after a start, before agents had time to come back).
+func (h *Hub) Online(agentID string) (online, ok bool) {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	if h.polls[agentID] > 0 {
+		return true, true
+	}
+	if t, seen := h.lastPoll[agentID]; seen {
+		return time.Since(t) < pollGrace, true
+	}
+	return false, time.Since(h.started) > pollHold+pollGrace
+}
+
+// Forget drops what the hub keeps about a deleted agent.
+func (h *Hub) Forget(agentID string) {
+	h.mu.Lock()
+	delete(h.jobs, agentID)
+	delete(h.ctrlWaiters, agentID)
+	delete(h.lastPoll, agentID)
+	h.mu.Unlock()
+}
+
+// WaitControl blocks until a job is queued for agentID, the timeout elapses
+// or the agent hangs up (done). The agent counts as online meanwhile.
+func (h *Hub) WaitControl(done <-chan struct{}, agentID string, timeout time.Duration) proto.ControlMessage {
+	h.mu.Lock()
+	h.polls[agentID]++
+	h.mu.Unlock()
+	defer func() {
+		h.mu.Lock()
+		if h.polls[agentID]--; h.polls[agentID] <= 0 {
+			delete(h.polls, agentID)
+		}
+		// A poll cut off by the agent is not a sign of life.
+		select {
+		case <-done:
+		default:
+			h.lastPoll[agentID] = time.Now()
+		}
+		h.mu.Unlock()
+	}()
+	t := time.NewTimer(timeout)
+	defer t.Stop()
+	deadline := t.C
 	for {
 		h.mu.Lock()
 		if q := h.jobs[agentID]; len(q) > 0 {
@@ -119,6 +184,9 @@ func (h *Hub) WaitControl(agentID string, timeout time.Duration) proto.ControlMe
 		case <-w:
 		case <-deadline:
 			return proto.ControlMessage{Type: proto.CtrlIdle}
+		case <-done:
+			// The job, if one comes, stays queued for the next poll.
+			return proto.ControlMessage{Type: proto.CtrlIdle}
 		}
 	}
 }
@@ -191,6 +259,19 @@ func (s *Session) close() { s.closeOnce.Do(func() { close(s.closed) }) }
 // Done returns a channel closed when the session ends.
 func (s *Session) Done() <-chan struct{} { return s.closed }

+// TakeSeq reports whether the browser message numbered seq is new, and takes
+// note of it. The browser sends them one at a time in rising order and sends
+// one again when it got no answer, so a number not above the last is a repeat.
+func (s *Session) TakeSeq(seq uint64) bool {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if seq <= s.inSeq {
+		return false
+	}
+	s.inSeq = seq
+	return true
+}
+
 // PushIn appends a downstream frame (panel -> agent) and wakes the agent poll.
 func (s *Session) PushIn(f proto.InFrame) {
 	s.mu.Lock()
@@ -202,6 +283,18 @@ func (s *Session) PushIn(f proto.InFrame) {
 	}
 }

+// Unpoll puts frames taken by PollIn back in front, for frames that could not
+// be delivered.
+func (s *Session) Unpoll(frames []proto.InFrame) {
+	s.mu.Lock()
+	s.inBuf = append(append([]proto.InFrame{}, frames...), s.inBuf...)
+	s.mu.Unlock()
+	select {
+	case s.inSignal <- struct{}{}:
+	default:
+	}
+}
+
 // PollIn drains queued downstream frames, blocking up to timeout for the first.
 func (s *Session) PollIn(timeout time.Duration) ([]proto.InFrame, bool) {
 	deadline := time.After(timeout)
@@ -239,10 +332,18 @@ func (s *Session) Out() <-chan proto.OutMessage { return s.out }

 // PollOut drains queued upstream messages, blocking up to timeout for the first.
 func (s *Session) PollOut(timeout time.Duration) ([]proto.OutMessage, bool) {
+	return s.PollOutUntil(nil, timeout)
+}
+
+// PollOutUntil is PollOut that also gives up when done closes, taking
+// nothing: for a reader that has gone, so no output is lost on it.
+func (s *Session) PollOutUntil(done <-chan struct{}, timeout time.Duration) ([]proto.OutMessage, bool) {
 	var batch []proto.OutMessage
 	select {
 	case m := <-s.out:
 		batch = append(batch, m)
+	case <-done:
+		return nil, true
 	case <-time.After(timeout):
 		return nil, true
 	case <-s.closed:
@@ -0,0 +1,302 @@
+package server
+
+import (
+	"bytes"
+	"context"
+	"encoding/base64"
+	"encoding/json"
+	"errors"
+	"io"
+	"mime/multipart"
+	"net/http"
+	"net/textproto"
+	"net/url"
+	"regexp"
+	"strconv"
+	"strings"
+	"time"
+)
+
+// Pictures for the assistant: the model asks for one in its answer - a
+// ```image block, a new picture or an edit of a photo - and the panel makes
+// it through the Vertex API (https://s2.x-grk.com/api/vertex/docs). The
+// work is a job there: it is put, then asked about until it is done. The
+// API key is the admins', set in Настройки and never sent to the browser.
+
+const (
+	cfgImageKey = "ai_image_key"
+	cfgImageURL = "ai_image_url" // not in the settings: the service's address, for tests
+
+	// DefaultImageURL is where the Vertex API is.
+	DefaultImageURL = "https://s2.x-grk.com"
+
+	imageMaxBytes = 20 << 20 // what the service takes of one photo
+)
+
+// imageConf is the service's address and the key (none: pictures are off).
+func (s *Server) imageConf() (base, key string) {
+	base, _ = s.db.GetConfig(cfgImageURL)
+	if base == "" {
+		base = DefaultImageURL
+	}
+	key, _ = s.db.GetConfig(cfgImageKey)
+	return strings.TrimRight(base, "/"), strings.TrimSpace(key)
+}
+
+// imagePrompt tells the model it can make pictures, and how - when there
+// is a key.
+func (s *Server) imagePrompt() string {
+	if _, key := s.imageConf(); key == "" {
+		return ""
+	}
+	return "\n\nКартинки. Ты умеешь рисовать и править фото: сам, по смыслу разговора, без просьбы «вызови инструмент» и без лишних вопросов, " +
+		"когда пользователь просит нарисовать, сгенерировать, изобразить, сделать картинку, арт, логотип, обои, иллюстрацию " +
+		"или изменить, дорисовать, убрать, заменить что-то на фото.\n" +
+		"```image\nописание картинки\n``` - создать новую. Опиши сцену, стиль, свет, детали; язык описания любой.\n" +
+		"```image edit\nчто изменить на фото\n``` - править фото пользователя: то, что приложено к его сообщению " +
+		"(приложено несколько - после edit назови файл: ```image edit имя.jpg```); фото нет - последнюю созданную картинку.\n" +
+		"В первой строке блока можно задать формат: 1:1 (по умолчанию), 16:9, 9:16, 3:2, 2:3, 4:3, 3:4, auto - и качество: " +
+		"fast (по умолчанию, 1 кредит), artist (5, лучше), 0.2plus (10, лучшее); повышай качество, только если пользователь просит. " +
+		"Например: ```image 16:9 artist```.\n" +
+		"Сервис по умолчанию сам улучшает описание (дописывает детали и стиль) - это хорошо для короткого запроса. " +
+		"Если пользователь дал готовое, точное описание (промпт целиком, логотип «ровно как сказано», текст на картинке, строгая композиция) " +
+		"или просит ничего не добавлять - добавь noenhance: ```image noenhance 3:2```. Для правки фото это не применяется.\n" +
+		"Картинку покажет сама панель: ссылку в ответ не вставляй, скажи коротко, что получилось, и предложи поправить. " +
+		"Делается она до пары минут. Одно действие за ответ."
+}
+
+// imageError says in Russian what an error code of the service means.
+func imageError(code, msg string) string {
+	switch code {
+	case "unauthorized":
+		return "сервис не принял API-ключ - проверьте его в Настройки › ИИ-ассистент › Генерация изображений"
+	case "banned":
+		return "аккаунт сервиса картинок заблокирован"
+	case "insufficient_credits":
+		return "на аккаунте сервиса картинок не хватает кредитов"
+	case "daily_limit":
+		return "исчерпан дневной лимит картинок"
+	case "job_busy":
+		return "уже делается другая картинка - дождитесь её"
+	case "invalid_prompt":
+		return "сервис не принял описание (пустое или длиннее 4000 символов)"
+	case "invalid_image":
+		return "сервис не принял фото (нужен png, jpg или webp)"
+	case "image_too_large":
+		return "фото больше 20 МБ"
+	case "tokens_exhausted":
+		return "сервис картинок перегружен - попробуйте позже"
+	case "generation_failed", "edit_failed":
+		return "сервис не справился с картинкой (кредиты вернутся)"
+	case "source_missing":
+		return "исходное фото потерялось на сервисе - загрузите его заново"
+	}
+	if msg == "" {
+		msg = "сервис картинок ответил ошибкой"
+	}
+	return msg
+}
+
+var imageClient = &http.Client{Timeout: 90 * time.Second}
+
+// imageCall sends the request to the service with the key and reads its
+// JSON; an error is words for the user.
+func imageCall(ctx context.Context, req *http.Request, key string, v any) error {
+	req = req.WithContext(ctx)
+	req.Header.Set("Authorization", "Bearer "+key)
+	req.Header.Set("Accept", "application/json")
+	resp, err := imageClient.Do(req)
+	if err != nil {
+		return errors.New("сервис картинок не отвечает: " + err.Error())
+	}
+	defer resp.Body.Close()
+	b, _ := io.ReadAll(io.LimitReader(resp.Body, 1<<20))
+	var e struct {
+		OK        *bool  `json:"ok"`
+		ErrorCode string `json:"error_code"`
+		Error     string `json:"error"`
+	}
+	if json.Unmarshal(b, &e) != nil {
+		return errors.New("сервис картинок ответил " + resp.Status)
+	}
+	if (e.OK != nil && !*e.OK) || resp.StatusCode/100 != 2 {
+		return errors.New(imageError(e.ErrorCode, e.Error))
+	}
+	return json.Unmarshal(b, v)
+}
+
+var (
+	imageRatios = map[string]bool{"1:1": true, "16:9": true, "9:16": true, "3:2": true, "2:3": true, "4:3": true, "3:4": true, "auto": true}
+	imageModels = map[string]bool{"fast": true, "artist": true, "0.2plus": true}
+	imageJobRe  = regexp.MustCompile(`^[A-Za-z0-9_-]{1,64}$`)
+	imageExt    = map[string]string{"image/png": "png", "image/jpeg": "jpg", "image/jpg": "jpg", "image/webp": "webp"}
+)
+
+// POST /api/panel/ai/image - {mode: generate|edit, prompt, model, ratio,
+// image: {mime, data (base64)} | image_url}: puts the job, answers its id.
+func (s *Server) handleAIImage(w http.ResponseWriter, r *http.Request) {
+	fail := func(msg string) { writeJSON(w, map[string]any{"ok": false, "error": msg}) }
+	if !s.aiOn(s.currentAdmin(r).ID) {
+		fail("ассистент выключен в профиле")
+		return
+	}
+	base, key := s.imageConf()
+	if key == "" {
+		fail("не задан API-ключ сервиса картинок (Настройки › ИИ-ассистент › Генерация изображений)")
+		return
+	}
+	var in struct {
+		Mode     string `json:"mode"`
+		Prompt   string `json:"prompt"`
+		Model    string `json:"model"`
+		Ratio    string `json:"ratio"`
+		Enhance  *bool  `json:"enhance"` // the service improves the description; on unless false
+		ImageURL string `json:"image_url"`
+		Image    struct {
+			MIME string `json:"mime"`
+			Data string `json:"data"`
+		} `json:"image"`
+	}
+	if err := json.NewDecoder(http.MaxBytesReader(w, r.Body, 32<<20)).Decode(&in); err != nil {
+		fail("плохой запрос")
+		return
+	}
+	in.Prompt = strings.TrimSpace(in.Prompt)
+	if in.Prompt == "" {
+		fail("пустое описание картинки")
+		return
+	}
+	if r := []rune(in.Prompt); len(r) > 4000 {
+		in.Prompt = string(r[:4000])
+	}
+	var job struct {
+		JobID string `json:"job_id"`
+		Cost  int    `json:"cost"`
+	}
+	ctx := r.Context()
+	if in.Mode != "edit" {
+		if !imageModels[in.Model] {
+			in.Model = "fast"
+		}
+		if !imageRatios[in.Ratio] {
+			in.Ratio = "1:1"
+		}
+		enhance := in.Enhance == nil || *in.Enhance
+		b, _ := json.Marshal(map[string]any{"prompt": in.Prompt, "model": in.Model, "ratio": in.Ratio, "enhance": enhance})
+		req, _ := http.NewRequest(http.MethodPost, base+"/api/vertex/v1/generate", bytes.NewReader(b))
+		req.Header.Set("Content-Type", "application/json")
+		if err := imageCall(ctx, req, key, &job); err != nil {
+			fail(err.Error())
+			return
+		}
+	} else {
+		mime, data, err := s.imageSource(ctx, base, in.Image.MIME, in.Image.Data, in.ImageURL)
+		if err != nil {
+			fail(err.Error())
+			return
+		}
+		var body bytes.Buffer
+		mw := multipart.NewWriter(&body)
+		h := textproto.MIMEHeader{}
+		h.Set("Content-Disposition", `form-data; name="image"; filename="photo.`+imageExt[mime]+`"`)
+		h.Set("Content-Type", mime)
+		part, _ := mw.CreatePart(h)
+		_, _ = part.Write(data)
+		_ = mw.WriteField("prompt", in.Prompt)
+		_ = mw.Close()
+		req, _ := http.NewRequest(http.MethodPost, base+"/api/vertex/v1/edit", &body)
+		req.Header.Set("Content-Type", mw.FormDataContentType())
+		if err := imageCall(ctx, req, key, &job); err != nil {
+			fail(err.Error())
+			return
+		}
+	}
+	if job.JobID == "" {
+		fail("сервис картинок не дал номер задачи")
+		return
+	}
+	writeJSON(w, map[string]any{"ok": true, "job_id": job.JobID, "cost": job.Cost})
+}
+
+// imageSource is the photo to edit: sent by the browser, or a picture made
+// before, taken from the service's own address (and from no other).
+func (s *Server) imageSource(ctx context.Context, base, mime, b64, picURL string) (string, []byte, error) {
+	if picURL != "" {
+		u, err := url.Parse(picURL)
+		bu, _ := url.Parse(base)
+		if err != nil || bu == nil || u.Host != bu.Host || (u.Scheme != "https" && u.Scheme != "http") {
+			return "", nil, errors.New("прежнюю картинку можно править только с сервиса картинок")
+		}
+		req, _ := http.NewRequestWithContext(ctx, http.MethodGet, u.String(), nil)
+		resp, err := imageClient.Do(req)
+		if err != nil || resp.StatusCode/100 != 2 {
+			if resp != nil {
+				resp.Body.Close()
+			}
+			return "", nil, errors.New("прежняя картинка больше не открывается")
+		}
+		defer resp.Body.Close()
+		data, _ := io.ReadAll(io.LimitReader(resp.Body, imageMaxBytes+1))
+		mime = strings.ToLower(strings.SplitN(resp.Header.Get("Content-Type"), ";", 2)[0])
+		if imageExt[mime] == "" {
+			mime = "image/png"
+		}
+		return mime, data, nil
+	}
+	mime = strings.ToLower(mime)
+	if imageExt[mime] == "" {
+		return "", nil, errors.New("править можно png, jpg и webp")
+	}
+	data, err := base64.StdEncoding.DecodeString(b64)
+	if err != nil || len(data) == 0 {
+		return "", nil, errors.New("нет фото для правки: прикрепите его к сообщению")
+	}
+	if len(data) > imageMaxBytes {
+		return "", nil, errors.New("фото больше 20 МБ")
+	}
+	return mime, data, nil
+}
+
+// GET /api/panel/ai/image/{job}?wait=1..45 - the job's state, waiting up to
+// wait seconds for it to end.
+func (s *Server) handleAIImageJob(w http.ResponseWriter, r *http.Request) {
+	fail := func(msg string) { writeJSON(w, map[string]any{"ok": false, "error": msg}) }
+	if !s.aiOn(s.currentAdmin(r).ID) {
+		fail("ассистент выключен в профиле")
+		return
+	}
+	base, key := s.imageConf()
+	id := r.PathValue("job")
+	if key == "" || !imageJobRe.MatchString(id) {
+		fail("нет такой задачи")
+		return
+	}
+	wait, _ := strconv.Atoi(r.URL.Query().Get("wait"))
+	if wait < 0 {
+		wait = 0
+	}
+	if wait > 45 {
+		wait = 45
+	}
+	req, _ := http.NewRequest(http.MethodGet, base+"/api/vertex/v1/jobs/"+id+"?wait="+strconv.Itoa(wait), nil)
+	var st struct {
+		Status    string `json:"status"`
+		PhotoURL  string `json:"photo_url"`
+		Cost      int    `json:"cost"`
+		Balance   int    `json:"balance"`
+		ErrorCode string `json:"error_code"`
+		Error     string `json:"error"`
+	}
+	if err := imageCall(r.Context(), req, key, &st); err != nil {
+		fail(err.Error())
+		return
+	}
+	out := map[string]any{"ok": true, "status": st.Status}
+	switch st.Status {
+	case "done":
+		out["photo_url"], out["cost"], out["balance"] = st.PhotoURL, st.Cost, st.Balance
+	case "failed":
+		out["error"] = imageError(st.ErrorCode, st.Error)
+	}
+	writeJSON(w, out)
+}
@@ -0,0 +1,305 @@
+package server
+
+import (
+	"bytes"
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"strings"
+	"sync"
+	"testing"
+)
+
+// fakeVertex is the image service: it records what it was asked and answers
+// like the real one (a job to poll, a picture when done).
+type fakeVertex struct {
+	srv  *httptest.Server
+	mu   sync.Mutex
+	auth []string
+	gen  map[string]any
+	edit struct {
+		prompt string
+		image  []byte
+		name   string
+	}
+	polls  int
+	failAs string // an error_code the job ends with
+}
+
+func newFakeVertex(t *testing.T) *fakeVertex {
+	f := &fakeVertex{}
+	f.srv = httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		f.mu.Lock()
+		defer f.mu.Unlock()
+		f.auth = append(f.auth, r.Header.Get("Authorization"))
+		// The pictures are open by their address, as at the real service.
+		if r.URL.Path == "/uploads/userphoto/ai/t.png" {
+			w.Header().Set("Content-Type", "image/png")
+			_, _ = w.Write([]byte("\x89PNG-original"))
+			return
+		}
+		w.Header().Set("Content-Type", "application/json")
+		if r.Header.Get("Authorization") != "Bearer vx_good" {
+			w.WriteHeader(401)
+			fmt.Fprint(w, `{"ok":false,"error_code":"unauthorized","error":"Неверный ключ"}`)
+			return
+		}
+		switch {
+		case r.URL.Path == "/api/vertex/v1/generate":
+			_ = json.NewDecoder(r.Body).Decode(&f.gen)
+			w.WriteHeader(202)
+			fmt.Fprint(w, `{"ok":true,"job_id":"job_gen1","status":"queued","cost":5}`)
+		case r.URL.Path == "/api/vertex/v1/edit":
+			if err := r.ParseMultipartForm(32 << 20); err != nil {
+				w.WriteHeader(400)
+				fmt.Fprint(w, `{"ok":false,"error_code":"invalid_image","error":"нет фото"}`)
+				return
+			}
+			f.edit.prompt = r.FormValue("prompt")
+			file, hdr, err := r.FormFile("image")
+			if err == nil {
+				f.edit.image, _ = io.ReadAll(file)
+				f.edit.name = hdr.Filename
+			}
+			w.WriteHeader(202)
+			fmt.Fprint(w, `{"ok":true,"job_id":"job_edit1","status":"queued","cost":2}`)
+		case strings.HasPrefix(r.URL.Path, "/api/vertex/v1/jobs/"):
+			f.polls++
+			if f.failAs != "" {
+				fmt.Fprintf(w, `{"ok":true,"job_id":"x","status":"failed","error_code":%q,"error":"сбой"}`, f.failAs)
+				return
+			}
+			if f.polls < 2 {
+				fmt.Fprint(w, `{"ok":true,"job_id":"x","status":"running"}`)
+				return
+			}
+			fmt.Fprintf(w, `{"ok":true,"job_id":"x","status":"done","photo_url":"%s/uploads/userphoto/ai/t.png","cost":5,"balance":42}`, f.srv.URL)
+		default:
+			http.NotFound(w, r)
+		}
+	}))
+	t.Cleanup(f.srv.Close)
+	return f
+}
+
+// setImage points the panel at the fake service with a key.
+func setImage(t *testing.T, s *Server, f *fakeVertex, key string) {
+	t.Helper()
+	_ = s.db.SetConfig(cfgImageURL, f.srv.URL)
+	_ = s.db.SetConfig(cfgImageKey, key)
+}
+
+func apiCall(t *testing.T, s *Server, c *http.Cookie, method, path, body string) string {
+	t.Helper()
+	req := httptest.NewRequest(method, path, strings.NewReader(body))
+	req.AddCookie(c)
+	w := httptest.NewRecorder()
+	s.Handler().ServeHTTP(w, req)
+	return w.Body.String()
+}
+
+// A picture from nothing: the prompt, model and ratio go to the service with
+// the key; the job's progress and its picture come back, the key never.
+func TestImageGenerate(t *testing.T) {
+	s, c := newTestServer(t)
+	f := newFakeVertex(t)
+	setImage(t, s, f, "vx_good")
+	got := apiCall(t, s, c, "POST", "/api/panel/ai/image", `{"mode":"generate","prompt":"cat in space","model":"artist","ratio":"3:4"}`)
+	if !strings.Contains(got, `"ok":true`) || !strings.Contains(got, `"job_id":"job_gen1"`) || strings.Contains(got, "vx_good") {
+		t.Fatalf("create: %s", got)
+	}
+	if f.gen["prompt"] != "cat in space" || f.gen["model"] != "artist" || f.gen["ratio"] != "3:4" || f.gen["enhance"] != true {
+		t.Fatalf("what the service got: %v", f.gen)
+	}
+	if got := apiCall(t, s, c, "GET", "/api/panel/ai/image/job_gen1?wait=1", ""); !strings.Contains(got, `"status":"running"`) {
+		t.Fatalf("first poll: %s", got)
+	}
+	got = apiCall(t, s, c, "GET", "/api/panel/ai/image/job_gen1?wait=1", "")
+	if !strings.Contains(got, `"status":"done"`) || !strings.Contains(got, "/uploads/userphoto/ai/t.png") || !strings.Contains(got, `"balance":42`) || strings.Contains(got, "vx_good") {
+		t.Fatalf("done: %s", got)
+	}
+}
+
+// Unknown models and ratios are not sent on: the defaults go instead.
+func TestImageGenerateDefaults(t *testing.T) {
+	s, c := newTestServer(t)
+	f := newFakeVertex(t)
+	setImage(t, s, f, "vx_good")
+	apiCall(t, s, c, "POST", "/api/panel/ai/image", `{"mode":"generate","prompt":"x","model":"gpt","ratio":"7:1"}`)
+	if f.gen["model"] != "fast" || f.gen["ratio"] != "1:1" {
+		t.Fatalf("defaults: %v", f.gen)
+	}
+}
+
+// Editing sends the user's photo as a file with the instruction.
+func TestImageEditFromAttachedPhoto(t *testing.T) {
+	s, c := newTestServer(t)
+	f := newFakeVertex(t)
+	setImage(t, s, f, "vx_good")
+	photo := []byte("\xff\xd8\xffJPEGDATA")
+	b, _ := json.Marshal(map[string]any{"mode": "edit", "prompt": "сделай закат",
+		"image": map[string]string{"mime": "image/jpeg", "data": base64.StdEncoding.EncodeToString(photo)}})
+	got := apiCall(t, s, c, "POST", "/api/panel/ai/image", string(b))
+	if !strings.Contains(got, `"job_id":"job_edit1"`) {
+		t.Fatalf("edit: %s", got)
+	}
+	if f.edit.prompt != "сделай закат" || !bytes.Equal(f.edit.image, photo) || !strings.HasSuffix(f.edit.name, ".jpg") {
+		t.Fatalf("what the service got: %q %q %q", f.edit.prompt, f.edit.image, f.edit.name)
+	}
+	// A format the service does not take is told so, not sent.
+	b, _ = json.Marshal(map[string]any{"mode": "edit", "prompt": "x", "image": map[string]string{"mime": "image/gif", "data": "R0lG"}})
+	if got := apiCall(t, s, c, "POST", "/api/panel/ai/image", string(b)); !strings.Contains(got, `"ok":false`) || !strings.Contains(got, "png") {
+		t.Fatalf("gif: %s", got)
+	}
+}
+
+// A picture made before can be edited again: fetched from the service's own
+// address only - never from another.
+func TestImageEditFromEarlierPicture(t *testing.T) {
+	s, c := newTestServer(t)
+	f := newFakeVertex(t)
+	setImage(t, s, f, "vx_good")
+	b, _ := json.Marshal(map[string]any{"mode": "edit", "prompt": "темнее", "image_url": f.srv.URL + "/uploads/userphoto/ai/t.png"})
+	if got := apiCall(t, s, c, "POST", "/api/panel/ai/image", string(b)); !strings.Contains(got, `"ok":true`) {
+		t.Fatalf("by url: %s", got)
+	}
+	if !bytes.Equal(f.edit.image, []byte("\x89PNG-original")) || !strings.HasSuffix(f.edit.name, ".png") {
+		t.Fatalf("the picture sent: %q %q", f.edit.image, f.edit.name)
+	}
+	b, _ = json.Marshal(map[string]any{"mode": "edit", "prompt": "x", "image_url": "http://127.0.0.1:9/secret.png"})
+	if got := apiCall(t, s, c, "POST", "/api/panel/ai/image", string(b)); !strings.Contains(got, `"ok":false`) {
+		t.Fatalf("a foreign address was fetched: %s", got)
+	}
+}
+
+// What goes wrong is told in words: no key, a wrong key, the service's own
+// codes, a job that failed.
+func TestImageErrors(t *testing.T) {
+	s, c := newTestServer(t)
+	f := newFakeVertex(t)
+	if got := apiCall(t, s, c, "POST", "/api/panel/ai/image", `{"mode":"generate","prompt":"x"}`); !strings.Contains(got, "ключ") {
+		t.Fatalf("no key: %s", got)
+	}
+	setImage(t, s, f, "vx_bad")
+	if got := apiCall(t, s, c, "POST", "/api/panel/ai/image", `{"mode":"generate","prompt":"x"}`); !strings.Contains(got, `"ok":false`) || !strings.Contains(got, "ключ") {
+		t.Fatalf("wrong key: %s", got)
+	}
+	setImage(t, s, f, "vx_good")
+	f.failAs = "insufficient_credits"
+	if got := apiCall(t, s, c, "GET", "/api/panel/ai/image/job_gen1", ""); !strings.Contains(got, `"status":"failed"`) || !strings.Contains(got, "кредит") {
+		t.Fatalf("failed job: %s", got)
+	}
+	if got := apiCall(t, s, c, "GET", "/api/panel/ai/image/..%2Fme", ""); !strings.Contains(got, `"ok":false`) {
+		t.Fatalf("a job id out of shape: %s", got)
+	}
+	if got := apiCall(t, s, c, "POST", "/api/panel/ai/image", `{"mode":"generate","prompt":""}`); !strings.Contains(got, `"ok":false`) {
+		t.Fatalf("empty prompt: %s", got)
+	}
+}
+
+// The assistant off in the profile means no pictures either.
+func TestImageNeedsAssistantOn(t *testing.T) {
+	s, c := newTestServer(t)
+	f := newFakeVertex(t)
+	setImage(t, s, f, "vx_good")
+	a, _ := s.db.AdminByUsername("adm")
+	_ = s.db.SetConfig(aiUserKey(a.ID), "0")
+	if got := apiCall(t, s, c, "POST", "/api/panel/ai/image", `{"mode":"generate","prompt":"x"}`); !strings.Contains(got, "выключен") {
+		t.Fatalf("off: %s", got)
+	}
+}
+
+// The key is saved from Настройки, shown back to the admin, and the chat
+// learns only that pictures are on.
+func TestImageKeySetting(t *testing.T) {
+	s, c := newTestServer(t)
+	postAIModels(t, s, c, [][7]string{{"", "M", "gradio", "", "", "", ""}})
+	f := url.Values{"csrf": {"tok"}, "m_type": {"gradio"}, "ai_image_key": {"vx_secret"}}
+	req := httptest.NewRequest(http.MethodPost, "/settings/ai", strings.NewReader(f.Encode()))
+	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+	req.AddCookie(c)
+	req.AddCookie(&http.Cookie{Name: csrfCookie, Value: "tok"})
+	s.Handler().ServeHTTP(httptest.NewRecorder(), req)
+	if _, k := s.imageConf(); k != "vx_secret" {
+		t.Fatalf("key not saved: %q", k)
+	}
+	if body := get(t, s, c, "/settings?frag=1").Body.String(); !strings.Contains(body, `value="vx_secret"`) {
+		t.Fatal("the settings page does not show the key")
+	}
+	state := get(t, s, c, "/api/panel/ai").Body.String()
+	if strings.Contains(state, "vx_secret") || !strings.Contains(state, `"image":true`) {
+		t.Fatalf("state: %s", state)
+	}
+}
+
+// With a key the model is told it can draw; without, it is not.
+func TestImagePromptOnlyWithKey(t *testing.T) {
+	s, _ := newTestServer(t)
+	if strings.Contains(s.imagePrompt(), "```image") {
+		t.Fatal("told about pictures with no key")
+	}
+	_ = s.db.SetConfig(cfgImageKey, "vx_good")
+	p := s.imagePrompt()
+	for _, want := range []string{"```image\n", "```image edit", "fast", "artist", "0.2plus", "16:9"} {
+		if !strings.Contains(p, want) {
+			t.Fatalf("the prompt lacks %q:\n%s", want, p)
+		}
+	}
+}
+
+// The chat gives the model the image instructions when pictures are on.
+func TestAIChatMentionsImageTool(t *testing.T) {
+	s, c := newTestServer(t)
+	var system string
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		var b map[string]any
+		_ = json.NewDecoder(r.Body).Decode(&b)
+		system, _ = b["messages"].([]any)[0].(map[string]any)["content"].(string)
+		fmt.Fprint(w, openAIChunk("content", "ok")+"data: [DONE]\n\n")
+	}))
+	defer srv.Close()
+	postAIModels(t, s, c, [][7]string{{"", "M", "openai", srv.URL, "m", "", ""}})
+	ask := func() {
+		apiCall(t, s, c, "POST", "/api/panel/ai/chat", `{"message":"нарисуй кота","context":"x"}`)
+	}
+	ask()
+	if strings.Contains(system, "```image") {
+		t.Fatal("image tool offered with no key")
+	}
+	_ = s.db.SetConfig(cfgImageKey, "vx_good")
+	ask()
+	if !strings.Contains(system, "```image") {
+		t.Fatalf("image tool not offered with a key:\n%s", system)
+	}
+}
+
+// The description is improved by the service unless the model asks for it
+// as it is.
+func TestImageEnhanceSwitch(t *testing.T) {
+	s, c := newTestServer(t)
+	f := newFakeVertex(t)
+	setImage(t, s, f, "vx_good")
+	apiCall(t, s, c, "POST", "/api/panel/ai/image", `{"mode":"generate","prompt":"x"}`)
+	if f.gen["enhance"] != true {
+		t.Fatalf("by default: %v", f.gen)
+	}
+	apiCall(t, s, c, "POST", "/api/panel/ai/image", `{"mode":"generate","prompt":"x","enhance":false}`)
+	if f.gen["enhance"] != false {
+		t.Fatalf("switched off: %v", f.gen)
+	}
+	apiCall(t, s, c, "POST", "/api/panel/ai/image", `{"mode":"generate","prompt":"x","enhance":true}`)
+	if f.gen["enhance"] != true {
+		t.Fatalf("switched on: %v", f.gen)
+	}
+	{
+		p := s.imagePrompt()
+		_ = s.db.SetConfig(cfgImageKey, "vx_good")
+		if !strings.Contains(s.imagePrompt(), "noenhance") {
+			t.Fatalf("the model is not told of the switch:\n%s", p)
+		}
+	}
+}
@@ -0,0 +1,644 @@
+package server
+
+import (
+	"bytes"
+	"crypto"
+	"crypto/ecdsa"
+	"crypto/ed25519"
+	"crypto/elliptic"
+	"crypto/rand"
+	"crypto/rsa"
+	"crypto/sha256"
+	"crypto/x509"
+	"encoding/base64"
+	"encoding/binary"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"math/big"
+	"net"
+	"net/http"
+	"net/url"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+)
+
+// Passkeys (WebAuthn): an admin signs in with a key held by the device - a
+// fingerprint, the phone's lock, a hardware key - instead of a password. With
+// a key in place, the admin can turn the password off in their account.
+//
+// Attestation is not checked ("none"): the panel trusts any authenticator,
+// it only needs the public key and, at sign-in, a signature made with it.
+
+var b64u = base64.RawURLEncoding
+
+// challenges are the ones handed out and not yet used, a few minutes each.
+type challenges struct {
+	mu sync.Mutex
+	m  map[string]challenge
+}
+
+type challenge struct {
+	adminID int64 // the admin registering a key; 0 for a sign-in
+	expires time.Time
+}
+
+func (c *challenges) issue(adminID int64) string {
+	b := make([]byte, 32)
+	if _, err := rand.Read(b); err != nil {
+		panic("crypto/rand failed: " + err.Error())
+	}
+	id := b64u.EncodeToString(b)
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	if c.m == nil {
+		c.m = map[string]challenge{}
+	}
+	for k, v := range c.m {
+		if time.Now().After(v.expires) {
+			delete(c.m, k)
+		}
+	}
+	c.m[id] = challenge{adminID: adminID, expires: time.Now().Add(5 * time.Minute)}
+	return id
+}
+
+// take uses up a challenge: true when it was issued, for this admin, and is
+// still fresh.
+func (c *challenges) take(id string, adminID int64) bool {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	ch, ok := c.m[id]
+	delete(c.m, id)
+	return ok && ch.adminID == adminID && time.Now().Before(ch.expires)
+}
+
+// mainHost is the main address's host name, set when the server starts.
+var mainHost = func() string { return "" }
+
+// rpID is the site the keys belong to: the host the browser is on, or the
+// main address's host when the browser is on it or under it - so the keys
+// made on lpra.example.com also sign in on direct.lpra.example.com.
+func rpID(r *http.Request) string {
+	host := r.Host
+	if h, _, err := net.SplitHostPort(host); err == nil {
+		host = h
+	}
+	if m := mainHost(); m != "" && strings.HasSuffix(host, "."+m) {
+		return m
+	}
+	return host
+}
+
+// checkClientData verifies what the browser signed over: the kind of
+// ceremony, our challenge and our origin. A proxy in front may speak plain
+// http to us, so the origin is matched by host, and must be https unless the
+// panel is on this machine.
+func checkClientData(r *http.Request, raw []byte, typ string, adminID int64, ch *challenges) error {
+	var cd struct {
+		Type      string `json:"type"`
+		Challenge string `json:"challenge"`
+		Origin    string `json:"origin"`
+	}
+	if err := json.Unmarshal(raw, &cd); err != nil {
+		return errors.New("ответ ключа не читается")
+	}
+	if cd.Type != typ {
+		return errors.New("ответ ключа не того вида")
+	}
+	if !ch.take(cd.Challenge, adminID) {
+		return errors.New("запрос устарел - попробуйте ещё раз")
+	}
+	u, err := url.Parse(cd.Origin)
+	if err != nil || u.Host != r.Host {
+		return errors.New("ключ подписал запрос для другого сайта")
+	}
+	local := u.Hostname() == "localhost" || u.Hostname() == "127.0.0.1" || u.Hostname() == "::1"
+	if u.Scheme != "https" && !local {
+		return errors.New("ключи доступа работают только по https")
+	}
+	return nil
+}
+
+// authData is the authenticator's part: rpIdHash, flags, counter, then the
+// new credential at registration.
+type authData struct {
+	rpIDHash  []byte
+	flags     byte
+	signCount uint32
+	credID    []byte
+	coseKey   []byte
+}
+
+func parseAuthData(b []byte, wantCred bool) (*authData, error) {
+	if len(b) < 37 {
+		return nil, errors.New("данные ключа слишком короткие")
+	}
+	ad := &authData{rpIDHash: b[:32], flags: b[32], signCount: binary.BigEndian.Uint32(b[33:37])}
+	if !wantCred {
+		return ad, nil
+	}
+	if ad.flags&0x40 == 0 || len(b) < 37+18 {
+		return nil, errors.New("ключ не прислал себя")
+	}
+	n := int(binary.BigEndian.Uint16(b[53:55]))
+	if len(b) < 55+n {
+		return nil, errors.New("данные ключа обрезаны")
+	}
+	ad.credID = b[55 : 55+n]
+	ad.coseKey = b[55+n:]
+	return ad, nil
+}
+
+func (ad *authData) check(r *http.Request) error {
+	sum := sha256.Sum256([]byte(rpID(r)))
+	if !bytes.Equal(ad.rpIDHash, sum[:]) {
+		return errors.New("ключ создан для другого сайта")
+	}
+	if ad.flags&0x01 == 0 {
+		return errors.New("ключ не подтвердил присутствие")
+	}
+	return nil
+}
+
+// coseToPKIX turns a COSE public key (ES256, RS256 or EdDSA) into PKIX DER.
+func coseToPKIX(raw []byte) ([]byte, error) {
+	v, _, err := cborDecode(raw)
+	if err != nil {
+		return nil, err
+	}
+	m, ok := v.(map[any]any)
+	if !ok {
+		return nil, errors.New("ключ не в формате COSE")
+	}
+	num := func(k int64) int64 { n, _ := m[k].(int64); return n }
+	bin := func(k int64) []byte { b, _ := m[k].([]byte); return b }
+	var pub any
+	switch num(1) { // kty
+	case 2: // EC2
+		x, y := bin(-2), bin(-3)
+		if num(-1) != 1 || len(x) != 32 || len(y) != 32 {
+			return nil, errors.New("поддерживается только кривая P-256")
+		}
+		k := &ecdsa.PublicKey{Curve: elliptic.P256(), X: new(big.Int).SetBytes(x), Y: new(big.Int).SetBytes(y)}
+		if !k.Curve.IsOnCurve(k.X, k.Y) {
+			return nil, errors.New("ключ не на кривой")
+		}
+		pub = k
+	case 3: // RSA
+		n, e := bin(-1), bin(-2)
+		if len(n) < 256 || len(e) == 0 || len(e) > 4 {
+			return nil, errors.New("неподходящий ключ RSA")
+		}
+		pub = &rsa.PublicKey{N: new(big.Int).SetBytes(n), E: int(new(big.Int).SetBytes(e).Int64())}
+	case 1: // OKP
+		x := bin(-2)
+		if num(-1) != 6 || len(x) != ed25519.PublicKeySize {
+			return nil, errors.New("поддерживается только Ed25519")
+		}
+		pub = ed25519.PublicKey(x)
+	default:
+		return nil, errors.New("неизвестный вид ключа")
+	}
+	return x509.MarshalPKIXPublicKey(pub)
+}
+
+func verifySig(der, data, sig []byte) bool {
+	pub, err := x509.ParsePKIXPublicKey(der)
+	if err != nil {
+		return false
+	}
+	sum := sha256.Sum256(data)
+	switch k := pub.(type) {
+	case *ecdsa.PublicKey:
+		return ecdsa.VerifyASN1(k, sum[:], sig)
+	case *rsa.PublicKey:
+		return rsa.VerifyPKCS1v15(k, crypto.SHA256, sum[:], sig) == nil
+	case ed25519.PublicKey:
+		return ed25519.Verify(k, data, sig)
+	}
+	return false
+}
+
+// ---------- CBOR, as much as WebAuthn needs ----------
+
+func cborDecode(b []byte) (any, []byte, error) {
+	r := &cborReader{b: b}
+	v, err := r.item(0)
+	return v, r.b[r.i:], err
+}
+
+type cborReader struct {
+	b []byte
+	i int
+}
+
+var errCBOR = errors.New("данные ключа повреждены")
+
+func (r *cborReader) arg(info byte) (uint64, error) {
+	size := map[byte]int{24: 1, 25: 2, 26: 4, 27: 8}
+	if info < 24 {
+		return uint64(info), nil
+	}
+	n, ok := size[info]
+	if !ok || r.i+n > len(r.b) {
+		return 0, errCBOR
+	}
+	var v uint64
+	for _, c := range r.b[r.i : r.i+n] {
+		v = v<<8 | uint64(c)
+	}
+	r.i += n
+	return v, nil
+}
+
+func (r *cborReader) take(n uint64) ([]byte, error) {
+	if n > uint64(len(r.b)-r.i) {
+		return nil, errCBOR
+	}
+	out := r.b[r.i : r.i+int(n)]
+	r.i += int(n)
+	return out, nil
+}
+
+func (r *cborReader) item(depth int) (any, error) {
+	if r.i >= len(r.b) || depth > 16 {
+		return nil, errCBOR
+	}
+	ib := r.b[r.i]
+	r.i++
+	major, info := ib>>5, ib&31
+	if major == 7 {
+		switch info {
+		case 20:
+			return false, nil
+		case 21:
+			return true, nil
+		case 22, 23:
+			return nil, nil
+		}
+		_, err := r.arg(info) // a float: not used, skipped
+		return nil, err
+	}
+	n, err := r.arg(info)
+	if err != nil {
+		return nil, err
+	}
+	switch major {
+	case 0:
+		return int64(n), nil
+	case 1:
+		return -1 - int64(n), nil
+	case 2:
+		return r.take(n)
+	case 3:
+		s, err := r.take(n)
+		return string(s), err
+	case 4:
+		if n > 1024 {
+			return nil, errCBOR
+		}
+		arr := make([]any, 0, n)
+		for k := uint64(0); k < n; k++ {
+			v, err := r.item(depth + 1)
+			if err != nil {
+				return nil, err
+			}
+			arr = append(arr, v)
+		}
+		return arr, nil
+	case 5:
+		if n > 1024 {
+			return nil, errCBOR
+		}
+		m := make(map[any]any, n)
+		for k := uint64(0); k < n; k++ {
+			key, err := r.item(depth + 1)
+			if err != nil {
+				return nil, err
+			}
+			v, err := r.item(depth + 1)
+			if err != nil {
+				return nil, err
+			}
+			switch key.(type) {
+			case int64, string:
+				m[key] = v
+			default:
+				return nil, errCBOR
+			}
+		}
+		return m, nil
+	case 6:
+		return r.item(depth + 1) // a tag: its content
+	}
+	return nil, errCBOR
+}
+
+// ---------- handlers ----------
+
+func credParams() []map[string]any {
+	return []map[string]any{
+		{"type": "public-key", "alg": -7},   // ES256
+		{"type": "public-key", "alg": -8},   // EdDSA
+		{"type": "public-key", "alg": -257}, // RS256
+	}
+}
+
+func userHandle(id int64) string {
+	b := make([]byte, 8)
+	binary.BigEndian.PutUint64(b, uint64(id))
+	return b64u.EncodeToString(b)
+}
+
+// GET /api/panel/account - who is signed in, and their passkeys.
+func (s *Server) handleAccount(w http.ResponseWriter, r *http.Request) {
+	a := s.currentAdmin(r)
+	keys, _ := s.db.ListAdminKeys(a.ID)
+	list := []map[string]any{}
+	for _, k := range keys {
+		list = append(list, map[string]any{"id": k.ID, "name": k.Name, "created": k.CreatedAt, "last_used": k.LastUsed})
+	}
+	writeJSON(w, map[string]any{"username": a.Username, "keys": list, "password_off": s.db.PasswordOff(a.ID), "pin": s.db.AdminPin(a.ID) != "",
+		"pw_locked": a.PwLocked, "admin": a.IsAdmin()})
+}
+
+// POST /api/panel/account/password/change - a new password, given the
+// current one.
+func (s *Server) handlePasswordChange(w http.ResponseWriter, r *http.Request) {
+	a := s.currentAdmin(r)
+	var in struct {
+		Current string `json:"current"`
+		New     string `json:"new"`
+	}
+	if err := json.NewDecoder(http.MaxBytesReader(w, r.Body, 4<<10)).Decode(&in); err != nil {
+		writeJSON(w, map[string]any{"ok": false, "error": "плохой запрос"})
+		return
+	}
+	ip := clientIP(r)
+	if s.limiter.blocked(ip) {
+		writeJSON(w, map[string]any{"ok": false, "error": "Слишком много попыток. Подождите немного."})
+		return
+	}
+	if !checkPassword(a.PassHash, in.Current) {
+		s.limiter.fin(ip, false)
+		writeJSON(w, map[string]any{"ok": false, "error": "текущий пароль не тот"})
+		return
+	}
+	if len(in.New) < 8 {
+		writeJSON(w, map[string]any{"ok": false, "error": "новый пароль - не короче 8 символов"})
+		return
+	}
+	hash, err := hashPassword(in.New)
+	if err == nil {
+		err = s.db.SetAdminPassword(a.ID, hash)
+	}
+	if err != nil {
+		writeJSON(w, map[string]any{"ok": false, "error": err.Error()})
+		return
+	}
+	s.limiter.fin(ip, true)
+	s.db.Audit(a.ID, "", "password_change")
+	writeJSON(w, map[string]any{"ok": true})
+}
+
+// POST /api/panel/account/password {"off": bool} - turn signing in with the
+// password off or on again. Off only with a passkey to sign in with.
+func (s *Server) handlePasswordToggle(w http.ResponseWriter, r *http.Request) {
+	a := s.currentAdmin(r)
+	var in struct {
+		Off bool `json:"off"`
+	}
+	if err := json.NewDecoder(http.MaxBytesReader(w, r.Body, 1<<10)).Decode(&in); err != nil {
+		writeJSON(w, map[string]any{"ok": false, "error": "плохой запрос"})
+		return
+	}
+	if a.PwLocked {
+		writeJSON(w, map[string]any{"ok": false, "error": "вход по паролю закрепил администратор"})
+		return
+	}
+	if in.Off && s.db.CountAdminKeys(a.ID) == 0 {
+		writeJSON(w, map[string]any{"ok": false, "error": "сначала добавьте ключ доступа"})
+		return
+	}
+	if err := s.db.SetPasswordOff(a.ID, in.Off); err != nil {
+		writeJSON(w, map[string]any{"ok": false, "error": err.Error()})
+		return
+	}
+	action := "password_on"
+	if in.Off {
+		action = "password_off"
+	}
+	s.db.Audit(a.ID, "", action)
+	writeJSON(w, map[string]any{"ok": true})
+}
+
+// POST /api/panel/account/keys/begin - options to make a new passkey with.
+func (s *Server) handleKeyRegisterBegin(w http.ResponseWriter, r *http.Request) {
+	a := s.currentAdmin(r)
+	keys, _ := s.db.ListAdminKeys(a.ID)
+	exclude := []map[string]any{}
+	for _, k := range keys {
+		exclude = append(exclude, map[string]any{"type": "public-key", "id": b64u.EncodeToString(k.CredID)})
+	}
+	writeJSON(w, map[string]any{"ok": true, "options": map[string]any{
+		"challenge":          s.challenges.issue(a.ID),
+		"rp":                 map[string]any{"id": rpID(r), "name": "LPRA"},
+		"user":               map[string]any{"id": userHandle(a.ID), "name": a.Username, "displayName": a.Username},
+		"pubKeyCredParams":   credParams(),
+		"excludeCredentials": exclude,
+		"authenticatorSelection": map[string]any{
+			"residentKey": "preferred", "userVerification": "preferred",
+		},
+		"attestation": "none",
+		"timeout":     120000,
+	}})
+}
+
+// POST /api/panel/account/keys/finish - keep the passkey the browser made.
+func (s *Server) handleKeyRegisterFinish(w http.ResponseWriter, r *http.Request) {
+	a := s.currentAdmin(r)
+	var in struct {
+		Name              string `json:"name"`
+		ClientDataJSON    string `json:"clientDataJSON"`
+		AttestationObject string `json:"attestationObject"`
+	}
+	if err := json.NewDecoder(http.MaxBytesReader(w, r.Body, 64<<10)).Decode(&in); err != nil {
+		writeJSON(w, map[string]any{"ok": false, "error": "плохой запрос"})
+		return
+	}
+	fail := func(err error) { writeJSON(w, map[string]any{"ok": false, "error": err.Error()}) }
+	cd, err1 := b64u.DecodeString(in.ClientDataJSON)
+	att, err2 := b64u.DecodeString(in.AttestationObject)
+	if err1 != nil || err2 != nil {
+		fail(errors.New("плохой запрос"))
+		return
+	}
+	if err := checkClientData(r, cd, "webauthn.create", a.ID, &s.challenges); err != nil {
+		fail(err)
+		return
+	}
+	v, _, err := cborDecode(att)
+	m, ok := v.(map[any]any)
+	if err != nil || !ok {
+		fail(errCBOR)
+		return
+	}
+	raw, _ := m["authData"].([]byte)
+	ad, err := parseAuthData(raw, true)
+	if err != nil {
+		fail(err)
+		return
+	}
+	if err := ad.check(r); err != nil {
+		fail(err)
+		return
+	}
+	der, err := coseToPKIX(ad.coseKey)
+	if err != nil {
+		fail(err)
+		return
+	}
+	if k, _ := s.db.AdminKeyByCredID(ad.credID); k != nil {
+		fail(errors.New("этот ключ уже добавлен"))
+		return
+	}
+	name := strings.TrimSpace(in.Name)
+	if name == "" {
+		name = "ключ " + time.Now().Format("02.01.2006")
+	}
+	if len(name) > 60 {
+		name = name[:60]
+	}
+	if err := s.db.AddAdminKey(AdminKey{AdminID: a.ID, CredID: ad.credID, PublicKey: der, SignCount: ad.signCount, Name: name}); err != nil {
+		fail(err)
+		return
+	}
+	s.db.Audit(a.ID, "", "passkey_add:"+name)
+	writeJSON(w, map[string]any{"ok": true})
+}
+
+// POST /api/panel/account/keys/{id}/delete
+func (s *Server) handleKeyDelete(w http.ResponseWriter, r *http.Request) {
+	a := s.currentAdmin(r)
+	id, _ := strconv.ParseInt(r.PathValue("id"), 10, 64)
+	if err := s.db.DeleteAdminKey(a.ID, id); err != nil {
+		writeJSON(w, map[string]any{"ok": false, "error": err.Error()})
+		return
+	}
+	s.db.Audit(a.ID, "", "passkey_delete:"+strconv.FormatInt(id, 10))
+	writeJSON(w, map[string]any{"ok": true})
+}
+
+// POST /api/login/key/begin - options to sign in with a passkey. With a
+// username, its keys are named, for keys that do not keep the account
+// themselves.
+func (s *Server) handleKeyLoginBegin(w http.ResponseWriter, r *http.Request) {
+	if s.limiter.blocked(clientIP(r)) {
+		writeJSON(w, map[string]any{"ok": false, "error": "Слишком много попыток. Подождите немного."})
+		return
+	}
+	var in struct {
+		Username string `json:"username"`
+	}
+	_ = json.NewDecoder(http.MaxBytesReader(w, r.Body, 4<<10)).Decode(&in)
+	allow := []map[string]any{}
+	if u := strings.TrimSpace(in.Username); u != "" {
+		if a, _ := s.db.AdminByUsername(u); a != nil {
+			keys, _ := s.db.ListAdminKeys(a.ID)
+			for _, k := range keys {
+				allow = append(allow, map[string]any{"type": "public-key", "id": b64u.EncodeToString(k.CredID)})
+			}
+		}
+	}
+	writeJSON(w, map[string]any{"ok": true, "options": map[string]any{
+		"challenge":        s.challenges.issue(0),
+		"rpId":             rpID(r),
+		"allowCredentials": allow,
+		"userVerification": "preferred",
+		"timeout":          120000,
+	}})
+}
+
+// POST /api/login/key/finish - check the signature and sign the admin in.
+func (s *Server) handleKeyLoginFinish(w http.ResponseWriter, r *http.Request) {
+	ip := clientIP(r)
+	if s.limiter.blocked(ip) {
+		writeJSON(w, map[string]any{"ok": false, "error": "Слишком много попыток. Подождите немного."})
+		return
+	}
+	var in struct {
+		ID                string `json:"id"`
+		ClientDataJSON    string `json:"clientDataJSON"`
+		AuthenticatorData string `json:"authenticatorData"`
+		Signature         string `json:"signature"`
+	}
+	if err := json.NewDecoder(http.MaxBytesReader(w, r.Body, 64<<10)).Decode(&in); err != nil {
+		writeJSON(w, map[string]any{"ok": false, "error": "плохой запрос"})
+		return
+	}
+	fail := func(msg string) {
+		s.limiter.fin(ip, false)
+		writeJSON(w, map[string]any{"ok": false, "error": msg})
+	}
+	credID, e1 := b64u.DecodeString(in.ID)
+	cd, e2 := b64u.DecodeString(in.ClientDataJSON)
+	rawAD, e3 := b64u.DecodeString(in.AuthenticatorData)
+	sig, e4 := b64u.DecodeString(in.Signature)
+	if e1 != nil || e2 != nil || e3 != nil || e4 != nil {
+		fail("плохой запрос")
+		return
+	}
+	k, _ := s.db.AdminKeyByCredID(credID)
+	if k == nil {
+		fail("этот ключ здесь не привязан ни к одному аккаунту")
+		return
+	}
+	if err := checkClientData(r, cd, "webauthn.get", 0, &s.challenges); err != nil {
+		fail(err.Error())
+		return
+	}
+	ad, err := parseAuthData(rawAD, false)
+	if err == nil {
+		err = ad.check(r)
+	}
+	if err != nil {
+		fail(err.Error())
+		return
+	}
+	cdHash := sha256.Sum256(cd)
+	if !verifySig(k.PublicKey, append(append([]byte{}, rawAD...), cdHash[:]...), sig) {
+		fail("подпись ключа не сошлась")
+		return
+	}
+	// A counter that goes back means a copy of the key is in use.
+	if ad.signCount != 0 && k.SignCount != 0 && ad.signCount <= k.SignCount {
+		fail("ключ похож на копию: счётчик не вырос")
+		return
+	}
+	_ = s.db.UseAdminKey(k.ID, ad.signCount)
+	s.limiter.fin(ip, true)
+	if err := s.setSession(w, k.AdminID); err != nil {
+		writeJSON(w, map[string]any{"ok": false, "error": "внутренняя ошибка"})
+		return
+	}
+	s.db.Audit(k.AdminID, "", "login_passkey:"+k.Name)
+	writeJSON(w, map[string]any{"ok": true})
+}
+
+// POST /settings/admins/keys/reset - drop all passkeys of an admin, who signs
+// in with the password again: for one who lost theirs.
+func (s *Server) handleResetAdminKeys(w http.ResponseWriter, r *http.Request) {
+	if !checkCSRF(r) {
+		http.Error(w, "bad csrf", http.StatusForbidden)
+		return
+	}
+	id, _ := strconv.ParseInt(r.FormValue("id"), 10, 64)
+	_ = s.db.DeleteAdminKeys(id)
+	if a := s.currentAdmin(r); a != nil {
+		s.db.Audit(a.ID, "", fmt.Sprintf("passkeys_reset:%d", id))
+	}
+	http.Redirect(w, r, "/settings", http.StatusSeeOther)
+}
@@ -0,0 +1,108 @@
+package server
+
+import (
+	"encoding/json"
+	"net/http"
+	"regexp"
+	"sync"
+)
+
+// The PIN: four digits an admin can set, asked for by the page in every new
+// browser tab (a reload of the same tab does not ask again). The server
+// checks it; five wrong ones in a row end the session.
+
+var pinRe = regexp.MustCompile(`^[0-9]{4}$`)
+
+// pinMisses counts wrong PINs per session.
+type pinMisses struct {
+	mu sync.Mutex
+	m  map[string]int
+}
+
+func (p *pinMisses) miss(sid string) int {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	if p.m == nil {
+		p.m = map[string]int{}
+	}
+	p.m[sid]++
+	return p.m[sid]
+}
+
+func (p *pinMisses) clear(sid string) {
+	p.mu.Lock()
+	delete(p.m, sid)
+	p.mu.Unlock()
+}
+
+// GET /api/panel/pin - whether the admin has a PIN to ask for.
+func (s *Server) handlePinState(w http.ResponseWriter, r *http.Request) {
+	a := s.currentAdmin(r)
+	w.Header().Set("Cache-Control", "no-store")
+	writeJSON(w, map[string]any{"pin": s.db.AdminPin(a.ID) != ""})
+}
+
+// POST /api/panel/pin/check {"pin"} - the PIN typed in a new tab.
+func (s *Server) handlePinCheck(w http.ResponseWriter, r *http.Request) {
+	a := s.currentAdmin(r)
+	var in struct {
+		Pin string `json:"pin"`
+	}
+	_ = json.NewDecoder(http.MaxBytesReader(w, r.Body, 1<<10)).Decode(&in)
+	h := s.db.AdminPin(a.ID)
+	c, _ := r.Cookie(sessionCookie)
+	if h == "" || (pinRe.MatchString(in.Pin) && checkPassword(h, in.Pin)) {
+		s.pinMisses.clear(c.Value)
+		writeJSON(w, map[string]any{"ok": true})
+		return
+	}
+	if n := s.pinMisses.miss(c.Value); n >= 5 {
+		s.pinMisses.clear(c.Value)
+		s.clearSession(w, r)
+		s.db.Audit(a.ID, "", "pin_lockout")
+		writeJSON(w, map[string]any{"ok": false, "out": true, "error": "слишком много неверных попыток"})
+		return
+	} else {
+		writeJSON(w, map[string]any{"ok": false, "left": 5 - n, "error": "неверный PIN"})
+	}
+}
+
+// POST /api/panel/account/pin {"pin", "current"} - set or change the PIN;
+// with pin empty, remove it. A PIN in place is needed to change or drop it.
+func (s *Server) handlePinSet(w http.ResponseWriter, r *http.Request) {
+	a := s.currentAdmin(r)
+	var in struct {
+		Pin     string `json:"pin"`
+		Current string `json:"current"`
+	}
+	if err := json.NewDecoder(http.MaxBytesReader(w, r.Body, 1<<10)).Decode(&in); err != nil {
+		writeJSON(w, map[string]any{"ok": false, "error": "плохой запрос"})
+		return
+	}
+	if h := s.db.AdminPin(a.ID); h != "" && !checkPassword(h, in.Current) {
+		writeJSON(w, map[string]any{"ok": false, "error": "текущий PIN не тот"})
+		return
+	}
+	hash := ""
+	if in.Pin != "" {
+		if !pinRe.MatchString(in.Pin) {
+			writeJSON(w, map[string]any{"ok": false, "error": "PIN - ровно 4 цифры"})
+			return
+		}
+		var err error
+		if hash, err = hashPassword(in.Pin); err != nil {
+			writeJSON(w, map[string]any{"ok": false, "error": err.Error()})
+			return
+		}
+	}
+	if err := s.db.SetAdminPin(a.ID, hash); err != nil {
+		writeJSON(w, map[string]any{"ok": false, "error": err.Error()})
+		return
+	}
+	action := "pin_set"
+	if hash == "" {
+		action = "pin_remove"
+	}
+	s.db.Audit(a.ID, "", action)
+	writeJSON(w, map[string]any{"ok": true})
+}
@@ -0,0 +1,80 @@
+package server
+
+import (
+	"encoding/json"
+	"net/http"
+	"strconv"
+	"strings"
+)
+
+// Each user's look of the panel (Аккаунт › Вид), kept on the server so it
+// is the same on every device: where a tab's icons go, the terminal's font
+// size, a compact file list, the time column, animations, and whether a
+// terminal or file pane opened «Здесь» starts in the active pane's folder;
+// and the assistant's model: which one, and whether the chat always offers
+// the choice.
+type viewPrefs struct {
+	TabIcons string `json:"tabIcons,omitempty"` // left (default), right, hide
+	TermFont int    `json:"termFont,omitempty"` // 11-20; 0: the default
+	Compact  bool   `json:"compact,omitempty"`  // denser file lists
+	FileTime string `json:"fileTime,omitempty"` // show (default), hide
+	Motion   string `json:"motion,omitempty"`   // on (default), off
+	OpenHere string `json:"openHere,omitempty"` // on (default), off
+	// AIModelPick: the model menu in the chat - when there are several
+	// (default) or always. AIModel: the id of the model chosen.
+	AIModelPick string `json:"aiModelPick,omitempty"`
+	AIModel     string `json:"aiModel,omitempty"`
+}
+
+func prefsKey(id int64) string { return "prefs_" + strconv.FormatInt(id, 10) }
+
+// clean keeps known values only.
+func (p viewPrefs) clean() viewPrefs {
+	if p.TabIcons != "right" && p.TabIcons != "hide" {
+		p.TabIcons = ""
+	}
+	if p.TermFont < 11 || p.TermFont > 20 {
+		p.TermFont = 0
+	}
+	if p.FileTime != "hide" {
+		p.FileTime = ""
+	}
+	if p.Motion != "off" {
+		p.Motion = ""
+	}
+	if p.OpenHere != "off" {
+		p.OpenHere = ""
+	}
+	if p.AIModelPick != "always" {
+		p.AIModelPick = ""
+	}
+	if len(p.AIModel) > 32 || strings.Trim(p.AIModel, "0123456789abcdefghijklmnopqrstuvwxyz") != "" {
+		p.AIModel = ""
+	}
+	return p
+}
+
+func (s *Server) prefs(id int64) viewPrefs {
+	var p viewPrefs
+	if v, _ := s.db.GetConfig(prefsKey(id)); v != "" {
+		_ = json.Unmarshal([]byte(v), &p)
+	}
+	return p.clean()
+}
+
+// GET /api/panel/account/prefs
+func (s *Server) handlePrefs(w http.ResponseWriter, r *http.Request) {
+	writeJSON(w, s.prefs(s.currentAdmin(r).ID))
+}
+
+// POST /api/panel/account/prefs - the whole set.
+func (s *Server) handlePrefsSet(w http.ResponseWriter, r *http.Request) {
+	var p viewPrefs
+	if err := json.NewDecoder(http.MaxBytesReader(w, r.Body, 4<<10)).Decode(&p); err != nil {
+		writeJSON(w, map[string]any{"ok": false, "error": "плохой запрос"})
+		return
+	}
+	b, _ := json.Marshal(p.clean())
+	_ = s.db.SetConfig(prefsKey(s.currentAdmin(r).ID), string(b))
+	writeJSON(w, map[string]any{"ok": true})
+}
@@ -0,0 +1,282 @@
+package server
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"html"
+	"io"
+	"log"
+	"net/http"
+	"net/url"
+	"regexp"
+	"strconv"
+	"strings"
+	"time"
+)
+
+// Web search for the assistant, when the user turned «Поиск» on: DuckDuckGo's
+// plain pages, no key and nothing to install. The light page first, the
+// HTML one if that fails; DuckDuckGo turns away too many requests from one
+// address, and then the assistant is told so.
+
+type searchResult struct {
+	Title   string `json:"title"`
+	URL     string `json:"url"`
+	Snippet string `json:"snippet"`
+}
+
+var (
+	reLiteLink    = regexp.MustCompile(`(?s)<a[^>]+href="([^"]+)"[^>]*class='result-link'[^>]*>(.*?)</a>`)
+	reLiteSnippet = regexp.MustCompile(`(?s)<td class='result-snippet'>(.*?)</td>`)
+	reHTMLLink    = regexp.MustCompile(`(?s)<a[^>]+class="result__a"[^>]+href="([^"]+)"[^>]*>(.*?)</a>`)
+	reHTMLSnippet = regexp.MustCompile(`(?s)<a[^>]+class="result__snippet"[^>]*>(.*?)</a>`)
+	reTags        = regexp.MustCompile(`<[^>]+>`)
+)
+
+// text is a bit of a results page as plain text.
+func text(s string) string {
+	return strings.Join(strings.Fields(html.UnescapeString(reTags.ReplaceAllString(s, ""))), " ")
+}
+
+// realURL takes DuckDuckGo's redirect (/l/?uddg=…) back to the address.
+func realURL(h string) string {
+	h = html.UnescapeString(h)
+	if strings.HasPrefix(h, "//") {
+		h = "https:" + h
+	}
+	if u, err := url.Parse(h); err == nil {
+		if t := u.Query().Get("uddg"); t != "" {
+			return t
+		}
+	}
+	return h
+}
+
+// parseDDG reads the results of the light or the HTML page.
+func parseDDG(page string) []searchResult {
+	links, snips := reLiteLink.FindAllStringSubmatch(page, -1), reLiteSnippet.FindAllStringSubmatch(page, -1)
+	if len(links) == 0 {
+		links, snips = reHTMLLink.FindAllStringSubmatch(page, -1), reHTMLSnippet.FindAllStringSubmatch(page, -1)
+	}
+	var out []searchResult
+	for i, l := range links {
+		r := searchResult{Title: text(l[2]), URL: realURL(l[1])}
+		if i < len(snips) {
+			r.Snippet = text(snips[i][1])
+		}
+		// Ads lead back through DuckDuckGo itself: left out.
+		if strings.Contains(r.URL, "duckduckgo.com/y.js") || r.Title == "" {
+			continue
+		}
+		out = append(out, r)
+	}
+	return out
+}
+
+var searchClient = &http.Client{Timeout: 15 * time.Second}
+
+// The engine is the admins' choice (Настройки › ИИ-ассистент): DuckDuckGo,
+// a SearXNG of one's own, Brave Search or Tavily; when the chosen one fails,
+// DuckDuckGo answers instead.
+const (
+	cfgSearchEngine = "ai_search"
+	cfgSearchURL    = "ai_search_url"
+	cfgSearchKey    = "ai_search_key"
+)
+
+type searchConf struct{ Engine, URL, Key string }
+
+func (s *Server) searchConf() searchConf {
+	e, _ := s.db.GetConfig(cfgSearchEngine)
+	u, _ := s.db.GetConfig(cfgSearchURL)
+	k, _ := s.db.GetConfig(cfgSearchKey)
+	return searchConf{Engine: e, URL: strings.TrimRight(u, "/"), Key: k}
+}
+
+var (
+	braveURL  = "https://api.search.brave.com/res/v1/web/search"
+	tavilyURL = "https://api.tavily.com/search"
+	ddgSearch = webSearch
+)
+
+// engineName is how the engine is called to people and to the model.
+func engineName(e string) string {
+	switch e {
+	case "searxng":
+		return "SearXNG"
+	case "brave":
+		return "Brave Search"
+	case "tavily":
+		return "Tavily"
+	}
+	return "DuckDuckGo"
+}
+
+// searchWith asks the engine c names; DuckDuckGo if that one fails. It
+// tells which engine the results came from (and why, when it was not the
+// chosen one).
+func searchWith(ctx context.Context, c searchConf, q string, n int) ([]searchResult, string, error) {
+	var rs []searchResult
+	var err error
+	switch c.Engine {
+	case "searxng":
+		rs, err = searchSearx(ctx, c, q)
+	case "brave":
+		rs, err = searchBrave(ctx, c, q, n)
+	case "tavily":
+		rs, err = searchTavily(ctx, c, q, n)
+	default:
+		rs, err = ddgSearch(ctx, q, n)
+		return rs, "DuckDuckGo", err
+	}
+	if err != nil || len(rs) == 0 {
+		why := "ничего не нашёл"
+		if err != nil {
+			why = err.Error()
+		}
+		log.Printf("search: %s failed (%s), DuckDuckGo instead", engineName(c.Engine), why)
+		rs, err = ddgSearch(ctx, q, n)
+		return rs, "DuckDuckGo (" + engineName(c.Engine) + " не ответил: " + why + ")", err
+	}
+	if len(rs) > n {
+		rs = rs[:n]
+	}
+	return rs, engineName(c.Engine), nil
+}
+
+// searchPrompt tells the model it can search, and with what.
+func searchPrompt(c searchConf) string {
+	return "\nПоиск в интернете включён (поисковик: " + engineName(c.Engine) + "): блок ```search\nзапрос\n``` - панель найдёт и пришлёт результаты " +
+		"(заголовок, адрес, отрывок) следующим сообщением, с пометкой, через какой поисковик они пришли.\n" +
+		"Ищи активно: свежие данные, версии, документация, тексты ошибок, всё, в чём не уверен, - сначала поиск, потом ответ со ссылками на найденное. " +
+		"Чтобы прочитать найденную страницу целиком (или адрес, который дал пользователь), - блок ```fetch\nhttps://адрес\n```: придёт её текст. " +
+		"Одно действие за ответ. Ссылки не выдумывай."
+}
+
+// getJSON fetches url (with the headers) into v.
+func getJSON(ctx context.Context, method, url string, body io.Reader, hdr map[string]string, v any) error {
+	req, err := http.NewRequestWithContext(ctx, method, url, body)
+	if err != nil {
+		return err
+	}
+	req.Header.Set("Accept", "application/json")
+	for k, val := range hdr {
+		req.Header.Set(k, val)
+	}
+	resp, err := searchClient.Do(req)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode/100 != 2 {
+		return errors.New("поисковик ответил " + resp.Status)
+	}
+	return json.NewDecoder(io.LimitReader(resp.Body, 4<<20)).Decode(v)
+}
+
+// searchSearx: a SearXNG with JSON output on (search.formats: json).
+func searchSearx(ctx context.Context, c searchConf, q string) ([]searchResult, error) {
+	if c.URL == "" {
+		return nil, errors.New("не задан адрес SearXNG")
+	}
+	var out struct {
+		Results []struct{ Title, URL, Content string } `json:"results"`
+	}
+	if err := getJSON(ctx, http.MethodGet, c.URL+"/search?format=json&q="+url.QueryEscape(q), nil, nil, &out); err != nil {
+		return nil, err
+	}
+	var rs []searchResult
+	for _, r := range out.Results {
+		rs = append(rs, searchResult{Title: r.Title, URL: r.URL, Snippet: text(r.Content)})
+	}
+	return rs, nil
+}
+
+func searchBrave(ctx context.Context, c searchConf, q string, n int) ([]searchResult, error) {
+	var out struct {
+		Web struct {
+			Results []struct{ Title, URL, Description string } `json:"results"`
+		} `json:"web"`
+	}
+	err := getJSON(ctx, http.MethodGet, braveURL+"?count="+strconv.Itoa(n)+"&q="+url.QueryEscape(q), nil,
+		map[string]string{"X-Subscription-Token": c.Key}, &out)
+	if err != nil {
+		return nil, err
+	}
+	var rs []searchResult
+	for _, r := range out.Web.Results {
+		rs = append(rs, searchResult{Title: text(r.Title), URL: r.URL, Snippet: text(r.Description)})
+	}
+	return rs, nil
+}
+
+func searchTavily(ctx context.Context, c searchConf, q string, n int) ([]searchResult, error) {
+	b, _ := json.Marshal(map[string]any{"query": q, "max_results": n})
+	var out struct {
+		Results []struct{ Title, URL, Content string } `json:"results"`
+	}
+	err := getJSON(ctx, http.MethodPost, tavilyURL, strings.NewReader(string(b)),
+		map[string]string{"Authorization": "Bearer " + c.Key, "Content-Type": "application/json"}, &out)
+	if err != nil {
+		return nil, err
+	}
+	var rs []searchResult
+	for _, r := range out.Results {
+		rs = append(rs, searchResult{Title: r.Title, URL: r.URL, Snippet: r.Content})
+	}
+	return rs, nil
+}
+
+// webSearch asks DuckDuckGo for q: up to n results.
+func webSearch(ctx context.Context, q string, n int) ([]searchResult, error) {
+	var last error
+	for _, base := range []string{"https://lite.duckduckgo.com/lite/?q=", "https://html.duckduckgo.com/html/?q="} {
+		req, _ := http.NewRequestWithContext(ctx, http.MethodGet, base+url.QueryEscape(q), nil)
+		req.Header.Set("User-Agent", "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/124.0 Safari/537.36")
+		req.Header.Set("Accept-Language", "ru,en;q=0.8")
+		resp, err := searchClient.Do(req)
+		if err != nil {
+			last = err
+			continue
+		}
+		b, _ := io.ReadAll(io.LimitReader(resp.Body, 2<<20))
+		resp.Body.Close()
+		rs := parseDDG(string(b))
+		if resp.StatusCode == http.StatusOK && len(rs) > 0 {
+			if len(rs) > n {
+				rs = rs[:n]
+			}
+			return rs, nil
+		}
+		if resp.StatusCode == http.StatusOK {
+			last = errors.New("ничего не нашлось")
+		} else {
+			last = errors.New("поисковик не ответил (" + resp.Status + "), возможно, временно ограничил запросы")
+		}
+	}
+	return nil, last
+}
+
+// POST /api/panel/ai/search - {q}: the results, for a user with the
+// assistant on (the «Поиск» switch is the page's: it lets the model ask).
+func (s *Server) handleAISearch(w http.ResponseWriter, r *http.Request) {
+	a := s.currentAdmin(r)
+	if !s.aiOn(a.ID) {
+		writeJSON(w, map[string]any{"ok": false, "error": "ассистент выключен в профиле"})
+		return
+	}
+	var in struct {
+		Q string `json:"q"`
+	}
+	if err := json.NewDecoder(http.MaxBytesReader(w, r.Body, 4<<10)).Decode(&in); err != nil || strings.TrimSpace(in.Q) == "" {
+		writeJSON(w, map[string]any{"ok": false, "error": "пустой запрос"})
+		return
+	}
+	rs, used, err := searchWith(r.Context(), s.searchConf(), strings.TrimSpace(in.Q), 6)
+	if err != nil {
+		writeJSON(w, map[string]any{"ok": false, "error": err.Error(), "engine": used})
+		return
+	}
+	writeJSON(w, map[string]any{"ok": true, "data": rs, "engine": used})
+}
@@ -0,0 +1,107 @@
+package server
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"strings"
+	"testing"
+)
+
+// The results of DuckDuckGo's light page: titles, real addresses (not its
+// redirects), snippets without tags.
+func TestParseDDGLite(t *testing.T) {
+	b, err := os.ReadFile("testdata/ddg_lite.html")
+	if err != nil {
+		t.Fatal(err)
+	}
+	rs := parseDDG(string(b))
+	if len(rs) < 5 {
+		t.Fatalf("results: %d", len(rs))
+	}
+	r := rs[0]
+	if r.URL != "https://go.dev/doc/database/cancel-operations" || !strings.Contains(r.Title, "Canceling in-progress operations") ||
+		!strings.Contains(r.Snippet, "Learn how to use context.Context") || strings.Contains(r.Snippet, "<b>") {
+		t.Fatalf("first: %+v", r)
+	}
+}
+
+// Each search engine of the settings, and DuckDuckGo when the chosen one
+// fails.
+func TestSearchProviders(t *testing.T) {
+	var gotKey, gotQ string
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		switch {
+		case r.URL.Path == "/search" && r.URL.Query().Get("format") == "json": // SearXNG
+			gotQ = r.URL.Query().Get("q")
+			fmt.Fprint(w, `{"results":[{"title":"SX","url":"https://a.example/","content":"from searx"}]}`)
+		case r.URL.Path == "/res/v1/web/search": // Brave
+			gotKey, gotQ = r.Header.Get("X-Subscription-Token"), r.URL.Query().Get("q")
+			fmt.Fprint(w, `{"web":{"results":[{"title":"BR","url":"https://b.example/","description":"from <strong>brave</strong>"}]}}`)
+		case r.URL.Path == "/search" && r.Method == http.MethodPost: // Tavily
+			var in map[string]any
+			_ = json.NewDecoder(r.Body).Decode(&in)
+			gotKey, gotQ = r.Header.Get("Authorization"), in["query"].(string)
+			fmt.Fprint(w, `{"results":[{"title":"TV","url":"https://t.example/","content":"from tavily"}]}`)
+		default:
+			http.Error(w, "no", 500)
+		}
+	}))
+	defer srv.Close()
+	braveURL, tavilyURL = srv.URL+"/res/v1/web/search", srv.URL+"/search"
+	ctx := context.Background()
+
+	rs, used, err := searchWith(ctx, searchConf{Engine: "searxng", URL: srv.URL}, "q1", 6)
+	if err != nil || len(rs) != 1 || rs[0].Title != "SX" || gotQ != "q1" || used != "SearXNG" {
+		t.Fatalf("searxng: %+v %v", rs, err)
+	}
+	rs, _, err = searchWith(ctx, searchConf{Engine: "brave", Key: "bk"}, "q2", 6)
+	if err != nil || rs[0].Snippet != "from brave" || gotKey != "bk" || gotQ != "q2" {
+		t.Fatalf("brave: %+v %v %q", rs, err, gotKey)
+	}
+	rs, used, err = searchWith(ctx, searchConf{Engine: "tavily", Key: "tk"}, "q3", 6)
+	if err != nil || rs[0].Title != "TV" || gotKey != "Bearer tk" || gotQ != "q3" || used != "Tavily" {
+		t.Fatalf("tavily: %+v %v %q", rs, err, gotKey)
+	}
+	// The chosen one fails: DuckDuckGo instead (stood in for here).
+	ddgSearch = func(ctx context.Context, q string, n int) ([]searchResult, error) {
+		return []searchResult{{Title: "DDG"}}, nil
+	}
+	rs, used, err = searchWith(ctx, searchConf{Engine: "searxng", URL: srv.URL + "/broken"}, "q4", 6)
+	if err != nil || rs[0].Title != "DDG" || !strings.Contains(used, "DuckDuckGo") || !strings.Contains(used, "SearXNG не ответил") {
+		t.Fatalf("fallback: %+v %v", rs, err)
+	}
+}
+
+// The chosen engine's limit spent (429 and the like): DuckDuckGo answers.
+func TestSearchLimitFallsBack(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		http.Error(w, `{"error":"rate limit"}`, http.StatusTooManyRequests)
+	}))
+	defer srv.Close()
+	old := ddgSearch
+	defer func() { ddgSearch = old }()
+	ddgSearch = func(ctx context.Context, q string, n int) ([]searchResult, error) {
+		return []searchResult{{Title: "DDG " + q}}, nil
+	}
+	braveURL, tavilyURL = srv.URL, srv.URL
+	for _, e := range []string{"brave", "tavily", "searxng"} {
+		rs, _, err := searchWith(context.Background(), searchConf{Engine: e, Key: "k", URL: srv.URL}, "x", 6)
+		if err != nil || len(rs) != 1 || rs[0].Title != "DDG x" {
+			t.Fatalf("%s: %+v %v", e, rs, err)
+		}
+	}
+}
+
+// The model is told which engine it searches with.
+func TestSearchPromptNamesEngine(t *testing.T) {
+	if p := searchPrompt(searchConf{Engine: "tavily"}); !strings.Contains(p, "Tavily") || strings.Contains(p, "DuckDuckGo") {
+		t.Fatalf("tavily: %s", p)
+	}
+	if p := searchPrompt(searchConf{}); !strings.Contains(p, "DuckDuckGo") {
+		t.Fatalf("default: %s", p)
+	}
+}
@@ -1,7 +1,9 @@
 package server

 import (
+	"crypto/sha256"
 	"embed"
+	"encoding/hex"
 	"html/template"
 	"io/fs"
 	"log"
@@ -9,6 +11,8 @@ import (
 	"net/http"
 	"strconv"
 	"strings"
+	"sync"
+	"sync/atomic"
 	texttemplate "text/template"
 )

@@ -24,7 +28,8 @@ type Options struct {
 	// nginx TLS); set false only for plain-HTTP local testing.
 	SecureCookies bool
 	// TunnelAddr is the listen address for the direct TCP+UDP forward tunnel
-	// (default ":8446"). Empty disables direct forwarding.
+	// Empty disables direct forwarding. The port can be overridden from the
+	// settings page.
 	TunnelAddr string
 }

@@ -33,12 +38,36 @@ type Server struct {
 	db            *DB
 	hub           *Hub
 	fwd           *forwardManager
+	tun           *tunnelHub
+	udp           *udpRelay
 	ufw           *ufwManager
 	tmpl          *template.Template
 	limiter       *loginLimiter
 	distDir       string
 	secureCookies bool
 	installTmpl   *texttemplate.Template
+
+	// Direct tunnel: bind host and port of the -tunnel address, and the port
+	// currently listened on (the settings override, else the default).
+	// tunnelDefault 0 means the tunnel is disabled.
+	tunnelBind    string
+	tunnelDefault int
+	tunnelMu      sync.Mutex // serializes port changes
+	tunnelPort    atomic.Int64
+
+	stats      statCache         // last load sample per agent, for the status page
+	relays     speedRelays       // speed tests that run through the browser
+	meters     speedMeters       // byte counts of the speed tests under way
+	xfers      xfers             // files on their way between a browser and an agent
+	ship       shipping          // files on their way from one machine to another
+	viaDirectA sync.Map          // agent id -> true while it reaches the server at the direct address
+	challenges challenges        // passkey challenges handed out
+	wsAgents   wsAgents          // agents on their WebSocket now
+	pinMisses  pinMisses         // wrong PINs per session
+	assets     map[string]string // static file -> hash of its content
+
+	upd    updState                  // the server's own updating
+	updRun func(script []byte) error // runs the install script; the real one unless a test sets it
 }

 // New builds the server, parsing embedded templates.
@@ -46,7 +75,15 @@ func New(opts Options) (*Server, error) {
 	if err := opts.DB.ensureDefaults(); err != nil {
 		return nil, err
 	}
-	tmpl, err := template.ParseFS(webFS, "web/templates/*.html")
+	mainHost = func() string { return directHost(opts.DB.HostAddress()) }
+	staticFS, _ := fs.Sub(webFS, "web/static")
+	assets := assetHashes(staticFS)
+	funcs := template.FuncMap{
+		// asset is a static file's URL with its content hash, so a new
+		// release is a new URL that no browser or proxy has cached.
+		"asset": func(name string) string { return "/static/" + name + "?v=" + assets[name] },
+	}
+	tmpl, err := template.New("").Funcs(funcs).ParseFS(webFS, "web/templates/*.html")
 	if err != nil {
 		return nil, err
 	}
@@ -65,26 +102,88 @@ func New(opts Options) (*Server, error) {
 		db:            opts.DB,
 		hub:           hub,
 		fwd:           newForwardManager(hub, tun, udp),
-		ufw:           newUfwManager(opts.DB, portFromAddr(opts.TunnelAddr)),
+		tun:           tun,
+		udp:           udp,
 		tmpl:          tmpl,
 		limiter:       newLoginLimiter(),
 		distDir:       opts.DistDir,
 		secureCookies: opts.SecureCookies,
 		installTmpl:   installTmpl,
+		assets:        assets,
 	}
-	// Start the direct forward tunnel (TCP mux + UDP) on 8446.
+	s.ufw = newUfwManager(opts.DB, s.TunnelPort)
+	// Start the direct forward tunnel (TCP mux + UDP), on the port from the
+	// settings page if one is set there.
 	if opts.TunnelAddr != "" {
-		if err := tun.listen(opts.TunnelAddr); err != nil {
-			log.Printf("tunnel tcp listen %s: %v", opts.TunnelAddr, err)
+		s.tunnelBind, s.tunnelDefault = splitAddr(opts.TunnelAddr)
+	}
+	if s.tunnelDefault > 0 {
+		port := s.tunnelDefault
+		if p := s.db.TunnelPort(); p > 0 {
+			port = p
 		}
-		if err := udp.listen(opts.TunnelAddr); err != nil {
-			log.Printf("tunnel udp listen %s: %v", opts.TunnelAddr, err)
+		s.tunnelPort.Store(int64(port))
+		addr := s.tunnelListenAddr(port)
+		if err := tun.listen(addr); err != nil {
+			log.Printf("tunnel tcp listen %s: %v", addr, err)
+		}
+		if err := udp.listen(addr); err != nil {
+			log.Printf("tunnel udp listen %s: %v", addr, err)
 		}
 	}
 	s.restoreForwards()
+	go s.ufw.sync()
 	return s, nil
 }

+// TunnelPort is the port the direct tunnel listens on (0 = disabled).
+func (s *Server) TunnelPort() int { return int(s.tunnelPort.Load()) }
+
+func (s *Server) tunnelListenAddr(port int) string {
+	return net.JoinHostPort(s.tunnelBind, strconv.Itoa(port))
+}
+
+// tunnelAdvert is the tunnel address handed to agents as "host:port". The host
+// is the one set in Settings, else the direct address's (the main one may be
+// behind a proxy that carries no raw TCP), else empty: agents then use the
+// panel's host.
+func (s *Server) tunnelAdvert() string {
+	port := s.TunnelPort()
+	if port == 0 {
+		return ""
+	}
+	host := s.db.TunnelHost()
+	if host == "" {
+		host = directHost(s.db.DirectAddress())
+	}
+	return net.JoinHostPort(host, strconv.Itoa(port))
+}
+
+// setTunnelPort moves the direct tunnel to another port. Connected agents are
+// dropped and redial the new port once their next poll tells them about it.
+func (s *Server) setTunnelPort(port int) error {
+	s.tunnelMu.Lock()
+	defer s.tunnelMu.Unlock()
+	old := s.TunnelPort()
+	if old == 0 || port == old {
+		return nil
+	}
+	addr := s.tunnelListenAddr(port)
+	if err := s.tun.listen(addr); err != nil {
+		return err
+	}
+	if err := s.udp.listen(addr); err != nil {
+		// Keep TCP and UDP on the same port: go back to the old one.
+		if rerr := s.tun.listen(s.tunnelListenAddr(old)); rerr != nil {
+			log.Printf("tunnel tcp listen %s: %v", s.tunnelListenAddr(old), rerr)
+		}
+		return err
+	}
+	s.tunnelPort.Store(int64(port))
+	go s.ufw.sync()
+	return nil
+}
+
 // restoreForwards re-opens the host listeners for all saved forward rules.
 func (s *Server) restoreForwards() {
 	rules, err := s.db.ListForwardRules()
@@ -93,6 +192,12 @@ func (s *Server) restoreForwards() {
 		return
 	}
 	for _, r := range rules {
+		// Rules of an agent deleted by an older version: drop them.
+		if a, err := s.db.GetAgent(r.AgentID); err == nil && a == nil {
+			log.Printf("forward rule %d: agent %s is gone, removing", r.ID, r.AgentID)
+			s.removeForward(r.ID)
+			continue
+		}
 		if err := s.fwd.open(r); err != nil {
 			log.Printf("restore forward rule %d (%s:%d): %v", r.ID, r.ListenAddr, r.HostPort, err)
 		}
@@ -105,7 +210,7 @@ func (s *Server) Handler() http.Handler {

 	// Static assets (xterm.js etc.) from the embedded FS.
 	staticFS, _ := fs.Sub(webFS, "web/static")
-	mux.Handle("GET /static/", http.StripPrefix("/static/", http.FileServer(http.FS(staticFS))))
+	mux.Handle("GET /static/", http.StripPrefix("/static/", staticHandler(staticFS, s.assets)))

 	// Public: install script + agent binary downloads.
 	mux.HandleFunc("GET /install.sh", s.handleInstallScript)
@@ -120,35 +225,103 @@ func (s *Server) Handler() http.Handler {
 	mux.HandleFunc("GET /login", s.handleLoginForm)
 	mux.HandleFunc("POST /login", s.handleLoginSubmit)
 	mux.HandleFunc("POST /logout", s.handleLogout)
+	mux.HandleFunc("POST /api/login/key/begin", s.handleKeyLoginBegin)
+	mux.HandleFunc("POST /api/login/key/finish", s.handleKeyLoginFinish)

 	// Panel (admin-only).
 	mux.Handle("GET /{$}", s.requireAdmin(s.handleDashboard))
-	mux.Handle("GET /agents/{id}/terminal", s.requireAdmin(s.handleTerminalPage))
-	mux.Handle("GET /agents/{id}/files", s.requireAdmin(s.handleFilesPage))
+	mux.Handle("GET /workspace", s.requireAdmin(s.handleShell))
+	mux.Handle("GET /terminal", s.requireAdmin(s.handleShell)) // the old address
+	mux.Handle("GET /agents/{id}/terminal", s.requireAdmin(s.handleShell))
+	mux.Handle("GET /agents/{id}/{kind}", s.requireAdmin(s.handleShell)) // files
 	mux.Handle("GET /agents/{id}/forwards", s.requireAdmin(s.handleForwardsPage))
+	mux.Handle("GET /agents/{id}/status", s.requireAdmin(s.handleStatusPage))
 	mux.Handle("GET /agents/{id}/edit", s.requireAdmin(s.handleAgentEdit))
 	mux.Handle("POST /agents/{id}/rename", s.requireAdmin(s.handleAgentRename))
 	mux.Handle("POST /agents/{id}/update", s.requireAdmin(s.handleAgentUpdate))
 	mux.Handle("POST /agents/{id}/user", s.requireAdmin(s.handleAgentSetUser))
+	mux.Handle("POST /agents/{id}/transport", s.requireAdmin(s.handleAgentTransport))
 	mux.Handle("POST /agents/{id}/users/add", s.requireAdmin(s.handleAgentAddUser))
-	mux.Handle("POST /agents/{id}/delete", s.requireAdmin(s.handleAgentDelete))
-	mux.Handle("GET /settings", s.requireAdmin(s.handleSettings))
-	mux.Handle("POST /settings/host", s.requireAdmin(s.handleSetHost))
-	mux.Handle("POST /settings/secret/rotate", s.requireAdmin(s.handleRotateSecret))
-	mux.Handle("POST /settings/admins/add", s.requireAdmin(s.handleAddAdmin))
-	mux.Handle("POST /settings/admins/delete", s.requireAdmin(s.handleDeleteAdmin))
-	mux.Handle("POST /settings/ufw/toggle", s.requireAdmin(s.handleUfwToggle))
-	mux.Handle("POST /settings/ufw/revoke", s.requireAdmin(s.handleUfwRevoke))
+	mux.Handle("POST /agents/{id}/delete", s.adminsOnly(s.handleAgentDelete))
+	mux.Handle("GET /settings", s.adminsOnly(s.handleSettings))
+	mux.Handle("POST /settings/host", s.adminsOnly(s.handleSetHost))
+	mux.Handle("POST /settings/tunnel", s.adminsOnly(s.handleSetTunnel))
+	mux.Handle("POST /settings/secret/rotate", s.adminsOnly(s.handleRotateSecret))
+	mux.Handle("POST /settings/install/code", s.adminsOnly(s.handleInstallCode))
+	mux.Handle("POST /settings/admins/add", s.adminsOnly(s.handleAddAdmin))
+	mux.Handle("POST /settings/admins/delete", s.adminsOnly(s.handleDeleteAdmin))
+	mux.Handle("GET /api/panel/users/{id}/agents", s.adminsOnly(s.handleUserAgents))
+	mux.Handle("POST /api/panel/users/{id}", s.adminsOnly(s.handleUserEdit))
+	mux.Handle("POST /settings/admins/keys/reset", s.adminsOnly(s.handleResetAdminKeys))
+	mux.Handle("GET /api/panel/account", s.requireAdmin(s.handleAccount))
+	mux.Handle("GET /api/panel/account/prefs", s.requireAdmin(s.handlePrefs))
+	mux.Handle("POST /api/panel/account/prefs", s.requireAdmin(s.handlePrefsSet))
+	mux.Handle("GET /api/panel/ai", s.requireAdmin(s.handleAIState))
+	mux.Handle("GET /api/panel/ssh/hosts", s.requireAdmin(s.handleSSHHosts))
+	mux.Handle("POST /api/panel/ssh/hosts", s.requireAdmin(s.handleSSHHostAdd))
+	mux.Handle("POST /api/panel/ssh/hosts/{hid}/delete", s.requireAdmin(s.handleSSHHostDelete))
+	mux.Handle("POST /api/panel/ai/toggle", s.requireAdmin(s.handleAIToggle))
+	mux.Handle("POST /api/panel/ai/chat", s.requireAdmin(s.handleAIChat))
+	mux.Handle("GET /api/panel/ai/chats", s.requireAdmin(s.handleAIChats))
+	mux.Handle("POST /api/panel/ai/chats", s.requireAdmin(s.handleAIChatNew))
+	mux.Handle("GET /api/panel/ai/chats/{cid}", s.requireAdmin(s.handleAIHistory))
+	mux.Handle("POST /api/panel/ai/chats/{cid}/delete", s.requireAdmin(s.handleAIChatDelete))
+	mux.Handle("POST /api/panel/ai/note", s.requireAdmin(s.handleAINote))
+	mux.Handle("POST /api/panel/ai/search", s.requireAdmin(s.handleAISearch))
+	mux.Handle("POST /api/panel/ai/fetch", s.requireAdmin(s.handleAIFetch))
+	mux.Handle("POST /api/panel/ai/image", s.requireAdmin(s.handleAIImage))
+	mux.Handle("GET /api/panel/ai/image/{job}", s.requireAdmin(s.handleAIImageJob))
+	mux.Handle("POST /settings/ai", s.adminsOnly(s.handleSetAI))
+	mux.Handle("POST /settings/autoupdate", s.adminsOnly(s.handleSetAutoUpdate))
+	mux.Handle("POST /api/panel/update/check", s.adminsOnly(s.handleUpdateCheck))
+	mux.Handle("GET /api/panel/update/offer", s.adminsOnly(s.handleUpdateOffer))
+	mux.Handle("POST /api/panel/update/decline", s.adminsOnly(s.handleUpdateDecline))
+	mux.Handle("POST /api/panel/update/run", s.adminsOnly(s.handleUpdateRun))
+	mux.Handle("POST /settings/db", s.adminsOnly(s.handleSetDB))
+	mux.Handle("POST /settings/db/restart", s.adminsOnly(s.handleRestart))
+	mux.Handle("POST /api/panel/account/keys/begin", s.requireAdmin(s.handleKeyRegisterBegin))
+	mux.Handle("POST /api/panel/account/keys/finish", s.requireAdmin(s.handleKeyRegisterFinish))
+	mux.Handle("POST /api/panel/account/keys/{id}/delete", s.requireAdmin(s.handleKeyDelete))
+	mux.Handle("POST /api/panel/account/password", s.requireAdmin(s.handlePasswordToggle))
+	mux.Handle("POST /api/panel/account/pin", s.requireAdmin(s.handlePinSet))
+	mux.Handle("GET /api/panel/pin", s.requireAdmin(s.handlePinState))
+	mux.Handle("POST /api/panel/pin/check", s.requireAdmin(s.handlePinCheck))
+	mux.Handle("POST /api/panel/account/password/change", s.requireAdmin(s.handlePasswordChange))
+	mux.Handle("POST /settings/ufw/toggle", s.adminsOnly(s.handleUfwToggle))
+	mux.Handle("POST /settings/ufw/add", s.adminsOnly(s.handleUfwAdd))
+	mux.Handle("POST /settings/ufw/revoke", s.adminsOnly(s.handleUfwRevoke))

 	// Panel terminal over HTTP long-polling (admin-only).
 	mux.Handle("POST /api/panel/term/{agentID}/open", s.requireAdmin(s.handlePanelOpen))
 	mux.Handle("GET /api/panel/term/{sid}/out", s.requireAdmin(s.handlePanelOut))
 	mux.Handle("POST /api/panel/term/{sid}/in", s.requireAdmin(s.handlePanelIn))
+	mux.Handle("GET /api/panel/term/{sid}/ws", s.requireAdmin(s.handlePanelTermWS))
 	mux.Handle("POST /api/panel/term/{sid}/close", s.requireAdmin(s.handlePanelClose))

 	// Panel file manager (admin-only).
 	mux.Handle("GET /api/panel/agents/{id}/fs/download", s.requireAdmin(s.handleFSDownload))
+	mux.Handle("POST /api/panel/agents/{id}/fs/upload", s.requireAdmin(s.handleFSUploadStart))
+	mux.Handle("PUT /api/panel/fs/xfer/{xid}/{i}", s.requireAdmin(s.handleXferPut))
+	mux.Handle("POST /api/panel/fs/xfer/{xid}/cancel", s.requireAdmin(s.handleXferCancel))
+	mux.Handle("GET /api/panel/fs/xfer/{xid}/result", s.requireAdmin(s.handleXferResult))
+	mux.Handle("POST /api/panel/agents/{id}/fs/ship", s.requireAdmin(s.handleFSShip))
+	mux.Handle("GET /api/panel/fs/job/{jid}", s.requireAdmin(s.handleShipJob))
+	mux.Handle("POST /api/panel/fs/job/{jid}/cancel", s.requireAdmin(s.handleShipCancel))
 	mux.Handle("POST /api/panel/agents/{id}/fs/{op}", s.requireAdmin(s.handleFSOp))
+	mux.Handle("POST /api/panel/agents/{id}/sshfs/open", s.requireAdmin(s.handleSSHFSOpen))
+	mux.Handle("GET /api/panel/agents/{id}/sshfs/{conn}/download", s.requireAdmin(s.handleSSHFSDownload))
+	mux.Handle("POST /api/panel/agents/{id}/sshfs/{conn}/upload", s.requireAdmin(s.handleSSHFSUpload))
+	mux.Handle("POST /api/panel/agents/{id}/sshfs/{conn}/{op}", s.requireAdmin(s.handleSSHFSOp))
+
+	// Machine status (admin).
+	mux.Handle("GET /api/panel/agents/presence", s.requireAdmin(s.handlePresence))
+	mux.Handle("GET /api/panel/agents/{id}/stat", s.requireAdmin(s.handleAgentStat))
+	mux.Handle("POST /api/panel/agents/{id}/speed", s.requireAdmin(s.handleAgentSpeed))
+	mux.Handle("GET /api/panel/agents/{id}/speed/progress", s.requireAdmin(s.handleSpeedProgress))
+	mux.Handle("GET /api/panel/ping", s.requireAdmin(s.handlePanelPing))
+	mux.Handle("POST /api/panel/agents/{id}/speed/relay", s.requireAdmin(s.handleSpeedRelayOpen))
+	mux.Handle("POST /api/panel/agents/{id}/speed/down", s.requireAdmin(s.handleSpeedRelayFeed))
+	mux.Handle("GET /api/panel/agents/{id}/speed/up", s.requireAdmin(s.handleSpeedRelayDrain))

 	// Panel port forwarding (admin-only).
 	mux.Handle("POST /agents/{id}/forwards/add", s.requireAdmin(s.handleForwardAdd))
@@ -157,10 +330,21 @@ func (s *Server) Handler() http.Handler {
 	// Agent API (token/secret auth inside handlers).
 	mux.HandleFunc("POST /api/agent/enroll", s.handleEnroll)
 	mux.HandleFunc("GET /api/agent/poll", s.handlePoll)
+	mux.HandleFunc("GET /api/agent/ws", s.handleAgentWS)
+	mux.HandleFunc("GET /api/agent/config", s.handleAgentConfig)
 	mux.HandleFunc("GET /api/agent/term/{sid}/in", s.handleTermIn)
 	mux.HandleFunc("POST /api/agent/term/{sid}/out", s.handleTermOut)
 	mux.HandleFunc("GET /api/agent/task/{id}", s.handleTaskFetch)
 	mux.HandleFunc("POST /api/agent/task/{id}/result", s.handleTaskResult)
+	mux.HandleFunc("GET /api/agent/speed/down", s.handleSpeedDown)
+	mux.HandleFunc("POST /api/agent/speed/up", s.handleSpeedUp)
+	mux.HandleFunc("GET /api/agent/speed/relay/down", s.handleSpeedRelayDown)
+	mux.HandleFunc("POST /api/agent/speed/relay/up", s.handleSpeedRelayUp)
+	mux.HandleFunc("GET /api/agent/fs/xfer/{xid}/{i}", s.handleAgentXferGet)
+	mux.HandleFunc("POST /api/agent/fs/xfer/{xid}/{i}", s.handleAgentXferPost)
+	mux.HandleFunc("POST /api/agent/fs/job/{jid}/progress", s.handleShipProgress)
+	mux.HandleFunc("POST /api/agent/fs/relay/{rid}/{i}", s.handleRelayPost)
+	mux.HandleFunc("GET /api/agent/fs/relay/{rid}/{i}", s.handleRelayGet)

 	return s.logRequests(mux)
 }
@@ -177,6 +361,36 @@ func (s *Server) requireAdmin(h http.HandlerFunc) http.Handler {
 			http.Redirect(w, r, "/login", http.StatusSeeOther)
 			return
 		}
+		// A user who is not an admin uses only the machines given to them:
+		// any other is as if it were not there.
+		if !admin.IsAdmin() {
+			p := r.URL.Path
+			if strings.HasPrefix(p, "/agents/") || strings.HasPrefix(p, "/api/panel/agents/") || strings.HasPrefix(p, "/api/panel/term/") {
+				id := r.PathValue("id")
+				if id == "" {
+					id = r.PathValue("agentID")
+				}
+				if id != "" && id != "presence" && !s.db.CanUseAgent(admin, id) {
+					http.NotFound(w, r)
+					return
+				}
+			}
+		}
+		h(w, r)
+	})
+}
+
+// adminsOnly lets only admins through: the settings, users, the firewall.
+func (s *Server) adminsOnly(h http.HandlerFunc) http.Handler {
+	return s.requireAdmin(func(w http.ResponseWriter, r *http.Request) {
+		if !s.currentAdmin(r).IsAdmin() {
+			if r.Method == http.MethodGet && !strings.HasPrefix(r.URL.Path, "/api/") {
+				http.Redirect(w, r, "/", http.StatusSeeOther)
+				return
+			}
+			http.Error(w, "только для администраторов", http.StatusForbidden)
+			return
+		}
 		h(w, r)
 	})
 }
@@ -202,17 +416,15 @@ func (s *Server) render(w http.ResponseWriter, name string, data map[string]any)
 	}
 }

-// portFromAddr extracts the numeric port from a "host:port" or ":port" address.
-func portFromAddr(addr string) int {
-	if addr == "" {
-		return 0
-	}
-	_, p, err := net.SplitHostPort(addr)
+// splitAddr splits a "host:port" or ":port" listen address. The port is 0 when
+// the address has none.
+func splitAddr(addr string) (host string, port int) {
+	h, p, err := net.SplitHostPort(addr)
 	if err != nil {
-		return 0
+		return "", 0
 	}
 	n, _ := strconv.Atoi(p)
-	return n
+	return h, n
 }

 func clientIP(r *http.Request) string {
@@ -232,3 +444,44 @@ func clientIP(r *http.Request) string {
 	}
 	return host
 }
+
+// assetHashes hashes every static file, for asset URLs and ETags.
+func assetHashes(fsys fs.FS) map[string]string {
+	out := map[string]string{}
+	_ = fs.WalkDir(fsys, ".", func(p string, d fs.DirEntry, err error) error {
+		if err != nil || d.IsDir() {
+			return nil
+		}
+		if data, err := fs.ReadFile(fsys, p); err == nil {
+			sum := sha256.Sum256(data)
+			out[p] = hex.EncodeToString(sum[:8])
+		}
+		return nil
+	})
+	return out
+}
+
+// staticHandler serves the embedded assets. Pages ask for them by URLs that
+// carry the content hash (?v=): such a file never changes and is kept for a
+// year, by the browser and by a proxy in front such as Cloudflare. Asked for
+// without it, a file is checked every time against its ETag.
+func staticHandler(fsys fs.FS, hashes map[string]string) http.Handler {
+	files := http.FileServer(http.FS(fsys))
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		// The JS tests sit beside the scripts but are not served.
+		if strings.HasSuffix(r.URL.Path, ".test.js") {
+			http.NotFound(w, r)
+			return
+		}
+		h := hashes[strings.TrimPrefix(r.URL.Path, "/")]
+		if h != "" {
+			w.Header().Set("ETag", `"`+h+`"`)
+		}
+		if v := r.URL.Query().Get("v"); h != "" && v == h {
+			w.Header().Set("Cache-Control", "public, max-age=31536000, immutable")
+		} else {
+			w.Header().Set("Cache-Control", "no-cache")
+		}
+		files.ServeHTTP(w, r)
+	})
+}
@@ -0,0 +1,496 @@
+package server
+
+import (
+	"context"
+	"encoding/json"
+	"net/http"
+	"path"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/x-grk/longpolling-remote-access/internal/proto"
+)
+
+// Sending a file or folder to another machine. The sending agent packs it as
+// a tar stream; to another agent the stream goes in pieces through a relay
+// here, a few pieces held at most, and the receiving agent unpacks it as it
+// comes. To an SSH host the sending agent writes it there itself. The panel
+// follows a job: how far the sender is, and the result.
+
+// relay carries one stream between two agents, in numbered pieces.
+type relay struct {
+	id, from, to string
+
+	mu      sync.Mutex
+	changed chan struct{}
+	chunks  map[int][]byte
+	low     int // pieces below it were taken
+	end     int // the last piece's number, -1 until it came
+	err     string
+}
+
+func (x *relay) notify() {
+	close(x.changed)
+	x.changed = make(chan struct{})
+}
+
+// await waits until ready() holds and returns true with x.mu held.
+func (x *relay) await(ctx context.Context, d time.Duration, ready func() bool) bool {
+	t := time.NewTimer(d)
+	defer t.Stop()
+	for {
+		x.mu.Lock()
+		if ready() {
+			return true
+		}
+		ch := x.changed
+		x.mu.Unlock()
+		select {
+		case <-ch:
+		case <-t.C:
+			return false
+		case <-ctx.Done():
+			return false
+		}
+	}
+}
+
+func (x *relay) fail(msg string) {
+	x.mu.Lock()
+	if x.err == "" {
+		x.err = msg
+		x.chunks = nil
+		x.notify()
+	}
+	x.mu.Unlock()
+}
+
+type shipJob struct {
+	id      string
+	mu      sync.Mutex
+	changed chan struct{}
+	ver     int
+	prog    proto.ShipProgress
+	done    bool
+	res     proto.TaskResult
+	cancel  context.CancelFunc
+	stopped bool
+}
+
+func (j *shipJob) update(fn func()) {
+	j.mu.Lock()
+	fn()
+	j.ver++
+	close(j.changed)
+	j.changed = make(chan struct{})
+	j.mu.Unlock()
+}
+
+type shipping struct {
+	mu     sync.Mutex
+	relays map[string]*relay
+	jobs   map[string]*shipJob
+}
+
+func (c *shipping) relay(id string) *relay {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	return c.relays[id]
+}
+
+func (c *shipping) job(id string) *shipJob {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	return c.jobs[id]
+}
+
+// shipReq is what the panel asks for: Src on this agent to Dir/Name on agent
+// To, or on the SSH host.
+type shipReq struct {
+	Src      string           `json:"src"`
+	Name     string           `json:"name"`
+	Dir      string           `json:"dir"`
+	Conflict string           `json:"conflict"`
+	Move     bool             `json:"move"`
+	To       string           `json:"to"`
+	SSH      *proto.SSHTarget `json:"ssh"`
+	// FromConn, ToConn: that side is an SSH host held by its agent for a
+	// file pane (its connection id); To is still the agent holding ToConn.
+	FromConn string `json:"from_conn"`
+	ToConn   string `json:"to_conn"`
+	// More: other things of Src's folder sent along, under their own names.
+	More []string `json:"more"`
+}
+
+// POST /api/panel/agents/{id}/fs/ship - start sending; the answer names the
+// job to follow.
+func (s *Server) handleFSShip(w http.ResponseWriter, r *http.Request) {
+	from := r.PathValue("id")
+	var q shipReq
+	if err := json.NewDecoder(http.MaxBytesReader(w, r.Body, 64<<10)).Decode(&q); err != nil {
+		writeJSON(w, proto.TaskResult{Error: "bad request"})
+		return
+	}
+	q.Name, q.Dir = strings.TrimSpace(q.Name), strings.TrimSpace(q.Dir)
+	if q.Src == "" || q.Name == "" || strings.Contains(q.Name, "/") || q.Dir == "" {
+		writeJSON(w, proto.TaskResult{Error: "не указано, что и куда"})
+		return
+	}
+	if !s.fsAgent(w, from, true) {
+		return
+	}
+	where := ""
+	if err := s.fillSaved(s.currentAdmin(r).ID, q.SSH); err != nil {
+		writeJSON(w, proto.TaskResult{Error: err.Error()})
+		return
+	}
+	if q.SSH != nil {
+		t := q.SSH
+		t.Host, t.User = strings.TrimSpace(t.Host), strings.TrimSpace(t.User)
+		if t.Port == 0 {
+			t.Port = 22
+		}
+		if t.Host == "" || t.User == "" || t.Port < 1 || t.Port > 65535 {
+			writeJSON(w, proto.TaskResult{Error: "нужны хост, порт и пользователь"})
+			return
+		}
+		where = "ssh:" + t.User + "@" + t.Host + ":" + strconv.Itoa(t.Port)
+	} else {
+		if q.To == "" && q.ToConn != "" {
+			q.To = from
+		}
+		if q.To == "" {
+			writeJSON(w, proto.TaskResult{Error: "не выбрана машина"})
+			return
+		}
+		if !s.db.CanUseAgent(s.currentAdmin(r), q.To) {
+			writeJSON(w, proto.TaskResult{Error: "нет доступа к той машине"})
+			return
+		}
+		if !s.fsAgent(w, q.To, true) {
+			return
+		}
+		where = "agent:" + q.To
+	}
+	ctx, cancel := context.WithTimeout(context.Background(), xferTimeout)
+	j := &shipJob{id: randToken()[:24], changed: make(chan struct{}), cancel: cancel}
+	s.ship.mu.Lock()
+	if s.ship.jobs == nil {
+		s.ship.jobs, s.ship.relays = map[string]*shipJob{}, map[string]*relay{}
+	}
+	s.ship.jobs[j.id] = j
+	s.ship.mu.Unlock()
+	if admin := s.currentAdmin(r); admin != nil {
+		op := "copy"
+		if q.Move {
+			op = "move"
+		}
+		s.db.Audit(admin.ID, from, "fs.ship."+op+":"+q.Src+" -> "+where+":"+strings.TrimSuffix(q.Dir, "/")+"/"+q.Name)
+	}
+	go s.runShip(ctx, j, from, q)
+	data, _ := json.Marshal(map[string]string{"job": j.id})
+	writeJSON(w, proto.TaskResult{OK: true, Data: data})
+}
+
+func (s *Server) runShip(ctx context.Context, j *shipJob, from string, q shipReq) {
+	defer j.cancel()
+	res := s.ship1(ctx, j, from, q)
+	if !res.OK && j.stopped {
+		res.Error = "отменено"
+	}
+	j.update(func() { j.done, j.res = true, res })
+	// The result waits a while for the panel to come for it.
+	time.AfterFunc(xferIdle, func() {
+		s.ship.mu.Lock()
+		delete(s.ship.jobs, j.id)
+		s.ship.mu.Unlock()
+	})
+}
+
+func oldAgent(res proto.TaskResult) proto.TaskResult {
+	if unknownOp(res) {
+		res.Error = "агент не умеет отправлять на другие машины - обновите его"
+	}
+	return res
+}
+
+func (s *Server) ship1(ctx context.Context, j *shipJob, from string, q shipReq) proto.TaskResult {
+	if len(q.More) > 0 && !s.shipsSeveral(from, q) {
+		// One at a time: an SSH address, or an agent from before 0.2.0.
+		var last proto.TaskResult
+		done, skipped := 0, 0
+		for i, p := range append([]string{q.Src}, q.More...) {
+			one := q
+			one.Src, one.More = p, nil
+			if i > 0 {
+				one.Name = path.Base(path.Clean(p))
+			}
+			if last = s.ship1(ctx, j, from, one); !last.OK {
+				return last
+			}
+			var d struct{ Done, Skipped int }
+			_ = json.Unmarshal(last.Data, &d)
+			done, skipped = done+d.Done, skipped+d.Skipped
+		}
+		data, _ := json.Marshal(map[string]int{"done": done, "skipped": skipped})
+		return proto.TaskResult{OK: true, Data: data}
+	}
+	args := proto.FSShipArgs{Src: q.Src, Name: q.Name, Dir: q.Dir, Conflict: q.Conflict, Job: j.id, More: q.More}
+	if q.SSH != nil {
+		args.SSH, args.Move = q.SSH, q.Move
+		res, err := s.waitTask(ctx, from, proto.TaskFSShipOut, args, xferTimeout)
+		if err != nil {
+			return proto.TaskResult{Error: err.Error()}
+		}
+		return oldAgent(res)
+	}
+
+	x := &relay{id: randToken()[:24], from: from, to: q.To, changed: make(chan struct{}), chunks: map[int][]byte{}, end: -1}
+	s.ship.mu.Lock()
+	s.ship.relays[x.id] = x
+	s.ship.mu.Unlock()
+	defer func() {
+		s.ship.mu.Lock()
+		delete(s.ship.relays, x.id)
+		s.ship.mu.Unlock()
+	}()
+	go func() { <-ctx.Done(); x.fail("отменено") }()
+	args.Relay, args.Chunk = x.id, xferChunk
+	inArgs := args
+	args.Conn, inArgs.Conn = q.FromConn, q.ToConn
+
+	var in proto.TaskResult
+	inDone := make(chan struct{})
+	go func() {
+		defer close(inDone)
+		res, err := s.waitTask(ctx, q.To, proto.TaskFSShipIn, inArgs, xferTimeout)
+		if err != nil {
+			res = proto.TaskResult{Error: err.Error()}
+		}
+		in = oldAgent(res)
+		if !in.OK {
+			x.fail(in.Error)
+		}
+	}()
+	out, err := s.waitTask(ctx, from, proto.TaskFSShipOut, args, xferTimeout)
+	if err != nil {
+		out = proto.TaskResult{Error: err.Error()}
+	}
+	out = oldAgent(out)
+	if !out.OK {
+		x.fail(out.Error)
+	}
+	<-inDone
+	if !in.OK {
+		return proto.TaskResult{Error: "на той машине: " + in.Error}
+	}
+	if !out.OK {
+		return out
+	}
+	if q.Move {
+		for _, p := range append([]string{q.Src}, q.More...) {
+			task, del := proto.TaskFSDelTree, any(proto.FSPathArgs{Path: p})
+			if q.FromConn != "" {
+				raw, _ := json.Marshal(proto.FSPathArgs{Path: p})
+				task, del = proto.TaskSSHFSOp, proto.SSHFSArgs{Conn: q.FromConn, Op: "deltree", Args: raw}
+			}
+			res, err := s.waitTask(ctx, from, task, del, fsTaskTimeout)
+			if err == nil && !res.OK {
+				err = errText(res.Error)
+			}
+			if err != nil {
+				return proto.TaskResult{Error: "отправлено, но здесь не удалилось: " + err.Error()}
+			}
+		}
+	}
+	// The receiver's count: what it put down and what it kept as it was.
+	return in
+}
+
+type errText string
+
+func (e errText) Error() string { return string(e) }
+
+// GET /api/panel/fs/job/{jid}?v=N - the job's state once it differs from
+// version N, or after a while anyway.
+func (s *Server) handleShipJob(w http.ResponseWriter, r *http.Request) {
+	j := s.ship.job(r.PathValue("jid"))
+	if j == nil {
+		writeJSON(w, map[string]any{"done": true, "result": proto.TaskResult{Error: "задание не найдено"}})
+		return
+	}
+	seen, _ := strconv.Atoi(r.URL.Query().Get("v"))
+	t := time.NewTimer(25 * time.Second)
+	defer t.Stop()
+	for {
+		j.mu.Lock()
+		if j.ver != seen || j.done {
+			out := map[string]any{"v": j.ver, "progress": j.prog, "done": j.done}
+			if j.done {
+				out["result"] = j.res
+			}
+			j.mu.Unlock()
+			writeJSON(w, out)
+			return
+		}
+		ch := j.changed
+		j.mu.Unlock()
+		select {
+		case <-ch:
+		case <-t.C:
+			seen = -1 // answer with what there is
+		case <-r.Context().Done():
+			return
+		}
+	}
+}
+
+// POST /api/panel/fs/job/{jid}/cancel
+func (s *Server) handleShipCancel(w http.ResponseWriter, r *http.Request) {
+	if j := s.ship.job(r.PathValue("jid")); j != nil {
+		j.update(func() { j.stopped = true })
+		j.cancel()
+	}
+	w.WriteHeader(http.StatusNoContent)
+}
+
+// POST /api/agent/fs/job/{jid}/progress - the sender's progress. 410: the
+// job is over or cancelled, stop.
+func (s *Server) handleShipProgress(w http.ResponseWriter, r *http.Request) {
+	if s.authenticateAgent(r) == nil {
+		http.Error(w, "unauthorized", http.StatusUnauthorized)
+		return
+	}
+	j := s.ship.job(r.PathValue("jid"))
+	var p proto.ShipProgress
+	if j == nil || json.NewDecoder(http.MaxBytesReader(w, r.Body, 4096)).Decode(&p) != nil {
+		http.Error(w, "gone", http.StatusGone)
+		return
+	}
+	stop := false
+	j.update(func() { j.prog, stop = p, j.stopped || j.done })
+	if stop {
+		http.Error(w, "gone", http.StatusGone)
+		return
+	}
+	w.WriteHeader(http.StatusNoContent)
+}
+
+// POST /api/agent/fs/relay/{rid}/{i} - piece i of the stream from the
+// sender, X-Last on the last. 503: no room yet, again; 410: it is over.
+func (s *Server) handleRelayPost(w http.ResponseWriter, r *http.Request) {
+	a := s.authenticateAgent(r)
+	if a == nil {
+		http.Error(w, "unauthorized", http.StatusUnauthorized)
+		return
+	}
+	x := s.ship.relay(r.PathValue("rid"))
+	i, err := strconv.Atoi(r.PathValue("i"))
+	if x == nil || x.from != a.ID || err != nil || i < 0 {
+		http.Error(w, "передача не найдена", http.StatusGone)
+		return
+	}
+	data, err := readPiece(w, r)
+	if err != nil {
+		http.Error(w, "кусок не дошёл", http.StatusBadRequest)
+		return
+	}
+	if !x.await(r.Context(), xferWait, func() bool { return x.err != "" || i < x.low+xferBuffer }) {
+		http.Error(w, "нет места, повторите", http.StatusServiceUnavailable)
+		return
+	}
+	defer x.mu.Unlock()
+	if x.err != "" {
+		http.Error(w, x.err, http.StatusGone)
+		return
+	}
+	if i >= x.low && x.chunks[i] == nil {
+		x.chunks[i] = data
+		if r.Header.Get("X-Last") != "" {
+			x.end = i
+		}
+		x.notify()
+	}
+	w.WriteHeader(http.StatusNoContent)
+}
+
+// GET /api/agent/fs/relay/{rid}/{i} - piece i for the receiver, X-Last on
+// the last. Asking for i says every piece below it is written, so those are
+// let go. 503: not here yet, ask again; 410: it is over.
+func (s *Server) handleRelayGet(w http.ResponseWriter, r *http.Request) {
+	a := s.authenticateAgent(r)
+	if a == nil {
+		http.Error(w, "unauthorized", http.StatusUnauthorized)
+		return
+	}
+	x := s.ship.relay(r.PathValue("rid"))
+	i, err := strconv.Atoi(r.PathValue("i"))
+	if x == nil || x.to != a.ID || err != nil || i < 0 {
+		http.Error(w, "передача не найдена", http.StatusGone)
+		return
+	}
+	x.mu.Lock()
+	if i > x.low {
+		for k := x.low; k < i; k++ {
+			delete(x.chunks, k)
+		}
+		x.low = i
+		x.notify()
+	}
+	x.mu.Unlock()
+	if !x.await(r.Context(), xferWait, func() bool { return x.err != "" || x.chunks[i] != nil }) {
+		http.Error(w, "кусок ещё не пришёл", http.StatusServiceUnavailable)
+		return
+	}
+	if x.err != "" {
+		msg := x.err
+		x.mu.Unlock()
+		http.Error(w, msg, http.StatusGone)
+		return
+	}
+	data, last := x.chunks[i], i == x.end
+	x.mu.Unlock()
+	w.Header().Set("Content-Type", "application/octet-stream")
+	w.Header().Set("Content-Length", strconv.Itoa(len(data)))
+	if last {
+		w.Header().Set("X-Last", "1")
+	}
+	_, _ = w.Write(data)
+}
+
+// shipsSeveral: both agents take several things in one stream (0.2.0 on).
+func (s *Server) shipsSeveral(from string, q shipReq) bool {
+	if q.SSH != nil {
+		return false
+	}
+	for _, id := range []string{from, q.To} {
+		a, _ := s.db.GetAgent(id)
+		if a == nil || !versionAtLeast(a.Version, "0.2.0") {
+			return false
+		}
+	}
+	return true
+}
+
+// versionAtLeast: version v (dotted numbers) is min or newer; anything else
+// is taken for older.
+func versionAtLeast(v, min string) bool {
+	a, b := strings.Split(v, "."), strings.Split(min, ".")
+	for i := range b {
+		var x, y int
+		if i < len(a) {
+			n, err := strconv.Atoi(a[i])
+			if err != nil {
+				return false
+			}
+			x = n
+		}
+		y, _ = strconv.Atoi(b[i])
+		if x != y {
+			return x > y
+		}
+	}
+	return true
+}
@@ -0,0 +1,109 @@
+package server
+
+import (
+	"encoding/json"
+	"io"
+	"net/http"
+	"strings"
+
+	"github.com/x-grk/longpolling-remote-access/internal/proto"
+)
+
+// Files on an SSH host through a machine, for the panel's file panes: the
+// machine's agent keeps the SSH connection (open gives its id) and runs the
+// operations there. Downloads and uploads go in the same pieces as a
+// machine's own files.
+
+// POST /api/panel/agents/{id}/sshfs/open - {"ssh": {...}} → {conn, home}.
+func (s *Server) handleSSHFSOpen(w http.ResponseWriter, r *http.Request) {
+	agentID := r.PathValue("id")
+	var in struct {
+		SSH *proto.SSHTarget `json:"ssh"`
+	}
+	if err := json.NewDecoder(http.MaxBytesReader(w, r.Body, 64<<10)).Decode(&in); err != nil || in.SSH == nil {
+		writeJSON(w, proto.TaskResult{Error: "не указан хост"})
+		return
+	}
+	if err := s.fillSaved(s.currentAdmin(r).ID, in.SSH); err != nil {
+		writeJSON(w, proto.TaskResult{Error: err.Error()})
+		return
+	}
+	t := in.SSH
+	t.Host, t.User = strings.TrimSpace(t.Host), strings.TrimSpace(t.User)
+	if t.Port == 0 {
+		t.Port = 22
+	}
+	if t.Host == "" || t.User == "" || t.Port < 1 || t.Port > 65535 {
+		writeJSON(w, proto.TaskResult{Error: "нужны хост, порт и пользователь"})
+		return
+	}
+	if !s.fsAgent(w, agentID, true) {
+		return
+	}
+	res, err := s.waitTask(r.Context(), agentID, proto.TaskSSHFSOpen, proto.SSHFSArgs{SSH: t}, fsTaskTimeout)
+	if err != nil {
+		res = proto.TaskResult{Error: err.Error()}
+	}
+	if unknownOp(res) {
+		res = proto.TaskResult{Error: "агент не умеет файлы по SSH - обновите его"}
+	}
+	if res.OK {
+		if admin := s.currentAdmin(r); admin != nil {
+			s.db.Audit(admin.ID, agentID, "sshfs.open:"+t.User+"@"+t.Host)
+		}
+	}
+	writeJSON(w, res)
+}
+
+// sshfsChanges are the operations that change files, for the audit log.
+var sshfsChanges = map[string]bool{"write": true, "mkdir": true, "delete": true, "deltree": true, "move": true, "copy": true, "chmod": true, "zip": true, "unzip": true}
+
+// POST /api/panel/agents/{id}/sshfs/{conn}/{op} - an operation on the host;
+// the body is in the shape of the machine's own fs.{op}. "close" drops the
+// connection.
+func (s *Server) handleSSHFSOp(w http.ResponseWriter, r *http.Request) {
+	agentID, conn, op := r.PathValue("id"), r.PathValue("conn"), r.PathValue("op")
+	body, err := io.ReadAll(http.MaxBytesReader(w, r.Body, 64<<20))
+	if err != nil {
+		http.Error(w, "bad request", http.StatusBadRequest)
+		return
+	}
+	if !s.fsAgent(w, agentID, true) {
+		return
+	}
+	task, args := proto.TaskSSHFSOp, proto.SSHFSArgs{Conn: conn, Op: op, Args: json.RawMessage(body)}
+	if op == "close" {
+		task, args = proto.TaskSSHFSClose, proto.SSHFSArgs{Conn: conn}
+	}
+	if len(args.Args) == 0 {
+		args.Args = json.RawMessage("{}")
+	}
+	if sshfsChanges[op] {
+		var d struct{ Path, Src, Dst string }
+		_ = json.Unmarshal(body, &d)
+		if admin := s.currentAdmin(r); admin != nil {
+			s.db.Audit(admin.ID, agentID, "sshfs."+op+":"+strings.TrimSpace(d.Path+" "+d.Src+" "+d.Dst))
+		}
+	}
+	res, err := s.waitTask(r.Context(), agentID, task, args, fsTaskTimeout)
+	if err != nil {
+		res = proto.TaskResult{Error: err.Error()}
+	}
+	if unknownOp(res) && op != "close" {
+		res = proto.TaskResult{Error: "агент не умеет файлы по SSH - обновите его"}
+	}
+	writeJSON(w, res)
+}
+
+// GET /api/panel/agents/{id}/sshfs/{conn}/download?path=...[&inline=1]
+func (s *Server) handleSSHFSDownload(w http.ResponseWriter, r *http.Request) {
+	s.download(w, r, proto.TaskSSHFSSend, r.PathValue("conn"))
+}
+
+// POST /api/panel/agents/{id}/sshfs/{conn}/upload?path=...&size=N
+func (s *Server) handleSSHFSUpload(w http.ResponseWriter, r *http.Request) {
+	if admin := s.currentAdmin(r); admin != nil {
+		s.db.Audit(admin.ID, r.PathValue("id"), "sshfs.upload:"+r.URL.Query().Get("path"))
+	}
+	s.uploadStart(w, r, proto.TaskSSHFSPut, r.PathValue("conn"))
+}
@@ -0,0 +1,211 @@
+package server
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/rand"
+	"encoding/base64"
+	"encoding/hex"
+	"encoding/json"
+	"errors"
+	"net/http"
+	"os"
+	"strconv"
+	"strings"
+	"sync"
+
+	"github.com/x-grk/longpolling-remote-access/internal/proto"
+)
+
+// Saved SSH hosts: each user keeps their own list of hosts with the way in -
+// password or key - so the SSH dialog connects with one choice. The secret is
+// sealed with AES-256-GCM under the server's key, which lives apart from the
+// database (LPRA_SECRET_KEY, or a file beside the database made on first
+// use), and bound to its owner: a row read out of the database, or moved to
+// another user, opens to nobody.
+
+type savedHost struct {
+	ID    int64  `json:"id"`
+	Label string `json:"label"`
+	Host  string `json:"host"`
+	Port  int    `json:"port"`
+	User  string `json:"user"`
+	Auth  string `json:"auth"` // password, key or agent
+}
+
+type sshSecret struct {
+	Password   string `json:"password,omitempty"`
+	Key        string `json:"key,omitempty"`
+	Passphrase string `json:"passphrase,omitempty"`
+}
+
+var (
+	secretKeyOnce sync.Once
+	secretKey     []byte
+	secretKeyErr  error
+)
+
+// sealKey is the server's key for saved secrets.
+func (s *Server) sealKey() ([]byte, error) {
+	secretKeyOnce.Do(func() {
+		if v := strings.TrimSpace(os.Getenv("LPRA_SECRET_KEY")); v != "" {
+			k, err := hex.DecodeString(v)
+			if err != nil || len(k) != 32 {
+				k, err = base64.StdEncoding.DecodeString(v)
+			}
+			if err != nil || len(k) != 32 {
+				secretKeyErr = errors.New("LPRA_SECRET_KEY: нужны 32 байта (hex или base64)")
+				return
+			}
+			secretKey = k
+			return
+		}
+		path := s.db.path + ".key"
+		if b, err := os.ReadFile(path); err == nil {
+			k, err := hex.DecodeString(strings.TrimSpace(string(b)))
+			if err != nil || len(k) != 32 {
+				secretKeyErr = errors.New(path + ": испорчен ключ")
+				return
+			}
+			secretKey = k
+			return
+		}
+		k := make([]byte, 32)
+		_, _ = rand.Read(k)
+		if err := os.WriteFile(path, []byte(hex.EncodeToString(k)+"\n"), 0o600); err != nil {
+			secretKeyErr = err
+			return
+		}
+		secretKey = k
+	})
+	return secretKey, secretKeyErr
+}
+
+func (s *Server) seal(owner int64, plain []byte) (string, error) {
+	k, err := s.sealKey()
+	if err != nil {
+		return "", err
+	}
+	blk, _ := aes.NewCipher(k)
+	g, _ := cipher.NewGCM(blk)
+	nonce := make([]byte, g.NonceSize())
+	_, _ = rand.Read(nonce)
+	out := g.Seal(nonce, nonce, plain, []byte("ssh:"+strconv.FormatInt(owner, 10)))
+	return base64.StdEncoding.EncodeToString(out), nil
+}
+
+func (s *Server) open(owner int64, sealed string) ([]byte, error) {
+	k, err := s.sealKey()
+	if err != nil {
+		return nil, err
+	}
+	b, err := base64.StdEncoding.DecodeString(sealed)
+	blk, _ := aes.NewCipher(k)
+	g, _ := cipher.NewGCM(blk)
+	if err != nil || len(b) < g.NonceSize() {
+		return nil, errors.New("испорчена запись")
+	}
+	return g.Open(nil, b[:g.NonceSize()], b[g.NonceSize():], []byte("ssh:"+strconv.FormatInt(owner, 10)))
+}
+
+func (s *Server) saveSSHHost(owner int64, h savedHost, sec sshSecret) (int64, error) {
+	plain, _ := json.Marshal(sec)
+	sealed, err := s.seal(owner, plain)
+	if err != nil {
+		return 0, err
+	}
+	return s.db.sql.insert(`INSERT INTO ssh_hosts (admin_id, label, host, port, login, auth, secret) VALUES (?, ?, ?, ?, ?, ?, ?)`,
+		owner, h.Label, h.Host, h.Port, h.User, h.Auth, sealed)
+}
+
+func (s *Server) listSSHHosts(owner int64) []savedHost {
+	rows, err := s.db.sql.Query(`SELECT id, label, host, port, login, auth FROM ssh_hosts WHERE admin_id = ? ORDER BY label, host`, owner)
+	list := []savedHost{}
+	if err != nil {
+		return list
+	}
+	defer rows.Close()
+	for rows.Next() {
+		var h savedHost
+		if rows.Scan(&h.ID, &h.Label, &h.Host, &h.Port, &h.User, &h.Auth) == nil {
+			list = append(list, h)
+		}
+	}
+	return list
+}
+
+// fillSaved puts the saved host t.Saved of owner - address and way in - into
+// t, which then goes on as if typed in.
+func (s *Server) fillSaved(owner int64, t *proto.SSHTarget) error {
+	if t == nil || t.Saved == 0 {
+		return nil
+	}
+	var h savedHost
+	var sealed string
+	err := s.db.sql.QueryRow(`SELECT host, port, login, auth, secret FROM ssh_hosts WHERE id = ? AND admin_id = ?`, t.Saved, owner).
+		Scan(&h.Host, &h.Port, &h.User, &h.Auth, &sealed)
+	if err != nil {
+		return errors.New("сохранённый хост не найден")
+	}
+	plain, err := s.open(owner, sealed)
+	if err != nil {
+		return errors.New("сохранённый хост не расшифровался")
+	}
+	var sec sshSecret
+	_ = json.Unmarshal(plain, &sec)
+	*t = proto.SSHTarget{Host: h.Host, Port: h.Port, User: h.User, Password: sec.Password, Key: sec.Key, Passphrase: sec.Passphrase}
+	return nil
+}
+
+// GET /api/panel/ssh/hosts - the user's saved hosts, without secrets.
+func (s *Server) handleSSHHosts(w http.ResponseWriter, r *http.Request) {
+	writeJSON(w, s.listSSHHosts(s.currentAdmin(r).ID))
+}
+
+// POST /api/panel/ssh/hosts - save a host: {label, host, port, user, auth,
+// password | key, passphrase}.
+func (s *Server) handleSSHHostAdd(w http.ResponseWriter, r *http.Request) {
+	var in struct {
+		savedHost
+		sshSecret
+	}
+	if err := json.NewDecoder(http.MaxBytesReader(w, r.Body, 64<<10)).Decode(&in); err != nil {
+		writeJSON(w, map[string]any{"ok": false, "error": "плохой запрос"})
+		return
+	}
+	h := in.savedHost
+	h.Host, h.User, h.Label = strings.TrimSpace(h.Host), strings.TrimSpace(h.User), strings.TrimSpace(h.Label)
+	if h.Port == 0 {
+		h.Port = 22
+	}
+	if h.Host == "" || h.User == "" || h.Port < 1 || h.Port > 65535 || strings.ContainsAny(h.Host+h.User, " \t\r\n/") {
+		writeJSON(w, map[string]any{"ok": false, "error": "нужны хост, порт и пользователь"})
+		return
+	}
+	if h.Label == "" {
+		h.Label = h.User + "@" + h.Host
+	}
+	sec := in.sshSecret
+	switch h.Auth {
+	case "key":
+		sec.Password = ""
+	case "agent":
+		sec = sshSecret{}
+	default:
+		h.Auth = "password"
+		sec.Key, sec.Passphrase = "", ""
+	}
+	id, err := s.saveSSHHost(s.currentAdmin(r).ID, h, sec)
+	if err != nil {
+		writeJSON(w, map[string]any{"ok": false, "error": err.Error()})
+		return
+	}
+	writeJSON(w, map[string]any{"ok": true, "id": id})
+}
+
+// POST /api/panel/ssh/hosts/{hid}/delete
+func (s *Server) handleSSHHostDelete(w http.ResponseWriter, r *http.Request) {
+	id, _ := strconv.ParseInt(r.PathValue("hid"), 10, 64)
+	_, _ = s.db.sql.Exec(`DELETE FROM ssh_hosts WHERE id = ? AND admin_id = ?`, id, s.currentAdmin(r).ID)
+	writeJSON(w, map[string]any{"ok": true})
+}
@@ -0,0 +1,54 @@
+package server
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	"github.com/x-grk/longpolling-remote-access/internal/proto"
+)
+
+// A saved host's secret is stored encrypted, and only its owner gets it back.
+func TestSavedSSHHosts(t *testing.T) {
+	s, _ := newTestServer(t)
+	a, _ := s.db.AdminByUsername("adm")
+	id, err := s.saveSSHHost(a.ID, savedHost{Label: "web", Host: "h", Port: 22, User: "root", Auth: "password"}, sshSecret{Password: "s3cret-pass"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	var raw string
+	_ = s.db.sql.QueryRow(`SELECT secret FROM ssh_hosts WHERE id = ?`, id).Scan(&raw)
+	if raw == "" || strings.Contains(raw, "s3cret-pass") {
+		t.Fatalf("secret stored as %q", raw)
+	}
+	got := &proto.SSHTarget{Saved: id}
+	if err := s.fillSaved(a.ID, got); err != nil || got.Password != "s3cret-pass" || got.Host != "h" || got.User != "root" || got.Saved != 0 {
+		t.Fatalf("own: %+v %v", got, err)
+	}
+	if err := s.fillSaved(a.ID+1, &proto.SSHTarget{Saved: id}); err == nil {
+		t.Fatal("another user got the host")
+	}
+	if list := s.listSSHHosts(a.ID); len(list) != 1 || list[0].Label != "web" {
+		t.Fatalf("list: %+v", list)
+	}
+	if len(s.listSSHHosts(a.ID+1)) != 0 {
+		t.Fatal("another user sees the host")
+	}
+}
+
+// The routes: a saved host shows without its secret.
+func TestSavedSSHHostsRoute(t *testing.T) {
+	s, c := newTestServer(t)
+	req := httptest.NewRequest(http.MethodPost, "/api/panel/ssh/hosts", strings.NewReader(`{"label":"db","host":"h2","user":"u","auth":"password","password":"pw-xyz"}`))
+	req.AddCookie(c)
+	w := httptest.NewRecorder()
+	s.Handler().ServeHTTP(w, req)
+	if !strings.Contains(w.Body.String(), `"ok":true`) {
+		t.Fatalf("save: %s", w.Body.String())
+	}
+	w = get(t, s, c, "/api/panel/ssh/hosts")
+	if !strings.Contains(w.Body.String(), `"h2"`) || strings.Contains(w.Body.String(), "pw-xyz") {
+		t.Fatalf("list: %s", w.Body.String())
+	}
+}
@@ -0,0 +1,23 @@
+package server
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"testing/fstest"
+)
+
+func TestStaticHidesTests(t *testing.T) {
+	fsys := fstest.MapFS{
+		"wsutil.js":      {Data: []byte("x")},
+		"wsutil.test.js": {Data: []byte("y")},
+	}
+	h := staticHandler(fsys, map[string]string{})
+	for path, want := range map[string]int{"/wsutil.js": 200, "/wsutil.test.js": 404} {
+		w := httptest.NewRecorder()
+		h.ServeHTTP(w, httptest.NewRequest(http.MethodGet, path, nil))
+		if w.Code != want {
+			t.Errorf("%s: got %d, want %d", path, w.Code, want)
+		}
+	}
+}
@@ -0,0 +1,34 @@
+package server
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+)
+
+// A terminal opened with a folder asks the agent to start there; a folder
+// that is not an absolute path is left out (the shell starts at home).
+func TestPanelOpenDir(t *testing.T) {
+	s, cookie := newTestServer(t)
+	for body, want := range map[string]string{
+		`{"dir":"/srv/my app"}`: "/srv/my app",
+		`{"dir":"relative"}`:    "",
+		``:                      "",
+	} {
+		req := httptest.NewRequest(http.MethodPost, "/api/panel/term/x1/open", strings.NewReader(body))
+		req.AddCookie(cookie)
+		w := httptest.NewRecorder()
+		s.Handler().ServeHTTP(w, req)
+		if w.Code != 200 {
+			t.Fatalf("%s: code %d %s", body, w.Code, w.Body)
+		}
+		s.hub.mu.Lock()
+		jobs := s.hub.jobs["x1"]
+		s.hub.jobs["x1"] = nil
+		s.hub.mu.Unlock()
+		if len(jobs) != 1 || jobs[0].Dir != want {
+			t.Fatalf("%s: jobs %+v, want dir %q", body, jobs, want)
+		}
+	}
+}
@@ -0,0 +1,732 @@
+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
+<html>
+
+<head>
+  <meta http-equiv="content-type" content="text/html; charset=UTF-8">
+  <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=3.0, user-scalable=1;">
+  <meta name="referrer" content="origin">
+  <meta name="HandheldFriendly" content="true" />
+  <meta name="robots" content="noindex, nofollow" />
+  <title>golang context cancel at DuckDuckGo</title>
+  <link title="DuckDuckGo (Lite)" type="application/opensearchdescription+xml" rel="search" href="//duckduckgo.com/opensearch_lite_v2.xml">
+  <link href="//duckduckgo.com/favicon.ico" rel="shortcut icon" />
+  <link rel="icon" href="//duckduckgo.com/favicon.ico" type="image/x-icon" />
+  <link id="icon60" rel="apple-touch-icon" href="//duckduckgo.com/assets/icons/meta/DDG-iOS-icon_60x60.png?v=2"/>
+  <link id="icon76" rel="apple-touch-icon" sizes="76x76" href="//duckduckgo.com/assets/icons/meta/DDG-iOS-icon_76x76.png?v=2"/>
+  <link id="icon120" rel="apple-touch-icon" sizes="120x120" href="//duckduckgo.com/assets/icons/meta/DDG-iOS-icon_120x120.png?v=2"/>
+  <link id="icon152" rel="apple-touch-icon" sizes="152x152" href="//duckduckgo.com/assets/icons/meta/DDG-iOS-icon_152x152.png?v=2"/>
+  <link rel="image_src" href="//duckduckgo.com/assets/icons/meta/DDG-icon_256x256.png">
+  <link rel="stylesheet" media="handheld, all" href="//duckduckgo.com/dist/lr.48ddfe4eadf6a534e93f.css" type="text/css"/>
+</head>
+
+<body>
+  <p class='extra'>&nbsp;</p>
+  <div class="header">
+    DuckDuckGo
+  </div>
+  <p class='extra'>&nbsp;</p>
+
+  <form action="/lite/" method="post">
+      <input class='query' type="text" size="40" name="q" value="golang context cancel">
+      <input class='submit' type="submit" value="Search">
+      
+      
+      
+      
+
+      <div class="filters">
+        <select class="submit" name="kl">
+          
+            <option value="" >All Regions</option>
+          
+            <option value="ar-es" >Argentina</option>
+          
+            <option value="au-en" >Australia</option>
+          
+            <option value="at-de" >Austria</option>
+          
+            <option value="be-fr" >Belgium (fr)</option>
+          
+            <option value="be-nl" >Belgium (nl)</option>
+          
+            <option value="br-pt" >Brazil</option>
+          
+            <option value="bg-bg" >Bulgaria</option>
+          
+            <option value="ca-en" >Canada (en)</option>
+          
+            <option value="ca-fr" >Canada (fr)</option>
+          
+            <option value="ct-ca" >Catalonia</option>
+          
+            <option value="cl-es" >Chile</option>
+          
+            <option value="cn-zh" >China</option>
+          
+            <option value="co-es" >Colombia</option>
+          
+            <option value="hr-hr" >Croatia</option>
+          
+            <option value="cz-cs" >Czech Republic</option>
+          
+            <option value="dk-da" >Denmark</option>
+          
+            <option value="ee-et" >Estonia</option>
+          
+            <option value="fi-fi" >Finland</option>
+          
+            <option value="fr-fr" >France</option>
+          
+            <option value="de-de" >Germany</option>
+          
+            <option value="gr-el" >Greece</option>
+          
+            <option value="hk-tzh" >Hong Kong</option>
+          
+            <option value="hu-hu" >Hungary</option>
+          
+            <option value="is-is" >Iceland</option>
+          
+            <option value="in-en" >India (en)</option>
+          
+            <option value="id-en" >Indonesia (en)</option>
+          
+            <option value="ie-en" >Ireland</option>
+          
+            <option value="il-en" >Israel (en)</option>
+          
+            <option value="it-it" >Italy</option>
+          
+            <option value="jp-jp" >Japan</option>
+          
+            <option value="kr-kr" >Korea</option>
+          
+            <option value="lv-lv" >Latvia</option>
+          
+            <option value="lt-lt" >Lithuania</option>
+          
+            <option value="my-en" >Malaysia (en)</option>
+          
+            <option value="mx-es" >Mexico</option>
+          
+            <option value="nl-nl" >Netherlands</option>
+          
+            <option value="nz-en" >New Zealand</option>
+          
+            <option value="no-no" >Norway</option>
+          
+            <option value="pk-en" >Pakistan (en)</option>
+          
+            <option value="pe-es" >Peru</option>
+          
+            <option value="ph-en" >Philippines (en)</option>
+          
+            <option value="pl-pl" >Poland</option>
+          
+            <option value="pt-pt" >Portugal</option>
+          
+            <option value="ro-ro" >Romania</option>
+          
+            <option value="ru-ru" >Russia</option>
+          
+            <option value="xa-ar" >Saudi Arabia</option>
+          
+            <option value="sg-en" >Singapore</option>
+          
+            <option value="sk-sk" >Slovakia</option>
+          
+            <option value="sl-sl" >Slovenia</option>
+          
+            <option value="za-en" >South Africa</option>
+          
+            <option value="es-ca" >Spain (ca)</option>
+          
+            <option value="es-es" >Spain (es)</option>
+          
+            <option value="se-sv" >Sweden</option>
+          
+            <option value="ch-de" >Switzerland (de)</option>
+          
+            <option value="ch-fr" >Switzerland (fr)</option>
+          
+            <option value="tw-tzh" >Taiwan</option>
+          
+            <option value="th-en" >Thailand (en)</option>
+          
+            <option value="tr-tr" >Turkey</option>
+          
+            <option value="us-en" >US (English)</option>
+          
+            <option value="us-es" >US (Spanish)</option>
+          
+            <option value="ua-uk" >Ukraine</option>
+          
+            <option value="uk-en" >United Kingdom</option>
+          
+            <option value="vn-en" >Vietnam (en)</option>
+          
+        </select>
+
+        <select class="submit" name="df">
+          
+            <option value="" selected>Any Time</option>
+          
+            <option value="d" >Past Day</option>
+          
+            <option value="w" >Past Week</option>
+          
+            <option value="m" >Past Month</option>
+          
+            <option value="y" >Past Year</option>
+          
+        </select>
+      </div>
+  </form>
+
+  
+    <p class="extra">&nbsp;</p>
+    <table border="0">
+      <tr>
+        <td>
+          
+        </td>
+        <td>
+          
+            <!-- Next Page Button Sub-template -->
+<form class="next_form" action="/lite/" method="post">
+    <input type="submit" class='navbutton' value="Next Page &gt;">
+    <input type="hidden" name="q" value="golang context cancel">
+    <input type="hidden" name="s" value="10">
+    <input type="hidden" name="nextParams" value="">
+    <input type="hidden" name="v" value="l">
+    <input type="hidden" name="o" value="json">
+    <input type="hidden" name="dc" value="11">
+    <input type="hidden" name="api" value="d.js">
+    <input type="hidden" name="vqd" value="4-288446547072343849888557955747865435943">
+    &nbsp;&nbsp;&nbsp;&nbsp;
+    
+    
+    
+      <input name="kl" value="wt-wt" type="hidden">
+    
+    
+    
+    
+</form>
+          
+        </td>
+      </tr>
+    </table>
+  
+
+  
+
+  <p class='extra'>&nbsp;</p>
+
+  <table border="0">
+    
+  </table>
+
+  <table border="0">
+    
+      
+      <!-- Web results are present -->
+      
+        
+            <tr>
+              
+                <td valign="top">
+                  
+                    1.&nbsp;
+                  
+                </td>
+                <td>
+                  <a rel="nofollow" href="//duckduckgo.com/l/?uddg=https%3A%2F%2Fgo.dev%2Fdoc%2Fdatabase%2Fcancel%2Doperations&amp;rut=114b1aa13c9158c8c2b077ccd5f890f8a940277c1fc938e7bdcaad636c444a06" class='result-link'>Canceling in-progress operations - The Go Programming Language</a>
+                </td>
+                
+            </tr>
+
+            
+              
+                <!-- Only show abstract separately if there's a click URL (not EOF) -->
+                <tr>
+                  <td>&nbsp;&nbsp;&nbsp;</td>
+                  <td class='result-snippet'>
+                    Learn how to use <b>context</b>.<b>Context</b> to manage and <b>cancel</b> database operations in Go. See examples of how to set a timeout, deadline, and propagate cancellation requests with <b>context</b>.
+                  </td>
+                </tr>
+              
+            
+
+            
+              <tr>
+                <td>&nbsp;&nbsp;&nbsp;</td>
+                <td>
+                  <span class='link-text'>go.dev/doc/database/cancel-operations</span>
+                  
+                </td>
+              </tr>
+            
+
+            <tr>
+              <td>&nbsp;</td>
+              <td>&nbsp;</td>
+            </tr>
+
+        
+      
+        
+            <tr>
+              
+                <td valign="top">
+                  
+                    2.&nbsp;
+                  
+                </td>
+                <td>
+                  <a rel="nofollow" href="//duckduckgo.com/l/?uddg=https%3A%2F%2Fgolangtutorial.com%2Fgolang%2Dcontext%2F&amp;rut=c8e3cbb5601e47ba9c55f0ad6b52790e09acc1c0d3caf33c676b68ee65a1f419" class='result-link'>Go Context Tutorial: Cancellation and Deadlines</a>
+                </td>
+                
+            </tr>
+
+            
+              
+                <!-- Only show abstract separately if there's a click URL (not EOF) -->
+                <tr>
+                  <td>&nbsp;&nbsp;&nbsp;</td>
+                  <td class='result-snippet'>
+                    Learn Go <b>context</b> with practical cancellation, timeout, HTTP request, and goroutine examples.
+                  </td>
+                </tr>
+              
+            
+
+            
+              <tr>
+                <td>&nbsp;&nbsp;&nbsp;</td>
+                <td>
+                  <span class='link-text'>golangtutorial.com/golang-context/</span>
+                  
+                    &nbsp;&nbsp;&nbsp;
+                    <span class='timestamp'>2026-07-29T00:00:00.0000000</span>
+                  
+                </td>
+              </tr>
+            
+
+            <tr>
+              <td>&nbsp;</td>
+              <td>&nbsp;</td>
+            </tr>
+
+        
+      
+        
+            <tr>
+              
+                <td valign="top">
+                  
+                    3.&nbsp;
+                  
+                </td>
+                <td>
+                  <a rel="nofollow" href="//duckduckgo.com/l/?uddg=https%3A%2F%2Fstackoverflow.com%2Fquestions%2F52799280%2Fcontext%2Dconfusion%2Dregarding%2Dcancellation&amp;rut=0fa1c305fa28cede62f85c49d0501954cac2eba160d5c48f155a1008367ae78c" class='result-link'>go - Context confusion regarding cancellation - Stack Overflow</a>
+                </td>
+                
+            </tr>
+
+            
+              
+                <!-- Only show abstract separately if there's a click URL (not EOF) -->
+                <tr>
+                  <td>&nbsp;&nbsp;&nbsp;</td>
+                  <td class='result-snippet'>
+                    Additional info #1: calling <b>cancel</b> () right after <b>context</b> initialized As per <b>context</b> documentation regarding the <b>cancel</b> () function: Canceling this <b>context</b> releases resources associated with it, so code should call <b>cancel</b> as soon as the operations running in this <b>Context</b> complete. It&#x27;s good to always call <b>cancel</b> () function right after the <b>context</b> declaration. doesn&#x27;t matter whether it&#x27;s also ...
+                  </td>
+                </tr>
+              
+            
+
+            
+              <tr>
+                <td>&nbsp;&nbsp;&nbsp;</td>
+                <td>
+                  <span class='link-text'>stackoverflow.com/questions/52799280/context-confusion-regarding-cancellation</span>
+                  
+                </td>
+              </tr>
+            
+
+            <tr>
+              <td>&nbsp;</td>
+              <td>&nbsp;</td>
+            </tr>
+
+        
+      
+        
+            <tr>
+              
+                <td valign="top">
+                  
+                    4.&nbsp;
+                  
+                </td>
+                <td>
+                  <a rel="nofollow" href="//duckduckgo.com/l/?uddg=https%3A%2F%2Fpkg.go.dev%2Fcontext&amp;rut=925dd34b1fc94c2b0cb26f6e920e10aa3131c3cfc14163fd7c01b17554611b77" class='result-link'>context package - context - Go Packages</a>
+                </td>
+                
+            </tr>
+
+            
+              
+                <!-- Only show abstract separately if there's a click URL (not EOF) -->
+                <tr>
+                  <td>&nbsp;&nbsp;&nbsp;</td>
+                  <td class='result-snippet'>
+                    Package <b>context</b> defines the <b>Context</b> type, which carries deadlines, cancellation signals, and other request-scoped values across API boundaries and between processes.
+                  </td>
+                </tr>
+              
+            
+
+            
+              <tr>
+                <td>&nbsp;&nbsp;&nbsp;</td>
+                <td>
+                  <span class='link-text'>pkg.go.dev/context</span>
+                  
+                    &nbsp;&nbsp;&nbsp;
+                    <span class='timestamp'>2026-10-08T00:00:00.0000000</span>
+                  
+                </td>
+              </tr>
+            
+
+            <tr>
+              <td>&nbsp;</td>
+              <td>&nbsp;</td>
+            </tr>
+
+        
+      
+        
+            <tr>
+              
+                <td valign="top">
+                  
+                    5.&nbsp;
+                  
+                </td>
+                <td>
+                  <a rel="nofollow" href="//duckduckgo.com/l/?uddg=https%3A%2F%2Fstackoverflow.com%2Fquestions%2F70042646%2Fbest%2Dpractices%2Don%2Dgo%2Dcontext%2Dcancelation%2Dfunctions&amp;rut=f3a199db4b71e24ff5a3b0d4cbf7241ee53a03312bc2e2bcadf6d9cb20aaa474" class='result-link'>Best practices on go context cancelation functions</a>
+                </td>
+                
+            </tr>
+
+            
+              
+                <!-- Only show abstract separately if there's a click URL (not EOF) -->
+                <tr>
+                  <td>&nbsp;&nbsp;&nbsp;</td>
+                  <td class='result-snippet'>
+                    So, is passing this cancellation function actually an issue? Are there any best practices related to the use of the <b>context</b> package and their <b>cancel</b> function?
+                  </td>
+                </tr>
+              
+            
+
+            
+              <tr>
+                <td>&nbsp;&nbsp;&nbsp;</td>
+                <td>
+                  <span class='link-text'>stackoverflow.com/questions/70042646/best-practices-on-go-context-cancelation-functions</span>
+                  
+                </td>
+              </tr>
+            
+
+            <tr>
+              <td>&nbsp;</td>
+              <td>&nbsp;</td>
+            </tr>
+
+        
+      
+        
+            <tr>
+              
+                <td valign="top">
+                  
+                    6.&nbsp;
+                  
+                </td>
+                <td>
+                  <a rel="nofollow" href="//duckduckgo.com/l/?uddg=https%3A%2F%2Fgolangbot.com%2Fcontext%2Dtimeout%2Dcancellation%2F&amp;rut=dc6314fa589ab9eac3160a9b8df6a7ca4604e480917f0b99cf558d081c78ab02" class='result-link'>Golang Context - Cancellation, Timeout and Propagation | golangbot.com</a>
+                </td>
+                
+            </tr>
+
+            
+              
+                <!-- Only show abstract separately if there's a click URL (not EOF) -->
+                <tr>
+                  <td>&nbsp;&nbsp;&nbsp;</td>
+                  <td class='result-snippet'>
+                    Learn how to <b>cancel</b> long running tasks in Go using <b>context</b> cancellation and timeout. This tutorial also teaches how to terminate outstanding web requests which were cancelled by the client.
+                  </td>
+                </tr>
+              
+            
+
+            
+              <tr>
+                <td>&nbsp;&nbsp;&nbsp;</td>
+                <td>
+                  <span class='link-text'>golangbot.com/context-timeout-cancellation/</span>
+                  
+                    &nbsp;&nbsp;&nbsp;
+                    <span class='timestamp'>2026-07-08T00:00:00.0000000</span>
+                  
+                </td>
+              </tr>
+            
+
+            <tr>
+              <td>&nbsp;</td>
+              <td>&nbsp;</td>
+            </tr>
+
+        
+      
+        
+            <tr>
+              
+                <td valign="top">
+                  
+                    7.&nbsp;
+                  
+                </td>
+                <td>
+                  <a rel="nofollow" href="//duckduckgo.com/l/?uddg=https%3A%2F%2Fgo.dev%2Fblog%2Fcontext&amp;rut=6d324e0f7c589513830578b05d2a0a5ccedf509c8d4181ac590b3a229c8b9057" class='result-link'>Go Concurrency Patterns: Context - The Go Programming Language</a>
+                </td>
+                
+            </tr>
+
+            
+              
+                <!-- Only show abstract separately if there's a click URL (not EOF) -->
+                <tr>
+                  <td>&nbsp;&nbsp;&nbsp;</td>
+                  <td class='result-snippet'>
+                    Learn how to use the <b>context</b> package to pass request-scoped values, cancellation signals, and deadlines across API boundaries in Go servers. See a complete example of an HTTP server that handles Google Web Search requests with <b>context</b>.
+                  </td>
+                </tr>
+              
+            
+
+            
+              <tr>
+                <td>&nbsp;&nbsp;&nbsp;</td>
+                <td>
+                  <span class='link-text'>go.dev/blog/context</span>
+                  
+                </td>
+              </tr>
+            
+
+            <tr>
+              <td>&nbsp;</td>
+              <td>&nbsp;</td>
+            </tr>
+
+        
+      
+        
+            <tr>
+              
+                <td valign="top">
+                  
+                    8.&nbsp;
+                  
+                </td>
+                <td>
+                  <a rel="nofollow" href="//duckduckgo.com/l/?uddg=https%3A%2F%2Fwww.sohamkamani.com%2Fgolang%2Fcontext%2F&amp;rut=7274980ce55c2a5b88f9299c12e1228a7ecfffbb5fabbab8a837cbad990a1a87" class='result-link'>How to Use Context in Golang (Deadlines, Cancellation, and Passing Values)</a>
+                </td>
+                
+            </tr>
+
+            
+              
+                <!-- Only show abstract separately if there's a click URL (not EOF) -->
+                <tr>
+                  <td>&nbsp;&nbsp;&nbsp;</td>
+                  <td class='result-snippet'>
+                    In this post, we&#x27;ll learn about Go&#x27;s <b>context</b> package, and more specifically, how we can use it to improve our applications performance. The main purpose of using <b>Context</b> is to manage long-running processes (like an HTTP request, a database call, or a network call) in a way that doesn&#x27;t waste resources. If used correctly, the <b>context</b> package can help you: <b>Cancel</b> long running processes ...
+                  </td>
+                </tr>
+              
+            
+
+            
+              <tr>
+                <td>&nbsp;&nbsp;&nbsp;</td>
+                <td>
+                  <span class='link-text'>www.sohamkamani.com/golang/context/</span>
+                  
+                </td>
+              </tr>
+            
+
+            <tr>
+              <td>&nbsp;</td>
+              <td>&nbsp;</td>
+            </tr>
+
+        
+      
+        
+            <tr>
+              
+                <td valign="top">
+                  
+                    9.&nbsp;
+                  
+                </td>
+                <td>
+                  <a rel="nofollow" href="//duckduckgo.com/l/?uddg=https%3A%2F%2Fgolangdoc.github.io%2Fpkg%2F1.12%2Fcontext%2Findex.html&amp;rut=4baaf27a174aa7e8bbcc0cfe1985ad916fe3ff014eb45fc06dd68178fc84e261" class='result-link'>context - The Go Programming Language</a>
+                </td>
+                
+            </tr>
+
+            
+              
+                <!-- Only show abstract separately if there's a click URL (not EOF) -->
+                <tr>
+                  <td>&nbsp;&nbsp;&nbsp;</td>
+                  <td class='result-snippet'>
+                    The returned <b>context&#x27;s</b> Done channel is closed when the deadline expires, when the returned <b>cancel</b> function is called, or when the parent <b>context&#x27;s</b> Done channel is closed, whichever happens first.
+                  </td>
+                </tr>
+              
+            
+
+            
+              <tr>
+                <td>&nbsp;&nbsp;&nbsp;</td>
+                <td>
+                  <span class='link-text'>golangdoc.github.io/pkg/1.12/context/index.html</span>
+                  
+                </td>
+              </tr>
+            
+
+            <tr>
+              <td>&nbsp;</td>
+              <td>&nbsp;</td>
+            </tr>
+
+        
+      
+        
+            <tr>
+              
+                <td valign="top">
+                  
+                    10.&nbsp;
+                  
+                </td>
+                <td>
+                  <a rel="nofollow" href="//duckduckgo.com/l/?uddg=https%3A%2F%2Fwww.golinuxcloud.com%2Fgolang%2Dcontext%2F&amp;rut=efdde246db353602fc52ef95d8d09a146270aeb46114aa061f320d037adea574" class='result-link'>Golang context — WithCancel, WithTimeout, WithDeadline, Background</a>
+                </td>
+                
+            </tr>
+
+            
+              
+                <!-- Only show abstract separately if there's a click URL (not EOF) -->
+                <tr>
+                  <td>&nbsp;&nbsp;&nbsp;</td>
+                  <td class='result-snippet'>
+                    The <b>golang</b> <b>context</b> package ties cancellation, timeouts, and optional request values to a <b>Context</b> value you pass through your call stack. Use Background (or TODO temporarily) as the root, WithTimeout / WithDeadline for time bounds, WithCancel for explicit shutdown, and WithValue only for small, request-scoped metadata—always defer <b>cancel</b> ...
+                  </td>
+                </tr>
+              
+            
+
+            
+              <tr>
+                <td>&nbsp;&nbsp;&nbsp;</td>
+                <td>
+                  <span class='link-text'>www.golinuxcloud.com/golang-context/</span>
+                  
+                </td>
+              </tr>
+            
+
+            <tr>
+              <td>&nbsp;</td>
+              <td>&nbsp;</td>
+            </tr>
+
+        
+      
+    
+
+    
+      
+      <tr>
+        <td colspan=2>
+          
+          
+            <!-- Next Page Button Sub-template -->
+<form class="next_form" action="/lite/" method="post">
+    <input type="submit" class='navbutton' value="Next Page &gt;">
+    <input type="hidden" name="q" value="golang context cancel">
+    <input type="hidden" name="s" value="10">
+    <input type="hidden" name="nextParams" value="">
+    <input type="hidden" name="v" value="l">
+    <input type="hidden" name="o" value="json">
+    <input type="hidden" name="dc" value="11">
+    <input type="hidden" name="api" value="d.js">
+    <input type="hidden" name="vqd" value="4-288446547072343849888557955747865435943">
+    &nbsp;&nbsp;&nbsp;&nbsp;
+    
+    
+    
+      <input name="kl" value="wt-wt" type="hidden">
+    
+    
+    
+    
+</form>
+          
+          
+        </td>
+      </tr>
+    
+  </table>
+
+  <p class='extra'>&nbsp;</p>
+
+  <form action="/lite/" method="post">
+      <input class='query' type="text" size="40" name="q" value="golang context cancel" >
+      <input class='submit' type="submit" value="Search">
+      
+      
+      
+      
+      
+        <input name="kl" value="wt-wt" type="hidden">
+      
+  </form>
+
+  <p class='extra'>&nbsp;</p>
+
+  
+    <img src="//duckduckgo.com/t/sl_l"/>
+  
+  <div id='end-spacer'>&nbsp;</div>
+
+</body>
+</html>
@@ -39,6 +39,7 @@ func readLine(r io.Reader, max int) (string, error) {
 type tunnelHub struct {
 	db     *DB
 	mu     sync.Mutex
+	ln     net.Listener
 	agents map[string]*agentTunnel
 }

@@ -57,12 +58,30 @@ type agentTunnel struct {
 	streams map[uint32]net.Conn
 }

-// listen runs the 8446 TCP tunnel acceptor until the listener closes.
+// listen runs the TCP tunnel acceptor until the listener closes. Listening
+// again moves the tunnel: the previous listener is closed and its agents are
+// dropped, so they redial the new address.
 func (h *tunnelHub) listen(addr string) error {
 	ln, err := net.Listen("tcp", addr)
 	if err != nil {
 		return err
 	}
+	h.mu.Lock()
+	old := h.ln
+	h.ln = ln
+	var stale []*agentTunnel
+	if old != nil {
+		for _, at := range h.agents {
+			stale = append(stale, at)
+		}
+	}
+	h.mu.Unlock()
+	if old != nil {
+		old.Close()
+	}
+	for _, at := range stale {
+		at.conn.Close()
+	}
 	log.Printf("tunnel: listening on %s (direct TCP forwarding)", addr)
 	go func() {
 		for {
@@ -11,18 +11,19 @@ import (
 	"github.com/x-grk/longpolling-remote-access/internal/tunnel"
 )

-// udpRelay carries UDP forwards over the direct 8446 UDP channel. The agent
+// udpRelay carries UDP forwards over the direct UDP channel. The agent
 // registers its UDP return address; end-user datagrams arriving on a rule's
 // host port are relayed to the agent and replies are sent back.
 //
-// Datagram framing on the 8446 control socket:
+// Datagram framing on the tunnel control socket:
 //
 //	registration (agent->server): "R <agentID> <sig>"
 //	data         (both):          'D' | sid(4) | port(2) | payload
 type udpRelay struct {
-	db   *DB
-	mu   sync.Mutex
-	ctrl *net.UDPConn
+	db     *DB
+	mu     sync.Mutex
+	ctrl   *net.UDPConn
+	gcOnce sync.Once

 	agentAddr map[string]*net.UDPAddr // agentID -> last registered addr
 	sessions  map[uint32]*udpSession
@@ -48,7 +49,8 @@ func newUDPRelay(db *DB) *udpRelay {
 	}
 }

-// listen opens the shared 8446 UDP control socket.
+// listen opens the shared UDP control socket. Listening again moves it: the
+// previous socket is closed and agents register anew on the new address.
 func (u *udpRelay) listen(addr string) error {
 	ua, err := net.ResolveUDPAddr("udp", addr)
 	if err != nil {
@@ -58,17 +60,26 @@ func (u *udpRelay) listen(addr string) error {
 	if err != nil {
 		return err
 	}
+	u.mu.Lock()
+	old := u.ctrl
 	u.ctrl = c
+	if old != nil {
+		u.agentAddr = map[string]*net.UDPAddr{}
+	}
+	u.mu.Unlock()
+	if old != nil {
+		old.Close()
+	}
 	log.Printf("tunnel: listening on %s/udp (direct UDP forwarding)", addr)
-	go u.ctrlLoop()
-	go u.gc()
+	go u.ctrlLoop(c)
+	u.gcOnce.Do(func() { go u.gc() })
 	return nil
 }

-func (u *udpRelay) ctrlLoop() {
+func (u *udpRelay) ctrlLoop(ctrl *net.UDPConn) {
 	buf := make([]byte, 65535)
 	for {
-		n, src, err := u.ctrl.ReadFromUDP(buf)
+		n, src, err := ctrl.ReadFromUDP(buf)
 		if err != nil {
 			return
 		}
@@ -171,6 +182,7 @@ func (u *udpRelay) rulePortLoop(rule ForwardRule, c *net.UDPConn) {
 		}
 		u.mu.Lock()
 		aAddr := u.agentAddr[rule.AgentID]
+		ctrl := u.ctrl
 		// Find existing session for this (rule, user).
 		var sess *udpSession
 		for _, s := range u.sessions {
@@ -190,7 +202,7 @@ func (u *udpRelay) rulePortLoop(rule ForwardRule, c *net.UDPConn) {
 		sess.last = time.Now()
 		u.mu.Unlock()

-		if aAddr == nil {
+		if aAddr == nil || ctrl == nil {
 			continue // agent has not registered its UDP endpoint yet
 		}
 		// 'D' | sid(4) | clientPort(2) | payload
@@ -199,7 +211,7 @@ func (u *udpRelay) rulePortLoop(rule ForwardRule, c *net.UDPConn) {
 		binary.BigEndian.PutUint32(out[1:5], sess.id)
 		binary.BigEndian.PutUint16(out[5:7], uint16(rule.ClientPort))
 		copy(out[7:], buf[:n])
-		_, _ = u.ctrl.WriteToUDP(out, aAddr)
+		_, _ = ctrl.WriteToUDP(out, aAddr)
 	}
 }

@@ -3,8 +3,11 @@ package server
 import (
 	"fmt"
 	"log"
+	"net"
+	"os"
 	"os/exec"
 	"strings"
+	"sync"
 )

 // ufwManager integrates with the host firewall (ufw) when it is installed and
@@ -14,31 +17,53 @@ import (
 // ufw requires root, so this only works when the server process can run ufw
 // (e.g. running as root). When it cannot, integration is simply inactive.
 type ufwManager struct {
-	db         *DB
-	tunnelPort int
+	db *DB
+	// tunnelPort returns the current direct-tunnel port (0 = tunnel disabled).
+	tunnelPort func() int
+
+	mu      sync.Mutex
+	lastErr string // last failed ufw command, shown in Settings
 }

-func newUfwManager(db *DB, tunnelPort int) *ufwManager {
+func newUfwManager(db *DB, tunnelPort func() int) *ufwManager {
 	return &ufwManager{db: db, tunnelPort: tunnelPort}
 }

+// ufwRun runs ufw with a fixed C locale: its output is translated, and we
+// match on the English text.
+func ufwRun(args ...string) (string, error) {
+	cmd := exec.Command("ufw", args...)
+	cmd.Env = append(os.Environ(), "LC_ALL=C", "LANG=C", "LANGUAGE=C")
+	out, err := cmd.CombinedOutput()
+	return strings.TrimSpace(string(out)), err
+}
+
 // status reports whether ufw is installed, active, and runnable by this process.
 func (u *ufwManager) status() (installed, active, runnable bool) {
-	path, err := exec.LookPath("ufw")
-	if err != nil {
+	if _, err := exec.LookPath("ufw"); err != nil {
 		return false, false, false
 	}
 	installed = true
-	out, err := exec.Command(path, "status").CombinedOutput()
+	out, err := ufwRun("status")
 	if err != nil {
 		// Typically a permission error (not root) -> not runnable.
 		return true, false, false
 	}
 	runnable = true
-	active = strings.Contains(string(out), "Status: active")
+	active = strings.Contains(out, "Status: active")
 	return installed, active, runnable
 }

+// enabled reports whether the integration is switched on and ufw is there to
+// drive. Unlike available it runs nothing, so pages can ask it freely.
+func (u *ufwManager) enabled() bool {
+	if !u.db.UfwEnabled() {
+		return false
+	}
+	_, err := exec.LookPath("ufw")
+	return err == nil
+}
+
 // available reports whether we can and should drive ufw now.
 func (u *ufwManager) available() bool {
 	if !u.db.UfwEnabled() {
@@ -48,30 +73,70 @@ func (u *ufwManager) available() bool {
 	return installed && active && runnable
 }

-// allow opens port/proto in ufw (if integration is available) and records it,
-// bound to the given forward rule id (0 = shared/manual).
-func (u *ufwManager) allow(port int, proto string, ruleID int64) {
-	if !u.available() {
-		return
-	}
+func (u *ufwManager) setErr(msg string) {
+	u.mu.Lock()
+	u.lastErr = msg
+	u.mu.Unlock()
+}
+
+// LastError returns the last failed ufw command ("" when the last one worked).
+func (u *ufwManager) LastError() string {
+	u.mu.Lock()
+	defer u.mu.Unlock()
+	return u.lastErr
+}
+
+// allow opens port/proto in ufw and records it, bound to the given forward
+// rule id (0 = shared, ufwManual = added in Settings). It reports whether the
+// panel now tracks the rule. The caller has checked available().
+func (u *ufwManager) allow(port int, proto string, ruleID int64) bool {
 	if u.db.HasUfwRule(port, proto) {
-		return
+		return true
 	}
 	spec := fmt.Sprintf("%d/%s", port, proto)
-	if out, err := exec.Command("ufw", "allow", spec).CombinedOutput(); err != nil {
-		log.Printf("ufw allow %s: %v: %s", spec, err, strings.TrimSpace(string(out)))
-		return
+	out, err := ufwRun("allow", spec)
+	if err != nil {
+		log.Printf("ufw allow %s: %v: %s", spec, err, out)
+		u.setErr(fmt.Sprintf("ufw allow %s: %v: %s", spec, err, out))
+		return false
+	}
+	u.setErr("")
+	if strings.Contains(out, "Skipping") {
+		// The rule was there before the panel asked for it, so it is not ours
+		// to track (and later delete).
+		return false
 	}
 	_ = u.db.AddUfwRule(port, proto, ruleID)
 	log.Printf("ufw: allowed %s", spec)
+	return true
+}
+
+// allowManual opens a port the admin asked for in Settings. A port the panel
+// already opened for a forward or the tunnel becomes the admin's, so it stays
+// when they no longer need it. It returns the error key for the settings page
+// ("" on success).
+func (u *ufwManager) allowManual(port int, proto string) string {
+	if !u.available() {
+		return "ufw_off"
+	}
+	if !u.allow(port, proto, ufwManual) {
+		if u.LastError() != "" {
+			return "ufw_failed"
+		}
+		return "ufw_exists"
+	}
+	_ = u.db.SetUfwRuleManual(port, proto)
+	return ""
 }

 // revokeRule deletes one tracked ufw rule from ufw and the tracking table.
 func (u *ufwManager) revokeRule(r UfwRule) {
 	spec := fmt.Sprintf("%d/%s", r.Port, r.Proto)
-	if out, err := exec.Command("ufw", "delete", "allow", spec).CombinedOutput(); err != nil {
-		log.Printf("ufw delete allow %s: %v: %s", spec, err, strings.TrimSpace(string(out)))
+	if out, err := ufwRun("delete", "allow", spec); err != nil {
+		log.Printf("ufw delete allow %s: %v: %s", spec, err, out)
+		u.setErr(fmt.Sprintf("ufw delete allow %s: %v: %s", spec, err, out))
 	} else {
+		u.setErr("")
 		log.Printf("ufw: revoked %s", spec)
 	}
 	_ = u.db.DeleteUfwRule(r.ID)
@@ -86,8 +151,8 @@ func (u *ufwManager) revoke(id int64) {
 	u.revokeRule(*r)
 }

-// revokeForRule removes the ufw rules bound to a specific forward rule. The
-// shared tunnel port (rule_id 0) is left alone, since other forwards use it.
+// revokeForRule removes the ufw rules bound to a specific forward rule, and
+// the shared tunnel port once no forward needs it any more.
 func (u *ufwManager) revokeForRule(ruleID int64) {
 	rules, err := u.db.ListUfwRulesByRule(ruleID)
 	if err != nil {
@@ -96,24 +161,77 @@ func (u *ufwManager) revokeForRule(ruleID int64) {
 	for _, r := range rules {
 		u.revokeRule(r)
 	}
+	u.pruneShared()
+}
+
+// pruneShared revokes shared (rule_id 0) ufw rules that nothing uses: anything
+// but the current tunnel port, and the tunnel port itself for a protocol that
+// has no direct forward left.
+func (u *ufwManager) pruneShared() {
+	shared, err := u.db.ListUfwRulesByRule(0)
+	if err != nil || len(shared) == 0 {
+		return
+	}
+	forwards, err := u.db.ListForwardRules()
+	if err != nil {
+		return
+	}
+	used := map[string]bool{}
+	for _, f := range forwards {
+		if !f.NoUfw {
+			used[f.Proto] = true
+		}
+	}
+	port := u.tunnelPort()
+	for _, r := range shared {
+		if r.Port != port || !used[r.Proto] {
+			u.revokeRule(r)
+		}
+	}
 }

 // allowForward opens the host ports a forward rule needs: its host port (bound
-// to the rule so it is revoked with it) plus the shared 8446 tunnel port for
-// direct tcp/udp modes (bound to 0 — shared across rules).
+// to the rule so it is revoked with it) plus the shared tunnel port for direct
+// tcp/udp modes (bound to 0 - shared across rules). A rule made "without ufw"
+// opens nothing, so nothing is revoked with it either.
 func (u *ufwManager) allowForward(rule ForwardRule) {
-	switch rule.Proto {
-	case "udp":
-		u.allow(rule.HostPort, "udp", rule.ID)
-		if u.tunnelPort > 0 {
-			u.allow(u.tunnelPort, "udp", 0)
-		}
-	case "tcp":
-		u.allow(rule.HostPort, "tcp", rule.ID)
-		if u.tunnelPort > 0 {
-			u.allow(u.tunnelPort, "tcp", 0)
-		}
-	default: // http long-poll listener is TCP
-		u.allow(rule.HostPort, "tcp", rule.ID)
+	if !u.available() {
+		return
+	}
+	u.allowForwardPorts(rule)
+}
+
+func (u *ufwManager) allowForwardPorts(rule ForwardRule) {
+	if rule.NoUfw {
+		return
+	}
+	// "http" (long-poll) and "tcp" forwards both listen on TCP on the host.
+	hostProto, direct := "tcp", rule.Proto == "tcp"
+	if rule.Proto == "udp" {
+		hostProto, direct = "udp", true
+	}
+	// A listener bound to loopback is not reachable from outside anyway.
+	if ip := net.ParseIP(rule.ListenAddr); ip == nil || !ip.IsLoopback() {
+		u.allow(rule.HostPort, hostProto, rule.ID)
+	}
+	if port := u.tunnelPort(); direct && port > 0 {
+		u.allow(port, hostProto, 0)
 	}
 }
+
+// sync brings ufw in line with the saved forward rules: it opens what is
+// missing (rules made while ufw or the integration was off, or a tunnel port
+// that has since changed) and drops shared rules nothing uses.
+func (u *ufwManager) sync() {
+	if !u.available() {
+		return
+	}
+	forwards, err := u.db.ListForwardRules()
+	if err != nil {
+		return
+	}
+	for _, f := range forwards {
+		u.allowForwardPorts(f)
+	}
+	u.pruneShared()
+}
@@ -0,0 +1,89 @@
+package server
+
+import (
+	"encoding/json"
+	"net/http"
+	"strconv"
+)
+
+// GET /api/panel/users/{id}/agents - every machine, and which of them the
+// user may use, for the editor of a user's machines.
+func (s *Server) handleUserAgents(w http.ResponseWriter, r *http.Request) {
+	id, _ := strconv.ParseInt(r.PathValue("id"), 10, 64)
+	u, _ := s.db.AdminByID(id)
+	if u == nil {
+		http.NotFound(w, r)
+		return
+	}
+	agents, _ := s.db.ListAgents()
+	mine := s.db.UserAgents(id)
+	type item struct {
+		ID       string `json:"id"`
+		Name     string `json:"name"`
+		Hostname string `json:"hostname"`
+		Online   bool   `json:"online"`
+		On       bool   `json:"on"`
+	}
+	out := make([]item, 0, len(agents))
+	for _, a := range agents {
+		out = append(out, item{a.ID, a.Name, a.Hostname, s.online(&a), mine[a.ID]})
+	}
+	writeJSON(w, map[string]any{"username": u.Username, "agents": out})
+}
+
+// POST /api/panel/users/{id} - change a user: the role, the machines, the
+// password sign-in, and whether they may switch it themselves. Fields left
+// out stay as they are.
+func (s *Server) handleUserEdit(w http.ResponseWriter, r *http.Request) {
+	me := s.currentAdmin(r)
+	id, _ := strconv.ParseInt(r.PathValue("id"), 10, 64)
+	u, _ := s.db.AdminByID(id)
+	if u == nil {
+		writeJSON(w, map[string]any{"ok": false, "error": "нет такого пользователя"})
+		return
+	}
+	var in struct {
+		Role        *string   `json:"role"`
+		Agents      *[]string `json:"agents"`
+		PasswordOff *bool     `json:"password_off"`
+		PwLocked    *bool     `json:"pw_locked"`
+	}
+	if err := json.NewDecoder(http.MaxBytesReader(w, r.Body, 64<<10)).Decode(&in); err != nil {
+		writeJSON(w, map[string]any{"ok": false, "error": "плохой запрос"})
+		return
+	}
+	fail := func(msg string) { writeJSON(w, map[string]any{"ok": false, "error": msg}) }
+	if in.Role != nil {
+		role := *in.Role
+		if role != RoleAdmin && role != RoleUser {
+			fail("нет такой роли")
+			return
+		}
+		if role == RoleUser && u.IsAdmin() && s.db.CountRole(RoleAdmin) <= 1 {
+			fail("это последний администратор")
+			return
+		}
+		_ = s.db.SetUserRole(id, role)
+		s.db.Audit(me.ID, "", "user_role:"+u.Username+":"+role)
+	}
+	if in.Agents != nil {
+		_ = s.db.SetUserAgents(id, *in.Agents)
+		s.db.Audit(me.ID, "", "user_agents:"+u.Username+":"+strconv.Itoa(len(*in.Agents)))
+	}
+	if in.PasswordOff != nil {
+		if *in.PasswordOff && s.db.CountAdminKeys(id) == 0 {
+			fail("у пользователя нет ключей доступа - без пароля он не войдёт")
+			return
+		}
+		_ = s.db.SetPasswordOff(id, *in.PasswordOff)
+		action := "password_on"
+		if *in.PasswordOff {
+			action = "password_off"
+		}
+		s.db.Audit(me.ID, "", action+":"+u.Username)
+	}
+	if in.PwLocked != nil {
+		_ = s.db.SetPwLocked(id, *in.PwLocked)
+	}
+	writeJSON(w, map[string]any{"ok": true})
+}
@@ -1 +1 @@
 .0.2
 .2.5