fix: ended page scopes start no timers; SSH transfers keep their connection from the idle sweep; linked files download whole; only the sent item unpacks on an SSH host, replace and skip as on a machine

internal/server/web/static/wsutil.js

@@ -22,6 +22,28 @@
     if (n < 1073741824) return (n / 1048576).toFixed(1) + ' M';
     return (n / 1073741824).toFixed(1) + ' G';
   }
-  const api = {shellQuote, shellQuoteAll, dropAction, fmtSize};
+  // scope gives a module timers, requests and listeners that end with it;
+  // once ended it starts nothing new (a request's late answer cannot set a
+  // timer going again).
+  function scope() {
+    let ended = false;
+    const timers = new Set(), offs = [], ac = new AbortController();
+    return {
+      timeout(fn, ms) { if (ended) return 0; const id = setTimeout(() => { timers.delete(id); fn(); }, ms); timers.add(id); return id; },
+      interval(fn, ms) { if (ended) return 0; const id = setInterval(fn, ms); timers.add(id); return id; },
+      clear(id) { clearTimeout(id); clearInterval(id); timers.delete(id); },
+      fetch(url, opt) {
+        const o = Object.assign({credentials: 'same-origin'}, opt || {});
+        // A request with its own signal ends on either.
+        o.signal = o.signal && AbortSignal.any ? AbortSignal.any([o.signal, ac.signal]) : (o.signal || ac.signal);
+        return fetch(url, o);
+      },
+      on(target, ev, fn, opt) { target.addEventListener(ev, fn, opt); offs.push(() => target.removeEventListener(ev, fn, opt)); },
+      signal: ac.signal,
+      end() { ended = true; timers.forEach(id => { clearTimeout(id); clearInterval(id); }); timers.clear(); offs.forEach(f => f()); ac.abort(); }
+    };
+  }
+
+  const api = {shellQuote, shellQuoteAll, dropAction, fmtSize, scope};
   if (typeof module !== 'undefined') module.exports = api; else root.WSUtil = api;
 })(this);