saving a connection now tells the other panels

reported on the first successful save: everything still showed no data and the
form stayed open, and a manual page refresh was the only way through.

two faults, one report. the form did not close itself — nothing cleared
?config, so a save left the settings view sitting on top of a plugin that now
worked. and the two reader panels are SIBLINGS in a workspace layout: they are
mounted independently, neither owns the other, and ConnectionPanel cannot call
into them. so they went on showing the failure they had loaded back when no
connection existed.

a channel is the sanctioned answer for exactly this — docs/navigation-audit.md
puts addressable state in the URL and leaves channels for "something changed,
re-read it". nobody wants to link to the moment after a save.

the nonce is a plain module counter, copied deliberately from officerdev's
channels.ts along with the reason: setSignal(n => n + 1) applies against the
value captured at render, so two bumps in one render window both compute
snapshot + 1 and the second overwrites the first — and nobody re-reads.
Date.now() is the same bug at millisecond scale.

disconnect bumps it too. the panels must stop showing hosts they can no longer
reach.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Officer-Session: 656f5c85-e49a-4f1f-b9f3-042a04b4d043

web/channel.ts

@@ -0,0 +1,43 @@
+import { useCallback, useRef } from 'react';
+import { defineChannel } from 'hooks/usePanelChannel';
+
+/**
+ * "The connection changed — anyone reading NPM should read it again."
+ *
+ * ── Why a channel and not the URL ──
+ *
+ * `docs/navigation-audit.md` draws the line: anything ADDRESSABLE goes in the URL, and a channel is only
+ * for a signal — "something changed, re-read it". This is the second kind. Nobody wants to link to "the
+ * moment after the connection was saved", and there is nothing to select.
+ *
+ * ── Why it is needed at all ──
+ *
+ * The panels are siblings in a workspace layout. `ConnectionPanel` cannot call into `CertificatesPanel`
+ * and should not try — they are mounted independently and neither owns the other. Before this, saving a
+ * connection left both panels showing whatever they had failed to load a minute earlier, and the only fix
+ * a person had was a manual refresh. Reported on 2026-08-25 the first time a connection was saved through
+ * the form.
+ *
+ * ── The nonce is a plain counter, and that is not an accident ──
+ *
+ * Copied deliberately from `officerdev/src/channels.ts`, which records why. `setSignal(n => n + 1)` is
+ * WRONG here: the functional setter applies against the value captured at render, so two bumps inside one
+ * render window both compute `snapshot + 1` and the second silently overwrites the first — nobody
+ * re-reads. `Date.now()` has the same flaw in miniature, two bumps in one millisecond being one number.
+ * A module counter never reads React state, so it cannot be wrong however often it is called.
+ */
+const useConnectionChangedChannel = defineChannel<number>('proxy-manager:connection-changed', 0);
+
+let nonce = 0;
+
+export const useConnectionChanged = () => {
+  const [signal, setSignal] = useConnectionChangedChannel();
+
+  // The setter is a fresh closure every render and this `bump` goes into dependency lists, so it is read
+  // through a ref — stable identity without freezing the first render's setter.
+  const setRef = useRef(setSignal);
+  setRef.current = setSignal;
+  const bump = useCallback(() => setRef.current(++nonce), []);
+
+  return [signal, bump] as const;
+};