zebra-spaces: re-apply sink on every attach + per-tick ctx.sink telemetry (kill blanka-chrome sink drift)

After caa0548 (fixes A + B for ticket 0001), blanka-chrome was still
silent. Fresh telemetry pinned a third failure mode:

  21:31:31  audio via AudioContext 47e5 sink=c38572ec…   ← good
  …leave + rejoin…
  21:31:33  audio via AudioContext 47e5 sink=default     ← drifted

No `audioCtx sink → c38572ec…` log line between the two attaches.
applySinkToAudioCtx was only invoked inside the `if (!audioCtx)` branch
in attachAudioStreamViaWorklet — a persistent audioCtx whose .sinkId
getter returned '' (system default) after a leave/rejoin never got
its sink re-applied, so every subsequent attach emitted to the system
default speaker instead of the device the user picked in the dropdown.

Fix: when audioCtx already exists AND speakerDeviceId is set AND
audioCtx.sinkId !== speakerDeviceId, call applySinkToAudioCtx() to
restore routing. Idempotent (same-sink call is a noop).

Telemetry: every 5s tick now includes `ctx.sink=…` and `want=…` when
the active sink doesn't match the picked one, so drift is visible
without grepping for the rare attach event.

Test: attach re-applies sink when audioCtx persists across leave/rejoin
and the picked sink drifted. Sandbox now exposes setSpeakerDeviceId so
the test can drive the picked-device path through the real
attachAudioStreamViaWorklet branch.

Ticket 0001 updated with the second-pass telemetry and fix (C).

web/zebra-spaces.html

@@ -3281,6 +3281,19 @@ function attachAudioStreamViaWorklet(uuid, stream, targetSeconds){
       applySinkToAudioCtx();
     }
     catch(e){ logLine('err','audioCtx create: '+e.message); return false; }
+  } else if (speakerDeviceId
+             && typeof audioCtx.setSinkId === 'function'
+             && audioCtx.sinkId !== speakerDeviceId){
+    /* audioCtx survived a leave→re-enter but its sinkId drifted back
+     * to '' (system default). Re-apply the picked sink so the worklet
+     * keeps emitting to the device the user picked in the dropdown.
+     * Fox 2026-06-07 blanka-chrome telemetry: first attach
+     * `sink=c38572ec…`, a leave/rejoin later, next attach
+     * `sink=default` and no `audioCtx sink → …` success line —
+     * applySinkToAudioCtx only ran inside the `!audioCtx` branch above,
+     * so a persistent audioCtx with reset sinkId stayed default
+     * forever. Idempotent: same-sink call is a noop. */
+    applySinkToAudioCtx();
   }
   if (audioCtx.state === 'suspended'){
     audioCtx.resume().catch(()=>{});
@@ -5830,6 +5843,23 @@ async function dumpTelemetry(){
   /* reset per-tick whisper counters */
   _whisperTick.sent = 0; _whisperTick.dropped = 0;
   _whisperTick.emitted = 0; _whisperTick.totalLatencyMs = 0;
+  /* audioCtx sink visibility on EVERY tick — the one-shot 'sink=…' in
+   * the attach log only captures the moment of attach; if the sink
+   * drifts later (Chrome's audioCtx.sinkId getter can revert to '' on
+   * device-changes, leave/rejoin, suspend/resume), this surfaces it
+   * every 5s instead of needing to grep for the rare attach event.
+   * Fox 2026-06-07 blanka-chrome: per-attach sink looked fine but the
+   * silent-listener state persisted because the GETTER value drifted
+   * between attaches. */
+  if (audioCtx){
+    const cs = (audioCtx.sinkId === undefined) ? 'n/a'
+             : (audioCtx.sinkId || 'default');
+    const want = speakerDeviceId || 'default';
+    parts.push('ctx.sink=' + (cs.length > 12 ? cs.slice(0,8) : cs)
+               + (cs !== want && audioCtx.sinkId !== undefined
+                  ? ' want=' + (want.length > 12 ? want.slice(0,8) : want)
+                  : ''));
+  }
   /* receiver stats from sfuSubPC (the main listener path) */
   if (sfuSubPC && typeof sfuSubPC.getStats === 'function'){
     try {
@@ -8183,8 +8213,8 @@ logLine('', 'ready — pick a handle, type a rendezvous code, enter the space');
 
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