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).

docs/tickets/0001-fedora-chrome-cannot-hear-speakers.md

@@ -168,11 +168,49 @@ for >5s, swap the worklet back to the cached SFU stream — same
 pattern the `connectionState === 'failed'` path already uses at line
 6755.
 
+## 2026-06-07 second telemetry pass — sink DRIFT identified
+
+After deploying (A) + (B), blanka-chrome was still silent. Fresh
+telemetry pinned a different per-attach failure mode:
+
+```
+21:31:30  audio attach uuid=47e5 target=0.5s (current pool=1)
+21:31:31  audio via AudioContext 47e5 target=0.5s ctxState=running sink=c38572ec…
+21:31:31  jitter-buffer started uuid=47e5 target=0.5s
+…leave/rejoin cycle…
+21:31:33  audio attach uuid=47e5 target=0.5s (current pool=1)
+21:31:33  audio via AudioContext 47e5 target=0.5s ctxState=running sink=default   ← drifted
+```
+
+No `audioCtx sink → c38572ec…` log line ever appeared. So
+`applySinkToAudioCtx()` either never ran or hit the
+`typeof audioCtx.setSinkId !== 'function'` early-return at the moment
+of execution. The earlier sink fix only invoked
+`applySinkToAudioCtx()` inside the `if (!audioCtx)` branch — a
+persistent audioCtx whose `.sinkId` getter returned `''` (default) was
+never re-corrected.
+
+## Fix (C) — re-apply sink on every attach when it drifted
+
+`attachAudioStreamViaWorklet` now: if `audioCtx` already exists AND
+`speakerDeviceId` is set AND `audioCtx.sinkId !== speakerDeviceId`,
+call `applySinkToAudioCtx()`. Idempotent — same-sink call is a no-op.
+
+Also added per-tick `ctx.sink=` to the telemetry stream so sink drift
+is visible on every 5s line instead of needing to find the rare attach
+log. When the active sink doesn't match the picked one, the line
+includes `want=…` so the mismatch jumps out.
+
 ## Status notes
 
-- **2026-06-07 (in-progress):** sink hypothesis ruled out by fresh
-  telemetry; root cause is (A) tracks=0 race + (B) mesh-swap orphan.
-  Implementing both fixes in this branch.
+- **2026-06-07 (in-progress, fix C deployed):** sink-drift on
+  audioCtx-persistent path identified + patched. Need a third telemetry
+  pass to confirm the per-tick `ctx.sink=` line now stays on the
+  picked device across leave/rejoin.
+- **2026-06-07 (fixes A + B deployed):** sink hypothesis from 467146a
+  ruled out by fresh telemetry; (A) tracks=0 race + (B) mesh-swap
+  orphan landed in caa0548. blanka-chrome was still silent, leading
+  to fix (C) above.
 - **2026-06-06:** the Jun 5 cascade + flushSfuStreams prefix-match fix
   (`0ce1339`) helped firefox but not chrome. Telemetry above ruled out
   the FSM / attach defects.

test/listener-audio-attach.test.js

@@ -252,6 +252,15 @@ function makeBrowser(role){
       return el;
     }
     function applySinkTo(){ return Promise.resolve(); }
+    function applySinkToAudioCtx(){
+      /* sandbox stub for the sink-routing fan-out — real impl awaits
+       * audioCtx.setSinkId(speakerDeviceId). Tests that care about
+       * the setSinkId call inspect ctx._setSinkCalls in the override
+       * below; this stub just hits the same code path. */
+      try { audioCtx.setSinkId(speakerDeviceId || ''); } catch(_){}
+    }
+    let speakerDeviceId = '';
+    function setSpeakerDeviceId(id){ speakerDeviceId = id || ''; }
     function startMeter(){}
     function stopMeter(){}
     function registerLipSyncAudio(){}
@@ -320,7 +329,7 @@ function makeBrowser(role){
     '  attachAudioStreamViaWorklet, attachListenerStreamViaAudioContext,\n' +
     '  attachSfuTrack, flushSfuStreams, setWorkletStream, detachListenerStream,\n' +
     '  handleRemoteSfuTrack,\n' +
-    '  triggerWorkletReady, setRole,\n' +
+    '  triggerWorkletReady, setRole, setSpeakerDeviceId,\n' +
     '  __seedLipSync,\n' +
     '  get audioCtx(){ return audioCtx; },\n' +
     '  get workletReady(){ return workletReady; },\n' +
@@ -1076,6 +1085,38 @@ test('audioCtx.setSinkId is called on creation so the worklet routes to the user
   truthy(typeof b.ctx.setSinkId === 'function', 'setSinkId is wired');
 });
 
+test('attach re-applies sink when audioCtx persists across leave/rejoin and the picked sink drifted (kills blanka-chrome silent-after-rejoin)', () => {
+  /* Fox 2026-06-07 blanka-chrome telemetry showed:
+   *   - first attach: audio via AudioContext ... sink=c38572ec…   (good)
+   *   - leave + re-enter the space
+   *   - second attach: audio via AudioContext ... sink=default    (BAD — sink reverted)
+   *   - no `audioCtx sink → c38572ec…` log between them
+   *
+   * Root cause: applySinkToAudioCtx() only ran inside the
+   * `if (!audioCtx)` branch — fresh ctx → apply sink. A persistent
+   * audioCtx that somehow had its sinkId getter return '' (default)
+   * stayed default forever, because attach saw audioCtx already
+   * existed and skipped the apply.
+   *
+   * Pin the fix: when audioCtx exists AND speakerDeviceId is set AND
+   * the ctx's current sinkId !== speakerDeviceId, attach must call
+   * setSinkId again to restore routing. */
+  const b = makeBrowser('listener');
+  addMember(b, UUID_A, PUB_A);
+  const calls = [];
+  b.ctx.setSinkId = function(id){
+    calls.push(id);
+    /* simulate setSinkId behaviour: the getter now reflects the call */
+    b.ctx.sinkId = id;
+    return Promise.resolve();
+  };
+  b.ctx.sinkId = '';                    /* default sink */
+  b.api.setSpeakerDeviceId('dev-1234'); /* user picked a specific device */
+  b.api.attachAudioStreamViaWorklet(UUID_A, makeStream(), RECV);
+  truthy(calls.includes('dev-1234'),
+    'attach called setSinkId("dev-1234") to restore the picked sink on the persistent audioCtx');
+});
+
 test('audioCtx without setSinkId support (older browser) does not throw — silent fallback to default', () => {
   /* Firefox <116 and Chrome <110 don't have audioCtx.setSinkId.
    * applySinkToAudioCtx must check before calling. */

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');
 
 <footer style="margin:2.2rem auto 0;font-size:0.65rem;color:#999;line-height:1.7;word-break:break-all;font-family:monospace">
   <span id="pi-seal" style="color:#777;cursor:default;user-select:none" title="">page integrity</span> &nbsp;·&nbsp; built <span class="stamp-date">2026-06-07</span><br>
-  md5 <span class="stamp-md5">bb5c7dea19fcb19f88c479d1cb26f24f</span><br>
-  sha256 <span class="stamp-sha">03e08e3499cf18fac3aec4b5dbeb808e6b3b6bceb5222ca560026c6d65864d38</span><br>
+  md5 <span class="stamp-md5">1e77ac2d270d5b6b8697257a6d7f43cc</span><br>
+  sha256 <span class="stamp-sha">6b76bd2486a0b366599cc8e22c1e11d51072e3bf09df3afed6f0208e5af8b0a9</span><br>
   <span style="color:#bbb">hashes are of this page with these two fields zeroed — to verify, blank them and re-hash</span><br>
   <span style="color:#bbb">one self-contained file — <strong>save a copy</strong> and verify against these hashes; point at your own servers with ?signal= and ?turncred=, or <a href="host-your-own.html" style="color:#999">host your own community</a></span>
 </footer>