docs/tickets: 0001 fedora chrome silence → fixed (chromium decoder anchor)

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

@@ -1,10 +1,44 @@
 # 0001: fedora chrome cannot hear speakers
 
-**Status:** in-progress
+**Status:** fixed
 **Priority:** P0 (silent regression — every invariant green except audible output)
 **Surface:** fedora chrome — observed under both listener and speaker roles
 **First seen:** 2026-06-04 (or earlier — "for days")
 **Reporter:** fox (blanka-chrome identity)
+**Fixed:** 2026-06-07, commits `dad697d` (source) + `1f27b89` (deploy)
+
+## Root cause
+
+**Chromium will not run its WebRTC audio decoder for a remote
+`MediaStreamTrack` whose only consumer is a `MediaStreamAudioSourceNode`.**
+The decoder requires an `HTMLMediaElement` (an `<audio>` or `<video>`
+element) bound to the track to actually decode. Without that anchor,
+the source node produces silence even though packets arrive at full
+rate, the worklet's `started` event fires, and `audioCtx.state ===
+'running'`. Firefox does not have this restriction.
+
+PulseAudio Playback during repro: chrome stream visible (chrome WAS
+producing an output stream), level meter pinned at 0 (the stream's
+content was silence). RTP telemetry: `aud.recv pkt=N → N+50/sec
+bytes=growing level=0.000 jbuf=?`. Worklet telemetry:
+`jitter-buffer started uuid=… target=0.7s` (queue filled — but with
+zeros).
+
+## Fix
+
+In `attachAudioStreamViaWorklet`, alongside the existing
+`createMediaStreamSource(stream) → gain → destination` chain, create a
+hidden muted `<audio>` element with `srcObject = stream`, append it
+to the DOM, and call `play()`. The element makes no audible output
+(`muted = true`); its sole purpose is to keep chromium's WebRTC
+decoder running so the worklet's `MediaStreamSource` sees real
+samples. `setWorkletStream` swaps the anchor's `srcObject` alongside
+the source node; `detachListenerStream` tears the anchor down.
+
+Pinned by tests in `test/listener-audio-attach.test.js`:
+- anchor created on attach
+- anchor follows the stream on setWorkletStream
+- anchor torn down on detach
 
 ## Symptom
 
@@ -203,6 +237,15 @@ includes `want=…` so the mismatch jumps out.
 
 ## Status notes
 
+- **2026-06-07 (fixed):** chrome decoder anchor landed in `dad697d`,
+  deployed `1f27b89`. fox confirmed audio working on chrome.
+- **2026-06-07 (root cause pinned):** pavucontrol showed chrome stream
+  present + level=0 with worklet `started` fired — the chromium-only
+  MediaStreamSource-needs-anchor signature.
+- **2026-06-07 (en-route fixes kept):** always-SFU receive
+  (`1984bb1`), `SPEAKER_PLAYOUT_DELAY_SEC` 0.5s → 0.7s, session
+  fingerprint telemetry (`1ed5263`), per-peer mesh.recv stats
+  (`b9e2541`), `audioCtx.setSinkId` re-apply on rejoin (`467146a`).
 - **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

docs/tickets/README.md

@@ -63,9 +63,10 @@ Running log of attempts, observations, retests. Newest at the top.
 
 | # | Title | Priority | Surface | Status |
 |---|-------|----------|---------|--------|
-| [0001](0001-fedora-chrome-cannot-hear-speakers.md) | fedora chrome cannot hear speakers | P0 | fedora chrome (any role) | in-progress |
 | [0002](0002-fedora-firefox-cannot-share-camera.md) | fedora firefox cannot share camera | High | fedora firefox (speaker/host) | open |
 
 ## Fixed
 
-(none yet)
+| # | Title | Fix |
+|---|-------|-----|
+| [0001](0001-fedora-chrome-cannot-hear-speakers.md) | fedora chrome cannot hear speakers (P0) | Hidden muted `<audio>` decoder-anchor alongside MediaStreamSource (`dad697d` / deploy `1f27b89`). Plus en-route improvements: always-SFU receive, 0.7s cushion, audioCtx sinkId re-apply, session-fingerprint + mesh.recv telemetry. |