From 59c407f1c71e45cd153ce4611c3e3cfca48e7bd8 Mon Sep 17 00:00:00 2001
From: "russell@unturf.com" <russell@unturf.com>
Date: Fri, 5 Jun 2026 19:41:22 -0400
Subject: [PATCH] zebra-spaces: idempotent attach + drop stale stream cache

---
 zebra-report/zebra-spaces.html | 42 +++++++++++++++++++++++++++++++---
 1 file changed, 39 insertions(+), 3 deletions(-)

diff --git a/zebra-report/zebra-spaces.html b/zebra-report/zebra-spaces.html
index 8c48c75..3eb798b 100644
--- a/zebra-report/zebra-spaces.html
+++ b/zebra-report/zebra-spaces.html
@@ -3180,6 +3180,20 @@ function applyLipSyncForPub(pubHex){
  * applied only when role==='listener' — speakers don't need lock-
  * screen transport controls. */
 function attachAudioStreamViaWorklet(uuid, stream, targetSeconds){
+  /* Reject streams that have no live audio tracks. flushSfuStreams hands
+   * us whatever sfuStreamsByPubHex cached for the publisher's pubkey —
+   * after a publisher leaves and rejoins with the SAME pubkey, the old
+   * cached stream's tracks are ended even though the cache entry still
+   * exists. Without this guard, attach creates a silent MediaStreamSource
+   * → fallback to <audio> path → double-audio when the real ontrack
+   * arrives moments later. Fox 2026-06-05 telemetry: "host hearing two"
+   * after peer-joined u=64b0 fired three attaches in 1s. */
+  const liveAudio = (stream && stream.getAudioTracks ? stream.getAudioTracks() : [])
+    .filter(t => t.readyState === 'live');
+  if (liveAudio.length === 0){
+    logLine('', 'audio attach skip uuid='+uuid.slice(0,4)+' — no live audio tracks');
+    return false;
+  }
   if (!audioCtx){
     try { audioCtx = new (window.AudioContext || window.webkitAudioContext)(); }
     catch(e){ logLine('err','audioCtx create: '+e.message); return false; }
@@ -3189,6 +3203,15 @@ function attachAudioStreamViaWorklet(uuid, stream, targetSeconds){
   }
   logLine('', 'audio attach uuid='+uuid.slice(0,4)+' target='+targetSeconds+'s (current pool='+listenerAudioNodes.size+')');
   const existing = listenerAudioNodes.get(uuid);
+  /* IDEMPOTENT: if we already have a chain for this uuid AND it points at
+   * THIS exact stream object, treat as no-op. Multiple paths (peer-joined
+   * → flushSfuStreams, sub PC ontrack, mid-spotlight supplant) can each
+   * race to attach the same stream within the same tick — without this,
+   * each rebuilds the chain and two of them overlap audibly. */
+  if (existing && existing.stream === stream){
+    logLine('', 'audio attach no-op uuid='+uuid.slice(0,4)+' — same stream already attached');
+    return true;
+  }
   if (existing){
     try { existing.src.disconnect(); } catch(_){}
     try { if (existing.jbuf) existing.jbuf.disconnect(); } catch(_){}
@@ -4644,8 +4667,21 @@ function handleRemoteSfuTrack(ev){
   try { if (ev.receiver) ev.receiver.playoutDelayHint = playoutDelayForRole(myRole); } catch(_){}
   try { if (ev.receiver) ev.receiver.jitterBufferTarget = playoutDelayForRole(myRole) * 1000; } catch(_){}
   /* cache by full pubkey (already resolved above) so it survives the
-   * member's session uuid changing across leave/rejoin */
+   * member's session uuid changing across leave/rejoin. When the cached
+   * track ends (publisher leaves), drop the cache entry — flushSfuStreams
+   * was handing the dead stream to attachAudioStreamViaWorklet on the
+   * NEXT peer-joined with matching pubkey, racing the live ontrack.
+   * Fox 2026-06-05 telemetry: peer-joined u=64b0 fired "audio attach
+   * fresh=1 tracks=0" before the real attach. */
   sfuStreamsByPubHex.set(pubHex, ev.streams[0]);
+  try {
+    ev.track.addEventListener('ended', () => {
+      if (sfuStreamsByPubHex.get(pubHex) === ev.streams[0]){
+        sfuStreamsByPubHex.delete(pubHex);
+        logLine('', 'sfu cache drop pub='+pubHex.slice(0,4)+' — track ended');
+      }
+    }, { once: true });
+  } catch(_){}
   for (const [uuid, mm] of members){
     try {
       if (mm.pubkey && hex(unb64(mm.pubkey)) === pubHex){
@@ -7786,8 +7822,8 @@ logLine('', 'ready — pick a handle, type a rendezvous code, enter the space');
 
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