fix: clean rewrite of audio recovery matching Kima Hub design

playCurrent():
- Remove canplay listener from before play() — it caused a race where
  both the listener and the initial play() fired simultaneously
- canplay is now only registered in the catch (failure path only),
  eliminating the double-play race entirely
- AbortError: reload src+load() with _trackChanging=true (OS interruption
  recovery); canplay fires once buffered and retries play()
- Other errors: reset _trackChanging, let canplay retry (not throttled
  by Android background timers unlike setTimeout)
- Add 10s safety net to reset _trackChanging if Doze kills everything
  (matches Kima Hub's reload failsafe)

main.js error handler:
- Skip when _trackChanging=true (playCurrent already recovering) to
  prevent conflicting dual recovery attempts
- _onForeground: reset _trackChanging on play() failure so the flag
  can't get stuck when foreground recovery also fails

index.html:
- Add crossorigin=anonymous: Navidrome and NovaSonic backend both send
  Access-Control-Allow-Origin:* so this is safe, and it enables proper
  cross-context HTTP caching for cover art and audio responses

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

index.html

@@ -590,7 +590,7 @@
 <div class="jobs-panel" id="jobs-panel"></div>
 
 <div class="toast-container" id="toast-container"></div>
-<audio id="audio-element" preload="auto" playsinline></audio>
+<audio id="audio-element" preload="auto" playsinline crossorigin="anonymous"></audio>
 <audio id="preview-audio"></audio>
 <audio id="abs-audio"></audio>
 

src/main.js

@@ -148,13 +148,15 @@ window.addEventListener('load', () => {
   let _errRetries = 0, _errTimer = null;
   S.audio.addEventListener('play', () => { _errRetries = 0; clearTimeout(_errTimer); }, { capture: true });
   S.audio.addEventListener('error', () => {
-    if(!S.queue[S.qIdx]) return;
+    // Skip if playCurrent() is already handling recovery (_trackChanging = true means
+    // we're mid-transition or waiting for canplay — don't conflict with that)
+    if(!S.queue[S.qIdx] || S._trackChanging) return;
     _errRetries++;
     const delay = Math.min(1000 * Math.pow(2, _errRetries - 1), 8000); // 1s, 2s, 4s, 8s
     clearTimeout(_errTimer);
     _errTimer = setTimeout(() => {
-      if(!S.queue[S.qIdx]) return;
+      if(!S.queue[S.qIdx] || S._trackChanging) return;
-      S._trackChanging = true; // prevent load()'s pause event from dismissing Samsung notification
+      S._trackChanging = true;
       S.audio.load();
       S.audio.play().catch(() => { S._trackChanging = false; });
     }, delay);
@@ -171,7 +173,7 @@ window.addEventListener('load', () => {
       navigator.mediaSession.playbackState = S.audio.paused ? 'paused' : 'playing';
     // If audio was playing before backgrounding but is now paused (OS kill), try to resume
     if(!S.audio.paused) return;
-    if(s && S.audio.src) S.audio.play().catch(() => {});
+    if(s && S.audio.src) S.audio.play().catch(() => { S._trackChanging = false; });
   }
 
   document.addEventListener('visibilitychange', () => {

src/player.js

@@ -71,45 +71,41 @@ export function playCurrent() {
   if(S.qIdx < 0 || S.qIdx >= S.queue.length) return;
   const s = S.queue[S.qIdx];
   S._trackChanging = true;
-  // Explicitly keep Samsung notification alive — set playing BEFORE metadata swap
+  // Keep Samsung notification alive — set playing BEFORE metadata swap
   if(navigator.mediaSession) navigator.mediaSession.playbackState = 'playing';
-  updatePlayerUI(s);        // update metadata/notification BEFORE src change
+  updatePlayerUI(s);
   onNpSongChange(s.id);
   renderQueue();
-  // Reuse preloaded URL so Chrome can serve from its in-memory buffer
   const src = (_preId === s.id && _preUrl) ? _preUrl : streamUrl(s.id);
   _clearPreload();
   S.audio.src = src;
-  // canplay is fired by the audio element's internal state machine — not throttled like
+  // 10s safety net: if neither play-event nor catch fires (e.g. Doze killed everything),
-  // setTimeout in background. Use it as a reliable retry trigger when play() is rejected.
+  // reset _trackChanging so the pause-event guard doesn't stay stuck forever
-  S.audio.addEventListener('canplay', () => {
+  const _guard = setTimeout(() => { S._trackChanging = false; }, 10000);
-    if (S.queue[S.qIdx]?.id === s.id && S.audio.paused) {
-      S._trackChanging = true;
-      S.audio.play().catch(() => { S._trackChanging = false; });
-    }
-  }, { once: true });
-  const _tryPlay = (attempt) => {
   try { if(navigator.audioSession) navigator.audioSession.type = 'playback'; } catch {}
-    S.audio.play().catch(err => {
+  S.audio.play()
-      S._trackChanging = false;
+    .then(() => clearTimeout(_guard))
-      if (S.queue[S.qIdx]?.id !== s.id) return; // song changed while we waited — stop
+    .catch(err => {
+      clearTimeout(_guard);
+      if (S.queue[S.qIdx]?.id !== s.id) { S._trackChanging = false; return; }
       if (err?.name === 'AbortError') {
-        // Audio element in bad state (interruption or load race) — reload like Kima Hub does
+        // Audio element in bad state (OS interruption / load race) — Kima Hub pattern:
-        S._trackChanging = true;
+        // reload the src so the element settles, then let canplay trigger the retry
         S.audio.src = src;
-        S.audio.load(); // canplay listener above will call play() once buffered
+        S.audio.load(); // _trackChanging stays true; load()'s pause event is suppressed
-        return;
+      } else {
+        // NotAllowed / network error — reset flag, wait for canplay to retry
+        S._trackChanging = false;
       }
-      if (attempt < 4) {
+      // canplay fires from the audio engine (not throttled by Android background timers).
-        setTimeout(() => {
+      // Registered ONLY here (in the failure path) — no race with the initial play() call.
-          if (S.queue[S.qIdx]?.id !== s.id) return;
+      S.audio.addEventListener('canplay', () => {
+        if (S.queue[S.qIdx]?.id !== s.id || !S.audio.paused) return;
         S._trackChanging = true;
-          _tryPlay(attempt + 1);
+        try { if(navigator.audioSession) navigator.audioSession.type = 'playback'; } catch {}
-        }, Math.min(500 * Math.pow(2, attempt), 8000)); // 500ms, 1s, 2s, 4s, 8s
+        S.audio.play().catch(() => { S._trackChanging = false; });
-      }
+      }, { once: true });
     });
-  };
-  _tryPlay(0);
 }
 
 export function updatePlayerUI(s) {