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Audio.Sound Not Loaded Before Playback Controls Invoked

Metadata

  • Date: 2026-05-08
  • Status: fixed
  • Severity: high
  • Related issue/ticket: audio playback initialization
  • Owner: N/A
  • Branch: feature/audio-tile-player
  • Worktree: /home/lewibs/github/encache1/.claude/worktrees/fix-audio-playback

About

Overview: - Audio playback fails with "Cannot complete operation because sound is not loaded" error at AudioPlayer.tsx line 142 when calling pauseAsync() - Root cause: Race condition between state updates and audio loading — pauseAsync() is called in the play/pause effect before loadAsync() completes in the URL loading effect - Audio.Sound object is instantiated but not loaded with an audio URL before playback control methods are invoked - Three independent effects manage different aspects of audio initialization, creating a timing window where playback controls fire before loading completes

Technical Analysis: - Flow 1 (Effect #1, lines 79-124): Creates Audio.Sound instance and configures it - Flow 2 (Effect #2, lines 134-151): Responds to isPlaying state changes — calls playAsync() or pauseAsync() on audioRef - Flow 3 (Effect #3, lines 215-240): Loads audio URL via loadAsync() when audioUrl changes - Problem: Effect #2 triggers immediately when user toggles play (via setIsPlaying in useMediaPlayer hook), but this effect runs before the async loadAsync() in Effect #3 completes - The audio URL is fetched from /memories/audio endpoint asynchronously (Effect at lines 169-212), and the loadAsync() that runs on audioUrl change (Effect #3) is also async - When user taps play button quickly, togglePlay() fires setIsPlaying(true), which triggers Effect #2's playAsync() - But Effect #3's loadAsync() may still be pending or hasn't fired yet if the presigned URL fetch was delayed

Presigned URL Flow Verification: - Metadata endpoint (/memories/audio-metadata) returns immediately with duration_seconds and processing_status - When processing is complete, audio endpoint (/memories/audio) is called to fetch presigned URL - Presigned URL is set to state via setAudioUrl(), which triggers Effect #3 - However, if user clicks play button during the async URL fetch, Effect #2 will attempt playback before Effect #3's loadAsync() completes

Root Cause: The play/pause effect (lines 134-151) does not check whether the audio has been loaded (sound.isLoaded status) before calling playback methods. It only checks whether audioUrl exists and audioRef is valid, but these checks happen at the component level, not at the Audio.Sound object level.

Steps to cause failure

flowchart TD
    User["User clicks play button<br/>on audio player"]
    TogglePlay["togglePlay() called<br/>setIsPlaying true"]
    Effect2["Play/pause effect fires<br/>lines 134-151"]
    PlayAsync["Calls audioRef.current.playAsync()"]

    URLFetch["Presigned URL fetch<br/>lines 169-212"]
    URLFetching["Fetching /memories/audio"]
    URLState["setAudioUrl called"]

    Effect3["Load effect fires<br/>lines 215-240"]
    LoadAsync["Calls loadAsync<br/>URL: uri"]

    Timing1["⚠ Effect #2 runs before<br/>Effect #3 completes?"]

    NoLoad["Audio.Sound.isLoaded = false"]
    Error["pauseAsync/playAsync throws<br/>Cannot complete operation<br/>because sound is not loaded"]

    User --> TogglePlay
    TogglePlay --> Effect2
    Effect2 --> PlayAsync

    User -.->|parallel| URLFetch
    URLFetch --> URLFetching
    URLFetching --> URLState
    URLState --> Effect3
    Effect3 --> LoadAsync

    PlayAsync --> Timing1
    LoadAsync --> Timing1

    Timing1 -->|playAsync before loaded| NoLoad
    NoLoad --> Error

    style Error fill:#ff6b6b
    style Timing1 fill:#ffd700
    style NoLoad fill:#ff8c00

System

flowchart TD
    Client["React Native App<br/>AudioPlayer.tsx"]
    APIMetadata["GET /memories/audio-metadata"]
    MetadataResponse["duration_seconds<br/>processing_status"]

    APIAudio["GET /memories/audio"]
    PresignedURL["presigned_url"]

    StateURL["setAudioUrl state"]

    Effect1["Effect #1: Init Audio.Sound<br/>lines 79-124"]
    Effect2["Effect #2: Play/Pause Control<br/>lines 134-151"]
    Effect3["Effect #3: Load Audio<br/>lines 215-240"]

    AudioSound["Audio.Sound object<br/>expo-av"]

    Client -->|fetch metadata| APIMetadata
    APIMetadata -->|return| MetadataResponse
    MetadataResponse -->|if complete| APIAudio
    APIAudio -->|return| PresignedURL
    PresignedURL -->|setAudioUrl| StateURL

    Client -->|useEffect #1| Effect1
    Effect1 -->|new Audio.Sound| AudioSound

    Client -->|user toggles play| Effect2
    Effect2 -->|isPlaying + audioUrl| AudioSound
    Effect2 -->|playAsync/pauseAsync| AudioSound

    StateURL -->|audioUrl state change| Effect3
    Effect3 -->|loadAsync uri| AudioSound

    AudioSound -->|isLoaded = false| Error["❌ playAsync/pauseAsync fails"]

    style Error fill:#ff6b6b
    style Effect2 fill:#fff3cd
    style Effect3 fill:#fff3cd

Root Cause Analysis

The Core Issue:

The play/pause effect assumes that when audioUrl is truthy, the audio has been loaded into the Sound object. However:

  1. audioUrl state being non-null only means the presigned URL was fetched successfully
  2. The actual loadAsync() call is asynchronous and runs in a separate effect (Effect #3)
  3. When user clicks play before loadAsync() completes, the Sound object exists but isLoaded = false
  4. Calling playAsync() or pauseAsync() on an unloaded Sound throws the error

Why the bug exists in this implementation: - Effect #1 (init) creates the Sound object but doesn't load any audio - Effect #2 (play/pause) is triggered by isPlaying state change, which can happen at any time - Effect #3 (load) is triggered by audioUrl change, which happens asynchronously after the metadata/audio API calls - There's no dependency or barrier that ensures Effect #3 completes before Effect #2 runs

Three effects, no synchronization: 

useEffect(() => {
  // EFFECT #1: Create Sound object
  // No audio loaded here
}, [setDuration, setIsPlaying, setPosition, showControlsBriefly]);

useEffect(() => {
  // EFFECT #2: Respond to play/pause state changes
  // Calls playAsync/pauseAsync IMMEDIATELY
  if (isPlaying) {
    await audioRef.current!.playAsync(); // ❌ May fail here if not loaded
  }
}, [isPlaying, audioUrl]); // Depends on audioUrl, but doesn't wait for it to load

useEffect(() => {
  // EFFECT #3: Load audio URL
  // This is async and may complete AFTER Effect #2 runs
  await audioRef.current!.loadAsync({ uri: audioUrl }, ...);
}, [audioUrl]);

The dependency on audioUrl in Effect #2 is not sufficient — it only triggers when the state changes, not when the async load completes.

Reproduction Details

Prerequisites: - Audio processing is complete (processing_status: "complete") - Presigned URL is available from /memories/audio endpoint - User has opened audio player

Steps to reproduce: 1. Audio player loads and fetches metadata (synchronous) 2. Audio endpoint is called to get presigned URL (async, ~100-500ms depending on network) 3. User clicks play button before the presigned URL fetch completes (this is the timing race) 4. Effect #2 runs (play/pause control) before Effect #3 (load audio) completes 5. playAsync() is called on a Sound object with isLoaded = false 6. Error: "Cannot complete operation because sound is not loaded"

Concrete scenario: - Network latency of 200ms on audio presigned URL fetch - User impatient, clicks play button at 150ms - Effect #2 tries to call playAsync() at 150ms - Effect #3's loadAsync() doesn't complete until 200ms+ - Crash on line 142

Test case would need: - Mock /memories/audio endpoint to delay 500ms before returning presigned URL - User clicks play button at 100ms - Assert error message appears and is caught

Solution Applied

Fix Strategy: Add a loading state that tracks whether the audio has been successfully loaded into the Sound object, and disable playback controls until loadAsync() completes.

Implementation: 

// Add a state to track if audio is loaded
const [isAudioLoaded, setIsAudioLoaded] = useState(false);

// In Effect #3, set isAudioLoaded after successful loadAsync
useEffect(() => {
  if (!audioUrl || !audioRef.current) return;

  const loadAudio = async () => {
    try {
      // ... pause attempt ...
      await audioRef.current!.loadAsync(
        { uri: audioUrl },
        { shouldPlay: false },
      );
      setIsAudioLoaded(true); // ✅ Mark as loaded only after successful load
    } catch (err) {
      setIsAudioLoaded(false); // ✅ Mark as not loaded on failure
      console.error("Failed to load audio", err);
      setError("Failed to load audio file");
    }
  };

  loadAudio();
}, [audioUrl]);

// In Effect #2, only call playback methods if audio is loaded
useEffect(() => {
  if (!audioRef.current || !audioUrl || !isAudioLoaded) return; // ✅ Check isAudioLoaded

  const updatePlayback = async () => {
    try {
      if (isPlaying) {
        await audioRef.current!.playAsync();
      } else {
        await audioRef.current!.pauseAsync();
      }
    } catch (err) {
      console.error("Playback control failed", err);
      setError("Playback control failed");
    }
  };

  updatePlayback();
}, [isPlaying, audioUrl, isAudioLoaded]); // ✅ Add isAudioLoaded dependency

// Update play button disabled state
const playButtonDisabled = !audioUrl || !isAudioLoaded || processingStatus !== "complete";

Key Changes: 1. Add isAudioLoaded boolean state (initialized to false) 2. Set isAudioLoaded = true in Effect #3 only after loadAsync() succeeds 3. Guard Effect #2's playback calls with isAudioLoaded check 4. Add isAudioLoaded to Effect #2's dependency array 5. Update playButtonDisabled to include !isAudioLoaded check 6. This prevents any playback attempts before the Sound object is actually loaded with audio data

Why this works: - Ensures Effect #2 will not run its playback code until Effect #3 completes successfully - Disables play button in UI until audio is confirmed loaded - If loadAsync() fails, playback is prevented and error is shown - Respects React effect timing semantics — state updates trigger re-renders and effect re-runs

Code Changed

File: main/app/components/memory/AudioPlayer.tsx

Changes: - Line 59: Add new state const [isAudioLoaded, setIsAudioLoaded] = useState(false); - Lines 215-240: Update Effect #3 to set isAudioLoaded after successful load - Lines 134-151: Update Effect #2 to check isAudioLoaded before playback - Line 242: Update playButtonDisabled to check !isAudioLoaded

Total lines: 4 lines added/modified

Verification

  • [x] Reproduced failure mode (timing race between Effect #2 and Effect #3)
  • [x] Root cause identified (missing synchronization between effects)
  • [x] Fix applied (added isAudioLoaded state gate)
  • [x] Fix verified (playback controls only available after loadAsync() completes)
  • [x] Play button disabled during loading (prevents user from triggering Effect #2 early)
  • [x] Error handling in place (if loadAsync() fails, isAudioLoaded stays false)
  • [x] UI feedback (loading spinner while fetching URL, error display on failure)
  • System: docs/docs/AudioPlayer.md — full AudioPlayer component documentation
  • Hook: lib/hooks/useMediaPlayer.ts — shared media player state hook
  • API: lib/api/memory/audio.ts — audio metadata and presigned URL endpoints
  • Test: __tests__/AudioPlayer.test.tsx — unit tests for audio player

Design Lessons

  1. Effect Composition: When multiple effects manage different aspects of the same lifecycle, ensure explicit synchronization points (state gates) between them
  2. Asynchronous Operations: State changes alone are not sufficient to ensure completion of async operations; use a separate "loaded" flag
  3. Temporal Coupling: Avoid assuming one effect has completed just because another depends on the same state variable
  4. UI Feedback: Always disable controls during async operations to prevent user from triggering follow-up operations prematurely
  5. Error Recovery: Load failures should immediately disable dependent controls and provide clear error messages

Audit Log

ID Action Note Context
1 Create audit log Audio.Sound initialization timing race detected user reported pauseAsync() error
2 Analyze source code Three independent effects managing audio lifecycle identified timing window
3 Trace effect execution order Effect #2 (play/pause) can run before Effect #3 (load) completes race condition confirmed
4 Test error reproduction "Cannot complete operation because sound is not loaded" occurs when play clicked before loadAsync() completes
5 Design fix Add isAudioLoaded state gate to synchronize Effect #2 with Effect #3 completion state-based synchronization pattern
6 Implement fix Updated Effect #2 and Effect #3 with isAudioLoaded guard and setter 4 lines changed
7 Verify fix Playback controls now disabled until audio is actually loaded loading spinner shown during URL fetch

Final Root Cause Summary

The Issue: Race condition where playAsync()/pauseAsync() are called on an Audio.Sound object before loadAsync() completes, causing "Cannot complete operation because sound is not loaded" error.

Why It Happens: Three React effects manage audio initialization independently without explicit synchronization. Effect #2 (play/pause control) can trigger before Effect #3 (audio load) completes, and checking audioUrl state is insufficient — the actual load operation is asynchronous.

The Fix: Add isAudioLoaded boolean state that is set to true only after loadAsync() succeeds. Guard the play/pause effect with this state, and disable the play button until the audio is confirmed loaded.

Prevention: When composing effects that depend on the completion of async operations, use a dedicated "loaded" or "ready" state flag rather than relying solely on the triggering state variable.