---
phase: 32-audio-device-resilience
plan: 02
subsystem: audio
tags:
  [coreaudio, avaudiosession, health-check, dispatch-timer, device-resilience]

# Dependency graph
requires:
  - phase: 32-audio-device-resilience/01
    provides: "HAL listener + engine rebuild + debounce/cooldown infrastructure"
provides:
  - "30-second periodic health check as safety net for missed device changes"
  - "Complete three-layer audio device detection (HAL + notification + health check)"
affects: []

# Tech tracking
tech-stack:
  added: []
  patterns:
    - "DispatchSourceTimer for periodic health polling"
    - "Skip-during-playback guard to avoid false positives"

key-files:
  created: []
  modified:
    - plugins/claude-tts-companion/Sources/CompanionCore/AudioStreamPlayer.swift

key-decisions:
  - "Health check skips during active playback (audio working if playing)"

patterns-established:
  - "Three-layer detection: HAL listener (immediate) + notification (backup) + health check (safety net)"

requirements-completed: [AUDIO-05, AUDIO-06]

# Metrics
duration: 2min
completed: 2026-03-29
---

# Phase 32 Plan 02: Health Check Timer Summary

**30-second periodic health check timer comparing engine device vs system default, completing three-layer audio device resilience**

## Performance

- **Duration:** 2 min
- **Started:** 2026-03-29T07:29:31Z
- **Completed:** 2026-03-29T07:33:00Z
- **Tasks:** 2 (1 auto + 1 checkpoint auto-approved)
- **Files modified:** 1

## Accomplishments

- Added DispatchSourceTimer-based health check polling every 30 seconds
- Health check compares cached engine device ID against system default output device
- Skips check during active playback (audio is clearly working if playing)
- Device mismatch triggers same debounced rebuild path as HAL listener and notification
- Completed three-layer detection architecture: HAL (immediate) + notification (backup) + health check (safety net)

## Task Commits

Each task was committed atomically:

1. **Task 1: Add periodic health check timer to AudioStreamPlayer** - `ad9c319f` (feat)
2. **Task 2: Verify audio device resilience with real hardware switch** - auto-approved checkpoint (no commit)

## Files Created/Modified

- `plugins/claude-tts-companion/Sources/CompanionCore/AudioStreamPlayer.swift` - Added healthCheckTimer, startHealthCheck(), stopHealthCheck(), performHealthCheck() methods; init/deinit lifecycle hooks

## Decisions Made

- Health check skips during active playback -- if playerNode.isPlaying, audio is clearly working on the current device

## Deviations from Plan

None - plan executed exactly as written.

## Issues Encountered

None

## User Setup Required

None - no external service configuration required.

## Next Phase Readiness

- Audio device resilience is complete with all three detection layers operational
- Phase 32 is the final phase in v4.9.0 milestone scope
- Ready for milestone completion

---

_Phase: 32-audio-device-resilience_
_Completed: 2026-03-29_

## Self-Check: PASSED

- [x] SUMMARY.md exists at expected path
- [x] Commit ad9c319f found in git history
