---
phase: 05-jamtrack-implementation
plan: 03
subsystem: ui
tags: [react, jamclient, media-playback, websocket]

# Dependency graph
requires:
  - phase: 05-jamtrack-implementation/05-02
    provides: JamTrack skeleton with initialization, sync checking, and cleanup
provides:
  - Playback control handlers (play/pause/stop) with jamClient integration
  - Visibility-aware polling (500ms/2000ms) for position and duration
  - Seek slider with UAT-003 fix (pending seek while paused)
  - End-of-track handling (auto-stop and reset)
  - formatTime utility for MM:SS display
affects: [05-04, 05-05, jamtrack-uat, session-playback]

# Tech tracking
tech-stack:
  added: []
  patterns:
    - "Visibility-aware polling (500ms visible, 2000ms hidden)"
    - "UAT-003 fix pattern (pending seek while paused, apply on resume)"
    - "End-of-track detection (stop when position >= duration)"
    - "Conditional state updates (only update if values changed)"

key-files:
  created: []
  modified:
    - jam-ui/src/components/client/JKSessionJamTrackPlayer.js

key-decisions:
  - "Used same visibility-aware polling pattern from Phase 3 Backing Track (500ms/2000ms)"
  - "Applied UAT-003 fix pattern from Phase 3 (pendingSeekRef for pause-seek-resume)"
  - "Error handling with typed errors (file/network red, playback yellow)"
  - "Conditional state updates in polling to prevent unnecessary re-renders"

patterns-established:
  - "jamClient playback APIs: JamTrackPlay/Pause/Resume/Stop/SeekMs"
  - "jamClient polling APIs: JamTrackGetPositionMs/GetDurationMs"
  - "isOperating flag to prevent rapid clicks during async operations"
  - "mountedRef check before setState in async callbacks"
  - "formatTime utility for consistent MM:SS time display"

issues-created: []

# Metrics
duration: 3min
completed: 2026-01-15
---

# Phase 05-03: JamTrack Playback Controls Summary

**Functional JamTrack player with play/pause/stop controls, real-time position updates via visibility-aware polling, and seek slider with UAT-003 fix for pause-seek-resume**

## Performance

- **Duration:** 3 min
- **Started:** 2026-01-14T19:16:46Z
- **Completed:** 2026-01-14T19:19:50Z
- **Tasks:** 3
- **Files modified:** 1

## Accomplishments
- Playback controls implemented with jamClient integration (play/pause/stop)
- Visibility-aware polling working (500ms visible, 2000ms hidden) for real-time position/duration updates
- Seek slider functional with UAT-003 fix (pending seek while paused, immediate while playing)
- End-of-track handling (automatic stop and reset when position >= duration)
- Time display formatted as MM:SS for better UX

## Task Commits

Each task was committed atomically:

1. **Task 1: Implement playback control handlers** - `217005c94` (feat)
2. **Task 2: Implement visibility-aware polling** - `e5e010292` (feat)
3. **Task 3: Implement seek slider** - `16af15c85` (feat)

## Files Created/Modified
- `jam-ui/src/components/client/JKSessionJamTrackPlayer.js` - Added playback controls (play/pause/stop), visibility-aware polling for position/duration, seek slider with UAT-003 fix, formatTime utility, and end-of-track handling

## Decisions Made

**1. Reused Phase 3 Backing Track patterns**
- Applied visibility-aware polling (500ms visible, 2000ms hidden)
- Applied UAT-003 fix pattern (pendingSeekRef for pause-seek-resume)
- Ensures consistency between Backing Track and JamTrack players

**2. Error handling with typed errors**
- File/network errors: red background (#fee)
- Playback errors: yellow background (#ffd)
- Dismissible error messages for better UX

**3. Conditional state updates in polling**
- Only dispatch setJamTrackState if position or duration changed
- Prevents unnecessary re-renders and improves performance

**4. isOperating flag for async operations**
- Prevents rapid clicks during loadJamTrack, pause, stop, seek operations
- Buttons disabled appropriately during operations and before duration loaded

## Deviations from Plan

None - plan executed exactly as written.

## Issues Encountered

None - all jamClient APIs worked as expected, polling implemented smoothly, and UAT-003 fix pattern applied successfully.

## Next Phase Readiness

- JamTrack playback controls fully functional
- Ready for Plan 04 (Track metadata display and styling)
- Ready for Plan 05 (Mixdown selection UI)
- No blockers for continued development

---
*Phase: 05-jamtrack-implementation*
*Completed: 2026-01-15*
