---
phase: 27-backing-track-sync
plan: 01
subsystem: ui
tags: [react, redux, async-cleanup, backing-track, media-sync]

# Dependency graph
requires:
  - phase: 26-jamtrack-polish
    provides: useMediaActions hook with openBackingTrack thunk
provides:
  - Backing track sync to session screen via Redux action
  - Async cleanup pattern for unmount state update prevention
affects: [28-backing-track-controls, media-players, session-screen]

# Tech tracking
tech-stack:
  added: []
  patterns:
    - ignore flag pattern for async useEffect cleanup

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

key-decisions:
  - "Use openBackingTrack action instead of direct jamClient call for centralized sync"
  - "Use ignore flag pattern (not AbortController) for simple async cleanup"

patterns-established:
  - "Ignore flag pattern: let ignore = false; ... if (ignore) return; ... return () => { ignore = true; }"

# Metrics
duration: 8min
completed: 2026-02-26
---

# Phase 27 Plan 01: Backing Track Sync Summary

**Backing track now syncs to session screen via Redux action, with async cleanup to prevent unmount warnings**

## Performance

- **Duration:** 8 min
- **Started:** 2026-02-26T10:00:00Z
- **Completed:** 2026-02-26T10:08:00Z
- **Tasks:** 2
- **Files modified:** 2

## Accomplishments
- Backing tracks now appear in session screen when opened (via Redux mediaSummary + syncTracksToServer)
- No more "state update on unmounted component" React warnings when closing backing track popup quickly
- Centralized media opening flow through useMediaActions hook

## Task Commits

Each task was committed atomically:

1. **Task 1: Use openBackingTrack action in handleBackingTrackSelected** - `d958b26` (feat)
2. **Task 2: Add ignore flag to duration fetch useEffect** - `bba12ac` (fix)

## Files Created/Modified
- `jam-ui/src/components/client/JKSessionScreen.js` - handleBackingTrackSelected now uses openBackingTrack action
- `jam-ui/src/components/client/JKSessionBackingTrackPlayer.js` - Duration fetch useEffect with ignore flag cleanup

## Decisions Made
- **Use openBackingTrack action:** Instead of calling jamClient.SessionOpenBackingTrackFile directly, use the openBackingTrack action from useMediaActions which handles jamClient call, Redux state update (mediaSummary.backingTrackOpen), and server sync (syncTracksToServer)
- **Ignore flag pattern:** Used simple ignore flag pattern rather than AbortController since we only need to skip state updates, not cancel the async operation itself

## Deviations from Plan

None - plan executed exactly as written.

## Issues Encountered
- Build verification could not be completed due to environment compatibility issues (Node-sass/arm64). Syntax verification passed via ESLint and Node --check.

## Next Phase Readiness
- Backing track sync to session screen is complete
- Ready for Phase 28 or additional backing track controls
- Build environment issues should be resolved for full verification in production

---
*Phase: 27-backing-track-sync*
*Completed: 2026-02-26*
