jam-cloud/.planning/phases/27-backing-track-sync/27-VERIFICATION.md

phase	verified	status	score
27-backing-track-sync	2026-02-26T11:53:24Z	passed	2/2 must-haves verified

Phase 27: Backing Track Sync Verification Report

Phase Goal: Backing Track appears in session screen when opened Verified: 2026-02-26T11:53:24Z Status: passed Re-verification: No - initial verification

Goal Achievement

Observable Truths

#	Truth	Status	Evidence
1	Opening a backing track file shows the track in session screen (not just popup)	VERIFIED	handleBackingTrackSelected at line 1137 calls await openBackingTrack(result.file) which triggers syncTracksToServer in useMediaActions hook
2	No "state update on unmounted component" warnings when closing backing track quickly	VERIFIED	JKSessionBackingTrackPlayer.js useEffect at line 90 has let ignore = false declaration and cleanup function at line 155-157 sets ignore = true

Score: 2/2 truths verified

Required Artifacts

Artifact	Expected	Status	Details
jam-ui/src/components/client/JKSessionScreen.js	handleBackingTrackSelected using openBackingTrack action	VERIFIED	Line 1144: await openBackingTrack(result.file); - uses action from useMediaActions (imported line 18, destructured line 153)
jam-ui/src/components/client/JKSessionBackingTrackPlayer.js	Duration fetch useEffect with cleanup	VERIFIED	Lines 90-158: useEffect with let ignore = false (line 91), async checks, and cleanup return () => { ignore = true; } (lines 155-157)

Key Link Verification

From	To	Via	Status	Details
JKSessionScreen.js handleBackingTrackSelected	useMediaActions openBackingTrack	async await call	VERIFIED	Line 1144: await openBackingTrack(result.file) - openBackingTrack destructured from useMediaActions() at line 153
JKSessionBackingTrackPlayer.js useEffect	cleanup function	return statement	VERIFIED	Lines 155-157: return () => { ignore = true; };
openBackingTrack hook function	syncTracksToServer	dispatch call	VERIFIED	useMediaActions.js line 60: dispatch(syncTracksToServer(sessionId, jamClient))

Requirements Coverage

Requirement	Status	Blocking Issue
BT-01: Use openBackingTrack() action to enable track sync to session screen	SATISFIED	None
BT-02: Add ignore flag to duration fetch useEffect	SATISFIED	None

Anti-Patterns Found

File	Line	Pattern	Severity	Impact
JKSessionScreen.js	1158	TODO comment about native window	Info	Pre-existing, not related to Phase 27 changes

Note: JKSessionBackingTrackPlayer.js has no TODO/FIXME patterns.

Human Verification Required

1. Visual Verification: Backing Track in Session Screen

Test: Open a backing track file in session Expected: Backing track appears in the session screen track list (not just in popup) Why human: Requires running app with native client to verify visual rendering

2. Console Warning Check

Test: Open backing track popup, then close it immediately (within 1-2 seconds) Expected: No React warning "Can't perform a React state update on an unmounted component" Why human: Requires running app and monitoring browser console during rapid open/close

Summary

All must-haves have been verified in the codebase:

1. Backing track sync: The handleBackingTrackSelected function now uses openBackingTrack(result.file) action from useMediaActions hook. This action:

   • Calls openBackingTrackThunk which invokes jamClient.SessionOpenBackingTrackFile
   • Sets mediaSummary.backingTrackOpen = true
   • Calls syncTracksToServer(sessionId, jamClient) to sync track to session screen

2. Async cleanup: The duration fetch useEffect in JKSessionBackingTrackPlayer.js implements the ignore flag pattern:

   • let ignore = false at useEffect start (line 91)
   • if (ignore) return checks before async operation (line 104) and after (line 119)
   • if (!ignore) guard in catch block (line 143)
   • Cleanup function return () => { ignore = true; } (lines 155-157)

The direct jamClient.SessionOpenBackingTrackFile call has been removed from handleBackingTrackSelected (grep confirms no matches).

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Verified: 2026-02-26T11:53:24Z Verifier: Claude (gsd-verifier)