- Designed JKSessionJamTrackPlayer with props interface and state management
- Defined sub-components: MixdownSelector, PlaybackControls, SeekBar, DownloadSyncProgress, ErrorBanner
- Documented component lifecycle and initialization pattern
- Implemented playback controls with UAT-003 fix (pending seek while paused)
- Applied Phase 3 performance patterns (visibility-aware polling, useCallback, lazy updates)
- Created props vs Redux decision matrix
- Compared to Backing Track player with reusable patterns identified