# Phase 5 Plan 1: Redux Infrastructure & Bug Fixes Summary

**Fixed critical fqId bug and established Redux foundation for JamTrack player**

## Accomplishments

- **CRITICAL BUG FIX**: Fixed loadJamTrack to use `fqId` format instead of `jamTrack.id`, unblocking all JamTrack functionality
- Extended mediaSlice with comprehensive jamTrackState (7 fields) and downloadState (8 fields, 6-state machine)
- Extended activeSessionSlice with mixdown management (availableMixdowns, activeMixdown, mixdownCache)
- Extended sessionUISlice with JamTrack UI preferences (openJamTrack, jamTrackUI)
- Added 10 new reducers across 3 slices for complete state management
- Added 8 new selectors for accessing JamTrack state

## Files Created/Modified

- `jam-ui/src/store/features/mediaSlice.js` - Critical bug fix + state extensions (commit: bb74c5046)
- `jam-ui/src/store/features/activeSessionSlice.js` - Mixdown state management (commit: 52ee8f3ea)
- `jam-ui/src/store/features/sessionUISlice.js` - JamTrack UI preferences (commit: 52ee8f3ea)

## Decisions Made

- **fqId construction**: Moved outside conditional block to ensure consistent availability for all jamClient calls
- **State organization**: Separated jamTrackState (playback), downloadState (sync machine), and mixdown state (availableMixdowns) for clear separation of concerns
- **Download state machine**: Implemented 6-state machine (idle → checking → downloading → keying → synchronized → error) following Phase 4 design
- **Mixdown types**: Support for master, custom-mix, and stem types with full metadata caching
- **UI preferences**: Separated user preferences (lastUsedMixdownId, volume) from session state for better state management

## Technical Details

### mediaSlice Changes
- **Bug fix**: Line 29 now uses `fqId` instead of `jamTrack.id` for JamTrackPlay call
- **jamTrackState**: 7 fields tracking real-time playback (isPlaying, isPaused, currentPositionMs, durationMs, selectedMixdownId, playbackMode, lastUpdate)
- **downloadState**: 8 fields tracking sync machine (jamTrackId, mixdownId, fqId, state, progress, currentStep, totalSteps, error)
- **New reducers**: setJamTrackState, setDownloadState, clearDownloadState
- **Updated reducers**: clearJamTrackState and clearAllMedia now properly reset to structured state
- **Updated extraReducers**: loadJamTrack now updates downloadState instead of simple boolean flag

### activeSessionSlice Changes
- **availableMixdowns**: Array for storing all mixdowns (master, custom-mix, stem)
- **activeMixdown**: Currently selected mixdown object
- **mixdownCache**: Map of packageId to metadata for efficient lookups
- **New reducers**: setAvailableMixdowns, setActiveMixdown, cacheMixdownPackage, clearMixdowns
- **clearSession**: Automatically resets mixdown state when user leaves session

### sessionUISlice Changes
- **openJamTrack**: Tracks currently open JamTrack ID (null when closed)
- **jamTrackUI**: User preferences object (lastUsedMixdownId, volume)
- **New reducers**: setOpenJamTrack, updateJamTrackUI, clearOpenJamTrack
- **resetUI**: Automatically resets JamTrack UI state when UI is reset

## Issues Encountered

None - implementation followed Phase 4 design specifications precisely.

## Next Step

Ready for Plan 2: Async Thunks & Component Core
- Implement 6 async thunks (enhanced loadJamTrack, downloadJamTrack, checkJamTrackSync, loadJMEP, seekJamTrack, closeJamTrack)
- Create JKSessionJamTrackPlayer component skeleton
- Wire up Redux connections and jamClient integration
