docs(03-02): complete error handling and resilience plan

.planning/ROADMAP.md

@@ -52,7 +52,7 @@ Plans:
 
 Plans:
 - [x] 03-01: Finalize volume/loop controls and resolve UAT-003
-- [ ] 03-02: Add comprehensive error handling and loading states
+- [x] 03-02: Add comprehensive error handling and loading states
 - [ ] 03-03: Performance optimization and final UAT
 
 ### Phase 4: JamTrack Research & Design
@@ -102,7 +102,7 @@ Phases execute in numeric order: 1 → 2 → 3 → 4 → 5 → 6 → 7
 |-------|----------------|--------|-----------|
 | 1. Backing Track Playback Monitoring | 1/1 | Complete | 2026-01-13 |
 | 2. Backing Track Seek Controls | 1/1 | Complete | 2026-01-14 |
-| 3. Backing Track Finalization | 1/3 | In progress | - |
+| 3. Backing Track Finalization | 2/3 | In progress | - |
 | 4. JamTrack Research & Design | 0/TBD | Not started | - |
 | 5. JamTrack Implementation | 0/TBD | Not started | - |
 | 6. Metronome Research & Design | 0/TBD | Not started | - |

.planning/STATE.md

@@ -10,16 +10,16 @@ See: .planning/PROJECT.md (updated 2026-01-13)
 ## Current Position
 
 Phase: 3 of 7 (Backing Track Finalization)
-Plan: 1 of 3 in current phase
-Status: Plan 03-01 complete
-Last activity: 2026-01-14 — Completed Plan 03-01: Controls finalization and UAT-003 fix
+Plan: 2 of 3 in current phase
+Status: Plan 03-02 complete
+Last activity: 2026-01-14 — Completed Plan 03-02: Error handling and resilience
 
-Progress: ████░░░░░░ 33%
+Progress: ████░░░░░░ 38%
 
 ## Performance Metrics
 
 **Velocity:**
-- Total plans completed: 3
+- Total plans completed: 4
 - Average duration: TBD
 - Total execution time: TBD
 
@@ -29,11 +29,11 @@ Progress: ████░░░░░░ 33%
 |-------|-------|-------|----------|
 | 1 | 1 | 3 min | 3 min |
 | 2 | 1 | 120 min | 120 min |
-| 3 | 1 | TBD | TBD |
+| 3 | 2 | TBD | TBD |
 
 **Recent Trend:**
-- Last 5 plans: 3 min, 120 min, TBD
-- Trend: Phase 3 Plan 1 focused on controls finalization and UAT-003 fix
+- Last 5 plans: 3 min, 120 min, TBD, TBD
+- Trend: Phase 3 Plan 2 added comprehensive error handling and resilience
 
 ## Accumulated Context
 
@@ -54,6 +54,13 @@ Recent decisions affecting current work:
 - UAT-003 resolved with state machine workaround (stores pending seek, applies on resume)
 - Remove conditional fallback code - use correct methods directly
 
+**From Phase 3 Plan 2 (03-backing-track-finalization):**
+- Error types: file (red), network (red), playback (yellow), general (yellow)
+- Loading states: isLoadingDuration (track fetch), isOperating (prevent rapid clicks)
+- Disabled logic: buttons disabled during loading/operating/error
+- Cleanup on unmount: stop playback to prevent stale state
+- Network resilience: stop after 3 consecutive polling failures
+
 ### Deferred Issues
 
 None currently.
@@ -65,7 +72,7 @@ None yet.
 ## Session Continuity
 
 Last session: 2026-01-14
-Stopped at: Completed Phase 3 Plan 1 (controls finalization and UAT-003 fix)
+Stopped at: Completed Phase 3 Plan 2 (error handling and resilience)
 Resume file: None
 
-**Next:** Phase 3 Plan 2 (Error Handling & Resilience) - Ready for execution
+**Next:** Phase 3 Plan 3 (Performance Optimization & Final UAT) - Ready for execution

.planning/phases/03-backing-track-finalization/03-02-SUMMARY.md

@@ -0,0 +1,59 @@
+# Phase 3 Plan 2: Error Handling & Resilience Summary
+
+**Added production-ready error handling, loading states, and resilience to backing track player**
+
+## Accomplishments
+
+- Implemented error state management with user-facing messages
+- Added loading states and disabled controls during transitions
+- Handled edge cases: invalid files, network issues, null jamClient
+- Added proper cleanup on component unmount
+- No uncaught exceptions in any scenario
+
+## Files Created/Modified
+
+- `jam-ui/src/components/client/JKSessionBackingTrackPlayer.js` - Error handling, loading states, edge cases
+
+## Commits
+
+- `acbddd35e` - feat(03-02): add comprehensive error handling with user feedback
+- `9c0455dc6` - feat(03-02): add loading states and disabled UI
+- `31bc9ea2a` - feat(03-02): handle file and network edge cases
+
+## Decisions Made
+
+- **Error display approach**: Banner/alert above controls with dismiss and retry buttons
+  - Color coding: red for critical errors (file/network), yellow for warnings (playback/general)
+  - Retry button for network/file errors only
+  - Applied to both popup and modal versions
+
+- **Loading indicator style**: "Loading track..." text during duration fetch, "..." suffix on buttons during operations
+
+- **Debounce strategy**: `isOperating` flag prevents rapid clicks on play/stop buttons
+  - Reset in finally block to ensure cleanup
+  - Seek slider not blocked (allows immediate UI updates)
+
+## Error Types Implemented
+
+1. **file** - Failed to load track duration, invalid files (red)
+2. **network** - Lost connection after 3 consecutive polling failures (red)
+3. **playback** - Failed playback operations (yellow)
+4. **general** - Audio engine not available (yellow)
+
+## Edge Cases Handled
+
+1. **Invalid/missing file**: Validates duration (rejects 0 or NaN), warns about suspicious values
+2. **Network disconnection**: Tracks consecutive polling errors, stops after 3 failures
+3. **jamClient null**: Guards in all handlers with early return
+4. **Stale state**: Cleanup on unmount stops playback
+5. **Invalid state recovery**: Polling syncs UI to jamClient state
+6. **Graceful degradation**: Error states show but player stays open
+7. **File format validation**: Warns about durations <1s or >10h
+
+## Issues Encountered
+
+None - all implementations worked as expected.
+
+## Next Phase Readiness
+
+Ready for Plan 03-03 (Performance Optimization & Final UAT). Player is now resilient and production-ready for error scenarios.