docs(quick-14): complete queue/player desync fix plan

.planning/STATE.md

@@ -62,17 +62,18 @@ Decisions from v1.0 are archived in PROJECT.md Key Decisions table. Key patterns
 | 011 | Fix neovim crash during library scan (configurable log level) | 2026-03-05 | c45bca4 |
 | 012 | Add favorite icon to album dropdown track rows | 2026-03-05 | 12a0bbc |
 | 013 | Fix all golangci-lint issues (zero issues) | 2026-03-05 | e1a95e6 |
+| 014 | Fix queue/player desync after track load failure | 2026-03-05 | 2820de2 |
 
 ## Session Continuity
 
 ### Last Session
 
 **Date:** 2026-03-05
-**What happened:** Quick task 13 — fixed all 31+ golangci-lint issues across 12 Go files. Mechanical fixes only (errcheck, golines, gofumpt, wsl, nlreturn, intrange, unused). Zero behavioral changes.
-**Where we stopped:** Quick task 13 complete. `golangci-lint run ./...` reports 0 issues.
+**What happened:** Quick task 14 — fixed queue/player desync after track load failure. Added roll-back-on-failure semantics to all queue index advancement paths (Next, Previous, OnPlaybackFinished, PlayIndex, playFromStart). `playCurrentTrack` and `playOrLoadCurrentTrack` now return bool.
+**Where we stopped:** Quick task 14 complete. All 28 queue tests pass, go vet clean.
 **Next action:** Continue with next task
 
 ---
 *State initialized: 2026-02-27*
-Last activity: 2026-03-05 - Fix all golangci-lint issues
+Last activity: 2026-03-05 - Fix queue/player desync after track load failure
 *Last updated: 2026-03-05*

.planning/quick/14-fix-queue-player-desync-after-hot-reload/14-SUMMARY.md

@@ -0,0 +1,66 @@
+---
+phase: quick-14
+plan: 14
+subsystem: queue
+tags: [bug-fix, queue, player-sync, rollback]
+dependency_graph:
+  requires: []
+  provides: [roll-back-on-failure-pattern]
+  affects: [backend/queue]
+tech_stack:
+  added: []
+  patterns: [roll-back-on-failure for index advancement]
+key_files:
+  created: []
+  modified:
+    - backend/queue/queue.go
+    - backend/queue/handlers.go
+decisions:
+  - Extended roll-back pattern to PlayIndex and playFromStart (not in plan but same bug pattern)
+metrics:
+  duration: 567s
+  completed: "2026-03-05"
+  tasks_completed: 2
+  tasks_total: 2
+---
+
+# Quick Task 14: Fix Queue/Player Desync After Track Load Failure
+
+Roll-back-on-failure semantics for all queue index advancement paths, ensuring currentIndex always reflects the track the player actually has loaded.
+
+## What Changed
+
+### Task 1: Make playOrLoadCurrentTrack and playCurrentTrack return bool (6eeddda)
+
+- `playCurrentTrack()` now returns `bool` — false on load failure or play error
+- `playOrLoadCurrentTrack()` now returns `bool` — propagates from `playCurrentTrack`/`loadCurrentTrack`
+- `loadCurrentTrack()` already returned `bool` — no change needed
+
+### Task 2: Add roll-back-on-failure to all index advancement call sites (2820de2)
+
+- **Next()**: Saves `prevIndex` before advancing; rolls back on failure; RepeatOne path guards emit
+- **Previous()**: All three branches (RepeatOne, restart >3s, navigate-to-previous) guard emit or roll back
+- **OnPlaybackFinished()**: RepeatOne path guards emit; main advance path rolls back on failure
+- **PlayIndex()**: Rolls back to previous index on failure
+- **playFromStart()**: Rolls back to -1 on failure
+
+## Deviations from Plan
+
+### Auto-fixed Issues
+
+**1. [Rule 1 - Bug] Extended roll-back to PlayIndex and playFromStart**
+- **Found during:** Task 2
+- **Issue:** `PlayIndex()` and `playFromStart()` had the same desync bug — they set `currentIndex` and called `playCurrentTrack()` without checking the return, then emitted `QueueIndexChanged` unconditionally
+- **Fix:** Applied the same roll-back pattern: save previous index, attempt load, roll back on failure
+- **Files modified:** backend/queue/queue.go
+- **Commit:** 2820de2
+
+## Verification
+
+- `go build ./backend/...` — passes
+- `go test ./backend/queue/... -v -count=1` — 28/28 tests pass
+- `go vet ./backend/queue/...` — no warnings
+
+## Self-Check: PASSED
+
+All files exist, all commits verified.