docs(09-01): complete scan control backend plan

- Create 09-01-SUMMARY.md with execution metrics and decisions - Update STATE.md with plan progress and session continuity - Update ROADMAP.md: mark 09-01 plan complete - Mark SCAN-01, SCAN-02, SCAN-03 requirements complete
2026-03-06 21:35:39 -05:00
parent cf22e52a64
commit 42add7fec4
4 changed files with 141 additions and 25 deletions
@@ -0,0 +1,112 @@
+---
+phase: 09-scan-cancellation-keyboard-shortcuts
+plan: 01
+subsystem: library
+tags: [context-cancellation, scan-control, wails-binding, goroutine-coordination]
+
+# Dependency graph
+requires:
+  - phase: 08-infrastructure
+    provides: Library struct, Scan() pipeline, events system
+provides:
+  - CancelScan, PauseScan, ResumeScan Wails-bound methods on Library
+  - IsScanActive, IsScanPaused state query methods
+  - waitIfPaused internal pause checkpoint helper
+  - LibraryScanCancelled, LibraryScanPaused, LibraryScanResumed events
+  - ScanMetrics.Cancelled field
+affects: [09-scan-cancellation-keyboard-shortcuts]
+
+# Tech tracking
+tech-stack:
+  added: []
+  patterns:
+    - "Per-scan cancellable context (scanCtx) threaded through pipeline, app context (l.ctx) for DB ops"
+    - "Blocking channel pattern for pause/resume (scanPauseCh closed to unblock all workers)"
+    - "Mutex-protected scan state fields with deferred cleanup"
+
+key-files:
+  created:
+    - backend/library/scan_control.go
+  modified:
+    - backend/events/events.go
+    - frontend/src/events.ts
+    - backend/library/library.go
+    - backend/library/metrics.go
+
+key-decisions:
+  - "scanCtx for worker cancellation, l.ctx for DB transactions — ensures in-flight commits complete"
+  - "Blocking channel pattern for pause — workers check waitIfPaused before each extraction"
+  - "Orphan cleanup and variant generation skipped on cancel — prevents incorrect file deletion"
+
+patterns-established:
+  - "Per-operation cancellable context pattern: create child context at operation start, defer cancel, clean up state in defer"
+  - "Channel-based pause/resume: create channel on pause, close on resume, select with ctx.Done for cancel-during-pause"
+
+requirements-completed: [SCAN-01, SCAN-02, SCAN-03]
+
+# Metrics
+duration: 16min
+completed: 2026-03-07
+---
+
+# Phase 9 Plan 01: Scan Control Backend Summary
+
+**Per-scan cancellable context with pause/resume channel coordination and 3 new scan lifecycle events**
+
+## Performance
+
+- **Duration:** 16 min
+- **Started:** 2026-03-07T02:14:23Z
+- **Completed:** 2026-03-07T02:31:08Z
+- **Tasks:** 2
+- **Files modified:** 5
+
+## Accomplishments
+- Created scan_control.go with CancelScan/PauseScan/ResumeScan/IsScanActive/IsScanPaused methods
+- Threaded per-scan cancellable context through walk and worker pipeline (3 select statements)
+- Added waitIfPaused checkpoint in worker pool so workers block when paused
+- Orphan cleanup and variant generation safely skipped on cancelled scans
+- Added LibraryScanCancelled/Paused/Resumed events with TypeScript sync via go generate
+
+## Task Commits
+
+Each task was committed atomically:
+
+1. **Task 1: Add scan control events and metrics fields** - `c695024` (feat)
+2. **Task 2: Add scan control fields to Library struct and create scan_control.go** - `cf22e52` (feat)
+
+## Files Created/Modified
+- `backend/library/scan_control.go` - CancelScan, PauseScan, ResumeScan, IsScanActive, IsScanPaused, waitIfPaused
+- `backend/events/events.go` - LibraryScanCancelled, LibraryScanPaused, LibraryScanResumed constants
+- `frontend/src/events.ts` - Auto-generated TypeScript event constants
+- `backend/library/library.go` - Scan control fields on Library struct, per-scan context threading, cancellation-aware orphan/variant phases
+- `backend/library/metrics.go` - Cancelled bool field on ScanMetrics
+
+## Decisions Made
+- Used scanCtx for worker cancellation and l.ctx for DB transactions — ensures in-flight batch commits always complete even when scan is cancelled
+- Blocking channel pattern for pause — `make(chan struct{})` on pause, `close()` on resume, all workers select against it
+- Orphan cleanup and variant generation skipped on cancel — existingPaths still contains unvisited files that would be incorrectly deleted
+
+## Deviations from Plan
+
+None - plan executed exactly as written.
+
+## Issues Encountered
+None
+
+## User Setup Required
+None - no external service configuration required.
+
+## Next Phase Readiness
+- Scan control backend complete, ready for Plan 02 (keyboard shortcuts config) and Plan 03 (frontend scan control UI)
+- All 5 new methods are exported and Wails-bindable
+- Events synced to TypeScript for frontend consumption
+
+## Self-Check: PASSED
+
+- All 5 key files verified on disk
+- Both task commits found in git log (c695024, cf22e52)
+
+---
+*Phase: 09-scan-cancellation-keyboard-shortcuts*
+*Completed: 2026-03-07*