yellowjacket/.planning/milestones/v1.1-phases/09-scan-cancellation-keyboard-shortcuts/09-01-SUMMARY.md

phase, plan, subsystem, tags, requires, provides, affects, tech-stack, key-files, key-decisions, patterns-established, requirements-completed, duration, completed

phase	plan	subsystem	tags	requires	provides	affects	tech-stack	key-files	key-decisions	patterns-established	requirements-completed	duration	completed
09-scan-cancellation-keyboard-shortcuts	01	library	context-cancellation scan-control wails-binding goroutine-coordination	phase provides 08-infrastructure Library struct, Scan() pipeline, events system	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	09-scan-cancellation-keyboard-shortcuts	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	created modified backend/library/scan_control.go backend/events/events.go frontend/src/events.ts backend/library/library.go backend/library/metrics.go	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	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	SCAN-01 SCAN-02 SCAN-03	16min	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)

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Phase: 09-scan-cancellation-keyboard-shortcuts Completed: 2026-03-07