yonlu
b514772547
- Created 14-03-SUMMARY.md with event delegation and store batching results - Updated STATE.md with plan progress, decisions, and session continuity - Updated ROADMAP.md with Phase 14 plan progress
119 lines
5.1 KiB
Markdown
119 lines
5.1 KiB
Markdown
---
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phase: 14-performance-optimization
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plan: 03
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subsystem: performance
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tags: [event-delegation, queueMicrotask, closure-elimination, scroll-perf, store-batching]
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# Dependency graph
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requires:
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- phase: 14-01
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provides: CSS containment and GPU scroll promotion for scroll containers
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provides:
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- Zero per-item closure allocation during scroll rendering in track-list and queue-panel
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- queueMicrotask notification batching in queue store
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- changeGeneration counter in library store for granular update skipping
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affects: [14-04, ui-performance]
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# Tech tracking
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tech-stack:
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added: []
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patterns:
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- Event delegation via data-index attributes replacing per-item inline closures
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- queueMicrotask batching for store notifications (now consistent across all stores)
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- changeGeneration counter to skip requestUpdate on loading-only state transitions
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key-files:
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created: []
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modified:
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- frontend/src/components/track-list/track-list.ts
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- frontend/src/components/queue-panel/queue-panel.ts
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- frontend/src/store/queue-store.ts
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- frontend/src/store/library-store.ts
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- frontend/src/store/controllers/library-controller.ts
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key-decisions:
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- "Event delegation via data-index + closest() instead of bound-method-per-row pattern"
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- "changeGeneration counter in library store instead of typed per-data subscriptions"
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patterns-established:
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- "Event delegation: attach handlers on virtualizer element, resolve item via closest + data-index"
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- "Store change generation: monotonic counter for data-only changes, skip updates on loading toggles"
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requirements-completed: [PERF-RENDER-01, PERF-RENDER-02]
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# Metrics
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duration: 4min
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completed: 2026-03-14
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---
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# Phase 14 Plan 03: Render & Store Optimization Summary
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**Event delegation eliminates per-scroll-frame closure allocation; queueMicrotask batching and changeGeneration counter reduce unnecessary re-renders**
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## Performance
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- **Duration:** 4 min
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- **Started:** 2026-03-14T17:49:45Z
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- **Completed:** 2026-03-14T17:54:13Z
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- **Tasks:** 2
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- **Files modified:** 5
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## Accomplishments
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- Eliminated all inline arrow function closures from `renderTrackRow` (track-list) and `renderTrackItem` (queue-panel), removing GC pressure during rapid scrolling
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- Added queueMicrotask-based notification batching to queue store, matching the library store pattern
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- Added changeGeneration counter to library store so LibraryController skips requestUpdate when only loading flags toggle (no actual data change)
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- Confirmed cover-grid already uses event delegation — no changes needed
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## Task Commits
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Each task was committed atomically:
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1. **Task 1: Eliminate per-item closure allocation in render hot paths** - `2f7ed70` (perf)
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2. **Task 2: Add notification batching to queue store and granular subscriptions to library store** - `d0c05dc` (perf)
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## Files Created/Modified
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- `frontend/src/components/track-list/track-list.ts` - Event delegation via data-index; removed 5 inline closures per row from renderTrackRow
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- `frontend/src/components/queue-panel/queue-panel.ts` - Event delegation via data-index; removed 5 inline closures per item from renderTrackItem
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- `frontend/src/store/queue-store.ts` - queueMicrotask batching for notify()
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- `frontend/src/store/library-store.ts` - changeGeneration counter incremented on actual data changes
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- `frontend/src/store/controllers/library-controller.ts` - Checks changeGeneration before requestUpdate
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## Decisions Made
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- **Event delegation via data-index + closest()** — chosen over per-row bound method references because it requires zero function objects in renderItem, not just stable ones. The virtualizer and its children share the same shadow root so event.target.closest() works correctly.
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- **changeGeneration counter** — chosen over typed per-data subscriptions (subscribeTo('tracks')) because it's simpler, backward-compatible, and eliminates the biggest source of unnecessary re-renders (loading flag transitions during eagerFetch cause 8+ requestUpdate calls) without requiring store API changes for existing subscribers.
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## Deviations from Plan
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### Auto-fixed Issues
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**1. [Rule 1 - Bug] Removed unused handleRemoveTrack method**
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- **Found during:** Task 1 (queue-panel event delegation)
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- **Issue:** After delegating remove-button click to the virtualizer handler, the old `handleRemoveTrack` method became unused, causing a TypeScript error (TS6133)
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- **Fix:** Removed the unused method; remove logic is now in `onDelegatedClick` which checks `closest('.remove-button')`
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- **Files modified:** frontend/src/components/queue-panel/queue-panel.ts
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- **Verification:** Build passes, pre-commit typecheck passes
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- **Committed in:** 2f7ed70 (Task 1 commit)
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---
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**Total deviations:** 1 auto-fixed (1 bug)
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**Impact on plan:** Trivial cleanup of dead code after refactoring. No scope creep.
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## Issues Encountered
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None
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## User Setup Required
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None - no external service configuration required.
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## Next Phase Readiness
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- Plans 14-01, 14-02, 14-03 complete
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- Ready for 14-04 (remaining rendering optimizations)
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## Self-Check: PASSED
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All 5 modified files verified on disk. Both task commits (2f7ed70, d0c05dc) verified in git history.
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---
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*Phase: 14-performance-optimization*
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*Completed: 2026-03-14*
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