docs(08-02): complete virtualizer repeat() directive migration plan

.planning/REQUIREMENTS.md

@@ -46,7 +46,7 @@ Requirements for the consolidation milestone. Each maps to roadmap phases.
 ### UX
 
 - [x] **UX-01**: Visual inconsistencies across components are audited and fixed (spacing, colors, typography, icon sizing follow a consistent pattern)
-- [ ] **UX-02**: Frontend rendering for large libraries (10k+ tracks) is smooth — no jank during scrolling, view switching, or search filtering
+- [x] **UX-02**: Frontend rendering for large libraries (10k+ tracks) is smooth — no jank during scrolling, view switching, or search filtering
 
 ## v2 Requirements
 
@@ -114,7 +114,7 @@ Which phases cover which requirements. Updated during roadmap creation.
 | TEST-05 | Phase 4: Queue, Config & Player Tests | Complete |
 | TEST-06 | Phase 5: Database & Library Tests | Complete |
 | UX-01 | Phase 8: Frontend Performance & UX | Complete |
-| UX-02 | Phase 8: Frontend Performance & UX | Pending |
+| UX-02 | Phase 8: Frontend Performance & UX | Complete |
 
 **Coverage:**
 - v1 requirements: 26 total

.planning/STATE.md

@@ -3,12 +3,12 @@ gsd_state_version: 1.0
 milestone: v1.0
 milestone_name: milestone
 status: in-progress
-last_updated: "2026-03-05T04:15:16Z"
+last_updated: "2026-03-05T04:17:06Z"
 progress:
   total_phases: 8
   completed_phases: 7
   total_plans: 17
-  completed_plans: 14
+  completed_plans: 15
 ---
 
 # YellowJacket — Consolidation Milestone State
@@ -16,17 +16,17 @@ progress:
 ## Project Reference
 
 **Core value:** The music player works reliably and feels solid — every interaction is correct, responsive, and trustworthy.
-**Current focus:** Phase 8 in progress — performance plumbing and design tokens (Plan 01) complete. Continuing with frontend polish.
+**Current focus:** Phase 8 in progress — Plans 01-02 complete. Virtualizer repeat() migration done. Continuing with frontend polish.
 **Milestone:** Consolidation (correctness, performance, code quality, UX polish, test coverage)
 
 ## Current Position
 
 **Phase:** 08-frontend-performance-ux
-**Plan:** 1/4 (Plan 01 complete)
+**Plan:** 2/4 (Plans 01-02 complete)
 **Status:** In progress
 
 ```
-Phase Progress: [########] 8/8 phases — Phase 8: 1/4 plans complete
+Phase Progress: [########] 8/8 phases — Phase 8: 2/4 plans complete
 ```
 
 ## Performance Metrics
@@ -34,8 +34,8 @@ Phase Progress: [########] 8/8 phases — Phase 8: 1/4 plans complete
 | Metric | Value |
 |--------|-------|
 | Phases complete | 7/8 |
-| Plans complete | 1/4 (Phase 8) |
+| Plans complete | 2/4 (Phase 8) |
-| Requirements delivered | 20/26 |
+| Requirements delivered | 22/26 |
 | Tests added | 84 |
 | Bugs fixed | 9 |
 | 01-01 duration | 11 min |
@@ -54,6 +54,7 @@ Phase Progress: [########] 8/8 phases — Phase 8: 1/4 plans complete
 | Phase 07 P01 | 5 min | 2 tasks | 2 files |
 | Phase 07 P02 | 1 min | 1 tasks | 1 files |
 | Phase 08 P01 | 1 min | 2 tasks | 3 files |
+| Phase 08 P02 | 3 min | 2 tasks | 5 files |
 
 ## Accumulated Context
 
@@ -88,6 +89,7 @@ Phase Progress: [########] 8/8 phases — Phase 8: 1/4 plans complete
 | queueMicrotask coalescing over setTimeout | Synchronous microtask batching is more predictable and lower latency than macrotask scheduling | Phase 8 |
 | 150ms search debounce with instant clear | Balances responsiveness with computation cost; empty clears are immediate for snappy UX | Phase 8 |
 | :host scoped design tokens | Component-level token scope matches Lit's shadow DOM encapsulation model | Phase 8 |
+| Inline repeat() keys over gridKeyFunction | Dead method removal; key logic is cleaner inline in repeat() calls | Phase 8 |
 
 ### TODOs
 
@@ -131,18 +133,18 @@ None currently.
 ### Last Session
 
 **Date:** 2026-03-05
-**What happened:** Executed Phase 8 Plan 01 — performance plumbing and design tokens
+**What happened:** Executed Phase 8 Plan 02 — virtualizer repeat() directive migration
-**Where we stopped:** Completed 08-01-PLAN.md (2 tasks, all verification passed). Phase 8: 1/4 plans complete.
+**Where we stopped:** Completed 08-02-PLAN.md (2 tasks, all verification passed). Phase 8: 2/4 plans complete.
-**Next action:** Execute Phase 8 Plan 02
+**Next action:** Execute Phase 8 Plan 03
 
 ### Context for Next Session
 
-- Phase 8 Plan 01 complete: queueMicrotask coalescing + search debounce + design tokens
+- Phase 8 Plans 01-02 complete
-- Library store now coalesces 8+ notifications into 1 per microtask tick
+- All 7 lit-virtualizer instances now use repeat() with stable entity keys
-- Design tokens in frontend/src/styles/tokens.css.ts ready for component adoption
+- DOM recycling enabled for scrolling/filtering in large libraries
-- 3 plans remaining in Phase 8
+- 2 plans remaining in Phase 8
 
 ---
 *State initialized: 2026-02-27*
-Last activity: 2026-03-05 - Completed 08-01: queueMicrotask coalescing + search debounce + design tokens
+Last activity: 2026-03-05 - Completed 08-02: virtualizer repeat() directive migration
 *Last updated: 2026-03-05*

.planning/phases/08-frontend-performance-ux/08-02-SUMMARY.md

@@ -0,0 +1,117 @@
+---
+phase: 08-frontend-performance-ux
+plan: 02
+subsystem: ui
+tags: [lit, virtualizer, repeat-directive, dom-recycling, performance]
+
+# Dependency graph
+requires:
+  - phase: 08-frontend-performance-ux
+    provides: "Phase context with virtualizer component analysis"
+provides:
+  - "All 7 lit-virtualizer instances use repeat() with stable keys for efficient DOM reuse"
+  - "Keyed rendering: FilePath (tracks), album.ID (covers), QueueTrack.id (queue), artist.ID (artists), genre.name (genres)"
+affects: [08-frontend-performance-ux]
+
+# Tech tracking
+tech-stack:
+  added: []
+  patterns: ["repeat() directive with stable keys on all lit-virtualizer instances"]
+
+key-files:
+  created: []
+  modified:
+    - frontend/src/components/track-list/track-list.ts
+    - frontend/src/components/queue-panel/queue-panel.ts
+    - frontend/src/components/cover-grid/cover-grid.ts
+    - frontend/src/components/artists-view/artists-view.ts
+    - frontend/src/components/genres-view/genres-view.ts
+
+key-decisions:
+  - "Inline album.ID key in repeat() calls instead of keeping gridKeyFunction method"
+  - "Use genre.name (lowercase) as key matching Genre interface, not genre.Name from plan"
+
+patterns-established:
+  - "Virtualizer pattern: always use repeat() with stable entity key as child of lit-virtualizer, keep .items for sizing"
+
+requirements-completed: [PERF-05, UX-02]
+
+# Metrics
+duration: 3min
+completed: 2026-03-05
+---
+
+# Phase 8 Plan 02: Virtualizer repeat() Directive Migration Summary
+
+**Migrated all 7 lit-virtualizer instances across 5 components to repeat() directive with stable entity keys for efficient DOM recycling during scrolling and filtering**
+
+## Performance
+
+- **Duration:** 3 min
+- **Started:** 2026-03-05T04:13:34Z
+- **Completed:** 2026-03-05T04:17:06Z
+- **Tasks:** 2
+- **Files modified:** 5
+
+## Accomplishments
+- All 7 virtualizer instances now use repeat() with stable keys for DOM node reuse
+- Removed .renderItem and .keyFunction properties from all lit-virtualizer elements
+- Removed dead gridKeyFunction method from cover-grid component
+- Stable keys: FilePath (tracks), QueueTrack.id (queue), album.ID (covers), artist.ID (artists), genre.name (genres)
+
+## Task Commits
+
+Each task was committed atomically:
+
+1. **Task 1: Migrate track-list and queue-panel virtualizers** - `d2d7d8c` (perf)
+2. **Task 2: Migrate cover-grid, artists-view, and genres-view virtualizers** - `1c3514d` (perf)
+
+## Files Created/Modified
+- `frontend/src/components/track-list/track-list.ts` - repeat() with FilePath key for track virtualizer
+- `frontend/src/components/queue-panel/queue-panel.ts` - repeat() with QueueTrack.id key for queue virtualizer
+- `frontend/src/components/cover-grid/cover-grid.ts` - repeat() with album.ID key for all 3 cover grid virtualizers, removed gridKeyFunction
+- `frontend/src/components/artists-view/artists-view.ts` - repeat() with artist.ID key
+- `frontend/src/components/genres-view/genres-view.ts` - repeat() with genre.name key
+
+## Decisions Made
+- **Inlined album.ID key instead of keeping gridKeyFunction:** The gridKeyFunction method was only used for .keyFunction property bindings. Since repeat() takes an inline key function, the method became dead code and was removed for cleanliness.
+- **Used genre.name (lowercase) not genre.Name:** The Genre interface in genres-view uses lowercase `name` field, not the Go-model-style `Name`. Plan referenced `genre.Name` but actual code uses `genre.name`.
+
+## Deviations from Plan
+
+### Auto-fixed Issues
+
+**1. [Rule 1 - Bug] Fixed renderGridEntry call signature in cover-grid repeat()**
+- **Found during:** Task 2 (cover-grid migration)
+- **Issue:** Plan template used `(entry, index) => this.renderGridEntry(entry, index)` but renderGridEntry only accepts 1 argument (GridEntry), not 2
+- **Fix:** Changed to `(entry) => this.renderGridEntry(entry)` for all 3 cover-grid virtualizers
+- **Files modified:** frontend/src/components/cover-grid/cover-grid.ts
+- **Verification:** TypeScript compiles without errors
+- **Committed in:** 1c3514d (Task 2 commit)
+
+**2. [Rule 1 - Bug] Corrected genre key from genre.Name to genre.name**
+- **Found during:** Task 2 (genres-view migration)
+- **Issue:** Plan specified `entry.genre.Name` but Genre interface uses lowercase `name` field
+- **Fix:** Used `entry.genre.name` as the repeat() key
+- **Files modified:** frontend/src/components/genres-view/genres-view.ts
+- **Verification:** TypeScript compiles without errors
+- **Committed in:** 1c3514d (Task 2 commit)
+
+---
+
+**Total deviations:** 2 auto-fixed (2 bugs)
+**Impact on plan:** Both fixes necessary for TypeScript correctness. No scope creep.
+
+## Issues Encountered
+None
+
+## User Setup Required
+None - no external service configuration required.
+
+## Next Phase Readiness
+- All virtualizer components now use repeat() with stable keys
+- Ready for remaining Phase 8 plans (08-03, 08-04)
+
+---
+*Phase: 08-frontend-performance-ux*
+*Completed: 2026-03-05*