docs(08-03): complete renderTrackRow optimization plan

- SUMMARY.md with classMap directive migration results
- STATE.md updated: 3/4 plans complete, decisions recorded
- ROADMAP.md updated with plan progress

.planning/STATE.md

@@ -3,12 +3,12 @@ gsd_state_version: 1.0
 milestone: v1.0
 milestone_name: milestone
 status: in-progress
-last_updated: "2026-03-05T04:17:06Z"
+last_updated: "2026-03-05T04:22:19Z"
 progress:
   total_phases: 8
   completed_phases: 7
   total_plans: 17
-  completed_plans: 15
+  completed_plans: 16
 ---
 
 # 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 — Plans 01-02 complete. Virtualizer repeat() migration done. Continuing with frontend polish.
+**Current focus:** Phase 8 in progress — Plans 01-03 complete. renderTrackRow/renderTrackItem optimized with classMap. One plan remaining.
 **Milestone:** Consolidation (correctness, performance, code quality, UX polish, test coverage)
 
 ## Current Position
 
 **Phase:** 08-frontend-performance-ux
-**Plan:** 2/4 (Plans 01-02 complete)
+**Plan:** 3/4 (Plans 01-03 complete)
 **Status:** In progress
 
 ```
-Phase Progress: [########] 8/8 phases — Phase 8: 2/4 plans complete
+Phase Progress: [########] 8/8 phases — Phase 8: 3/4 plans complete
 ```
 
 ## Performance Metrics
@@ -34,7 +34,7 @@ Phase Progress: [########] 8/8 phases — Phase 8: 2/4 plans complete
 | Metric | Value |
 |--------|-------|
 | Phases complete | 7/8 |
-| Plans complete | 2/4 (Phase 8) |
+| Plans complete | 3/4 (Phase 8) |
 | Requirements delivered | 22/26 |
 | Tests added | 84 |
 | Bugs fixed | 9 |
@@ -55,6 +55,7 @@ Phase Progress: [########] 8/8 phases — Phase 8: 2/4 plans complete
 | 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 |
+| Phase 08 P03 | 2 min | 2 tasks | 2 files |
 
 ## Accumulated Context
 
@@ -90,6 +91,8 @@ Phase Progress: [########] 8/8 phases — Phase 8: 2/4 plans complete
 | 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 |
+| classMap over array filter/join | Eliminates per-row array allocation; classMap diffs internally for efficient DOM updates | Phase 8 |
+| Hoist search term outside cols.map | Avoids redundant property access per column per row in render hot path | Phase 8 |
 
 ### TODOs
 
@@ -133,18 +136,18 @@ None currently.
 ### Last Session
 
 **Date:** 2026-03-05
-**What happened:** Executed Phase 8 Plan 02 — virtualizer repeat() directive migration
+**What happened:** Executed Phase 8 Plan 03 — renderTrackRow/renderTrackItem optimization with classMap
-**Where we stopped:** Completed 08-02-PLAN.md (2 tasks, all verification passed). Phase 8: 2/4 plans complete.
+**Where we stopped:** Completed 08-03-PLAN.md (2 tasks, all verification passed). Phase 8: 3/4 plans complete.
-**Next action:** Execute Phase 8 Plan 03
+**Next action:** Execute Phase 8 Plan 04
 
 ### Context for Next Session
 
-- Phase 8 Plans 01-02 complete
+- Phase 8 Plans 01-03 complete
-- All 7 lit-virtualizer instances now use repeat() with stable entity keys
+- classMap directive used in all render hot paths (track-list + queue-panel)
-- DOM recycling enabled for scrolling/filtering in large libraries
+- Search highlight short-circuits when term is empty
-- 2 plans remaining in Phase 8
+- 1 plan remaining in Phase 8
 
 ---
 *State initialized: 2026-02-27*
-Last activity: 2026-03-05 - Completed 08-02: virtualizer repeat() directive migration
+Last activity: 2026-03-05 - Completed 08-03: renderTrackRow classMap optimization
 *Last updated: 2026-03-05*

.planning/phases/08-frontend-performance-ux/08-03-SUMMARY.md

@@ -0,0 +1,95 @@
+---
+phase: 08-frontend-performance-ux
+plan: 03
+subsystem: frontend
+tags: [lit, classMap, performance, render-optimization, directives]
+
+# Dependency graph
+requires:
+  - phase: 08-frontend-performance-ux
+    provides: "repeat() directive migration on all virtualizer instances"
+provides:
+  - "classMap directive for conditional CSS classes in track-list renderTrackRow and queue-panel renderTrackItem"
+  - "Search highlight short-circuit when search term is empty"
+  - "Hoisted search term lookup outside per-column iteration loop"
+affects: [08-frontend-performance-ux]
+
+# Tech tracking
+tech-stack:
+  added: []
+  patterns: ["classMap directive for conditional CSS classes in render hot paths"]
+
+key-files:
+  created: []
+  modified:
+    - frontend/src/components/track-list/track-list.ts
+    - frontend/src/components/queue-panel/queue-panel.ts
+
+key-decisions:
+  - "classMap object literal per-call is acceptable — classMap internally diffs and only updates changed classes"
+  - "Hoisted searchCtrl.term outside cols.map to avoid repeated property access per column"
+
+patterns-established:
+  - "Render hot path pattern: use classMap directive instead of array filter/join for conditional CSS classes"
+
+requirements-completed: [PERF-05, UX-02]
+
+# Metrics
+duration: 2min
+completed: 2026-03-05
+---
+
+# Phase 8 Plan 03: renderTrackRow Optimization Summary
+
+**Replaced array filter/join class construction with classMap directive in track-list and queue-panel render hot paths, eliminating per-row array allocations during scrolling**
+
+## Performance
+
+- **Duration:** 2 min
+- **Started:** 2026-03-05T04:19:55Z
+- **Completed:** 2026-03-05T04:22:19Z
+- **Tasks:** 2
+- **Files modified:** 2
+
+## Accomplishments
+- All conditional CSS class construction in renderTrackRow (track-row, fav-icon, cell) converted from array filter/join to classMap directive
+- Queue-panel renderTrackItem class construction (track-item, active, selected, drop-before, drop-after) converted to classMap
+- Search term property lookup hoisted outside per-column loop to avoid repeated access
+- Search highlighting already short-circuits when term is empty — no additional optimization needed
+
+## Task Commits
+
+Each task was committed atomically:
+
+1. **Task 1: Replace class string construction with classMap directive in renderTrackRow** - `ad21027` (perf)
+2. **Task 2: Optimize column value computation and apply classMap to queue-panel renderTrackItem** - `62f41c2` (perf)
+
+## Files Created/Modified
+- `frontend/src/components/track-list/track-list.ts` - classMap for track-row, fav-icon, and cell classes; hoisted search term lookup
+- `frontend/src/components/queue-panel/queue-panel.ts` - classMap for track-item with active, selected, drop-before, drop-after states
+
+## Decisions Made
+- classMap object literal allocation per-call is acceptable since classMap internally diffs previous values and only applies DOM changes for actually changed classes — net benefit over string concatenation in Lit's update cycle
+- Hoisted searchCtrl.term outside the cols.map loop — avoids redundant property access per column per row
+
+## Deviations from Plan
+
+None - plan executed exactly as written.
+
+## Issues Encountered
+None
+
+## User Setup Required
+None - no external service configuration required.
+
+## Next Phase Readiness
+- All render hot path optimizations complete for track-list and queue-panel
+- Ready for Plan 04 (final phase 8 plan)
+
+## Self-Check: PASSED
+
+All key files exist on disk. All task commits verified in git history.
+
+---
+*Phase: 08-frontend-performance-ux*
+*Completed: 2026-03-05*