docs(14-02): complete view caching navigation plan

- Created 14-02-SUMMARY.md with execution results - Updated STATE.md with Phase 14 position and decisions - Updated ROADMAP.md progress for Phase 14 (1/4 plans)
2026-03-14 13:46:41 -04:00
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+---
+phase: 14-performance-optimization
+plan: 02
+subsystem: ui
+tags: [navigation, view-caching, dom, performance, display-toggle]
+
+# Dependency graph
+requires: []
+provides:
+  - View caching navigation system — primary views created once and visibility-toggled
+  - viewCache Map with bounded 6-entry cache for primary views
+  - Ephemeral detail view lifecycle (artist-details, playlist-details, genre-details)
+affects: [14-performance-optimization]
+
+# Tech tracking
+tech-stack:
+  added: []
+  patterns:
+    - "View cache Map<string, HTMLElement> for DOM-persistent primary views"
+    - "display:none/display:'' toggle instead of innerHTML destruction"
+    - "Ephemeral detail views (remove + create) vs cached primary views"
+
+key-files:
+  created: []
+  modified:
+    - frontend/index.ts
+
+key-decisions:
+  - "Primary views cached, detail views ephemeral — detail views depend on entity IDs that change per navigation"
+  - "Inline style.display toggle over CSS class — simpler, no specificity issues, direct JS control"
+  - "viewCache bounded at 6 entries (one per primary view) — negligible memory overhead"
+
+patterns-established:
+  - "View caching: create once, toggle visibility, never destroy primary views"
+  - "Detail view lifecycle: hide primary view, remove old detail, create new detail"
+
+requirements-completed: [PERF-NAV-01, PERF-NAV-02]
+
+# Metrics
+duration: 1min
+completed: 2026-03-14
+---
+
+# Phase 14 Plan 02: View Caching Navigation Summary
+
+**DOM-persistent view cache replacing innerHTML destruction — primary views created once and visibility-toggled for instant navigation**
+
+## Performance
+
+- **Duration:** 1 min
+- **Started:** 2026-03-14T17:43:20Z
+- **Completed:** 2026-03-14T17:44:52Z
+- **Tasks:** 1
+- **Files modified:** 1
+
+## Accomplishments
+- Replaced innerHTML-based navigation with a view caching system using a `Map<string, HTMLElement>`
+- Primary views (tracks, albums, artists, genres, playlists, settings) created once and kept in DOM
+- Navigation toggles `display:none` / `display:''` instead of destroying and recreating components
+- Detail views (artist-details, playlist-details, genre-details) remain ephemeral with proper lifecycle (remove old, create new)
+- Scroll positions naturally preserved since DOM is never destroyed
+- No virtualizer reinit, no data refetch, no cover art image reload on navigation
+
+## Task Commits
+
+Each task was committed atomically:
+
+1. **Task 1: Implement view caching navigation system** - `ad91043` (perf)
+
+## Files Created/Modified
+- `frontend/index.ts` - Replaced switch/innerHTML navigation with VIEW_TAGS map, viewCache Map, display toggle, and ephemeral detail view lifecycle
+
+## Decisions Made
+- **Primary views cached, detail views ephemeral** — Detail views (artist-details, playlist-details, genre-details) depend on entity IDs/names that change per navigation, so caching them would show stale content. Primary views are stateless navigation targets that benefit from persistence.
+- **Inline style.display toggle** — Using `element.style.display = 'none'` / `element.style.display = ''` rather than CSS classes avoids specificity issues and gives direct control. The empty string restores the element's natural display value from CSS (`.main-panel > * { height: 100% }`).
+- **viewCache bounded at 6 entries** — One entry per primary view tag in VIEW_TAGS. Memory overhead is negligible since the data each view holds is already in store caches regardless.
+
+## Deviations from Plan
+
+None - plan executed exactly as written.
+
+## Issues Encountered
+None
+
+## User Setup Required
+None - no external service configuration required.
+
+## Next Phase Readiness
+- View caching complete — ready for remaining Phase 14 plans (14-01 CSS containment, 14-03 store optimizations, 14-04 rendering optimizations)
+- Existing scroll save/restore logic in components preserved as fallback for data invalidation scenarios
+
+---
+## Self-Check: PASSED
+
+- ✅ frontend/index.ts exists
+- ✅ Commit ad91043 exists
+
+*Phase: 14-performance-optimization*
+*Completed: 2026-03-14*