yellowjacket/.planning/phases/14-performance-optimization/14-01-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
14-performance-optimization	01	ui	css-containment gpu-compositing will-change content-visibility scroll-performance		CSS containment on all app shell layout boundaries GPU-composited scrolling on all 6 scroll-heavy components content-visibility auto on album cards for off-screen rendering skip	14-performance-optimization	added patterns CSS contain for layout isolation will-change transform for GPU scroll promotion content-visibility auto for off-screen rendering skip	created modified frontend/index.css frontend/src/components/cover-grid/cover-grid-styles.ts frontend/src/components/track-list/track-list.ts frontend/src/components/queue-panel/queue-panel.ts frontend/src/components/artists-view/artists-view.ts frontend/src/components/genres-view/genres-view.ts frontend/src/components/playlist-view/playlist-view.ts	contain: strict on .main-panel (has explicit dimensions), layout style elsewhere (avoids breaking flex) will-change: transform only on scroll containers (not :host) to avoid wasting GPU memory content-visibility: auto on album cards with contain-intrinsic-size hint to prevent layout shift	CSS containment pattern: :host gets contain: layout style; scroll container gets contain: paint + will-change: transform content-visibility: auto with contain-intrinsic-size for cards in virtualized grids	PERF-SCROLL-01 PERF-SCROLL-02	3min	2026-03-14

Phase 14 Plan 01: CSS Containment & GPU Scroll Promotion Summary

CSS containment on app shell boundaries + GPU-composited scrolling on all 6 scroll-heavy components with content-visibility on album cards

Performance

• Duration: 3 min
• Started: 2026-03-14T17:43:01Z
• Completed: 2026-03-14T17:46:24Z
• Tasks: 2
• Files modified: 7

Accomplishments

• App shell layout boundaries (content-area, main-panel, sidebar, bottom-bar) isolated with CSS containment to prevent cross-boundary layout recalculation
• All 6 scroll-heavy components (cover-grid, track-list, queue-panel, artists-view, genres-view, playlist-view) now have CSS containment on :host and GPU layer promotion on scroll containers
• Album cards skip rendering when off-screen via content-visibility: auto with intrinsic size hints

Task Commits

Each task was committed atomically:

1. Task 1: Add CSS containment to app shell layout boundaries - efa06f7 (perf)
2. Task 2: Add GPU promotion and containment to all scroll containers - ac8a52e (perf)

Files Created/Modified

• frontend/index.css - CSS containment on .content-area, .main-panel, .main-panel > *, sidebar, .bottom-bar
• frontend/src/components/cover-grid/cover-grid-styles.ts - contain + will-change on scroll container, content-visibility on album cards
• frontend/src/components/track-list/track-list.ts - contain on :host, contain + will-change on lit-virtualizer
• frontend/src/components/queue-panel/queue-panel.ts - contain on :host, contain + will-change on lit-virtualizer
• frontend/src/components/artists-view/artists-view.ts - contain on :host, contain + will-change on grid scroll container
• frontend/src/components/genres-view/genres-view.ts - contain on :host, contain + will-change on grid scroll container
• frontend/src/components/playlist-view/playlist-view.ts - contain on :host, contain + will-change on playlist-list

Decisions Made

• Used contain: strict only on .main-panel (has explicit flex: 1 + overflow: hidden), used contain: layout style elsewhere to avoid breaking flex layouts
• Applied will-change: transform only to actual scroll containers (not :host elements) to avoid wasting GPU memory on non-scrolling elements
• Added content-visibility: auto with contain-intrinsic-size hints on album cards to prevent layout shift during scroll

Deviations from Plan

None - plan executed exactly as written.

Issues Encountered

None

User Setup Required

None - no external service configuration required.

Next Phase Readiness

• CSS containment foundation in place for all components
• Ready for Plan 02 (next performance optimization plan in phase 14)

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Phase: 14-performance-optimization Completed: 2026-03-14

Self-Check: PASSED