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yonlu 74473d4386 docs(14-04): complete scroll optimization & profiling guide plan

- SUMMARY.md with task commits, decisions, and metrics
- STATE.md updated with plan progress and session continuity
- ROADMAP.md updated with Phase 14 plan progress

2026-03-14 13:54:36 -04:00

4.1 KiB

Raw Blame History

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

frontend

scroll

requestAnimationFrame

profiling

pprof

devtools

performance

phase	provides
14-performance-optimization	CSS containment and GPU scroll layer promotion (Plan 01), view caching navigation (Plan 02)

RAF-throttled scroll position saving for cover grid

overflow-anchor CSS on queue panel virtualizer

Performance profiling guide (docs/PROFILING.md)

cover-grid

queue-panel

developer-documentation

added

patterns

RAF-throttled scroll saves instead of debounce

overflow-anchor for virtualizer scroll containers

created

modified

docs/PROFILING.md

frontend/src/components/cover-grid/scroll-manager.ts

frontend/src/components/queue-panel/queue-panel.ts

Keep monkey-patch alongside overflow-anchor: CSS overflow-anchor disables browser scroll anchoring but not lit-virtualizer's internal _correctScrollError, so the monkey-patch is still needed for scrollbar drag on large lists

RAF throttle over debounce for scroll saves: saves position once per frame during scrolling instead of only after scrolling stops, preventing lost positions on quick navigation

RAF-throttled scroll position saving: use requestAnimationFrame guard pattern instead of setTimeout debounce for continuous scroll position tracking

PERF-SCROLL-03

PERF-DIAG-01

2min

2026-03-14

Phase 14 Plan 04: Scroll Optimization & Profiling Guide Summary

RAF-throttled scroll position saves for cover grid, overflow-anchor on queue panel virtualizer, and comprehensive performance profiling guide

Performance

Duration: 2 min
Started: 2026-03-14T17:49:56Z
Completed: 2026-03-14T17:52:54Z
Tasks: 2 completed, 1 pending checkpoint
Files modified: 3

Accomplishments

Cover grid scroll position saves are now RAF-throttled (once per ~16ms frame) instead of 100ms debounced, capturing position during continuous scrolling
Queue panel lit-virtualizer has overflow-anchor: none CSS; monkey-patch retained with expanded documentation explaining why CSS alone is insufficient
Comprehensive profiling guide created covering pprof backend profiling, Chrome DevTools frontend profiling, and specific diagnostic workflows

Task Commits

Each task was committed atomically:

Task 1: Optimize scroll event handling and clean up queue panel scroll hack - 6ca0b3c (perf)
Task 2: Create performance profiling guide - 1ec8f82 (docs)
Task 3: Verify performance improvements - pending checkpoint:human-verify

Files Created/Modified

frontend/src/components/cover-grid/scroll-manager.ts - Replaced debounced scroll save with RAF-throttled save
frontend/src/components/queue-panel/queue-panel.ts - Added overflow-anchor: none CSS, expanded monkey-patch comments
docs/PROFILING.md - Performance profiling guide with backend, frontend, and workflow sections

Decisions Made

Keep monkey-patch alongside overflow-anchor: CSS overflow-anchor: none disables browser-native scroll anchoring but does not affect lit-virtualizer's internal _correctScrollError() method. The monkey-patch is still needed to suppress that internal correction during native scrollbar drag on large lists (20k+ items).
RAF throttle over debounce: requestAnimationFrame guard pattern fires once per frame (~16ms at 60fps) during active scrolling, unlike debounce which only fires after scrolling stops. This prevents lost positions if the user navigates away during scrolling.

Deviations from Plan

None - plan executed exactly as written.

Issues Encountered

None

User Setup Required

None - no external service configuration required.

Next Phase Readiness

Task 3 (human-verify checkpoint) pending: user verification of scroll smoothness, navigation speed, and profiling guide
After checkpoint approval, Phase 14 is complete and ready for transition

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

4.1 KiB Raw Blame History