Several pairs of near-identical code paths differ in one load-bearing
line. Each site now carries a comment naming the invariant that forces it
apart, backed by a characterization test so a future deduplication fails
loudly instead of silently changing behaviour.
Pinned: focusable wrapper vs. chip D-pad activation policy, profile
connection cleanup's raw-id vs. ServerId-typed server projections, live TV
tab loaders, video player display matching and playback service wiring,
track selection container ordering, tracker HTTP client status ladder, and
the MediaServerHttpClient shutdown/cancellation contract versus
ManagedHttpClient's closing guard.
New tests:
test/focus/dpad_activation_policy_test.dart
test/services/track_selection_container_ordinal_test.dart
test/services/trackers/tracker_status_ladder_test.dart
test/utils/media_server_http_client_shutdown_test.dart
Profile traces showed 100-370ms UI-thread frames while scrolling the
library screen, dominated by rebuilding and inflating media cards.
- Gate per-card focus/pointer chrome on input mode: FocusableWrapper
skips the scale/border wrappers and creates its AnimationController
lazily outside keyboard mode, and ClickableCursor plus the card tap
region only build MouseRegion/InkWell machinery on desktop - TV and
touch use a bare GestureDetector. Hub cards also drop their outer
gesture wrapper outside keyboard mode; the card's own tap region
always won the gesture arena anyway.
- Memoize sliver children (SliverChildMemo): browse/collections grids
and hub rows return identical widget instances for unchanged items,
so delegate swaps from pagination, watch-state, and deletion
setStates no longer rebuild every realized card inside layout. The
browse tab prunes the memo in lockstep with focus-node eviction so a
cached card can never resurrect a disposed FocusNode.
- Budget fresh inflation (CardInflationBudget): while a scrollable is
moving in pointer/touch mode at most one new card inflates per frame,
the rest render as SkeletonMediaCard and upgrade on following frames.
Hub rows also stop pre-inflating 250px of off-screen cards on entry.
Device traces: worst frame 373ms -> 103ms, per-card build 3.6ms ->
2.4ms median; remaining row-entry work is spread across frames.
edde746