Drag perf measured via new Playwright spec drag-perf.spec.ts which drives
a slow drag across the biggest column (~35 cards) while capturing per-frame
durations via rAF inside the page. Pre-fix metrics in HECHO column:
wrapper-renders=1942 body-renders=N/A
p50=16.7ms p95=83.3ms max=116.7ms (12fps stalls)
Root cause: useSortable inside KanbanCardImpl subscribes to dnd-kit context;
every pointermove during a drag re-renders ALL cards in the SortableContext.
With the old monolithic component, each re-render rebuilt the full Stack +
Menu + 4 Popovers JSX tree — even though no data had changed.
Fix: split KanbanCardImpl into a thin outer (useSortable + Paper wrapper +
sticker overlay handler + style) and a memoed KanbanCardBody (Stack +
sticker overlay + popover state). All popover/requesterDraft local state
lives inside the body now, so its props are stable across drag and
React.memo skips the body work entirely.
Post-fix metrics:
wrapper-renders=1943 body-renders=0
p50=16.7ms p95=16.8ms max=50.0ms (steady 60fps with a single 33ms spike)
E2E thresholds tightened: p50<20, p95<50, max<60, body-renders<5. Regression
in any of these will fail CI.
Probe helpers (_probeRender / _probeBodyRender) are no-ops unless
window._cardRenderProbe is set. Production cost: ~3ns per render call.
Also: `now` clock interval already pauses while dragging (previous commit
e656e8c). `animateLayoutChanges:() => false` kept; it does not visibly
change reorder UX with this codebase.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
