fix(board): slow the edge auto-scroll while dragging a card on mobile#47
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With a card held at the board's left/right edge, dnd-kit's default auto-scroll
(acceleration 10) pans the column strip at ~2000px/s — far too fast to land in
the intended column on a phone, where only ~one column is visible at a time, so
moving a card across columns overshoots constantly.
Pass autoScroll={{ acceleration: 5 }} to DndContext to halve the top edge-scroll
speed (~800px/s measured) while keeping the smooth 5ms scroll cadence — lowering
acceleration caps speed without the choppiness that raising `interval` would add.
acceleration is the single knob to dial further if it's still fast.
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Follow-up to the board mobile-drag work (#46). Now that dragging a card works on touch, holding it at the board's left/right edge to reach another column auto-scrolls far too fast to land in the column you want — on a phone only ~one column is visible at a time, so it overshoots constantly.
Cause
dnd-kit's edge auto-scroll runs
scrollBy(acceleration)everyinterval(5ms). At the defaultacceleration: 10that's ~2000 px/s.Fix
autoScroll={{ acceleration: 2 }}onDndContext— caps the edge-scroll at ~320 px/s (≈ one column per second) while keeping the smooth 5 ms cadence. Loweringaccelerationcaps speed without the choppiness that raisingintervalwould add; it's the single knob to dial.Verification
tsc -bclean;bun run test→ 84 pass.scrollLeftover an edge-hold with real touch events (CDP, 390px): measured ~340 px/s (default was ~2000; an earlier acceleration-5 pass measured ~800 and still felt too fast). Tap-to-open and within-column reorder unaffected.