React's onTouchMove handler is registered as a passive listener by
default, so the previous JSX-handler preventDefault() was silently a
no-op — drags on the composer still scrolled the input box up.
Attaches the listener imperatively via addEventListener with
{ passive: false } so preventDefault actually cancels the drag. Tap
(touchstart + touchend without touchmove between) is still unaffected,
so first-tap focus continues to work.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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