Merge-time fix for #674: the first travel past the tap slop decided the
axis for the whole contact, so a scroll that opened on a thumb arc
(+9 px across, +5 px down, then straight down) locked as 'swipe'. Every
later touchmove returned before the scroll code and SwipeHandler gave
the swipe up at its 50 px drift limit, so the gesture did nothing. Past
SwipeHandler.maxVerticalDrift the drag is now handed to 'y' (and the
published axis with it), so it scrolls; a clean sideways swipe, a
vertical scroll and a long-press drag are unchanged.
The source pin in test/session-swipe-gesture.test.ts moves with the
code and also pins the drift value, and a new browser test drives the
real touch listeners: the thumb-arc drag ends as a scroll (it fails
without the fallback, axis stays 'swipe') and a clean sideways swipe
stays a swipe with nothing scrolled. The architecture note and
src/web/CLAUDE.md now say a swipe drag is consumed only up to that
limit.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
