Two defects Iris reported from her phone on 2026-09-08, one root cause
each, both in how a gesture ends.
A widget that takes pointer capture cuts every other widget off from the
press completely -- no PressEnd, no Drop -- so anything else tracking it
was left with an open gesture at a stale origin, and the *next* touch
anywhere was measured from that origin. That is the transcript jumping on
a tap after a code fence was panned sideways. CursorSense::Cancel is the
missing state: delivered once to each loser of a capture race, the way
Android sends ACTION_CANCEL and the web sends pointercancel.
And registered click_or_drag|unclick, which never matches
a Drop, so a Scroll that had captured never saw its own gesture end and
stayed panning from where the finger left. That is the horizontal snap
back. CursorSense::drag_senses() states the rule once for every widget
driving a DragGesture instead of per call site.
The pointer's own state (who holds capture, who is tracking the press) no
longer lives in a Mutex on UiRenderState. It is Event::Global for the
cursor senses -- owned by the event manager that runs the dispatch,
reached by &mut, with a per-dispatch PointerRequests slot for handlers --
per Iris: never reach for locks first, and input-wide state belongs to
the general input handler. What had forced the lock was a Data: Send
bound on task_on that nothing needed; the spawned future never sees the
event's data.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
irisandClaude Opus 5
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