fix(devtools): handle pointercancel when dragging the indicator

[icyJoseph]

Fixes #98468

Claude explanation of the fix

useDrag listened for pointermove and pointerup, but never pointercancel.

When a user agent cancels a gesture — a browser or system gesture takes over, a second finger arrives — it fires pointercancel and no pointerup, implicitly releasing pointer capture as it does. So cancel() never ran: the state machine stayed { state: 'drag' } and cleanup.current was never invoked, leaving the pointermove/pointerup listeners on window.

The next pointerup anywhere on the page then hit those orphaned listeners, reached cancel() with the state still 'drag', and called releasePointerCapture() on a pointer that no longer existed — the reported NotFoundError. Each cancelled drag also leaked another listener pair.

This registers pointercancel alongside pointerup and removes it in the same cleanup, so the machine unwinds when a gesture is cancelled; and it releases pointer capture only when hasPointerCapture() says it is still held, which is preferable to try/catch swallowing genuine faults too.

Note touch-action: none (#97723) removed the common touch trigger, but not the defect: on canary a forced touchCancel still throws.

Screen.Recording.2026-09-10.at.17.04.00.mov

Fixed version

Screen.Recording.2026-09-10.at.17.05.11.mov

Browser checks

• Chrome, as describe by the bug report
• FF works fine pre and post fix (with and without the pointer simulation)
• iOS safari simulator, before the fix, I can't see an error, but, the drag gets frozen, with this fix it works correctly

Screen.Recording.2026-09-10.at.17.13.07.mov

🤖 Generated with Claude Code

[github-actions]

Tests Passed

Commit: aa250c6