[cixzhang]

Supersedes #9400 by @vjeux: the same three files, rebuilt as one commit on today's main with his authorship. Its intermediate docsite commit conflicts with main and was replaced within the branch, so the net change is unchanged. Harness and story only: no library code, no API, and no changeset.

Maintainer impact

Presented hit testing (spec:AST-094 FR11, FR19) is proven in CI's WebKit lane and in the iOS Simulator. But no story, sandbox or docs page attaches the gesture host, so a phone that opens a preview cannot exercise it. A check on a physical iPhone needs a page that does.

Intended invariant

spec:AST-017 FR21 and architecture:react-component-runtime INV13: Core's internal entries and gesture source stay with Core and Lab. This pull request adds no import of them from outside Core. The harness is a Core file, and the story renders it the way the a11y stories render Core's __tests__ renderings.

Change

• packages/core/src/__tests__/PresentedHitTestingLab.tsx (not exported): a sheet springs up over a full-page scrim on a spring slowed to a 3 s response, with Done in the sheet and a page behind it that scrolls.
  • It reads out what the engine hit-tested at each touch-down, Done's clicks and the scrim's taps, the sheet pan's translation, and how far the page scrolled in the last touch.
  • A native checkbox turns the gesture host's correction off, as the control.
  • Replay restarts the motion.
• PresentedHitTestingLab.test.tsx: its unit test (3 cases).
• apps/storybook/stories/PresentedHitTestingLab.stories.tsx: one full-screen story, "Presented hit testing" under "Core/Gestures".

Evidence

• Unit test: passes (3 of 3). Strict ESLint passes.
• Real Chrome at a phone viewport: the story renders the harness. Its correction only acts on iOS WebKit, which the status line says.
• The check itself: opening this story on a physical iPhone, which the harness exists for.

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Project	Deployment	Actions	Updated
astryx	Ready	Preview	Nov 5, 2026 9:57am UTC

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[astracat-bot]

AI review status for this pull request.

Review status	Updated
🟢 Reviewed (for maintainers only)	Nov 5, 2026, 10:10 AM UTC

[astracat-bot]

Approved pending CI: CI has not run on this head yet because the pull request is a draft, and it starts once the pull request is marked ready for review.

The harness and story are test tooling only, with nothing exported or shipped. spec:AST-094 lets the real-device evidence for presented hit testing follow merge, so the iPhone run is the next step rather than a condition here. The corrected-tap test is a real guard: it fails when the harness host is forced to presentedHitTesting: 'never'.

[Automated review]