ContextSheet and UploadSheet stay mounted (slid off-screen via translate-y) when
closed, but declared role="dialog" + aria-modal="true" — and kept their buttons
in the a11y tree + tab order — unconditionally. So a screen reader always saw
2+ simultaneous modal dialogs, and their controls (e.g. each sheet's "Abbrechen")
collided with real open dialogs.
Surfaced by the e2e a11y suite: focus-trap asserted exactly one [role=dialog]
[aria-modal] and got 2; upload-cancel-confirm's getByRole('button',{name:
'Abbrechen'}) matched the composer's X *and* a closed sheet's button.
Fix: when closed, drop role/aria-modal and mark the subtree aria-hidden + inert
so it's out of the a11y tree and tab order entirely. Open sheets are unchanged.
Verified: chromium-mobile a11y/gesture suite now 21 passed / 5 skipped / 0 a11y
failures (focus-trap + upload-cancel-confirm green); svelte-check 0 errors.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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