fix(datetime): prevent hidden-state observer from tearing down ready class on initial entry

[ShaneK]

Issue number: internal

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What is the current behavior?

ion-datetime runs two IntersectionObservers: one to detect when the host becomes visible (which adds datetime-ready) and one to detect when it becomes hidden (which removes the class and tears down listeners). When the host mounts offscreen, both observers receive an initial "not intersecting" entry on observe(). The hidden-state observer treats that initial entry as a real visible-to-hidden transition, queues a writeTask to remove datetime-ready, and races the layout-based fallback (ensureReadyIfVisible) that adds the class after 100ms. On WebKit the remove wins often enough that the e2e test for the fallback (added in #30793 to fix #30706) had to be skipped on Mobile Safari. Anything in production that adds datetime-ready outside of a real isIntersecting: true event is exposed to the same race.

What is the new behavior?

A hasBeenIntersecting flag is set true only when visibleCallback observes isIntersecting: true. The hidden-state observer's teardown is gated on this flag, so the synthetic initial "not intersecting" entry is ignored. The flag is reset when the host actually transitions to hidden and on disconnectedCallback. The previously duplicated init-listeners + ready-class block is consolidated into a single markReady helper. The WebKit skip on the IO-fallback e2e test has been removed.

Does this introduce a breaking change?

• Yes
• No

Other information

The asymmetry where ensureReadyIfVisible (the layout fallback) deliberately does NOT set hasBeenIntersecting is load-bearing: the flag must reflect a real observer signal, not a fallback-driven write, otherwise the bug returns. This is called out at the guard site so future cleanups don't undo it.

This test was most likely to fail in docker testing Linux Webkit with --repeat-each=20 because it was pretty flaky. I was able to force it to fail under these conditions and, after fixing it, it no longer failed.

Relevant Preview Link:

• https://ionic-framework-git-fw-7284-ionic1.vercel.app/src/components/datetime/test/basic

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Project	Deployment	Actions	Updated (UTC)
ionic-framework	Ready	Preview, Comment	Apr 30, 2026 7:52pm