A PTR reload lands while the standalone-PWA viewport is still settling and
re-races the --app-height measurement (Chromium settles without firing
resize), bringing the scroll room back ~50% of the time. The immersive page
is fixed-viewport, so overscroll-behavior-y: none on html+body removes the
gesture (and the race trigger) entirely; restored on route leave.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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