Gate-3 screenshot review (user): 'the chat tab looks like it is missing
per window config' — Chat Window 1's header rendered over a void at the
DEFAULT scroll offset because its 260px self-sized filter block
straddled the viewport's bottom edge and UiScrollablePanel hid
straddling rows WHOLE (AP-201's predicted symptom, now user-observed at
scroll position zero, upgrading it from polish to blocking).
By fix time the UI renderer HAD everything needed: UiRenderContext's
clip stack (PushClip/PopClip with rect intersection + per-draw quad
clipping) and UiElement's ClipsChildren hook, already honored by both
the generic draw walk and hit-testing. The fix is therefore exactly the
shape the filing asked for, in the panel itself:
- ClipsChildren => true: children draw and hit-test clipped to the
viewport rect.
- The layout cull keeps any INTERSECTING row Visible (was: fully-inside
only), with a half-pixel margin excluding zero-overlap edge rows;
fully-outside rows stay hidden as the cheap skip.
AP-201 retired in this commit (AP actives 142 -> 141); #371 closed; the
gate script's Chat-tab steps re-written to expect clean edge clipping
and to treat any whole-block vanish as a regression. Pinned by
StraddlingRow_StaysVisible_AndClipsInsteadOfVanishing (the exact gate-3
geometry: header + 260px straddler in a 430px viewport) and
ViewportClipsChildDrawingAndHitTesting (the clipped slice is not
clickable).
Full Release suite: 13,089 passed / 4 skipped / 0 failed.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
a59e077a66