* fix(chat): keep transcript pinned across composer auto-resize (#5514)
Reported by @JeffArcLogic.
autoResize() sets the textarea to height:'auto' before measuring scrollHeight
and restoring the height. The transient collapse grows the flex:1 #messages
viewport and the browser clamps a bottom-anchored scrollTop down by the collapse
delta, stranding the reader a few px above the bottom on every keystroke while
the composer is multi-row (delta proportional to composer height) — and the
clamp's async scroll event sticky-unpins the reader, dead-ending the #5516
grow-path re-pin and stream auto-follow. The prior #5516 fix only re-pinned on
NET growth, so a steady-state keystroke was missed.
Fix: snapshot #messages.scrollTop before the height round-trip and restore it
after, undoing the transient clamp within the same synchronous task. Protects
pinned AND near-bottom scrolled-up readers, takes no _programmaticScroll latch,
inert to iOS toolbar reflows. The grow-gated re-pin + ResizeObserver remain for
genuine net growth.
* test(#5514): make near-bottom-unpinned case non-vacuous (Codex gate nit)
The companion unpinned case used scrollTop=7900, below the transient clamp max
(7903), so it never actually clamped and passed on master too. Move it to 7990
(inside the clamp zone: 7903 < 7990 < settled-bottom 8023) so it genuinely
exercises the transient-clamp yank the fix prevents.
* Release exp-v0.52.52: keep transcript pinned across composer auto-resize (#5962, #5514)
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Co-authored-by: nesquena-hermes <agent@nesquena-hermes>
