extremely long transcripts made bottom-anchoring the virtualized list unreliable
(thousands of unmeasured variable-height items = a huge estimate the scroll never
lands on). now GET /chat/sessions/:id takes limit+before and returns a windowed
slice plus total+offset. the chat opens on the last 20 messages, anchors to the
bottom instantly, and scrolling near the top pages in the next older window,
prepending it and pinning the previously-top message so the view stays put.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
pastilhasandClaude Opus 4.8
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