* feat(desktop): add transcript outline with shared message scroller
* fix(desktop): avoid repeated outline work during streaming
* fix(ui): preserve transcript position when replacing rows
* fix(ui): respect reduced motion in MessageScrollerButton
The shared scroll-to-end button always passed shadcn's default smooth
behavior. Resolve it from prefers-reduced-motion like the outline does,
keeping an explicit behavior prop as an override.
* test(desktop): cover saved-session row swap and streaming growth
Add a regression test for continuing a saved session: history hydrates
after the provider mounts, a new prompt pins near the top, then the
activity row is swapped for the first answer row in one commit and the
viewport must stay on the new prompt. Make the streaming test grow the
transcript and deliver the resize notification instead of only changing
answer text.
* chore(ui): tidy message-scroller check in smoke-package
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Co-authored-by: Saoud Rizwan <7799382+saoudrizwan@users.noreply.github.com>
