fix: reliable auto-scroll with scroll-to-bottom button#150
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devartifex merged 1 commit intodevartifex:masterfrom Apr 14, 2026
Merged
fix: reliable auto-scroll with scroll-to-bottom button#150devartifex merged 1 commit intodevartifex:masterfrom
devartifex merged 1 commit intodevartifex:masterfrom
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Replace CSS scroll-behavior: smooth with explicit scroll tracking. The old approach used isNearBottom() position checks that broke when smooth scroll animations hadn't completed, permanently disengaging auto-follow with no way to re-engage. Changes: - Track sticky state with explicit stickToBottom flag instead of position-only checks - Use Svelte tick() + instant scroll (no animation race conditions) - Add scroll-to-bottom arrow button when user scrolls up - Re-engage auto-follow automatically when user sends a message - Use untrack() to prevent stickToBottom from triggering the scroll effect as a dependency - Wrap messages in container div for button positioning Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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LGTM — Excellent fix for the auto-scroll race condition. The explicit stickToBottom flag with untrack() correctly decouples the scroll state from reactive tracking. Using tick() + instant scroll instead of CSS smooth scroll eliminates the animation race window. The scroll-to-bottom button has proper aria-label for accessibility. Re-engaging auto-follow on isWaiting is a nice UX touch. All 399 unit tests pass (check failure is a pre-existing coverage threshold issue).
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Apr 14, 2026
Replace CSS scroll-behavior: smooth with explicit scroll tracking. The old approach used isNearBottom() position checks that broke when smooth scroll animations hadn't completed, permanently disengaging auto-follow with no way to re-engage. Changes: - Track sticky state with explicit stickToBottom flag instead of position-only checks - Use Svelte tick() + instant scroll (no animation race conditions) - Add scroll-to-bottom arrow button when user scrolls up - Re-engage auto-follow automatically when user sends a message - Use untrack() to prevent stickToBottom from triggering the scroll effect as a dependency - Wrap messages in container div for button positioning Co-authored-by: Dmitry Butko <dmitrybutko@microsoft.com> Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Fixes chat auto-scroll permanently disengaging when the user scrolls up, with no way to re-engage.
Root cause: CSS
scroll-behavior: smoothcaused a race condition - smooth scroll animations hadn't completed when the next position check fired, soisNearBottom()returned false mid-animation and auto-follow permanently disengaged.Changes:
stickToBottomflagtick()+ instant scroll instead of CSS smooth scroll (no animation race)untrack()to prevent the sticky flag from being a reactive dependency in the scroll effect