Preserve stop scroll decision on layout changes

[imanolmzd-svg]

Part of #11030

Why

A conversation can have temporary resizes as components go from direct rendering to virtualized rendering. We had logic in place that would force auto-scrolling if the container didn't overflow, causing a scenario where a user would scroll up - A resize would happen - Be forced again to the bottom.

Implementation

Remove logic that automatically unpaused scroll when the container temporarily stopped overflowing. Previously, layout changes that reduced content height below the viewport would reset the userScrolled flag, causing the chat to jump back to the bottom when the user had intentionally scrolled up.

The stop/pause function now accepts a force parameter to bypass the canScroll check, ensuring an explicit user pause is never cleared by transient layout changes.

Screenshots / Video

This is one of the fixes for the intermittent issue shown in this video (Note the force scroll to bottom)

jump-down.mov

Correct behaviour

correct-scroll-up.mov

Testing

• Manual testing
• Unit tests
• Typecheck

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

The fix is correct. All four !canScroll(el) branches that previously reset userScrolled → false now simply return without touching state, preventing transient layout changes (container temporarily stops overflowing during virtualized rendering) from clearing an intentional user scroll pause.

The force parameter on stop is a clean addition — pause: () => stop(true) correctly lets session restoration set the pause flag even on short content that hasn't yet overflowed, while the default force=false path used by handleWheel still guards against spurious pauses on non-scrollable content (verified by the new "does not pause for an upward wheel on short content" test).

The new tests cover all the key cases and test real implementation behaviour.

Files Reviewed (3 files)

• .changeset/preserve-chat-scroll-pause.md
• packages/kilo-ui/src/hooks/create-auto-scroll.tsx
• packages/kilo-ui/src/hooks/create-auto-scroll.test.tsx

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_{Reviewed by claude-sonnet-4.6 · 256,312 tokens}

_{Review guidance: REVIEW.md from base branch main}