fix(web): stop chat jitter when opening citations at the bottom

[brendan-kellam]

Fixes SOU-1486

Clicking a citation while scrolled to the bottom of a chat caused the view to jitter vertically (repeatedly, on every click).

The chat scroll container uses useStickToBottom. While the user is at (or within ~70px of) the bottom, the hook keeps the container anchored to the bottom and re-asserts that position whenever content resizes or scrolls. Selecting a citation kicks off a scrollIntoView (in chatThreadListItem.tsx) to reveal/center the reference, and useStickToBottom fights that scroll by yanking back to the bottom. The two compete for the scroll position for a frame or two on each click, which is the jitter. It only reproduces "at the bottom" because that's the only state where the stick-to-bottom lock is engaged.

Fix: release the stick-to-bottom lock (stopScroll()) when a citation reference is selected, so the reveal scroll can settle without a fight. This is the same state the hook enters when the user scrolls up manually, and it matches the intent of the interaction (you're now inspecting a citation, not following streaming output). Sending a new message re-engages auto-scroll as before.

Summary by CodeRabbit

• Bug Fixes
  • Fixed chat scrolling so it no longer jumps or feels jittery when opening a citation while you’re at the bottom of the conversation.
  • Citation selection now behaves more smoothly by releasing the auto-scroll lock before showing the reference.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: c5c8b431-7aab-4837-8cbf-9197cda4bdeb

📥 Commits

Reviewing files that changed from the base of the PR and between 3a7bf2d and 53fba91.

📒 Files selected for processing (3)

• CHANGELOG.md
• packages/web/src/ee/features/chat/components/chatThread/chatThread.tsx
• packages/web/src/ee/features/chat/components/chatThread/chatThreadListItem.tsx

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Walkthrough

Adds a stopScroll callback from useStickToBottom in ChatThread, passed as onStickToBottomRelease to ChatThreadListItem. That callback is invoked when a citation reference is selected, releasing the stick-to-bottom scroll lock. Includes a changelog entry.

Changes

Stick-to-bottom release fix

Layer / File(s)	Summary
Citation selection releases scroll lock packages/web/src/ee/features/chat/components/chatThread/chatThreadListItem.tsx	Adds optional onStickToBottomRelease prop, invokes it when a reference is selected, and updates memoization dependencies.
Wiring stopScroll from ChatThread packages/web/src/ee/features/chat/components/chatThread/chatThread.tsx	Destructures stopScroll from useStickToBottom and passes it as onStickToBottomRelease to each ChatThreadListItem.
Changelog entry CHANGELOG.md	Documents the fix for chat jittering when opening citations while scrolled to bottom.

Estimated code review effort: 1 (Trivial) | ~5 minutes

Sequence Diagram(s)

sequenceDiagram
  participant ChatThread
  participant ChatThreadListItem
  participant useStickToBottom

  ChatThread->>useStickToBottom: destructure stopScroll
  ChatThread->>ChatThreadListItem: onStickToBottomRelease=stopScroll
  ChatThreadListItem->>ChatThreadListItem: setSelectedReference(reference)
  ChatThreadListItem->>useStickToBottom: onStickToBottomRelease() (stopScroll)

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Possibly related PRs

• sourcebot-dev/sourcebot#1031: Both PRs modify the chat thread's useStickToBottom-driven scrolling behavior in chatThread.tsx.
• sourcebot-dev/sourcebot#1035: Both PRs hook into the reference-selection flow to affect chat scrolling behavior.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly describes the main user-facing fix: preventing chat jitter when opening citations at the bottom.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch brendan/sou-1486-chat-jitters-when-opening-citations-at-bottom-4767

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