Note

Persist changed-files expansion state per thread turn in UI store

• Adds threadChangedFilesExpandedById to uiStateStore.ts, tracking per-thread per-turn collapse state in localStorage. Only collapsed (false) states are stored to minimize persisted footprint.
• Lifts expansion state out of internal MessagesTimeline component state into the parent ChatView, passing it down via new changedFilesExpandedByTurnId and onSetChangedFilesExpanded props.
• Prunes stale expansion overrides when threads are pruned (syncThreads) or their UI state is cleared (clearThreadUi).
• Behavioral Change: the 'Changed files' expansion state now persists across page reloads and is shared across components reading from the same thread key.

^{Macroscope summarized b3979fc.}

Note

Low Risk
Low risk UI-state change: moves changed-files expand/collapse state from component-local state into the persisted uiStateStore, with pruning/sanitization to avoid unbounded localStorage growth.

Overview
Persists “Changed files” expand/collapse per thread/turn so the tree no longer resets when MessagesTimeline unmounts/remounts.

Adds threadChangedFilesExpandedById to uiStateStore (including localStorage hydrate/sanitize, persist, and pruning via syncThreads/clearThreadUi) and wires ChatView to read/write this state and pass it into MessagesTimeline, which is now controlled via new changedFilesExpandedByTurnId/onSetChangedFilesExpanded props. Tests were updated to cover the new store behavior and required props.

^{Reviewed by Cursor Bugbot for commit b3979fc. Bugbot is set up for automated code reviews on this repo. Configure here.}