- Updated EventController to keep foreground render mode active from agent_start through agent_end so live-region rebuild remains enabled during a turn.
- Pinned stop-reason assistant errors to the editor banner and suppressed the transcript's inline Error line while pinned, then restored it on the next agent_start.
- Added tests covering error-banner suppression/restoration and eager native scrollback rebuild ordering before loading animation.
- Added a persistent error banner so stream errors survive transcript scroll.
- Cleared the banner when the next turn starts.
- Skipped pinning for aborts and normal stops.