## What changed
- Ignore `thread/started` notifications for ephemeral threads whose feature source is `system`, preventing hidden helper threads from entering TUI thread routing or refreshing the agents overview.
- Continue routing persisted system threads normally.
## Testing
- Add coverage for hidden and persisted system-thread notifications in the agents overview.
- Add generated-title normalization cases for wrapping quotes, trailing punctuation, and meaningful leading punctuation.
GitOrigin-RevId: e1ea48502b4f9aa7d5a187c7407df69c55abe2a9