## Why
Command center search only filtered tasks already loaded for browsing, leaving older tasks undiscoverable without manually loading more history.
## What changed
- Scan history on the active backend for case-insensitive matches in task names, previews, and working directories, using a separate paging cursor for each query.
- Add loading, retry, and `Show more matches` states. Cancel superseded searches and ignore stale results.
- Keep history matches separate from browse results and restore the previous selection when leaving search.
- Preserve the original task preview for search while displaying the latest prompt in task details.
## Testing
Extend discovery and command center tests to cover older history matches, fresh queries after browse pagination is exhausted, selection restoration, actions on search results, loading and retry states, and separate original previews and latest prompts.
GitOrigin-RevId: 9864ee006a14bd232e9cfd7ab2ee099c84667597
Eric Traut
4e4767ffa7