- Added cancellation context helpers and hooks to track current events and safely arm/disarm handlers.
- Added cancel hooks and pre-cancel semantics in `WorkerPool` to execute cancel actions and mark canceled runs failed.
- Added dashboard cancel controls and `/api/cancel` endpoint with token validation and failure handling for bad deliveries.
- Updated gh_open_pr guidance and implementation to run `bun run fix`, commit style diffs, then `bun check`, and retry as needed.
- Added tests for gh_open_pr fix/check behavior and queue cancel edge cases, including pre-arm and unknown-delivery cases.
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