OverrideSlotService dispatches RunAsync before calling StartRunningAsync,
so a preflight failure (list not found, worktree setup) can reach MarkFailed
while the task is still Queued. The guard is intentional, not dead code.
- Add comment in FailAsync explaining the OverrideSlotService preflight gap
- Add FailAsync_FromQueued_TransitionsToFailed test
- Update CLAUDE.md transition table with the precise rationale
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>