- Recompute slice status when adding a feature so stale "complete" slices cascade back to milestone and mission statuses
- Require checkMissionCompletion to verify every feature is done before marking a mission complete
- Add mission-wide status-chain recomputation when stale complete slices or milestones are detected during reconciliation
- Expand core and engine tests to cover addFeature downgrades, stale complete states, and feature-level completion checks