Refiner application and rollback

Each task pins an immutable Harness release before it begins. A later proposal does not rewrite that task. It is materialized separately, validated, and admitted through a recorded release transition.

Safe application

1. Freeze the exact base release and proposal identity.
2. Validate the proposed target and runtime behavior.
3. Apply the transition atomically.
4. Record validation and application receipts.
5. Advance future work to the admitted release.

Rollback is another recorded transition. It does not delete prior tasks, evidence, or release history.

Next: Read Refiner receipts.