Core ideas
Promotion and rollback
Promote only what holds up. How a candidate agent setup is promoted on held-out evidence, and how to roll back from the promotion receipt.
Promotion changes the agent setup after a candidate holds up on work it did not see.
Promotion is gated on evidence the candidate did not see, and the exact diff is shown before anything changes.
If regressions appear, roll back to the prior version from the promotion receipt. A receipt is append-only, so the rollback is a new record that supersedes the old one rather than an edit to it.