Status: Accepted (draft v0.1) Date: 2026-07-04 Decision: a commit whose signature or required attestations cannot be verified has no level; the release fails. Rationale: T0 is a verified fact about a verified commit (“no accountable human”). Mapping verification failure to T0 would let an attacker degrade gracefully into the pre-release channel instead of being stopped, and would poison the meaning of T0 for analytics. Rejected: unverifiable→T0 fallback. Revisit trigger: adoption friction (flagged as a pressure-test item, §8).