With just those primitives, CI is a service that emits "ci/tested." Review emits "review/approved." A merge controller watches for sufficient attestations and requests a ref update. The forge kernel only evaluates whether claims satisfy policy.
Vouch shifts this even further left: attestations about people, not just code. "This person is trusted" is structurally the same kind of signed claim as "this commit passed CI." It gates participation itself, not just mergeability.
All this should ideally be part of a repo, not inside a closed platform like github. I like it and am curious to see where this stands in 5 years.