API Contract Change Board

A change-review team for public HTTP and gRPC contracts. The pipeline is ordered so the baseline is proven truthful before anything is classified: the spec curator pins the published artifact by digest and enumerates every disagreeing copy, and the conformance checker replays sampled production requests to report undocumented endpoints, undeclared response fields, nullability and type violations, and requests the server accepts that the spec forbids. Classification is direction-aware, because request and response break in opposite directions, and produces three classes rather than two so that semantic breakage - unit and scale changes, identifier format changes, default changes, ordering and pagination changes, error surface moves, validation tightening, response enum additions - is recorded where no schema diff can see it. Consumer impact is drawn from production traffic with the window justified by the longest known consumer cadence, the attribution method named, and the unattributed fraction quantified, so silence is never converted into permission. The deprecation planner sizes the sunset window by observed consumer rhythm, requires machine-readable deprecation and sunset signals in the response, and enforces the plan in CI. The gate blocks on either an unapproved breaking change or an unresolved spec-implementation divergence, and returns work to the role that owns it.