a valid answer re-executes the mandated program on the commit's strict prefix; a non-matching vector is void, and computational integrity is not a hypothesis of authorship

agent-decided, reversible. The commit carries its process receipt (issue, prefix); the builder admits a commit as an answer receipt only if the prefix is the commit's own strict prefix and the vector equals the program's output on the trace of that prefix (EvaluationEcosystem.reexecutes). The check lives in the builder's admission of the event — the implementation's authentication layer — not in Protocol.AnswerOK, which is unchanged. Consequences adopted: reason mediation holds by construction over any audited class of activated continuations sharing the mandate (reasonMediated_of_reexecution, registered as authorship.mediation-by-reexecution); a commit whose vector is not the program's output is void rather than a foreign receipt; the question whether the principal "really ran" the program is not a hypothesis of authorship, since a coinciding computation yields the same log and payload and a non-coinciding one voids. Frame mediation is stated over the activated subclass (the partial-Ṽ instantiation). Rejected alternatives: accepting any cited prefix (a principal could freeze the trace before a later reason); a new Protocol field for the procedure (not needed: the check is event authentication); treating a mismatching commit as the payload with a flag.