member_identity_state_mismatch· reason_code· applies to event_envelope, state_resolutionThe optional expected_state_digest optimistic-concurrency guard on ak.member.identity.update does not equal the digest of the current effective set for the same (realm_id, member_id, segment): sha256 over RFC 8785 JCS of the exact signed payload objects of the effective updates ordered by event_id ascending, [] when empty (zh/sync/current-results.md section 2). The Station MUST reject the Event with failed_precondition and zero writes instead of applying it as a valid replacement.