member_identity_replacement_digest_mismatch· reason_code· applies to event_envelope, state_resolutionA ak.member.identity.update replaces[] entry references an event whose payload.identity_payload carrier digest does not equal the declared payload_digest, or references an event under a different (realm_id, member_id, segment). The replacement edge is invalid; receivers MUST NOT remove the referenced event from the effective set on its basis. See zh/sync/client-sync.md §8.1.