object_id_not_event_derived· reason_code· applies to event_envelopeSub-reason for schema_violation when a create Event carries an object identifier in its payload for an object kind whose id MUST be derived from the create Event's event_id. Create payloads MUST omit the id; the reducer materialises it by retyping the complete event-derived EventId token. See zh/models/common-fields.md.