Type Alias AuthoringOp

AuthoringOp:
    | FieldMutationOp<AuthoringFieldRef>
    | { activity?: string; status: ActivityStatus; type: "status.set" }
    | {
        stampFields?: { actor?: string; at?: string };
        target: AuthoringFieldRef;
        type: "audit";
        value: ValueExpr;
    }

Like Op, plus: status.set's activity is optional (desugar fills the firing activity), and the audit sugar — a stamped append merging actor/at ValueExpr fields into its own value.