export declare const INSTANCE_TAKEN = "instance-taken-by-another-source";
export interface ProducerRefusal {
    code: typeof INSTANCE_TAKEN;
    params: {
        instance: string;
        producer: string;
    };
    message: string;
}
/** Who produced a twin, as one comparable string — or undefined when the origin says nothing usable. */
export declare function producerOf(origin: unknown): string | undefined;
/** null when `incoming` may rebuild the twin `prior` was made by; otherwise the refusal. */
export declare function refuseOverwriteByAnotherProducer(instance: string, priorOrigin: unknown, incomingOrigin: unknown): ProducerRefusal | null;