/**
 * `DeadLetterSink` — destination for messages whose handler exhausted retries.
 *
 * The runtime calls `sink(entry)` once per failed dispatch after `max + 1`
 * attempts have all thrown. Production wires plug in a real DLQ (BullMQ's
 * failed-jobs board, a Mongo collection, an SNS topic). Default is in-memory:
 * collect every entry so tests can assert on what got dead-lettered.
 */
import type { MessageEnvelope } from "@nwire/envelope";
export interface DeadLetterEntry {
    readonly actionName: string;
    readonly input: unknown;
    readonly envelope: MessageEnvelope;
    readonly attempts: number;
    readonly lastError: {
        name: string;
        message: string;
        stack?: string;
    };
    readonly enteredAt: string;
}
export interface DeadLetterSink {
    record(entry: DeadLetterEntry): Promise<void>;
    /** Return everything dead-lettered so far. Test/dev introspection. */
    list(): Promise<readonly DeadLetterEntry[]>;
}
export declare class InMemoryDeadLetterSink implements DeadLetterSink {
    private readonly entries;
    record(entry: DeadLetterEntry): Promise<void>;
    list(): Promise<readonly DeadLetterEntry[]>;
    clear(): void;
}
/**
 * Build a DeadLetterEntry from a thrown error and the dispatch state.
 */
export declare function buildDeadLetterEntry(actionName: string, input: unknown, envelope: MessageEnvelope, attempts: number, error: unknown): DeadLetterEntry;