import type { Email } from "../email.mjs";
import type { EmailQueue, WorkerOptions } from "./index.mjs";
/** A running worker. Call \`stop()\` to halt the loop; any in-flight sends
*  finish first. \`waitForIdle()\` resolves when the queue is empty and no
*  send is in flight. */
export interface QueueWorker {
	start: () => void;
	stop: () => Promise<void>;
	waitForIdle: () => Promise<void>;
	/** Run a single tick manually — useful in tests. */
	tick: () => Promise<void>;
}
/** Build a worker that drains \`queue\` by sending each item through
*  \`email\`. Keep the loop simple: pull → send → ack/fail. Advanced
*  drivers can skip this worker and drive \`email.send\` directly from
*  their own transport. */
export declare function startWorker(email: Email, queue: EmailQueue, options?: WorkerOptions): QueueWorker;