import { MessagePort, Worker } from 'node:worker_threads';

declare function isCoverageFlushMessage(msg: unknown): boolean;
/**
 * Worker side: handle flush requests by writing this thread's V8 coverage. Call
 * once near the top of each worker entry. No-op unless NODE_V8_COVERAGE is set.
 */
declare function registerWorkerCoverageFlush(port: MessagePort | null): void;
/**
 * Pool side: ask a worker to flush its V8 coverage and wait (briefly) for the ack,
 * so the write completes before the worker is terminated. No-op unless
 * NODE_V8_COVERAGE is set; always resolves (on ack or timeout) and never throws.
 */
declare function flushWorkerCoverage(worker: Worker, timeoutMs?: number): Promise<void>;

export { flushWorkerCoverage, isCoverageFlushMessage, registerWorkerCoverageFlush };