import type { Readable, Writable } from "node:stream";
/**
 * Serve recompression requests until the input stream ends.
 * @param input - frame stream of requests.
 * @param output - frame stream of replies.
 * @param diagnostics - human-readable failure destination; never the reply stream.
 * @returns the process exit code: 1 for a protocol or channel failure, otherwise 0.
 */
export declare function runImageWorker(input: Readable, output: Writable, diagnostics: Writable): Promise<number>;