/**
 * `attempts`: resumes in a row, with no bytes gained between them, before a
 * read fails. `backoffMs`: wait before the second and later ones, times the
 * attempt (a gateway whose host agent restarts is back within seconds).
 */
export declare const readResume: {
    attempts: number;
    backoffMs: number;
};
/**
 * `first`'s body, length-checked and resumed. `reopen(commit, done, left)`
 * returns the 206 for the `left` bytes after the first `done`. A response
 * without the length header (an older server) passes through unchanged.
 */
export declare function resumableBody(first: Response, reopen: (commit: string, done: number, left: number) => Promise<Response>, what: string, signal?: AbortSignal): ReadableStream<Uint8Array> | null;