/**
 * Detects if the current browser needs the streams ponyfill.
 *
 * Safari 16-17 fails to transfer `ReadableStream`/`TransformStream`
 * to/from Web Workers via `structuredClone` because they lack
 * the transferable streams implementation.
 *
 * @param userAgent - Optional user agent string for testing (defaults to feature detection)
 * @returns `true` if ponyfill is needed, `false` if native works
 */
declare function needsPolyfill(userAgent?: string): boolean;

/**
 * Ponyfill for Web Streams API that supports transfer to/from workers.
 *
 * Uses `web-streams-polyfill` internally but only loads it when needed.
 * This keeps bundle size small for non-Safari browsers.
 *
 * @see {@link needsPolyfill} for detection
 */
interface StreamPonyfillExports {
    ReadableStream: typeof ReadableStream;
    TransformStream: typeof TransformStream;
    WritableStream: typeof WritableStream;
}
/**
 * Lazily loads the web-streams-polyfill ponyfill.
 *
 * @returns Ponyfilled streams or native if not needed
 */
declare function ponyfillStreams(): Promise<StreamPonyfillExports>;

/**
 * MessagePort-based canalization utility for ReadableStreams.
 * Allows transparently transferring streams over `postMessage` in environments
 * that lack native transferable streams support (like Safari < 18).
 *
 * Implements a bidirectional Acknowledgment (Ack) protocol to strictly respect
 * Web Streams backpressure across the thread boundary, avoiding RAM bloating
 * and Event Loop starvation.
 */
/**
 * Serializes a native or ponyfilled `ReadableStream` into a `MessagePort`.
 * Spawns a message channel, reads chunks progressively, and pauses after each
 * chunk until the receiver acknowledges it is ready for more.
 *
 * @param stream - The ReadableStream to pipe.
 * @returns The remote MessagePort (port2) to be transferred.
 */
declare function serializeStreamToPort(stream: ReadableStream): MessagePort;
/**
 * Deserializes a `MessagePort` back into a `ReadableStream`.
 *
 * Enforces backpressure by delaying the `{ type: 'ack' }` handshake signal
 * if the internal stream controller queue becomes full, resuming only when the
 * consumer pulls more data.
 *
 * @param port - The transferred MessagePort (port2).
 * @returns A ReadableStream yielding chunks from the port.
 */
declare function deserializePortToStream(port: MessagePort): ReadableStream;

export { deserializePortToStream, needsPolyfill, ponyfillStreams, serializeStreamToPort };
export type { StreamPonyfillExports };