/**
 * WebSocket transport adapter for the {@link AhpClient}.
 *
 * Built on the global {@link WebSocket} constructor, so it works in
 * browsers and in Node 21+ without additional dependencies.
 *
 * @module ws/transport
 */
import { type AhpTransport, type TransportFrame } from '../client/transport.js';
import type { ProtocolMessage } from '../types/common/messages.js';
/** Options for {@link WebSocketTransport.connect}. */
export interface WebSocketTransportOptions {
    /**
     * WebSocket subprotocols to negotiate. Browsers do not allow setting
     * arbitrary HTTP headers; subprotocols and query-string parameters are
     * the main extension points.
     */
    protocols?: string | string[];
}
/** Information about a transport close. */
export interface WebSocketCloseInfo {
    readonly code: number;
    readonly reason: string;
    readonly wasClean: boolean;
}
/**
 * An {@link AhpTransport} backed by the global {@link WebSocket}.
 *
 * Browser caveats this transport exposes:
 *
 * - {@link send} only queues data; it does not wait for the bytes to be
 *   flushed to the socket. Use {@link bufferedAmount} to detect
 *   backpressure if needed.
 * - Browsers cannot send WebSocket ping frames. Use {@link AhpClient.ping}
 *   for protocol-level liveness.
 * - Custom HTTP headers are not supported; use subprotocols or
 *   query-string parameters for auth.
 */
export declare class WebSocketTransport implements AhpTransport {
    private readonly socket;
    private readonly inbox;
    private waiters;
    private closeInfo;
    private error;
    private closed;
    /**
     * Open a new WebSocket connection.
     *
     * Resolves once the socket emits `open`. Rejects with a
     * {@link TransportError} on early failure — either an `error` event or a
     * `close` event before `open`.
     */
    static connect(url: string | URL, options?: WebSocketTransportOptions): Promise<WebSocketTransport>;
    /**
     * Wrap an already-open WebSocket. Use this when you need to control
     * the handshake (custom subprotocols, query params, an existing
     * connection from another library).
     *
     * The socket MUST already be in the `OPEN` state.
     */
    static fromSocket(socket: WebSocket): WebSocketTransport;
    private constructor();
    /** Bytes still queued in the underlying socket's send buffer. */
    get bufferedAmount(): number;
    /**
     * Information about the most recent close, set once the socket emits
     * `close`. `null` while the connection is open.
     */
    get lastClose(): WebSocketCloseInfo | null;
    send(message: ProtocolMessage | string): void;
    recv(): Promise<TransportFrame | null>;
    close(): Promise<void>;
    private deliver;
    private drainWithError;
    private drainWithNull;
}
//# sourceMappingURL=transport.d.ts.map