/**
 * SOCKETS
 * =======
 *
 * A websocket handshake cannot carry headers in a browser, so the service and the
 * credential travel as subprotocols, with the credential falling back to the query
 * string when it contains characters a subprotocol token cannot hold.
 *
 * The global `WebSocket` is used where there is one (browsers, Node 22+). Node
 * before that gets the `ws` package if it is installed.
 */
export type SocketHandlers = {
    onOpen(): void;
    onMessage(data: string): void;
    onClose(code: number, reason: string): void;
    onError(error: unknown): void;
};
export type SocketConnection = {
    send(data: string): void;
    close(code?: number, reason?: string): void;
};
export type SocketFactory = (url: string, protocols: string[], handlers: SocketHandlers) => SocketConnection;
export type HandshakeTarget = {
    url: string;
    protocols: string[];
};
/**
 * Builds the websocket URL and subprotocols for a service.
 *
 * The credential prefers the subprotocol because a URL ends up in access logs.
 */
export declare function buildHandshake(serverUrl: string, service: string, apiKey: string): HandshakeTarget;
export declare const defaultSocketFactory: SocketFactory;