export interface CDPEvent {
    method: string;
    params: any;
    sessionId?: string;
}
export type CDPEventHandler = (event: CDPEvent) => void;
/**
 * Minimal Chrome DevTools Protocol client over WebSocket.
 * Talks to the browser debugger endpoint returned by /json/version
 * (or any target-level endpoint returned by attachToTarget flattening).
 *
 * Supports session-scoped commands via the CDP `sessionId` field.
 * No reconnection — fail-fast on lost connections.
 */
export declare class CDPClient {
    readonly url: string;
    private _ws;
    private _nextId;
    private readonly _pending;
    private readonly _handlers;
    private readonly _wildcardHandlers;
    private _closed;
    constructor(url: string);
    get connected(): boolean;
    connect(timeoutMs?: number): Promise<void>;
    send<T = any>(method: string, params?: Record<string, any>, sessionId?: string): Promise<T>;
    /**
     * Register an event listener. Pass '*' to match every event.
     * @returns an unsubscribe function.
     */
    on(method: string, handler: CDPEventHandler): () => void;
    close(): Promise<void>;
    private _onMessage;
    private _onClose;
    private _rejectAllPending;
}