import type WebSocket from 'ws';
/**
 * Heartbeat manager for WebSocket connection health monitoring.
 * Sends periodic pings and monitors for pong responses to detect stale connections.
 */
export declare class HeartbeatManager {
    private readonly heartbeatTimer;
    private readonly pongTimeoutTimer;
    private lastPongReceived;
    private readonly onStaleConnection;
    constructor(options: {
        onStaleConnection: () => void;
    });
    /**
     * Start the heartbeat loop.
     *
     * @param ws - WebSocket instance to send pings on
     */
    start(ws: WebSocket): void;
    /**
     * Stop the heartbeat loop.
     */
    stop(): void;
    /**
     * Record that a pong was received.
     */
    onPongReceived(): void;
    /**
     * Get time since last pong (for diagnostics).
     */
    getTimeSinceLastPong(): number;
}
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