/** Default per-target connect timeout. Short — a healthy network connects in
 *  tens of ms; a down network should be declared down quickly so the daemon tick
 *  isn't held up. */
export declare const PROBE_TIMEOUT_MS = 3000;
/** Resolve true iff a TCP connection to host:port completes within timeoutMs.
 *  Any error/timeout resolves false (never rejects). The socket is always torn
 *  down. Exported for unit testing against a local listener. */
export declare function tcpReachable(host: string, port: number, timeoutMs: number): Promise<boolean>;
/** True when the box can reach the internet (any PROBE_TARGET accepts a TCP
 *  connection within the timeout). The broker uses this for connection-fault
 *  retries. Never throws. */
export declare function probeOnline(timeoutMs?: number): Promise<boolean>;