import type { IncomingMessage, ServerResponse } from "http";
export interface MetricsHttpServer {
    /** Actual port (useful when the caller passed 0 to grab a random port). */
    port: number;
    close(): Promise<void>;
}
/**
 * Start a tiny Express server that serves `/metrics` and a `200 ok` on `/`
 * and `/health`. Any other path returns 404 via Express's default handler.
 *
 * When `host` is omitted, Node binds the unspecified IPv6 address (`::`) on
 * dual-stack systems, which also accepts IPv4 connections. This makes
 * `localhost` resolve to a working address regardless of whether `getaddrinfo`
 * returns the IPv4 or IPv6 entry first (Alpine images often prefer `::1`).
 */
export declare function startMetricsServer(port: number, handler: (req: IncomingMessage, res: ServerResponse) => void, host?: string): Promise<MetricsHttpServer>;
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