/**
 * Server-Sent Events route — `GET /api/events`.
 *
 * Hand-rolled (~40 lines vs. the 30 KB @fastify/sse-v2 dep). The wire format:
 *
 *   retry: 5000\n\n          ← reconnect hint
 *   : heartbeat\n\n          ← comment line, every 15 s
 *   event: <type>\n          ← event name
 *   data: <json>\n\n         ← payload
 *
 * The handler subscribes to the bus on connect, unsubscribes on client
 * disconnect, and ticks a heartbeat so corporate proxies don't close the
 * connection at the idle timeout.
 */
import type { FastifyInstance } from 'fastify';
import type { EventBus } from './bus.js';
export interface SseRouteOptions {
    events: EventBus;
    /** Test override: shorter heartbeat. */
    heartbeatIntervalMs?: number;
}
export declare function registerSseRoute(app: FastifyInstance, opts: SseRouteOptions): void;