import type { SubscriptionFiring } from "@uptimizr/schema";
/**
 * **In-process fan-out for subscription firings** (#311, sketch §F.3).
 *
 * The SSE half of delivery. It is deliberately *not* the live bus: the live bus
 * carries every ingested event and is hot, whereas this carries at most one
 * message per subscription per cooldown and exists only so
 * `GET /api/v1/subscriptions/stream` has something to read from. Keeping them
 * apart means a firing can never be dropped by a slow live consumer's queue, and
 * a subscription listener can never back-pressure ingest.
 *
 * Listeners are plain callbacks rather than async iterators because the SSE
 * route writes synchronously to a socket; there is nothing to buffer, and
 * nothing to bound beyond the connection cap the route already enforces.
 */
/** What an SSE listener receives. */
export interface SubscriptionStreamMessage {
    firing: SubscriptionFiring;
    /** The same bounded `format=summary` block a webhook would carry. */
    summary: Record<string, unknown> | null;
}
export type SubscriptionStreamListener = (message: SubscriptionStreamMessage) => void;
export interface SubscriptionStreamOptions {
    projectId: string;
    /** Deliver only this subscription's firings; omit for the whole project. */
    subscriptionId?: string;
}
export interface SubscriptionStream {
    /** Register a listener. Returns an idempotent unsubscribe. */
    subscribe(options: SubscriptionStreamOptions, listener: SubscriptionStreamListener): () => void;
    /** Fan a firing out to matching listeners. */
    publish(projectId: string, message: SubscriptionStreamMessage): void;
    /** Open listener count (for tests and the connection accounting). */
    readonly listenerCount: number;
    /** Drop every listener. */
    stop(): void;
}
/** Create the default in-process subscription stream. */
export declare function createSubscriptionStream(): SubscriptionStream;
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