/**
 * @name premium/stream-broker
 * @description SSE stream broker for premium real-time event delivery.
 *
 * After a session is activated (`status=active`), the stream broker opens a
 * provider subscription, enriches each event with session metadata, stores it
 * in the event store for replay, and delivers it to the buyer via SSE
 * (Server-Sent Events) over the `/premium/stream/:sessionId` HTTP endpoint.
 *
 * The broker enforces:
 *   - Unit quota: stops delivery when `requestedUnits` reaches zero.
 *   - Session status: only delivers for `status=active` sessions.
 *   - Event idempotency: deduplicates via `eventId` in the event store.
 *   - Graceful shutdown: closes all active streams on disconnect.
 *
 * @flow
 *   1. Buyer calls `GET /premium/stream/:sessionId` with `Accept: text/event-stream`.
 *   2. → `startStream()` validates session is active, loads provider adapter.
 *   3. → Provider `subscribe()` returns async iterable of `ProviderEvent`.
 *   4. → For each event: enrich with session metadata, `appendEvent()`, write SSE.
 *   5. → `decrementSessionQuota()` after each event; auto-close at zero.
 *   6. Client disconnects or quota exhausted → `stopStream()`.
 *
 * @module premium/stream-broker
 */
import type { PremiumStreamSubscription, ProviderEvent } from './types.js';
/**
 * @name startStream
 * @description Start a premium stream subscription for an active session.
 *
 * @param sessionId      - The activated premium session id.
 * @param subscriptionKey - De-duplication key from the stream input schema.
 * @param filters        - Narrow filters for the provider subscription.
 * @returns The `PremiumStreamSubscription` if successful, or `null` if the
 *   session is not active or the provider is not available.
 *
 * @usedBy `remote/server.ts` → `GET /premium/stream/:sessionId`
 */
export declare function startStream(sessionId: string, subscriptionKey: string, filters: Record<string, unknown>): Promise<PremiumStreamSubscription | null>;
/**
 * @name streamEvents
 * @description Async generator that yields enriched premium events for a session.
 *
 * This is the core delivery loop. It:
 *   1. Loads the provider adapter for the session's plugin/capability.
 *   2. Subscribes with the session's filters.
 *   3. For each provider event: enriches with session metadata, appends to the
 *      event store, decrements the unit quota, and yields the enriched event.
 *   4. Stops when the quota reaches zero, the provider iterable ends, or the
 *      stream is cancelled via `stopStream()`.
 *
 * @param sessionId - The active session id.
 * @returns Async generator yielding `ProviderEvent` enriched with session metadata.
 *
 * @usedBy `remote/server.ts` → SSE response writer
 */
export declare function streamEvents(sessionId: string): AsyncGenerator<ProviderEvent, void, unknown>;
/**
 * @name stopStream
 * @description Stop an active stream subscription.
 *
 * Aborts the provider async iterable and marks the subscription as inactive.
 * The session is not closed — the buyer can resume with a replay query.
 *
 * @param sessionId - The session id to stop streaming for.
 *
 * @usedBy `remote/server.ts` → client disconnect handler
 */
export declare function stopStream(sessionId: string): void;
/**
 * @name replayEvents
 * @description Replay past events for a session within the replay window.
 *
 * Used when a client reconnects and needs to catch up on events missed
 * during the disconnection period.
 *
 * @param sessionId - The session id to replay events for.
 * @param since     - Optional ISO timestamp; only events after this are returned.
 * @returns Array of `ProviderEvent` records from the event store.
 *
 * @usedBy `remote/server.ts` → SSE replay before live stream
 */
export declare function replayEvents(sessionId: string, since?: string): ProviderEvent[];
/**
 * @name getActiveStreamCount
 * @description Return the number of currently active stream subscriptions.
 *
 * @usedBy `metrics.ts`
 */
export declare function getActiveStreamCount(): number;
/**
 * @name stopAllStreams
 * @description Stop all active streams. Called during graceful shutdown.
 *
 * @usedBy `remote/server.ts` shutdown handler
 */
export declare function stopAllStreams(): void;
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