export interface SSEManager {
    addConnection(userId: string, controller: ReadableStreamDefaultController): void;
    removeConnection(userId: string, controller: ReadableStreamDefaultController): void;
    /** Number of live connections for a user (used to enforce a per-user cap). */
    connectionCount(userId: string): number;
    notifyUser(userId: string, data: unknown): void;
    notifyAll(data: unknown): void;
    isOnline(userId: string): boolean;
    getOnlineUserIds(): string[];
}
/**
 * In-process SSE connection registry. **Process-local by design** — presence
 * (`isOnline`, `getOnlineUserIds`) only sees connections owned by this
 * process, and there is no cross-instance seam. On multi-instance or
 * serverless deployments that means:
 *
 * - `isOnline` false-negatives for users whose stream lives on another
 *   instance: the service skips their live SSE event and falls back to push
 *   (delivery still happens, via the heavier channel, provided they have a
 *   push subscription).
 * - `recipients: 'online'` broadcasts only reach the users connected to the
 *   instance that runs `send()`.
 *
 * Treat the notification system as single-instance until a shared presence
 * backend exists — the same assumption the in-memory rate-limit store and the
 * forgot-password serverless note document. See docs/AUTH.md → Known
 * Limitations & Security Gaps.
 */
export declare function createSSEManager(): SSEManager;