/**
 * Layer 2: SSE connection manager.
 *
 * Manages Server-Sent Event streams for real-time agent progress
 * updates to the dashboard. Each connection is tracked by a unique
 * ID and associated with a task ID.
 *
 * This module does not import from Layer 1.
 */
import type { Client } from '@libsql/client';
import type { ResolvedConfig } from '../../config.js';
import type { AgentEvent } from './types.js';
type RequestEvent = Parameters<import('@sveltejs/kit').Handle>[0]['event'];
/**
 * Create a new SSE stream for a task.
 *
 * Returns the HTTP Response and a unique connection ID. The stream
 * sends an initial `connected` event with the task ID.
 *
 * @param taskId - The task to stream events for.
 * @returns The Response object and the connection ID.
 */
export declare function createSSEStream(taskId: string): {
    response: Response;
    connectionId: string;
};
/**
 * Remove an SSE connection by its ID.
 *
 * Closes the stream controller and removes the connection from the
 * registry. Safe to call with an ID that does not exist.
 */
export declare function removeSSEConnection(id: string): void;
/**
 * Broadcast an agent event to all SSE connections for a given task.
 *
 * Accepts both persistent AgentMarker events (progress, blocked, complete, error)
 * and ephemeral ActivityEvent events. Iterates all connections matching the task
 * ID and writes the event as an SSE message. Connections that throw on write
 * (disconnected clients) are automatically removed.
 */
export declare function broadcastToSSEClients(taskId: string, event: AgentEvent): void;
/**
 * Handle an SSE connection request for a task.
 *
 * If the request accepts `text/event-stream`, creates an SSE stream
 * and sends existing logs as catch-up events before streaming live.
 * Otherwise, returns the logs as a JSON array.
 *
 * @param event - The SvelteKit request event.
 * @param db - The database client.
 * @param _config - The resolved configuration (unused, reserved for future use).
 * @param params - Route parameters; expects `params.id` to be the task ID.
 */
export declare function handleSSEConnection(event: RequestEvent, db: Client, _config: ResolvedConfig, params: Record<string, string>): Promise<Response>;
/**
 * Get the number of active connections. Exposed for testing.
 * @internal
 */
export declare function _getConnectionCount(): number;
/**
 * Check if the heartbeat is running. Exposed for testing.
 * @internal
 */
export declare function _isHeartbeatRunning(): boolean;
/**
 * Clear all connections and stop heartbeat. Exposed for testing.
 * @internal
 */
export declare function _clearConnectionsForTesting(): void;
export {};
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