/**
 * Nexus Connect — Server-Sent Events handler.
 *
 * Returns a streaming Response that stays open until the client disconnects.
 * Works with any Web-standard Request/Response environment (Node 18+, Bun, Deno, Cloudflare Workers).
 *
 * SSE wire format:
 *   id: <message-id>\n
 *   event: message\n
 *   data: <json-payload>\n\n
 *
 *   : heartbeat\n\n   ← keep-alive comment (every 15s)
 */
export declare const CONNECT_PATH = "/_nexus/connect/";
export interface ConnectSseOptions {
    cors?: {
        allowOrigin?: string;
    };
}
/** Extract the topic name from a /_nexus/connect/:topic URL. */
export declare function topicFromUrl(url: URL): string;
/** Returns true if this request should be handled by Nexus Connect. */
export declare function isConnectRequest(url: URL): boolean;
/**
 * Creates a streaming SSE Response for the given topic.
 * The response stays open until the client disconnects (request.signal aborts).
 */
export declare function handleSSERequest(request: Request, topic: string, opts?: ConnectSseOptions): Response;
/**
 * Node.js adapter — writes SSE directly to a ServerResponse.
 * Use this when you cannot return a Web Response (e.g. in http.createServer callbacks).
 */
export declare function handleSSERequestNode(req: {
    signal?: AbortSignal;
    on?: (event: string, fn: () => void) => void;
}, res: {
    writeHead: (s: number, h: Record<string, string>) => void;
    write: (s: string) => boolean;
    end: () => void;
}, topic: string, opts?: ConnectSseOptions): void;
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