/**
 * Realtime SSE wire protocol — shared by the server SSE handlers (framework
 * in-process path + the hosted Realtime Gateway) and the client transport.
 *
 * Pure constants, types, and parsers only — NO h3/node/browser deps — so both
 * the Node server and the browser client import it.
 *
 * Frame taxonomy:
 *   - CHANGE / batch frames ride the default (unnamed) SSE `message` event and
 *     are parsed by the client's existing `normalizeEventPayload`. Unchanged.
 *   - CONTROL frames (handshake, token rotation) ride NAMED SSE events, so
 *     `EventSource.addEventListener(name)` routes them separately and an older
 *     client that only reads `onmessage` silently ignores them (backward safe).
 */
export declare const REALTIME_PROTOCOL_VERSION = 1;
/** Named SSE event carrying the one-time handshake ({@link RealtimeHandshake}). */
export declare const REALTIME_SSE_HANDSHAKE_EVENT = "handshake";
/** Named SSE event carrying a rotated subscribe token ({@link RealtimeTokenFrame}). */
export declare const REALTIME_SSE_TOKEN_EVENT = "token";
/**
 * Capability advertised by the hosted gateway: awareness/presence is NOT
 * forwarded (it lives only on the in-process emitter, never in `sync_events`),
 * so the collab client must keep its own presence cadence. The framework's
 * in-process SSE path forwards awareness and therefore sends no handshake — the
 * client treats an absent handshake as "all capabilities present."
 */
export declare const REALTIME_CAP_NO_AWARENESS = "no-awareness";
export interface RealtimeHandshake {
    protocol: number;
    capabilities: string[];
}
export interface RealtimeTokenFrame {
    token: string;
    /** ISO expiry, informational; the client re-mints/rotates before this. */
    expiresAt?: string;
}
export declare function buildHandshakeFrame(capabilities?: readonly string[]): RealtimeHandshake;
export declare function parseHandshakeFrame(data: string): RealtimeHandshake | null;
export declare function parseTokenFrame(data: string): RealtimeTokenFrame | null;
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