import type { SseEvent } from './sse-events';
type ParsedPayload = {
    /** Authoritative event name (lowercased), or '' if neither layer carried one. */
    event: string;
    /** Original (un-lowercased) event name — used to preserve casing for unknown events. */
    originalEvent?: string;
    /** Inner data payload (could be string, object, array, …). */
    data: unknown;
    /** True if the data string was a plain (non-JSON) literal — usually a token. */
    isPlainText: boolean;
};
/**
 * Parse a single SSE frame into the wrapped/native form, returning the
 * inner event name and data. Does NOT classify into the SseEvent union
 * yet — that's `parseFrame`'s job. Kept separate so callers can inspect
 * raw payloads (e.g. for debug logging).
 */
export declare function parsePayload(sseEvent: string | undefined, rawData: string): ParsedPayload;
/**
 * A flat `{ type: 'SCREAMING_SNAKE', ... }` object with no `event` key — the shape every
 * AG-UI frame takes, and one no legacy TORUK frame uses. Recognised structurally so the
 * streaming layer stays ignorant of AG-UI's semantics: it only decides that the frame
 * belongs to someone else, and `onEvent` hands it to whoever does understand it.
 */
export declare function isPassthroughFrame(payload: unknown): payload is Record<string, unknown>;
/**
 * Parse a single SSE frame into a typed `SseEvent`, or `null` if the
 * frame carries no usable payload (empty data, no event name resolvable).
 *
 * The 10-path `extractTokenText` fallback is applied for token-bearing
 * events so callers get a string directly, not the raw heterogeneous
 * payload shape from the backend.
 */
export declare function parseFrame(sseEvent: string | undefined, rawData: string): SseEvent | null;
export declare function extractTokenText(data: unknown): string;
export {};