export declare const STREAMING_FRAME_MESSAGE = "agent-native:streaming-frame";
/**
 * Marks a placeholder in a skeleton-first build. Preview frames keep its
 * frame drawn until a later edit replaces it.
 */
export declare const SKELETON_ATTRIBUTE = "data-skeleton";
export declare const STREAMING_FRAME_READY_MESSAGE = "agent-native:streaming-frame-ready";
export declare const STREAMING_FRAME_CONNECT_MESSAGE = "agent-native:streaming-frame-connect";
/**
 * The document a sandboxed streaming preview frame loads once. Streamed HTML
 * then arrives through `postStreamingFrameHtml` and is patched in place, so
 * the frame never reloads: a plain head script such as a CSS runtime runs
 * once when it arrives, body and deferred scripts run once the document is
 * complete, and elements already on screen stay put while new ones draft in.
 */
export declare function buildStreamingFrameDocument(options?: {
    baseHref?: string | undefined;
    /**
     * Echoed in the frame's ready message so the parent can tell this
     * document from one the frame navigated to. Pass the same value to
     * `isStreamingFrameReadyMessage`.
     */
    token?: string | undefined;
}): string;
/**
 * Opens the private channel streamed documents travel on. Call it once, on
 * the frame's ready message; the port only reaches the document that sent
 * it, so nothing posted on it can reach a page the frame navigates to.
 */
export declare function connectStreamingFrame(frame: HTMLIFrameElement): MessagePort | null;
/**
 * Sends the document so far over the frame's port. `accent` is a resolved
 * CSS color; when present, each new element's frame is drawn in it before the
 * element fills in.
 */
export declare function postStreamingFrameHtml(port: MessagePort, html: string, options?: {
    accent?: string | undefined;
}): void;
export declare function isStreamingFrameReadyMessage(event: MessageEvent, frame: HTMLIFrameElement | null, token?: string): boolean;