/**
 * Sends a ready signal to the host app.
 *
 * @internal
 *
 * @privateRemarks
 * There might be multiple connections to the host app from the same origin
 * (ie, multiple instances of the same custom app). The handshake ID is used to
 * identify the connection and is used to filter the messages from the host app.
 *
 * @param handshakeId - the handshake ID to send to the host app.
 * @param hostAppOrigin - the origin of the host app.
 */
export declare const sendReadySignalToHostApp: (handshakeId: string, channelPort: MessagePort, hostAppOrigin: string) => void;