import type { ExtensionUserMessageContent } from '../extensions/types/core.js';
export declare function extensionUserMessageContentToText(content: ExtensionUserMessageContent): string;
export declare function extensionCustomMessageContentToText(content: string | unknown[] | undefined): string;
export declare function extensionCustomMessageToTurnText(message: {
    customType: string;
    content?: string | unknown[];
    details?: unknown;
}): string;