import { AIMessage, Message } from '@langchain/langgraph-sdk';
/**
 * Extracts a string summary from a message's content, supporting multimodal (text, image, file, etc.).
 * - If text is present, returns the joined text.
 * - If not, returns a label for the first non-text modality (e.g., 'Image', 'Other').
 * - If unknown, returns 'Multimodal message'.
 */
export declare function getContentString(content: Message["content"]): string;
export declare function isAIMessage(message: Message): message is AIMessage;
export declare function isAiWithToolCalls(message: Message): boolean;
export declare function isToolMessage(message: Message): message is import('@langchain/langgraph-sdk').ToolMessage;
export declare function formatRelativeTime(timestamp: string): string;
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