import { ApiClient } from '../api-client';
import type { ChatFileInfo } from '../types';
export declare const ALLOWED_EXTENSIONS: Set<string>;
export declare function getContentType(filename: string): string;
export interface DownloadResult {
    downloadedPaths: string[];
    imagePaths: string[];
    failedCount: number;
    cleanup: () => void;
}
/**
 * S3 presigned URL 経由でファイルをダウンロードし、ローカルに保存する
 */
export declare function downloadChatFiles(client: ApiClient, _agentId: string, files: ChatFileInfo[], projectDir: string, conversationId: string): Promise<DownloadResult>;
/**
 * ファイルを S3 presigned URL 経由でアップロードする
 */
export declare function uploadFile(client: ApiClient, filePath: string, filename: string, conversationId: string, messageId: string, projectCode: string): Promise<{
    fileId: string;
    s3Key: string;
    fileSize: number;
}>;
/**
 * Returns true when the value is a non-null object with the three required string
 * fields that both parseChatFiles and parseConversationFiles need to validate.
 * Extracted to eliminate the duplicated field-presence check between the two parsers.
 */
export declare function hasChatFileBaseFields(item: unknown): item is {
    fileId: string;
    s3Key: string;
    filename: string;
};
/**
 * ChatPayload の files フィールドをパースして ChatFileInfo[] を返す
 */
export declare function parseChatFiles(files: unknown): ChatFileInfo[];
/**
 * ChatPayload の conversationFiles フィールドをパースして ChatFileInfo[] を返す
 * files と異なり contentType と fileSize は任意（デフォルト値で補完）
 */
export declare function parseConversationFiles(files: unknown): ChatFileInfo[];
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