export interface FileUploadRequestParams {
    fileBuffer: Buffer;
    fileName: string;
}
/**
 * Assume MIME type from filename extension
 */
export declare function getMimeType(filename: string): string;
/**
 * @private Build multipart/form-data payload for file uploads (Node.js only)
 */
export declare function buildMultipartPayload(params: FileUploadRequestParams): Promise<{
    payload: Buffer;
    contentType: string;
}>;