import { ApiPropertyOptions } from '@nestjs/swagger';
/**
 * Decorator for the 'alt' (alternative text) property of a thumbnail image.
 * Validates the text length dynamically based on options or defaults to minimum 3 characters.
 *
 * @param {ApiPropertyOptions} options - Swagger and validation options.
 * @returns {PropertyDecorator} Composed decorators for transformation, validation, and API docs.
 */
export declare function ThumbnailAlt(options?: ApiPropertyOptions): PropertyDecorator;