import type { FieldMeta } from "../Decorator/FieldMeta";
/**
 * Validates a single value against field metadata.
 * @param meta - The field metadata.
 * @param value - The current field value.
 * @returns The failure message, or undefined when the value is valid.
 */
export declare const validateField: (meta: FieldMeta, value: unknown) => string | undefined;