import type { z } from 'astro/zod';
import type { RSSOptions } from './index.js';
/** Normalize URL to its canonical form */
export declare function createCanonicalURL(url: string, trailingSlash?: RSSOptions['trailingSlash'], base?: string): URL;
/** Check if a URL is already valid */
export declare function isValidURL(url: string): boolean;
export declare const errorMap: z.ZodErrorMap;