/**
 * YouTube URL regex pattern for input rule
 * Matches: youtu.be/*, youtube.com/watch?v=*, youtube.com/embed/*, etc.
 *
 * Note: Allows trailing invisible characters (zero-width spaces, etc.) before the $ anchor.
 * These chars are common when copy-pasting from rich text editors. The character class
 * [\u200B-\u200D\uFEFF\u00AD] matches the same set stripped by youtube.ts's stripInvisibleChars.
 *
 * @internal Exported for testing only
 */
export declare const YOUTUBE_INPUT_REGEX: RegExp;
/**
 * Input rule: pasting/typing a YouTube URL creates an embed block
 */
export declare const youtubeInputRule: import('@milkdown/utils').$InputRule;