/**
 * Turning a pasted URL into a real embed.
 *
 * A model writing a newsletter puts a YouTube link on its own line and expects
 * a player. Send that through as a paragraph and Substack renders a blue link,
 * which is the single most visible way an AI-written post looks AI-written.
 *
 * Substack's editor does this conversion client-side, so it never happens for
 * anything written through the API. Doing it here is why a draft from this
 * server looks like one a person made in the editor.
 *
 * Node shapes were read off live drafts.
 */
import type { PMNode } from "./prosemirror.js";
/**
 * Pull an 11-character video id out of any YouTube URL shape: watch?v=,
 * youtu.be, /embed/, /shorts/, /live/. Extra parameters such as &list= and &t=
 * are ignored rather than breaking the match.
 */
export declare function extractYouTubeId(url: string): string | null;
/**
 * Map a standalone URL to its embed node, or null when the host is not one
 * Substack embeds. Callers fall back to a normal link for null.
 */
export declare function urlToEmbed(url: string): PMNode | null;
/** True when a line is nothing but a URL, so it is safe to replace with an embed. */
export declare function isBareUrl(line: string): boolean;