import type { LexicalEditor } from 'lexical';
import type { ElementTransformer } from '@lexical/markdown';
/**
 * Register the INSERT_HORIZONTAL_RULE_COMMAND handler on the given editor.
 * Returns a cleanup function to unregister the handler.
 */
export declare function registerHorizontalRulePlugin(editor: LexicalEditor): () => void;
/**
 * Markdown transformer for horizontal rules (---).
 * Use this with $convertToMarkdownString / $convertFromMarkdownString.
 */
export declare const HR_TRANSFORMER: ElementTransformer;
