import type { RootContent } from 'mdast';
import { MdxJsxFlowElement } from 'mdast-util-mdx-jsx';
export interface PreprocessCustomHeadingIdsOptions {
    /**
     * When true, preserves the original ID as-is (only removing characters unsafe
     * in HTML attributes). When false (default), also collapses whitespace to hyphens.
     */
    preserveOriginal?: boolean;
}
/**
 * Converts markdown headings with custom ID syntax into JSX heading elements.
 *
 * Transforms `## Heading text {#custom-id}` into `<h2 id="custom-id">Heading text</h2>`.
 * This avoids MDX parsing errors (MDX treats `{...}` as JS expressions) and
 * produces JSX heading elements that the existing remark pipeline already handles.
 *
 * Uses a line-by-line scan with fence state tracking to skip headings inside
 * code blocks, avoiding backtracking over large documents.
 */
export declare function preprocessCustomHeadingIds(content: string, options?: PreprocessCustomHeadingIdsOptions): string;
export interface JsxHeadingElement extends MdxJsxFlowElement {
    readonly __jsxHeading: true;
}
export declare const ALL_HEADING_NAMES: string[];
export declare const isJsxHeadingElement: (node: RootContent) => node is JsxHeadingElement;