# Extensions

# Extensions

Every built-in extension is available through a separate package entry.

## Callouts

Import from `@tanstack/markdown/extensions/callouts`.

### `calloutsExtension`

```ts
function calloutsExtension(): MarkdownExtension
```

Creates the block parser for GitHub-style `> [!KIND] Optional title` callouts.

### `parseCalloutBlock`

```ts
function parseCalloutBlock(
  context: BlockParseContext,
): CalloutNode | undefined
```

Low-level parser used by `calloutsExtension`.

## Comment components

Import from `@tanstack/markdown/extensions/comment-components`.

### `CommentComponentOptions`

Provides an optional `transformComponent(node)` callback that receives each parsed `ComponentNode`.

### `ComponentComment`

Parsed comment data with `block`, lowercase `name`, and string `attributes`.

### `commentComponentsExtension`

```ts
function commentComponentsExtension(
  options?: CommentComponentOptions,
): MarkdownExtension
```

Parses single `<!-- ::name -->` comments and paired `<!-- ::start:name -->` / `<!-- ::end:name -->` blocks.

### `parseCommentComponentBlock`

Parses a component at the current block context and optionally transforms it.

### `parseComponentComment`

```ts
function parseComponentComment(
  line: string,
): ComponentComment | undefined
```

Parses one component start or single-component comment.

### `parseAttributes`

```ts
function parseAttributes(value: string): Record<string, string>
```

Parses quoted, unquoted, and boolean-style attributes. A valueless attribute becomes the string `"true"`.

## Docs preset

Import from `@tanstack/markdown/extensions/docs`.

### `DocsMarkdownOptions`

Contains `collectHeadings?: boolean | HeadingCollectionOptions`.

### `docsMarkdownExtensions`

```ts
function docsMarkdownExtensions(
  options?: DocsMarkdownOptions,
): MarkdownExtension[]
```

Returns callouts, transformed comment components, and heading collection unless collection is disabled.

### `transformDocsComponent`

Routes `tabs` and `framework` component nodes to their built-in transforms and returns other nodes unchanged.

## Framework transform

Import from `@tanstack/markdown/extensions/framework`.

### `transformFrameworkComponent`

```ts
function transformFrameworkComponent(
  node: ComponentNode,
): ComponentNode
```

Splits level-one framework sections into `md-framework-panel` children, records available-framework and code-block metadata, and labels nested headings by framework.

## Heading collection

Import from `@tanstack/markdown/extensions/headings`.

### `HeadingCollectionOptions`

Contains `skipComponentNames?: ReadonlySet<string> | string[]`. The default skips headings inside `tabs` components.

### `headingCollectionExtension`

```ts
function headingCollectionExtension(
  options?: HeadingCollectionOptions,
): MarkdownExtension
```

Creates a document transform that writes collected headings to `document.headings`.

### `collectMarkdownHeadings`

```ts
function collectMarkdownHeadings(
  document: MarkdownDocument,
  options?: HeadingCollectionOptions,
): MarkdownHeading[]
```

Collects headings recursively through lists, blockquotes, callouts, and components while respecting skipped component names and framework labels.

## Streaming

Import from `@tanstack/markdown/extensions/streaming`.

### `streamingMarkdownExtension`

```ts
function streamingMarkdownExtension(): MarkdownExtension
```

Creates a document transform for accumulated AI responses. The transform removes an empty trailing heading, blockquote, or list item that is likely to be an incomplete block marker. All completed content keeps the core parser's normal output.

## Tab transforms

Import from `@tanstack/markdown/extensions/tabs`.

### `transformTabsComponent`

Dispatches by the component’s `variant` attribute. Unknown or missing variants use heading-based tabs.

### `transformFileTabs`

Turns code-block children into `md-tab-panel` elements and records file names, languages, and code in data properties.

### `transformPackageManagerTabs`

Parses `framework: package...` lines and records package groups plus `install`, `dev-install`, or `local-install` mode.

### `transformBundlerTabs`

Selects Vite and Rsbuild heading sections and converts them to panels.

### `transformHeadingTabs`

Splits content at the shallowest heading depth, creates stable tab slugs, and emits one panel per section.

The transforms return the original node when their expected input structure is absent.