Octane Rendering

This skill builds on render-markdown. Read it first for the syntax profile, parser options, AST, and core trust boundaries.

Octane Rendering

Setup

Install the optional Octane peer and render a fragment descriptor:

pnpm add @tanstack/markdown octane

import { createElement } from 'octane'
import { Markdown } from '@tanstack/markdown/octane'

export function Article({ source }: { source: string }) {
  return createElement(
    'article',
    null,
    Markdown({
      children: source,
    }),
  )
}

The adapter requires octane@0.1.12 or newer. Markdown returns an ElementDescriptor, not an HTML string.

Hooks and Components

Render Markdown from TSRX

import { Markdown } from '@tanstack/markdown/octane'

export function Article({ source }: { source: string }) @{
  <article>
    <Markdown>{source}</Markdown>
  </article>
}

The component returns an Octane fragment descriptor, so the application owns the surrounding semantic element.

Replace emitted links with an Octane component

import { createElement, type ComponentBody } from 'octane'
import { Markdown } from '@tanstack/markdown/octane'

const ArticleLink: ComponentBody<any> = props => {
  const external =
    typeof props.href === 'string' && props.href.startsWith('http')

  return createElement('a', {
    ...props,
    rel: external ? 'noreferrer' : props.rel,
    target: external ? '_blank' : props.target,
  })
}

export function Article({ source }: { source: string }) {
  return Markdown({
    children: source,
    components: { a: ArticleLink },
  })
}

components accepts host tag strings or Octane ComponentBody values keyed by emitted tag name.

Render static markup and styles

import { renderToStaticMarkup } from 'octane/server'
import { Markdown } from '@tanstack/markdown/octane'

const source = '# Server-rendered article'

export const { html, css } = renderToStaticMarkup(Markdown, {
  children: source,
})

octane/server returns an object containing both html and css.

Parse once before repeated Octane rendering

import { parseMarkdown } from '@tanstack/markdown/parser'
import { Markdown } from '@tanstack/markdown/octane'

const document = parseMarkdown('# Cached article\n\nRendered from an AST.')

export const article = Markdown({
  children: document,
})

Apply parser options and document transforms before caching the document.

Compose through the lower-level node API

import { Fragment, createElement } from 'octane'
import { parseMarkdown } from '@tanstack/markdown/parser'
import { renderMarkdownOctane } from '@tanstack/markdown/octane'

const document = parseMarkdown('# Parsed once')

export function ArticleBody() {
  return createElement(
    Fragment,
    null,
    ...renderMarkdownOctane(document),
  )
}

Use renderBlockOctane or renderInlineOctane only when custom tree composition needs individual public AST nodes.

Common Mistakes

HIGH Treating descriptors as HTML strings

Wrong:

import { Markdown } from '@tanstack/markdown/octane'

const source = '# Article'

export const html = String(Markdown({ children: source }))

Correct:

import { renderToStaticMarkup } from 'octane/server'
import { Markdown } from '@tanstack/markdown/octane'

const source = '# Article'

export const { html } = renderToStaticMarkup(Markdown, {
  children: source,
})

Markdown returns an ElementDescriptor; serialize it through octane/server when an HTML string is required.

Source: docs/reference/octane.md

HIGH Using a React component in the map

Wrong:

import type { ComponentProps } from 'react'
import { Markdown } from '@tanstack/markdown/octane'

function ReactLink(props: ComponentProps<'a'>) {
  return <a {...props} />
}

export const article = Markdown({
  children: '[Guide](/guide)',
  components: { a: ReactLink },
})

Correct:

import { createElement, type ComponentBody } from 'octane'
import { Markdown } from '@tanstack/markdown/octane'

const OctaneLink: ComponentBody<any> = props =>
  createElement('a', {
    ...props,
    'data-navigation': 'article',
  })

export const article = Markdown({
  children: '[Guide](/guide)',
  components: { a: OctaneLink },
})

Octane replacements must be host tag strings or Octane ComponentBody values.

Source: docs/guides/octane.md

MEDIUM Ignoring the static-render return structure

Wrong:

import { renderToStaticMarkup } from 'octane/server'
import { Markdown } from '@tanstack/markdown/octane'

export const markup = renderToStaticMarkup(Markdown, {
  children: '# Article',
})

Correct:

import { renderToStaticMarkup } from 'octane/server'
import { Markdown } from '@tanstack/markdown/octane'

export const { html, css } = renderToStaticMarkup(Markdown, {
  children: '# Article',
})

The static renderer returns { html, css }, not a bare HTML string.

Source: docs/guides/octane.md

HIGH Expecting HTML extension hooks in Octane

Wrong:

import type { MarkdownExtension } from '@tanstack/markdown'
import { Markdown } from '@tanstack/markdown/octane'

const paragraphHtml: MarkdownExtension = {
  name: 'paragraph-html',
  renderHtml(node) {
    return node.type === 'paragraph'
      ? '<aside>Rendered only by the HTML renderer</aside>'
      : undefined
  },
}

export const article = Markdown({
  children: 'Ordinary content',
  extensions: [paragraphHtml],
})

Correct:

import type { MarkdownExtension } from '@tanstack/markdown'
import { createElement, type ComponentBody } from 'octane'
import { Markdown } from '@tanstack/markdown/octane'

const panelExtension: MarkdownExtension = {
  name: 'panel',
  transformDocument(document) {
    return {
      ...document,
      children: [
        {
          type: 'component',
          name: 'panel',
          tagName: 'doc-panel',
          attributes: {},
          children: document.children,
        },
      ],
    }
  },
}

const Panel: ComponentBody<any> = props =>
  createElement('aside', {
    ...props,
    className: 'documentation-panel',
  })

export const article = Markdown({
  children: 'Ordinary content',
  components: { 'doc-panel': Panel },
  extensions: [panelExtension],
})

MarkdownExtension.renderHtml is HTML-specific; portable custom output uses ComponentNode and an emitted-tag component mapping.

Source: docs/guides/extensions.md

CRITICAL Enabling raw HTML for untrusted input

Wrong:

import { Markdown } from '@tanstack/markdown/octane'

export function UserPost({ source }: { source: string }) {
  return Markdown({
    allowHtml: true,
    children: source,
  })
}

Correct:

import { Markdown } from '@tanstack/markdown/octane'

export function UserPost({ source }: { source: string }) {
  return Markdown({
    children: source,
  })
}

With allowHtml, Octane receives dangerouslySetInnerHTML; TanStack Markdown does not sanitize that raw HTML.

Source: docs/core-concepts/security.md

HIGH Tension: renderer parity versus Octane customization

Core Octane static output is tested against renderHtml(). Octane component replacements, raw HTML, highlighter output, and HTML-only extension hooks are application-controlled boundaries outside that parity guarantee.

See also: custom-extensions for portable ComponentNode output.

Cross-References

• render-markdown - shared MarkdownInput, parser options, AST behavior, and syntax profile.
• custom-extensions - emit custom tags that Octane can replace through components.
• production-pipelines - audit raw HTML, highlighter output, untrusted content, and static SSR boundaries.