MDX

An .mdx file is a normal point. The top is the usual ESM head — imports and an export const … = … point chain; the bottom is a Markdown body. The chain renders that compiled body through a component named MDXContent, into which it spreads the page's render props. So you write the page chain you already know, then keep typing prose under it.

import { generalLayout } from '@/layouts/general'

export const page = generalLayout
  .lets('page', 'about', '/about')
  .head('About')
  .page((props) => (
    <div className="prose">
      <MDXContent {...props} />
    </div>
  ))

# About My App

My App is the best!

/about now renders that Markdown. The chain is an ordinary page; the only new thing is <MDXContent {...props} /> — the bridge from the chain to the body.

The shape of an .mdx point

Two halves, in this order:

import { Link } from '@/lib/navigation' // 1. ESM head: imports
import { generalLayout } from '@/layouts/general'

export const page = generalLayout // 2. the point chain (a page here)
  .lets('page', 'about', '/about')
  .head('About')
  .page((props) => (
    <div className="prose">
      <MDXContent {...props} /> // renders the body below
    </div>
  ))

# About IdeaNick // 3. the Markdown body

IdeaNick is a platform for creating and sharing ideas.

The chain is identical to a .tsx page — .lets(...).loader(...).head(...).page(...). The .page render fn receives props and forwards them with <MDXContent {...props} />. Everything after the chain (from the first # heading down) is the body, compiled to the component you just rendered.

Most apps wrap the body in a typography class — <div className="prose"> (Tailwind Typography) above, or a <Prose> component — so plain Markdown gets readable styling. That wrapper is yours; Point0 adds none.

MDXContent — where it comes from

MDXContent is not a Point0 symbol. It is the default export the MDX compiler emits for every .mdx module. It is in scope inside the chain because *.mdx is declared as a module whose default export is MDXContent:

// src/types/global.d.ts
declare module '*.mdx' {
  import type { ComponentType } from 'react'
  const MDXContent: ComponentType<any>
  export default MDXContent
  export const page: unknown
  export const frontmatter: Record<string, unknown>
}

Three things an .mdx module is declared to export: default (= MDXContent), page (your chain), and frontmatter (see below). create-point0-app and every example ship this *.mdx block; a hand-rolled app needs it too, or the JSX scope won't know MDXContent.

Props reach the body through {...props}

The body can read the page's props directly — but only because the render fn spread them into MDXContent. The compiled MDXContent is a component (function MDXContent(props)), and the body references that same props:

export const page = generalLayout
  .lets('page', 'about', '/about')
  .loader(async () => {
    const lastIdea = await prisma.idea.findFirst({ orderBy: { id: 'desc' } })
    if (!lastIdea) throw new AppError('Last Idea Not Found :–(')
    return { lastIdea: { id: lastIdea.id, title: lastIdea.title } } // becomes props.data
  })
  .head('About')
  .page((props) => (
    <div className="prose">
      <MDXContent {...props} />{' '}
      {/* without this spread, props.data below is undefined */}
    </div>
  ))

# About IdeaNick

Fresh idea: <Link route="ideaView"
input={{ id: props.data.lastIdea.id }}>{props.data.lastIdea.title}</Link>

The body mixes Markdown with JSX freely — <Link>, props.data.lastIdea.*, any imported component. props.data is the loader's return, exactly as in a .tsx page; the full prop list (data, params, search, props, …) is on the page page. Forget the {...props} spread and the body still compiles, but props inside it is empty.

Three extensions, one pipeline

.md, .mdx, and .mdc all compile the same way — the compiler detects them by extension and precompiles each into a JS program before Babel runs (raw Markdown isn't valid Babel syntax). After that the output is a normal module: every Point0 source transform applies to it (see below).

// detection, in the compiler
;/\.(md|mdx|mdc)$/.test(path)

One pipeline, two intended uses:

• .mdx — a page. You write a point chain plus a Markdown body and render it through <MDXContent {...props} />, exactly as above.
• .md / .mdc — plain Markdown you import for its content. Since the compiled module's default export is the MDXContent component and a YAML block becomes export const frontmatter, a plain import Article, { frontmatter } from './post.md' hands you both the rendered body and its metadata — no point chain required.

All three run through the same compileSync call and produce the same module shape (default = MDXContent, plus any page / frontmatter you export). The split above is convention, not a compiler check — nothing stops a .md from carrying a page chain or an .mdx from being imported for its body.

.md parses as MDX too (JSX-aware) unless you set format: 'md' in config (plain CommonMark — see Config).

Frontmatter

A YAML frontmatter block compiles to an export const frontmatter:

---
title: Privacy Policy
updated: 2025-01-01
---

# Privacy Policy

// the compiled module also exports:
export const frontmatter = { title: 'Privacy Policy', updated: '2025-01-01' }

The two frontmatter remark plugins are always on (remark-frontmatter + remark-mdx-frontmatter named frontmatter), so no config is needed for this. It's a plain module export — Point0 does not auto-feed it into .head() or anything else; import and use it yourself.

Discovery: include mdx in pointsGlob

The compiler treats .mdx as a point, but the engine only finds it if pointsGlob matches it. Add the extension:

export const engine = Engine.create({
  pointsGlob: '**/*.{ts,tsx,mdx}', // without mdx, the .mdx page is never discovered
  // ...
})

create-point0-app already ships '**/*.{ts,tsx,mdx}'; if you copy a leaner glob, widen it. Editing an .mdx body in dev hot-swaps without a server restart — the dev watcher follows the real import graph, not the glob, so a reachable .mdx page updates in place.

Point0 transforms run on the body

Because the MDX output is re-parsed as a normal module, the standard Point0 transforms apply inside the Markdown body — it is first-class source, not inert text:

# Status

{env.side.is.client ? 'client' : 'server'}
{/* env tree-shaken per side at build */}

<ClientOnly>
  <span>browser-only content</span> {/* stripped from the server render */}
</ClientOnly>

So env shaking and server-side <ClientOnly> stripping work in the body exactly as in a .tsx file. The browser bundle is public, so don't put secret content in Markdown expecting it to stay private — server-only code is stripped at compile time, but anything that survives into the render output ships to the client. Gate access in .with, not on render output.

Dev vs build runtime

You don't configure this: the compiler forces the MDX development flag from the build state — react/jsx-dev-runtime while developing, react/jsx-runtime in a production build. A user markdown config can override most fields, but not development. React must be the runtime either way (the compiler emits jsx-runtime calls, not raw JSX).

Config

App authors tune MDX through the engine's compiler.markdown option. It's the full @mdx-js/mdx CompileOptions, except the three plugin arrays (remarkPlugins, rehypePlugins, recmaPlugins) also accept string paths and [path, options] tuples (not just live function refs):

export const engine = Engine.create({
  // ...
  server: {
    compiler: {
      markdown: {
        format: 'md', // parse .md/.mdx as plain CommonMark instead of MDX
        remarkPlugins: [
          'remark-gfm', // a string path — require()d for you
          ['remark-toc', { tight: true }], // a [path, options] tuple
        ],
      },
    },
  },
})

Merge rules, from highest precedence to lowest:

• Scalar fields (format, outputFormat, …) are last-write-wins: a server- or client-specific markdown overrides the general one.
• Plugin arrays are concatenated, never replaced — the framework defaults (the two frontmatter plugins) come first, then general config, then specific. You can only add plugins, not drop the defaults.
• development is not overridable (see above).

markdown exists at the general, server, and client compiler levels, so you can run a different plugin set per side.

Reference

Default compile options

The compiler's standalone defaults (before your markdown config and the forced development):

Module exports of an .mdx point

Failure modes

• Empty compile output is a hard error: Failed to compile MDX/MDC file <abs>, empty content.
• No {...props} spread into MDXContent → the body's props is empty (no type error, just missing data).
• pointsGlob without mdx → the page is never discovered.

Passing through to @mdx-js/mdx

A couple of things the underlying MDX compiler allows but Point0 does not wire itself:

• components / wrapper on MDXContent. The compiled MDXContent accepts the standard MDX components map (and wrapper) to override how Markdown elements render. Reaching for it means relying on @mdx-js/mdx behavior directly.