--- title: Markdown mirror is actually markdown description: "Agents trust a `Content-Type: text/markdown` response to be markdown. Serving the rendered HTML page with a markdown content type defeats the purpose of having a mirror — the agent still has to run an HTML parser and extract the article, and the size-reduction win is gone." doc_version: 0.2.0 last_updated: "2026-05-16T07:09:43.142Z" --- ## How the check decides The check fetches the markdown mirror and looks for two failure shapes: 1. The body starts with an HTML prologue — ``, ``, `^{`, embedded ``) easily passes. Returns N/A if no mirror was published at all.

## How to implement it

Serialise the source markdown directly rather than converting from rendered HTML. If your build pipeline can only post-process HTML, run a real HTML→markdown converter (`turndown`, `pandoc`) rather than just changing the response's content type.

### Pass

```markdown
---
title: Install a14y
---

# Install a14y

Run `npm install -g @a14y/cli`, then `a14y https://example.com` to audit a site.

- Reads `llms.txt` if present.
- Falls back to crawling the sitemap.
```

### Fail

```html

Install a14y...

```

## Sitemap

Full docs site index: [/sitemap.md](/sitemap.md).}