What is Markdown content negotiation?
We request your homepage with Accept: text/markdown and record the content-type that came back.
What it is
Content negotiation is the part of HTTP where a client states what format it would like and the server answers in one it has. The client sends an `Accept` header and the server replies with a `Content-Type`.
A growing number of sites answer `Accept: text/markdown` with the same page as Markdown instead of HTML. The convention is emerging rather than settled, so this Check is a Warning when it is not answered.
We accept either text/markdown or text/plain as a Pass. Anything else, including text/html, is recorded as it came back.
Why an agent needs it
HTML is a rendering format and an agent has to reverse it into meaning. Markdown skips that step: the headings are headings and the links are links.
This is a Low priority Check today and a cheap one to satisfy if your pages come from Markdown already. It costs nothing to leave for later.
The Fix
Add a route or middleware that inspects the `Accept` header on page requests. When the client prefers text/markdown, return the Markdown source with that content-type.
Set `Vary: Accept` on those responses so caches do not serve Markdown to a browser or HTML to an agent.
If your site is not built from Markdown, treat this as optional. Publishing llms.txt gives an agent more for less work.
This one is a change in your own markup or edge configuration, so the Fix Pack cannot write it for you. A Report names every page it affects, with the Evidence.