Proposal

MyST provides a --headless argument to myst start that launches a live-updating content server. This feature makes it convenient to prototype changes to the MyST Theme, which can pull content from the content server.

Unfortunately, there is not a counterpart CLI invocation in the base MyST CLI that makes it easy to consume a --headless server's content and render it in the browser. This point was raised at the Scientific Python Dev Summit 2025, where @rossbar, @bsipocz, and @danielballan were exploring the solution space for non-Netlify PR previews. In order not to derail this issue with that context, I'll leave that discussion for another time.

I shared a "simple" Docker incantation to start the MyST Book Theme with a particular CDN (see here), but it would be nice to make this more elegant and built-in, e.g.

myst start --headless

myst preview http://localhost:3100

Right now, we don't expose the theme that was used to build the site. We might want to do that.