This was prototyped on codesandbox before they nuked their product. Each link goes to a specific version which you can test by running bun http.ts in the terminal which serves the content. I updated the article to include this info.

In the future I will keep everything self hosted to avoid this issue. I appreciate the patience.

For security reasons you cannot use some of the features in this code without setting a specific header (the blog mentions this).

The sandbox has a button that's basically "Open a preview in a separate tab". If you click that, the header will be sent, and the demo will work.

If you only use the "in-editor" preview, the proper header will not be sent.

Agree not intuitive. Hope it helps, it was a super cool demo.