This seems like a really good idea. I like that it's just markdown files and how seemless it is with an existing project. I have a few minor suggestions

1. I would really like a way to run the endpoint by clicking something in addition to command+enter (it wasn't obvious that I could open the sidebar and then click play but I see that now)

2. It would be good to include the evaluated request body and headers in the result sidebar

3. Duplicate file in the file tree context menu - I saw it in the tab context menu but that seems unintuitive

4. Maybe allow the user to set variables inside the markdown that can be imported to other files, for example a customerId variable that different requests could use which isn't part of the environment

5. Dragging text around appears like it will be moved but when releasing the mouse nothing happens

And finally 1 question I have: is this using an underlying text editor? It looks pretty robust but it doesn't look like VSCode, maybe something else? I am wondering if it's available to use for my own project