Interesting!
I have built a similar tool, but more geared toward speed and CI/CD pipelines (check my submission history if you really want to know, don't want to detract from this project in any Way).
This looks like a very "scratching your own itch" sort of a project. What led you to build this? Why does this meet your needs while other things have failed (to the point that you decided to build your own)?
Props on using Bun!
This project, for someone like me who hasn't touched typescript in a year or two looks like great example/refresher to just read through. It's very nicely written and works just as advertised. The inputs/ configs/ FetchStories are elegant.
As a cli tool to support testing of endpoints: very nicely contained and concise.
As a library for use in test code: I'm yet to try and use it this way but looks fun to use!