I'll add technical section to readme, but for short. I've used tui-rs[1] with crossterm[2] backend (which handles the actual terminal interaction). The docs may seem intimidating, but it's surprisingly easy to use.

I've considered using curses, but tui-rs seemed that it will be easier to handle. I can certainly recommend it for making tui applications.

I didn't actually use any documentation at all, it wasn't in the man page and I didn't feel like hunting for it, as it was pretty easy to understand just by looking at the output.

Sed debug works by running the code specified just as normal, but it annotates what it does to stdout. So it might look like this: https://gist.github.com/SoptikHa2/a50e90bd1b34c7238944c20d1a...

Sed actually has pretty well-designed interface IMO, it's pretty minimal and has no nasty surprises.

Edit: Here[3] is something I've written about it.

[1]: https://github.com/fdehau/tui-rs [2]: https://github.com/crossterm-rs/crossterm [3]: https://soptik.tech/articles/building-desed-the-sed-debugger...