I was looking for something like this. I used to use Replit to teach code (even integrated it into discussion sections when I was a TA) but they absolutely destroyed the product with AI vibecoding integrations over the past year.
Replit gets a total fail for me because the AI integration took the homework assignments I was giving my students, read the instructions to them, and then did their homework for them! There wasn't a way to turn it off when I talked to support, so I just had to tell my students "pretend you didn't see that". We moved off of Replit asap, after that.
I'm glad you liked it! I initially designed it as an alternative to replit, taking an anti-AI approach instead of their AI-first approach