Great questions! This is indeed a fork of the open source version. We're going to create an open source version of this fork when we've got it stable.
The plans page has been kept for older users to know that those plans are free, and will continue to be free forever, we can make that more clear on that page.
strivemath.org/ide will indeed be merged into this trinket version.
replyTrinket was first built more than 10 years ago, it's actually really interesting seeing how gpt 5.5 and Opus 4.8 are managing/struggling with modernizing the stack
i thought the plans were a clever jab at commercial services, but i also found them a bit confusing. now i see where you are coming from and that does make some sense. though maybe instead put one box in the center and write: all plans are merged and free.
replyi would also make clear what changed, if anything. are you really letting users host private courses on your servers? the middle plan says self host at the bottom, which is probably not what the original plan was about.
i'd also like to see a way to use the code editor without login. no server features. only save in the browser and allow downloading.