BTW, this is not an AI codebase :)

It was mostly crafted by hand.

Let's say, I've saved some "complexity space" for LLM to add features on top.

In other words, the project has dumb-simple code right now, and it is ready to hold some amount of "tech-debt" from an LLM.

Tanner Lisnley did this with React. He didn't share it but talked about his experience. Basically, he re-wrote React with only the parts he was interested in. Sort of like his own version of Preact. You might be interested in his blog post about the subject: https://tannerlinsley.com/posts/projecting-react