My 3.5yo is learning to use a mouse, and it's super interesting.
He's mastered clicks and drags, but he hasn't yet figured out lifting up the mouse when run out of mouse pad. That's a tricky case where you deliberately break the relationship between mouse and cursor movement.
Terminad is a really interesting approach to rendering markdown in the CLI. It deliberately doesn't render links, so you can always see both the link text and the URL.
In a browser you have hover to see URLs, but not necessarily in a terminal.
I think you could build an interesting IDE with a tiny embedded LLM in addition to the usual tooling.
Features like 'extract method' would be much nicer if an LLM could provide a name. Choosing a good name is virtually impossible from just a typed AST.