I love it ! It's very cool. I was thinking of doing the same kind of thing too. I'll throw here some ideas that I thought would be cool also: - adaptative level: just gradually starts to add more vocabulary in the conversations. I would assume an LLM already knows by design the most common and the most rare worsts - remembers past vocabulary, and uses more the vocabulary you struggle with - remembers grammar concepts, ideally makes a brief summary of a new concept, and refreshes your memory if it's a concept you've already seen, but forgot.

I currently struggle learning Korean because so much of the language uses particles, and they all look the same to me. I think I would greatly benefit a tool that tells me "hey ! you've seen this concept before, look: ___" and by repetition give reinforce my grammar knowledge

This is how I would see the ideal language learning companion