Maybe I'm missing something, but wouldn't using the most popular open source framework + most popular open source database be a much better fit as there's much more training data and you don't lock yourself into yet another framework?

I'd just go with Rails + Postgres and have all the documentation and options open to me.

This is exactly it, and people trying to invent these new tools and formats (wasn’t there a “LLM optimized JSON alternative the other day) are seriously not understanding how LLMs are trained a tremendous amount on understanding JSON and XML and standard tools and frameworks.