I use Ecto with Elixir in my day job, and it has a pretty good query building type solution. BUT: I still regularly come into issues where I have to use a fragment in order to do the specific SQL operation that I want, or I start my app and it turns out it has not caught the issue with my query (relating to my specific MySQL version or whatever). Which unfortunately defeats the purpose.

My experience with something like the latest Claude Code models these days has been that they are pretty good at SQL. I think some combination of LLM review of SQL code with smoke tests would do the trick here.