I think probably GPT 5.5, or 5.6 Sol - it was ~ 2 months ago.

Each time I get access to a new model, I do two things on all our active codebases:

- Security review of all the code and vulnerabilities (new models will find new stuff)

- Code review of test suite quality, and idiomatic patterns/code for the language of that codebase.

And in the case of swift and kotlin, it's even more important that an agent helps me with the code quality since I don't know what "idiomatic" swift or kotlin looks like, the way I do with JS, Elixir, C#, Ruby, etc.