> struggle to scale beyond much more than a single module

Yes. You must guide coding agents at the level of modules and above. In fact, you have to know good coding patterns and make these patterns explicit.

Claude 4 won’t use uv, pytest, pydantic, mypy, classes, small methods, and small files unless you tell it to.

Once you tell it to, it will do a fantastic job generating well-structured, type-checked Python.