There are solutions for this that those of us with the rare combination of experience, time and management buy-in are using - but they’re scary to people all-in on AI tools.

I’m talking about deterministic checkpoints and hooks. In every environment in which I need to use a coding agent I have had to essentially build a harness outside of the harness to be measurably productive. If you’re not using deterministic tools to box in what the agents are capable of doing, the problems you describe are ten times more rampant than anyone wants to admit.

If your files are named well and codebase is of reasonable size, it will find them and re-use them. I haven't experienced the problem of duplicate functions at all on any of my personal projects. The trick is that my code is separated into distinct modules in a clear hierarchy with one-way dependency; no module has more than 5k lines total, no more than 20 files or so. Basically, I treat every part of my system as an independent, fully self-contained black-box product which could potentially be used by third-parties in different business domains. The interface of each module is generally quite simple and it doesn't expose any internal details.

My AI agent never has to work with more than 5k lines of code and like 20 files at a time; and most are much smaller than that; like 1k or 2k lines... Even though one of my projects is almost 30k lines, my AI agent never has to consider more than 5k.

Larger models realize that a function might already exist and look around for it.

> was in a commit message 2 years ago, AI will just overwrite that without thinking.

Should be fixable by telling the model to check if there's a reason why something exists by checking the git history of that piece.

Only talking about Sol Max and Opus.