[jongjong]

The project foundation is everything. LLMs are sensitive to over-engineering. The LLM doesn't have an opinion about good code vs bad code.

If you show it bad code and ask it to add features on top, it will produce more bad code... It might work (kind of) but more likely to be buggy and have security holes. When the context you give to the LLM includes unnecessary complexity, it will assume that you want unnecessary complexity and it will generate more of it for you.

I tried Claude Code with both a bad codebase and a good codebase; the difference is stark. The first thing I notice is that, with the good code base without unnecessary complexity, it generates a lot LESS code for any given feature/prompt. It's really easy to review its output and it's very reliable.

With a bad, overengineered codebase, Claude Code will produce complex code that's hard to review... Even for similar size features. Also it will often get it wrong and the code won't work. Many times it adds code which does literally nothing at all. It says "I changed this so that ..., this should resolve the issue ..." - But then I test and the issue is still there.

Some bad coders may be tempted to keep asking Claude to do more to fix the issue and Claude keeps adding more mess on top. It becomes a giant buggy hack and eventually you have to ask it to rewrite a whole bunch of stuff because it becomes way too complicated and even Claude can't understand its own code... That's how you get to bus factor of 0. Claude will happily keep churning out code even if it doesn't know what it's doing. It will never tell you that your code is unmaintainable and unextendable. Show it the worst codebase in the world and it will adapt itself to become the worst coder in the world.