I think testing is really important (even without LLMs). Currently I have 2247 unit tests across 132 files in a ~150K LOC codebase (test code included in that count). It takes about 50s to run. There could be more, but it's not nothing. There is playwright for it to test drive the UI, although if I'm being perfectly honest even before LLMs I thought that kind of test tends to be brittle and annoying to write (I guess I don't have to write them anymore, but they are still brittle). I'm honestly trying to give it as much structure as I possibly can -- I'm not trying to setup the agent to fail so I can be like "gotcha!"

I'll also just point out my philosophy for using LLMs for this project, which is that I'm not trying to go as fast as I can. (I want to go at a good pace, but this isn't an experiment to just finish something over a weekend). The 150k LOC have come about since February, with some mix of me writing code and LLMs, so on average I'm probably bringing in about 800 LOC per day, which I imagine a lot of vibers would find to be glacial. To me that's the sustainable rate of what I can do when you factor in that I need to test drive every feature, make sure it doesn't conflict with another feature, check for bugs, check that the code looks reasonable, and debugging. (I also think that rate limit is specific to this project: I could see easier to test things going much faster, and harder to test things going slower)

Isn't being brittle kinda the point of playwright tests? Because each test uses the whole app those tests can catch errors that happen at many places in the code. But that means lots of things can cause a test failure.