Are you vibe coding or have the 200k LoC been human reviewed?
In my opinion, and this is really my opinion, in the age of coding with AI, code review is changing as well. If you speed up how much code can be produced, you need to speed up code review accordingly.
I use automated tools most of the time AND I do very thorough manual testing. I am thinking about a more sophisticated testing setup, including integration tests via using a headless browser. It definitely is a field where tooling needs to catch up.
My process is probably more robust than simply reviewing each line of code. But hey, I am not against doing it, if that is your policy. I had worked the old-fashioned way for over 15 years, I know exactly what pitfalls to watch out for.
The answer: you don't!
Seems like this reality will become increasingly justified and embraced in the months to come. Really though it feels like a natural progression of the package manager driven "dependency hell" style of development, except now it's your literal business logic that's essentially a dependency that has never been reviewed.
I do not claim this is vibe coding, and I do not ship unreviewed changes to safety critical systems (in case this is what people think). I claim that in 2025 reviewing every single changed line is not the only way to achieve quality at the scale that AI codegen enables. The unit of review is shifting from lines to specifications.
Building a bridge from steel that lasts 100 years and carries real living people in the tens or hundreds of thousands per day without failing under massive weather spikes is engineering.