I'm skeptical of the whole thing, it almost seems like a marketing campaign to encourage developers to use more tokens.
My experience as a software engineer, including with Claude Code itself, is that the more code you have, the more bugs there are. It quickly turns into a game of Whac-a-Mole where you fix 1 bug and 2 new bugs appear.
Looking at the functionality of Claude code. There is no way it requires 500k lines of code as claimed. It would make it very difficult to debug... Though it seems they have a team of 10 people which is a lot for a CLI wrapper.
It's more likely that somebody ran the real code through an agent to intentionally obfuscate it into a more complicated form before they leaked it. This is trivial to do with LLMs. You can take any short function of a couple of lines and turn it into a function hundreds of lines long which does the exact same thing.
It's actually a great way to obfuscate code in the AI era because LLMs are good at creating complexity and not good at reducing it. I've done tests where I ask Claude to turn a simple 1 line function which adds two numbers together into a 100 line function and when I asked it to simplify it down, it couldn't reduce it back to its original simple form after multiple attempts. I had to explicitly tell it what the original form of the function was for it to clean up properly. This approach doesn't scale to a whole codebase. Imagine doing this to an entire codebase, it would take more time for you to read and understand each function to tell the LLM how to clean it up than just re-generating the entire app from scratch.
The problem with large amounts of code is not only that it's harder to maintain and extend, it's often less performant.
While LLMs can allow us to get more out of bad code, they will allow us to get even more value out of the equivalent good code when it comes to maintainability, reliability and efficiency.