I personally find Claude Code has no real issues working and producing code in the 40k LoC Ruby on Rails repo I work in nor in the 45k LoC Elixir/Phoenix repo I work in. For the last few months I'd say 99% of all changes I do to both are purely via Claude Code, I almost never use my editor anymore at all. It's common things don't work on the first try or aren't exactly what I want but usually just giving an error to Claude or further instructions will fix it in an iteration or two.

I think the code organization isn't amazing, but it's fine and frankly not that much of a concern to me usually as I'm usually just reading diffs and not digging around in the code much myself.