My favorite uses of Claude code is to do code quality improvements that would be seen as a total waste of time if I was doing them by hand, but are perfectly fine when they are done mostly for free. Looking for repetitive patterns in unit tests/functional tests. Making sure that all json serialization is done in similar patterns unless there's a particularly good reason. Looking for functions that are way too complicated, or large chunks of duplication.

The PRs that it comes with are rarely even remotely controversial, shrink the codebase, and are likely saving tokens in the end when working on a real feature, because there's less to read, and it's more boring. Some patterns are so common you can just write them down, and throw them at different repos/sections of a monorepo. It's the equivalent of linting, but at a larger scale. Make the language hesitant enough, and it won't just be a steamroller either, and mostly fix egregrious things.

But again, this is the opposite of the "vibe coding" idea, where a feature appears from thin air. Vibe Linting, I guess.