To each his own, but it seems like all this could be one moderately-sized AGENTS.md/CLAUDE.md, and much of it doesn’t need to be detailed at all.

For example, you could just put “always follow TDD” in there. If you want to be very complete you could add “first write tests and make sure they’re red before continuing to code. Make sure tests are green on completion”.

Skills are useful for calling specific scripts, adding specific data (like branding info) or detailing truly unusual, bespoke workflows (like the use of cutting-edge machine learning algorithms you’ve developed yourself or something). If you’re detailing something like TDD, you’re probably hampering the model by giving it a definition that is less accurate than the one it has learned in training.