Some patterns I've found useful when writing AI skills:
1. composing skills within one another. Saw this first with
@mattpocockuk 's /grill-me and it has been really good for maintaining consistent behaviour
2. hiding skills behind a router. I have both /design and /testing-quality files that contain a bunch of useful skills and advice I've come across in references within the router skill
3. Freely editing skills from other devs but maintaining an UPSTREAM.md file of what I've changed so I can keep it up to date