I really wish they were called lessons instead of skills. It makes way more sense and prevents the overloading of the term "skill".
We'd just be overloading "lessons" as well, and even more so because it takes more work to ground the concept, given its larger semantic distance from what we're describing.
There is some papers [0] showing that the skill and agent files reduce the reasoning effectiveness in some use cases (e.g. autogenerated)
[0] https://arxiv.org/abs/2602.11988
reference: https://news.ycombinator.com/item?id=47034087