Open infrastructure for creating, evaluating, and composing reusable AI agent skills. Repository of 200K+ skills with a unified ontology. Evaluates across 5 dimensions (Safety, Completeness, Executability, Maintainability, Cost-awareness). Testing on ALFWorld, WebShop, ScienceWorld shows 40% average reward improvement and 30% fewer execution steps. Directly relevant to the "vibe coding" and agent builder community — formalizes skills as composable, evolving assets rather than one-off prompts.