If you're documenting systems with the C4 model, this handles the top layer: system context diagrams, personas, user journeys, and external dependencies. It walks you through identifying who uses your system (human and programmatic), what features they need, and what external systems you integrate with. The output is Mermaid diagrams and structured markdown meant to be readable by non-technical stakeholders. Good for kicking off architecture documentation or explaining a system's boundaries to new team members. It explicitly stays at the context level and won't dive into containers, components, or code, so you'll need those other C4 skills if you're going deeper.
npx skills add https://github.com/sickn33/antigravity-awesome-skills --skill c4-context