c4-architecture-docs

Use this skill to document the architecture of a big issue / epic / feature with the C4 model (c4model.com) -- producing system context, container, component, and dynamic diagrams as Mermaid .mmd plus a narrative doc. Trigger phrases: 'C4 model', 'architecture diagram', 'system context / container / component diagram', 'document the architecture of this epic', 'draw the containers for this feature'. Don't use it for: rendering an existing .mmd to HTML (use the project's Mermaid viewer/renderer, or the mmdc CLI); FigJam whiteboard diagrams (use figma:figma-generate-diagram); a pure decision record with no diagrams (use the ADR template — .claude/templates/adr-template.md, falling back to core's templates/adr-template.md).