creating-c4-diagramslisted

# Creating C4 Diagrams This skill is C4-specific: model architecture using C4 abstractions and notation (not generic box-and-arrow diagrams). ## Workflow: Creating a C4 diagram 1. **Identify the audience and scope.** Determine which diagram level is needed: - **Level 1 — System Context**: How the system fits into the world. Always create this first. - **Level 2 — Container**: Major technical building blocks and communication. Always create this second. - **Level 3 — Component**: Internal structure of a single container. Create only when it adds value. - **Dynamic**: Runtime behavior for a specific use case. Create for complex or non-obvious flows. - **Deployment**: How containers map to infrastructure. Create for production systems. - Skip Level 4 (Code) — auto-generate from IDE instead. 2. **Choose the tool.** - **Default: Structurizr DSL** — model-first, single model with multiple views, supports all diagram types. Use for any long-lived architecture documentation. - **Alternative: Mermaid** — use only for quick diagrams in Markdown files (READMEs, PRs, wikis). Limited to Context and Container levels; no dynamic or deployment diagrams. 3. **Identify the elements.** Map the system to C4 abstractions: - **Person**: A human user role. - **Software System**: A top-level system owned and deployed by one team. - **Container**: A separately deployable/runnable unit (app, database, queue, function). NOT a Docker container. - **Component**: A