c4-model-diagramlisted

# c4-model-diagram Produces a **C4 model** in Simon Brown's sense (c4model.com): a set of nested diagrams that describe a software system at **four levels of abstraction**, each zooming in one notch. C4 is *abstraction-first and notation-independent* — the value is the consistent set of boxes-and-lines abstractions (person, software system, container, component), not any particular drawing tool. Mermaid C4 is one rendering; the abstractions are the contract. ## The four levels (zoom in one level at a time) 1. **Level 1 — System Context.** The system as a single box, surrounded by its **users (people)** and the **other software systems** it talks to. Audience: everyone, technical and not. Answers "what is this and who/what uses it". 2. **Level 2 — Container.** Zooms into the system box to show the deployable / runnable **containers** (web app, API, mobile app, database, message broker — *not* Docker containers specifically) and how they communicate. Audience: technical people inside and outside the team. 3. **Level 3 — Component.** Zooms into one container to show its major **components** (groupings of related functionality behind an interface) and their relationships. Audience: developers of that container. 4. **Level 4 — Code.** Zooms into one component (classes / functions). **Usually omitted** — it ages fast and is better generated on demand from the IDE. Most C4 docs stop at Level 3. ## Pattern (each level is the same shape) - A **Mermaid C