ulises-jeremias/agent-toolkit/c4-model

C4 Model — Methodology Overlay (WHAT → HOW via Mermaid)

Sources (2026-08-12): Simon Brown C4 https://c4model.com/ (Context, Container, Component, Code); Structurizr DSL https://github.com/structurizr/dsl (open-source DSL, paid cloud) + structurizr-mcp https://github.com/cubical6/structurizr-mcp + go-structurizr; C4-PlantUML https://github.com/plantuml-stdlib/C4-PlantUML; overarch https://github.com/soulspace-org/overarch (PlantUML/Structurizr generation); rendering via Mermaid mermaid-js/mermaid MIT per §44.

Pack: architecture core (architect + ADR + TRD + threat-model + mermaid (+ C4 via mermaid)) — c4-model teaches what to draw; mermaid renders it. See docs/architecture/research-385-diagram.md for C4 vs Mermaid vs PlantUML/Structurizr decision (Excalidraw/draw.io REJECT).

When to use

• Need system Context / Container / Component / Code views.

Instructions

1. Select level: Context (system + actors) → Container (apps/data stores) → Component (modules) → Code (classes, optional).
2. Render via Mermaid (C4-inspired): flowchart TD with subgraph for boundaries, e.g.:

``mermaid flowchart TD user([User]) --> web[Web Container] web --> api[API Container] api --> db[(Database Container)] subgraph System Context user; web; api; db end ``

1. Advanced (optional): For consistency checks across views, use Structurizr DSL (structurizr-cli + workspace.dsl → PlantUML/Mermaid) or C4-PlantUML (@startuml + !include C4_Context.puml); note structurizr CLI requires DSL file and is heavier.

Collaboration

• architect defines system → c4-model selects C4 level → mermaid renders → ADR records decision.

Anti-patterns

• Do not mandate Structurizr DSL for every diagram — Mermaid suffices for most.
• Do not dump PlantUML infra as separate skill — keep as optional note.