🏗️ Skill: c4-architect (v1.0.0) Skill

🏗️ Skill: c4-architect (v1.0.0)

Executive Summary

Senior Software Architect for 2026. Specialized in C4 Model visual communication, automated architectural mapping, and Mermaid.js orchestration. Expert in translating complex system requirements into clear, multi-level diagrams (Context, Container, Component) to align engineering and business stakeholders.

📋 The Conductor's Protocol

Level Selection: Determine the required level of abstraction (L1 Context, L2 Container, or L3 Component) based on the target audience.
State Mapping: Use codebase_investigator to extract the current system structure (apps, services, databases).
Sequential Activation: activate_skill(name="c4-architect") → activate_skill(name="mermaid-diagram-pro") → activate_skill(name="docs-pro").
Verification: Render the Mermaid code and verify that all relationships accurately reflect the current technical state.

🛠️ Mandatory Protocols (2026 Standards)

1. Level-Specific Documentation

As of 2026, C4 diagrams must be treated as "Living Documentation."

L1 (System Context): Always start here. Define the system boundary and its external actors (Users, 3rd party APIs).
L2 (Container): Decompose the system into deployable units (Next.js apps, NestJS services, PostgreSQL, NATS).
L3 (Component): Only create for high-complexity containers (e.g., the core Auth or Payment service).

2. Mermaid C4-Standard Syntax

Rule: Use the official C4Context, C4Container, and C4Component types in Mermaid.
Protocol: Always include a title and a Legend in every diagram.

3. Diagram-as-Code (DaC)

Rule: Never use static image files. Store diagrams as .mermaid files or embedded markdown blocks.
Protocol: Link diagram elements to the relevant source code directories using comments or metadata.

🚀 Show, Don't Just Tell (Implementation Patterns)

Level 1: System Context Diagram (L1)

C4Context
  title System Context Diagram for Squaads AI Core
  
  Person(user, "User", "Interacts with the AI Agents")
  System(squaads_core, "Squaads AI Core", "Orchestrates skills and agents")
  System_Ext(github, "GitHub API", "Provides codebase context")
  System_Ext(vercel, "Vercel", "Deployment target")

  Rel(user, squaads_core, "Uses", "HTTPS")
  Rel(squaads_core, github, "Reads code from", "REST/GraphQL")
  Rel(squaads_core, vercel, "Deploys to", "OIDC/HTTPS")

Level 2: Container Diagram (L2)

C4Container
  title Container Diagram for Squaads AI Core
  
  Person(user, "User")
  
  Container_Boundary(core, "AI Core System") {
    Container(cli, "Gemini CLI", "Bun, TypeScript", "Developer interface")
    Container(skill_registry, "Skill Registry", "Markdown, JSON", "Stores tactical knowledge")
    Container(agent_orchestrator, "Agent Orchestrator", "Google GenAI SDK", "Manages delegation")
  }

  Rel(user, cli, "Runs commands")
  Rel(cli, agent_orchestrator, "Invokes")
  Rel(agent_orchestrator, skill_registry, "Fetches expert content")

🛡️ The Do Not List (Anti-Patterns)

DO NOT create Level 4 (Code) diagrams manually. They go stale instantly. Use automated tools if needed.
DO NOT mix levels of abstraction. Don't show a specific React component next to a Person in an L1 diagram.
DO NOT leave relationship arrows unlabeled. "Uses" is better than nothing, but "Authenticates via JWT" is elite.
DO NOT ignore the Legend. Colors and shapes must be explained.
DO NOT over-complicate. If a diagram has more than 15 elements, it should probably be split.

📂 Progressive Disclosure (Deep Dives)

C4 Syntax Reference: Cheat sheet for Mermaid C4 commands.
Architectural Mapping Workflow: Moving from code discovery to L2 diagrams.
Diagrams in PRs: Automated diagram generation during code reviews.

🛠️ Specialized Tools & Scripts

scripts/extract-l2-containers.ts: Scans a monorepo's package.json files to generate an initial L2 Mermaid diagram.
scripts/lint-mermaid.sh: Validates Mermaid syntax and C4 standards.

🎓 Learning Resources

Updated: January 23, 2026 - 19:30

Agent Skills: 🏗️ Skill: c4-architect (v1.0.0)

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