C4 Level 3: Component Diagram & Folder Mapping

Level 3 focuses on the internal architecture of a single container, bridging the gap between high-level containers and low-level code.

🎯 Stakeholder Focus

• Developers: Understanding internal module boundaries and dependencies.
• Architects: Ensuring proper layering and Separation of Concerns.

🛠 Folder Structure Mapping

Level 3 should ideally map to your folder structure:

• Controller/Handler: Maps to src/api, internal/handler.
• Service/Logic: Maps to src/services, internal/usecase.
• Repository/Data Access: Maps to src/db, internal/repository.
• Infrastructure Wrapper: Maps to pkg/email, src/adapters.

🚫 Anti-Patterns to Guard (Level 3)

• OVER-DETAILING: Don't draw every class. Only draw major logical groupings.
• MIXING CONTAINERS: Focus only on ONE container at a time.
• CIRCULAR DEPENDENCIES: Level 3 is the best place to identify and fix tight coupling.