Clean Architecture

Dependency rule

Inner layers must not import outer layers.

flowchart TD
  Presentation --> Application
  Application --> Domain
  Infrastructure --> Domain
  Infrastructure --> Application

Layer rules

Layer	Allowed dependencies	Forbidden dependencies
Domain	TypeScript standard library	Hono, DB clients, network calls, environment variables
Application	Domain contracts and utilities	HTTP context, request/response objects
Infrastructure	Domain interfaces, external clients	Presentation routes
Presentation	Application services, schemas, middleware	SQL queries, direct infrastructure state except app wiring

Pull request checklist

• New route has schema validation.
• New use case lives in Application, not Presentation.
• New persistence logic implements a Domain repository contract.
• Error shape is consistent with existing handlers.
• Docs and route inventory are updated.