# 004 Versioned HTTP API

Context
- The template needs explicit API versioning and an HTTP boundary that can be replaced later.
- FastAPI is the initial framework, but it must not become a hard dependency for core logic.

Decision
- Place HTTP transport code under `adapter/http/fastapi/`.
- Mount routers under `/api/v1` and keep version-specific routers in `routers/v1/`.
- Map HTTP requests to usecase calls through thin dependencies and handlers only.
- Keep framework-specific request and response models in the HTTP adapter layer.

Consequences
- New API versions can be introduced without changing usecase contracts.
- Replacing FastAPI means rewriting only the HTTP adapter.
- Domain and usecase layers remain free from transport concerns.