fastapi

SKILL.md

FastAPI

Official FastAPI skill to write code with best practices, keeping up to date with new versions and features.

Quick Reference

Serve frontend apps: use app.frontend() or router.frontend() for built frontend assets; see Serve Frontend Apps.

Server-Sent Events (SSE): use response_class=EventSourceResponse and yield; see Streaming and the streaming reference.

JSON Lines and byte streaming: see the streaming reference.

Dependencies: use Annotated[..., Depends(...)]; see Dependency Injection and the dependency injection reference for yield, scopes, and class dependencies.

Response models: prefer return types; use response_model when the public response schema differs from the internal return value; see the response reference.

Pydantic models: do not use ellipsis or RootModel; see the Pydantic reference.

Routing: declare router-level prefix, tags, and shared dependencies on the APIRouter; see the path operation reference.

Tooling and related libraries: use uv, Ruff, ty, Asyncer, SQLModel, and HTTPX when applicable; see the other tools reference.

Use the fastapi CLI

Run the development server on localhost with reload: