Скилл FastAPI

---
name: fastapi
description: FastAPI best practices and conventions. Use when working with FastAPI APIs, Pydantic models, dependencies, streaming responses including Server-Sent Events (SSE), and serving frontend apps. Keeps FastAPI code clean and up to date with the latest features and patterns.
---

# 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](#serve-frontend-apps).
* Server-Sent Events (SSE): use `response_class=EventSourceResponse` and `yield`; see [Streaming](#streaming-json-lines-sse-bytes) and [the streaming reference](references/streaming.md).
* JSON Lines and byte streaming: see [the streaming reference](references/streaming.md).
* Dependencies: use `Annotated[..., Depends(...)]`; see [Dependency Injection](#dependency-injection) and [the dependency injection reference](references/dependencies.md) 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](references/responses.md).
* Pydantic models: do not use ellipsis or `RootModel`; see [the Pydantic reference](references/pydantic.md).
* Routing: declare router-level prefix, tags, and shared dependencies on the `APIRouter`; see [the path operation reference](references/path-operations.md).
* Tooling and related libraries: use uv, Ruff, ty, Asyncer, SQLModel, and HTTPX when applicable; see [the other tools reference](references/other-tools.md).

## Use the `fastapi` CLI

Run the development server on localhost with reload:

```bash
fastapi dev
```

Run the production server:

```bash
fastapi run
```