fastapi-code-review

# FastAPI Code Review

## Quick Reference

| Issue Type | Reference |
|------------|-----------|
| APIRouter setup, response_model, status codes | [references/routes.md](references/routes.md) |
| Depends(), yield deps, cleanup, shared deps | [references/dependencies.md](references/dependencies.md) |
| Pydantic models, HTTPException, 422 handling | [references/validation.md](references/validation.md) |
| Async handlers, blocking I/O, background tasks | [references/async.md](references/async.md) |

## Review Checklist

- [ ] APIRouter with proper prefix and tags
- [ ] All routes specify `response_model` for type safety
- [ ] Correct HTTP methods (GET, POST, PUT, DELETE, PATCH)
- [ ] Proper status codes (200, 201, 204, 404, etc.)
- [ ] Dependencies use `Depends()` not manual calls
- [ ] Yield dependencies have proper cleanup
- [ ] Request/Response models use Pydantic
- [ ] HTTPException with status code and detail
- [ ] All route handlers are `async def`
- [ ] No blocking I/O (`requests`, `time.sleep`, `open()`)
- [ ] Background tasks for non-blocking operations
- [ ] No bare `except` in route handlers

## Valid Patterns (Do NOT Flag)

These are idiomatic FastAPI patterns that may appear problematic but are correct:

- **Pydantic validates request body automatically** - No manual validation needed when using typed Pydantic models as parameters
- **Dependency injection for database sessions** - Sessions come from `Depends()`, not passed as function arguments
- **HTTPException for all HTTP errors** - FastAPI handles conversion to proper HTTP responses
- **Async def endpoint without await** - May be using sync dependencies or simple operations; FastAPI handles this
- **Type annotation on Depends()** - This is documentation/IDE support, not a type assertion
- **Query/Path/Body defaults** - FastAPI processes these at runtime, not traditional Python defaults
- **Returning dict from endpoint** - Pydantic converts automatically if `response_model` is set

## Context-Sensitive