FastAPI modern Python web framework. Covers routing, Pydantic models,
dependency injection, and async support. Use when building Python APIs.
USE WHEN: user mentions "fastapi", "pydantic", "async python api", "python rest api",
asks about "dependency injection python", "python openapi", "python swagger",
"async endpoints", "python api validation", "fastapi middleware"
DO NOT USE FOR: Django apps - use `django` instead, Flask apps - use `flask` instead,
synchronous Python APIs without type hints, GraphQL-only APIs