fastapi-workflowlisted

# FastAPI Workflow-Driven Development Skill ## CRITICAL PRINCIPLE **DOCS FIRST, CODE SECOND** You MUST NEVER generate FastAPI code without first fetching relevant documentation via MCP tools. This is NON-NEGOTIABLE. Every workflow below has MANDATORY MCP fetch steps that MUST be completed before implementation. ## When to Use This Skill Use this skill for ALL FastAPI development tasks: - Creating API endpoints (routers) - Defining Pydantic models (request/response) - Implementing dependency injection - Database operations (SQLAlchemy) - Authentication/authorization - Background tasks - WebSocket endpoints - Any Python backend code with FastAPI ## Current Stack Requirements **Required Versions:** - Python 3.11+ (3.12+ recommended) - FastAPI 0.124+ - Pydantic 2.12+ (v2 is default, v1 support is DEPRECATED) - SQLAlchemy 2.0.44+ (async support) - Uvicorn (ASGI server) - scalar-fastapi (API docs — replaces Swagger UI and ReDoc) **DEPRECATED:** - Pydantic v1 compatibility will be removed in future FastAPI versions **Key Pydantic v2 Changes:** - `model_validator` instead of `validator` - `field_validator` instead of `validator` - `ConfigDict` instead of `class Config` - Performance boost (Rust core) - Strict mode available ## API Documentation Setup (Scalar) **ALWAYS use Scalar instead of Swagger UI / ReDoc.** Scalar provides modern, interactive API docs with dark mode, search, and code snippets. **Setup pattern:** ```python # requirements.txt scalar-fastapi>=1.6.0