Python & FastAPI Best Practices

Architectural patterns and performance guide for FastAPI, Pydantic v2, and SQLAlchemy 2.0 applications. Contains 38 rules across 8 categories, prioritized by impact. Focuses on patterns that linters cannot catch — async correctness, dependency injection, session management, schema design.

When to Apply

Reference these guidelines when:

• Writing new FastAPI endpoints or routers
• Designing Pydantic request/response models
• Implementing SQLAlchemy database queries or sessions
• Reviewing async Python code for correctness
• Refactoring existing FastAPI applications
• Setting up project structure for a new Python API

Target Versions