<essential principles SQLAlchemy 2.0 + Pydantic + PostgreSQL Best Practices This skill provides expert guidance for building production-ready database layers. Stack - SQLAlchemy 2.0 with async support (asyncpg driver) - Pydantic v2 for validation and serialization - Alembic for migrations - PostgreSQL only Core Principles 1. Separation of Concerns 2. Type Safety First Always use SQLAlchemy 2.0 style with type annotations: 3. Async by Default Use async engine and sessions for FastAPI: 4. Pydantic-SQLAlchemy Bridge Keep models and schemas separate but mappable: 5. Repository Pattern Abstract da…