10-backend-python

Backend Python Rules

These rules apply when working on backend Python code in core/ and edgekit/.

Technology Stack

• Framework: FastAPI (Python 3.11+)
• ORM: SQLAlchemy 2.x with async session patterns
• Migrations: Alembic
• Database: PostgreSQL 16
• Authentication: JWT (custom implementation)

Coding Standards

• Use ruff for linting and formatting (config in pyproject.toml)
• Always run ruff check . before committing
• Use mypy for type checking
• Python 3.11+ features are allowed (StrEnum, etc.)
• Use async/await patterns for all FastAPI endpoints

Database Operations

CRITICAL: All database operations MUST use RLS context helpers.

# User operations
async with with_user_context(session, user_id) as ctx:
    result = await ctx.execute(select(Model).where(Model.user_id == user_id))

# Admin operations
async with with_admin_context(session, user_id) as ctx:
    result = await ctx.execute(select(Model))

# System/background operations
async with with_system_context(session, "source_name") as ctx:
    result = await ctx.execute(insert(Model).values(data))

Never use direct session calls without RLS context wrappers.

Migration Workflow

alembic revision --autogenerate -m "description"  # Create migration
alembic upgrade head                               # Apply locally
# Review the generated migration file before committing
git add alembic/versions/
git commit -m "feat(db): add migration description [ASP-XXX]"

Rules:

• Always create proper Alembic migrations (never skip)
• Review auto-generated migrations for correctness
• Add RLS policies for any new tables
• Schema changes require System Architect approval

FastAPI Patterns

• Use dependency injection for database sessions
• Use Pydantic v2 models for request/response validation
• Use proper HTTP status codes
• Include OpenAPI documentation (FastAPI generates this)
• Use structured logging

Testing

• Use pytest with async support (pytest-asyncio)
• Run pytest tests/ before committing
• Integration tests go in tests/integration/
• E2E tests go in tests/e2e/