python

# Python Skill --- ## Type Hints - Use type hints on all function signatures - Use `typing` module for complex types - Run `mypy --strict` in CI ```python def process_user(user_id: int, options: dict[str, Any] | None = None) -> User: ... ``` --- ## Project Structure ``` project/ ├── src/ │ └── package_name/ │ ├── __init__.py │ ├── core/ # Pure business logic │ │ ├── __init__.py │ │ ├── models.py # Pydantic models / dataclasses │ │ └── services.py # Pure functions │ ├── infra/ # Side effects │ │ ├── __init__.py │ │ ├── api.py # FastAPI routes │ │ └── db.py # Database operations │ └── utils/ # Shared utilities ├── tests/ │ ├── unit/ │ └── integration/ ├── pyproject.toml └── CLAUDE.md ``` --- ## Tooling (Required) ```toml # pyproject.toml [tool.ruff] line-length = 100 select = ["E", "F", "I", "N", "W", "UP"] [tool.mypy] strict = true [tool.pytest.ini_options] testpaths = ["tests"] addopts = "--cov=src --cov-report=term-missing --cov-fail-under=80" ``` --- ## Testing with Pytest ```python # tests/unit/test_services.py import pytest from package_name.core.services import calculate_total class TestCalculateTotal: def test_returns_sum_of_items(self): # Arrange items = [{"price": 10}, {"price": 20}] # Act result = calculate_total(items) # Assert assert result == 30 def tes...