uv           # Package management (not pip/poetry)
ruff         # Lint + format (not flake8/black)
pytest       # Testing
mypy         # Type checking

def process_users(users: list[User], limit: int | None = None) -> list[Result]:
    ...

async def fetch_data(url: str, timeout: float = 30.0) -> dict[str, Any]:
    ...

from dataclasses import dataclass, field

@dataclass
class Config:
    host: str
    port: int = 8080
    tags: list[str] = field(default_factory=list)

match event:
    case {"type": "click", "x": x, "y": y}:
        handle_click(x, y)
    case {"type": "key", "code": code}:
        handle_key(code)
    case _:
        raise ValueError(f"Unknown event: {event}")

uv sync                    # Install deps
ruff check --fix .         # Lint and autofix
ruff format .              # Format
pytest -v                  # Test
mypy .                     # Type check