managing-python-dependencies

Detect the project's dependency manager first by checking for signal files like uv.lock, pyproject.toml, Pipfile, or requirements.txt, then use that tool's install command. Never run a global pip install, which can corrupt system or project environments.

Use `uv add <package>` when the project contains a uv.lock file or a pyproject.toml with a [tool.uv] section. Set up the environment with `uv sync` rather than pip-based commands.

The correct choice is whichever tool the project already uses: Poetry if pyproject.toml has [tool.poetry], Conda if environment.yml exists, and venv plus pip if only requirements.txt is present. Mixing managers in one project is prohibited.

Default to venv plus pip: create an isolated environment with `python3 -m venv .venv`, install packages via `.venv/bin/pip install <package>`, and preserve state with `.venv/bin/pip freeze > requirements.txt`.

Global pip installs modify the system Python environment, causing version conflicts and breaking other projects. The Skill prohibits this and requires explicit virtual environment paths like .venv/bin/pip instead.