# Managing Python Dependencies

> Ensures proper Python dependency management, avoiding global `pip install` and adhering to project-specific tooling. Use this skill if any of the following are true: 1. Attempting to run `pip install {package_name}`. 2. Python packages or dependencies need to be added or modified. 3. Initiating a new Python project. 4. Creating a new notebook, even if just using BigQuery cells. 5. Generating Python code that includes `import` statements for third-party libraries. 6. Before executing Python scripts via the terminal to ensure the correct virtual environment is active.

- Skill: `2428424081cn/managing-python-dependencies` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add 2428424081cn/managing-python-dependencies`
- Raw SKILL.md: https://api.skillmd.com/api/skills/2428424081cn/managing-python-dependencies/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- License: Apache-2.0
- Author: 2428424081cn (https://skillmd.com/u/2428424081cn)
- Updated: 2026-09-21
- Page: https://skillmd.com/skills/2428424081cn/managing-python-dependencies

---


# Python Dependency Management Rule

> [!CAUTION]
>
> **BEFORE any `pip install`**: You MUST first detect the project's existing
> dependency manager and use it correctly. Do NOT override the project's
> established tooling.

## Dependency Manager Detection

Before installing ANY Python package, check the workspace for these files **in
priority order**:

1.  **Signal:** `uv.lock` or `pyproject.toml` with `[tool.uv]`
    *   **Tool:** **uv**
    *   **Install:** `uv add <package>`
    *   **Setup:** `uv sync`
2.  **Signal:** `pyproject.toml` with `[tool.poetry]`
    *   **Tool:** **Poetry**
    *   **Install:** `poetry add <package>`
    *   **Setup:** `poetry install`
3.  **Signal:** `Pipfile`
    *   **Tool:** **Pipenv**
    *   **Install:** `pipenv install <package>`
    *   **Setup:** `pipenv install`
4.  **Signal:** `environment.yml`
    *   **Tool:** **Conda**
    *   **Install:** `conda install <package>`
    *   **Setup:** `conda env create -f environment.yml`
5.  **Signal:** `requirements.txt` only
    *   **Tool:** **venv + pip**
    *   **Install:** `.venv/bin/pip install <package>`
    *   **Setup:** `.venv/bin/pip install -r requirements.txt`
6.  **Signal:** None of the above
    *   **Tool:** **venv + pip** (default)
    *   **Install:** `.venv/bin/pip install <package>`
    *   **Setup:** `.venv/bin/pip install -r requirements.txt`

## Default: venv + pip

If no dependency manager is detected, use **venv + pip + requirements.txt** as
the default:

```bash
# Initialize environment
python3 -m venv .venv

# Add dependencies
.venv/bin/pip install <package>

# Preserve state
.venv/bin/pip freeze > requirements.txt
```

**Rules for venv + pip workflow:**

-   Always use `.venv/bin/pip` or `.venv/bin/python` (explicit path).
-   After installing, run: `.venv/bin/pip freeze > requirements.txt`.
-   When setting up: `.venv/bin/pip install -r requirements.txt`.

## Prohibited

-   **NEVER** run `pip install` globally
-   **NEVER** override an existing dependency manager with a different one