# Python

> Use Python for practical project setup, dependency install, script execution, and environment troubleshooting with safe defaults. Use when tasks involve pyproject.toml or requirements.txt, virtual environment setup, running Python scripts/tests, packaging basics, or fixing common Python errors (interpreter mismatch, pip resolver conflicts, missing modules, build failures).

- Skill: `dvcrn/python` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add dvcrn/python`
- Raw SKILL.md: https://api.skillmd.com/api/skills/dvcrn/python/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: dvcrn (https://skillmd.com/u/dvcrn)
- Updated: 2026-09-08
- Page: https://skillmd.com/skills/dvcrn/python

---


# Python

Use this skill to keep Python workflows reproducible and low-risk across local/dev shells.

## Safety Defaults

- Prefer project-local virtual environments (`.venv`) over global installs.
- Prefer `python3 -m pip ...` to avoid interpreter and pip mismatch.
- Inspect dependency files before install (`requirements*.txt`, `pyproject.toml`).
- Avoid executing unknown setup hooks or random install scripts without user approval.

## Standard Workflow

1. Detect current environment:

```bash
python3 --version
python3 -c "import sys; print(sys.executable)"
{baseDir}/scripts/python_env_tool.py doctor
```

2. Create or refresh a venv:

```bash
{baseDir}/scripts/python_env_tool.py bootstrap --venv .venv --requirements requirements.txt
```

3. Install project package (if `pyproject.toml` exists):

```bash
{baseDir}/scripts/python_env_tool.py install --venv .venv --editable
```

4. Run tests/tools from the venv interpreter:

```bash
.venv/bin/python -m pytest -q
.venv/bin/python -m pip list --outdated
```

## Task Recipes

```bash
# Install specific packages into venv
{baseDir}/scripts/python_env_tool.py install --venv .venv --package requests --package pydantic

# Install from requirements file
{baseDir}/scripts/python_env_tool.py install --venv .venv --requirements requirements-dev.txt

# Recreate corrupted venv from scratch
{baseDir}/scripts/python_env_tool.py bootstrap --venv .venv --recreate --requirements requirements.txt
```

## Troubleshooting Rules

- `ModuleNotFoundError`: verify command is run via `.venv/bin/python`, then reinstall deps.
- `externally-managed-environment`: stop global install attempts; use venv.
- Build failures on native deps: upgrade `pip setuptools wheel`, then retry.
- Multiple Python versions: always print and confirm `sys.executable` before fixes.

## Bundled Helper

Use the helper for repeatable environment setup and diagnosis:

```bash
{baseDir}/scripts/python_env_tool.py --help
{baseDir}/scripts/python_env_tool.py doctor
```