Python

Python Environment — PolicyEngine Standard

All PolicyEngine Python work uses uv with Python 3.13 and a local .venv.

Required tools

• uv — fast Python package and project manager
• Python 3.13 (installed/managed via uv)

Install uv if not present:

curl -LsSf https://astral.sh/uv/install.sh | sh

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Creating a new environment

Always create a .venv at the project root using Python 3.13:

uv venv --python 3.13
source .venv/bin/activate

On Windows:

uv venv --python 3.13
.venv\Scripts\activate

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Installing packages

Always use uv pip install, never bare pip install:

# Install a package
uv pip install policyengine

# Install from requirements file
uv pip install -r requirements.txt

# Install the current project in editable mode
uv pip install -e .

# Install with extras
uv pip install -e ".[dev]"

Verifying latest package versions

If the user asks for the "latest", "current", or "newest" version of a Python package, verify it from PyPI immediately before installing or pinning it. Do not treat search snippets, local installed versions, lockfiles, stale docs, or repo dependency constraints as proof of latest.

export PACKAGE=policyengine

# Authoritative PyPI metadata.
python - ` as an alternative to activating the venv manually
- If a venv conflict warning appears, use `deactivate` then `uv run`

## Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [PolicyEngine](https://github.com/PolicyEngine)
- **Source:** [PolicyEngine/policyengine-claude](https://github.com/PolicyEngine/policyengine-claude)
- **License:** MIT

Install and usage instructions live in the source repository linked above.