pkgreuse 0.1.0

Reuse installed Python packages from existing virtual environments.

PKGReuse

PKGReuse is an explicit Windows and Linux command-line wrapper that reuses compatible Python distributions already installed in other virtual environments. It can avoid downloading and unpacking a package when a safe local donor is available.

PKGReuse does not replace or intercept ordinary pip and uv commands. Local reuse is enabled only when you invoke the pkgreuse command.

PKGReuse 0.1 is alpha software. Use it in disposable virtual environments until its behavior has been validated for your workflow.

How resolution works

For a requirement such as filelock>=3,<4, PKGReuse scans its local environment index, filters locally installed versions against the requirement, and selects the highest satisfying local version. It delegates the original requirement to pip or uv only when the complete dependency closure cannot be reused locally. It does not query PyPI to maximize a locally satisfiable requirement.

Installation

py -m pip install pkgreuse

Run PKGReuse from an active standard Python virtual environment.

Usage

Use pip as the fallback installer:

pkgreuse pip install "requests>=2.31,<3"

Or use uv as the fallback installer:

pkgreuse uv pip install "requests>=2.31,<3"

On the first prefixed installation, PKGReuse automatically creates its local environment index. It scans every local fixed-drive root on Windows and / on Linux, while pruning operating-system trees and skipping inaccessible paths. Manual initialization with narrower roots is optional and can make discovery faster on very large filesystems:

pkgreuse init C:\Users\you\Desktop

pkgreuse init "$HOME/projects" /opt

Useful diagnostic and planning commands include:

pkgreuse status
pkgreuse find requests
pkgreuse resolve "requests>=2.31,<3"

Safety model

PKGReuse validates the complete local dependency plan before changing the target. Package content may be hard-linked on the same volume, while distribution metadata is copied. It rejects stale donors, target conflicts, unsafe RECORD traversal, executable or donor-specific .pth files, and editable installations. Donor launchers are not copied. If transfer or final validation fails, files created by the transaction are rolled back.

Development

py -m venv .venv
.\.venv\Scripts\python.exe -m pip install -e ".[dev]"
.\scripts\check-release.ps1

On Linux, run the equivalent checks directly:

python -m venv .venv
.venv/bin/python -m pip install -e '.[dev]'
.venv/bin/python -m ruff check .
.venv/bin/python -m ruff format --check .
.venv/bin/python -m mypy
.venv/bin/python -m pytest --cov=pkgreuse

The native NumPy check is opt-in because it requires a prepared compatible donor environment:

$env:PKGREUSE_NUMPY_REQUIREMENT = "numpy==2.3.3"
.\.venv\Scripts\python.exe -m pytest -m extended tests\extended\test_numpy_manual.py

See the resolution notes for the solver's local-maximization semantics.