Python Packaging Skill

---
name: python-packaging-skill
description: >-
  Python packaging for apps and libraries — pyproject.toml, Poetry, uv,
  setuptools, hatch, dependency management, PyPI publishing.
license: Apache-2.0
compatibility: opencode
category: Language-Specific
---

## What I do

Configure Python packaging for **applications** and **libraries**: pyproject.toml per backend (uv / Poetry / setuptools / hatch), dependency strategy, publishing.

## When to use me

Choosing a build tool; writing/restructuring pyproject.toml; app-vs-library dependency strategy; PyPI publishing; entry points; Python monorepo packages.

**Related:** `python-backend-skill` (app scaffolding — its pinned pyproject standard is the app baseline) · `python-ruff-linter-skill` / `python-pytest-creator-skill` (tool config sections) · `monorepo-management-skill` (JS/TS side).

## House decision rules

**App vs library (the deltas that change config):** apps pin exact dependency versions (lockfile discipline), build optional (wheel for Docker), version informal, no PyPI name constraints; libraries use minimum-compatible ranges, require sdist+wheel builds, semver, unique PyPI name, license, and published metadata completeness.

**Tool choice:** **uv** for new projects (house default — fastest resolution, lockfile, drop-in pip interface); **Poetry** where the team already standardizes on it (full-featured, lock file); **setuptools** for maximum compatibility/legacy; **hatch** when you want build + env management in one. All four configure via `[project]` in pyproject.toml (PEP 621) — backend sections differ, project metadata doesn't.

**Common traps:** dev/test deps go in dependency-groups or optional-extras (never install_requires); console entry points via `[project.scripts]` (`cli = "pkg.module:main"`); pin build-backend + its version; TestPyPI dry-run before a real PyPI release; trust publishing creds via OIDC (trusted publishing) over long-lived tokens.

> Removed 2026-09: per-backend pyproject.toml full listings (uv/Poetry/setuptools/hatch variants), venv walkthroughs, publishing step-by-steps, monorepo package example trees — backend-specific config the model regenerates on demand; kept the app-vs-library decision matrix, tool-choice rules, and the traps.