python3-tools

Python Tooling

Consult python3-core for standing defaults.

uv Package Management

• uv add for dependencies (not uv pip install)
• uv run for execution (not source .venv/bin/activate)
• uv sync --frozen for CI; uv sync --locked to detect stale lockfiles
• PEP 723 shebang: #!/usr/bin/env -S uv --quiet run --active --script
• uv venv --clear to overwrite existing environments (since 0.10.0)

Type Checker Detection

Check .pre-commit-config.yaml → CI config → pyproject.toml:

• Default for new work: ty (Astral)
• Project runs mypy: respect mypy.ini / [tool.mypy]; do not force ty
• Project runs pyright/basedpyright: respect that; do not force ty
• Do NOT infer active checker from presence of [tool.mypy] alone (may be stub config)

Build Backend

Hatchling preferred:

[build-system]
requires = ["hatchling"]
build-backend = "hatchling.build"

[tool.hatch.build.targets.wheel]
packages = ["src/my_package"]

Pre-commit

Detect installed tool: read .git/hooks/pre-commit line 2 to identify pre-commit vs prek. Both use the same config file.

TOML Editing

• tomlkit for read/write (preserves formatting) — open in text mode
• tomllib (stdlib) for read-only — tomllib.load() requires binary mode ("rb"), tomllib.loads() takes a string

PyPI Packaging

# pyproject.toml
[project]
name = "my-package"
version = "0.1.0"
requires-python = ">=3.11"
classifiers = ["Typing :: Typed"]

[project.scripts]
my-cli = "my_package.cli:app"

Standalone Tool Skills

Load these skills when the task is focused entirely on one tool:

• Load python-engineering:uv when the task involves uv commands, lockfiles, PEP 723 scripts, workspace configuration, Python version management, CI/CD integration, Docker setup with uv, or migration from pip/poetry/pyenv.
• Load python-engineering:ty when the task involves running ty type checks, configuring ty.toml or [tool.ty], suppressing diagnostics, interpreting ty error codes, ty editor integration, or migrating from mypy/pyright to ty.
• Load python-engineering:hatchling when the task involves Hatchling build hooks, custom builders, wheel/sdist configuration, editable installs, VCS version sources, PEP 517/518/621/660 compliance, or setuptools migration.
• Load python-engineering:toml-python when the task requires advanced TOML manipulation: comment-preserving read-modify-write, atomic config updates, tomlkit API patterns, or XDG config file management.
• Load python-engineering:pre-commit when the task requires configuring hook stages, writing .pre-commit-hooks.yaml definitions, implementing prepare-commit-msg hooks, or distributing a tool as a pre-commit hook.
• Load python-engineering:pypi-readme-creator when the task involves creating or validating a PyPI README, choosing between Markdown and RST formats, configuring readme in pyproject.toml, or running twine check.

References

• references/tooling-defaults.md — full tooling reference
• references/compatibility-lanes.md — version compatibility