py-ruff

name	py-ruff
description	Run ruff (Astral's Python linter & formatter) on Python code. Use when writing, editing, or reviewing Python code for lint issues and formatting. Triggers on: writing Python files, "lint", "format python", "run ruff", or after editing .py files.
allowed-tools	["Bash","Read","Edit","Write","Glob","Grep"]

ruff — Python Linter & Formatter (Astral)

Extremely fast Python linter and formatter written in Rust. Replaces Flake8, Black, isort, pyupgrade, pydocstyle, and autoflake. Repo: https://github.com/astral-sh/ruff

When to use

Run ruff check and ruff format after writing or editing Python code. Always lint and format before considering a Python task complete.

Installation

uv tool install ruff@latest       # preferred
# or: pip install ruff
# or: curl -LsSf https://astral.sh/ruff/install.sh | sh

Key commands

# Linting
ruff check                        # lint current directory
ruff check --fix                  # auto-fix fixable issues
ruff check --select F401          # check specific rule
ruff check path/to/file.py        # check specific file

# Formatting
ruff format                       # format current directory
ruff format path/to/file.py       # format specific file

# Info
ruff rule F401                    # explain a rule

Configuration

In pyproject.toml:

[tool.ruff]
line-length = 88
target-version = "py311"
src = ["src"]

[tool.ruff.lint]
select = ["E4", "E7", "E9", "F", "UP", "B", "I"]
ignore = ["E501"]
fixable = ["ALL"]

[tool.ruff.lint.per-file-ignores]
"__init__.py" = ["F401"]
"tests/**/*.py" = ["D100"]

[tool.ruff.format]
quote-style = "double"
indent-style = "space"
docstring-code-format = true

Key rule prefixes

Prefix	Source	What it checks
F	Pyflakes	Unused imports/vars, undefined names
E/W	pycodestyle	Style violations
UP	pyupgrade	Modernize syntax
B	flake8-bugbear	Common bugs
I	isort	Import sorting
S	flake8-bandit	Security issues
RUF	Ruff-specific	Custom rules

Workflow

1. After writing/editing Python code, run ruff check --fix to lint and auto-fix
2. Run ruff format to format
3. Review any remaining issues that couldn't be auto-fixed
4. Suppress intentional violations with # noqa: RULE comments