---
name: lint
description: Run linting and formatting checks on Ray code
---

# Lint Modified Files

Run pre-commit on the files you changed:

```bash
pre-commit run --files $(git diff --name-only HEAD)
```

`pre-commit run` without `--files` only operates on staged files, so pass the
modified file list explicitly.

If pre-commit is not installed:
```bash
pip install -c python/requirements_compiled.txt pre-commit && pre-commit install
```

## Handling remaining errors

Pre-commit auto-fixes simple issues (formatting, long lines, unused imports).
Review any remaining errors — these typically need code changes such as adding a
missing import, resolving a name conflict, or restructuring logic. Fix them by
editing the source code directly.

Use `# noqa` only for false positives that cannot be resolved by changing the code,
and include the rule code and reason: `# noqa: E501 — URL cannot be split`.

## Exclusions

pyproject.toml lists files in `per-file-ignores` and `extend-exclude`. When the PR
modifies a file that is on one of these lists, fix the lint issues in your changes
and consider removing the file from the list. Leave exclusion entries for files
outside the PR scope untouched.

## Reference

- Hook config: .pre-commit-config.yaml
- Ruff config: pyproject.toml (`[tool.ruff]` section)
- Docs: doc/source/ray-contribute/development.md ("Development tooling")