Python Lint Fix

Analyze Python files for lint violations, type errors, and security issues using ruff, mypy, and bandit. Automatically fix what can be fixed and explain remaining issues.

When to Use

You want to check Python files for code quality issues before committing
You need to find and fix lint violations, type errors, or security issues
You want to auto-fix formatting and import sorting with ruff
You are reviewing Python code and want a quick quality check

Prerequisites

The following tools must be installed. If missing, install them with:

uv pip install ruff mypy bandit

ruff -- fast Python linter and formatter
mypy -- static type checker for Python
bandit -- security-focused static analysis tool

Workflow

Identify target files -- determine which Python files to check. Use changed files from git or user-specified paths:
```
git diff --name-only HEAD -- '*.py'
```
If the user specifies files or directories, use those instead.
Run ruff check on the target files and capture the output:
```
ruff check <files>
```
Run mypy on the target files and capture the output:
```
mypy <files>
```
Run bandit on the target files and capture the output:
```
bandit -r <files>
```
Present findings grouped by tool. For each issue, include:
- File path and line number (file:line)
- Rule ID (e.g., E501, F841, B101)
- Severity (error, warning, info)
- Explanation of what the rule catches and why it matters
Offer to auto-fix issues that ruff can handle automatically:
```
ruff check --fix <files>
ruff format <files>
```
Re-run checks to confirm fixes were applied and report any remaining issues:
```
ruff check <files>
mypy <files>
bandit -r <files>
```

Troubleshooting

Problem	Cause	Solution
`ruff: command not found`	ruff is not installed	Run `uv pip install ruff` or `pip install ruff`
`mypy: command not found`	mypy is not installed	Run `uv pip install mypy` or `pip install mypy`
`bandit: command not found`	bandit is not installed	Run `uv pip install bandit` or `pip install bandit`
mypy reports `Cannot find implementation or library stub`	Missing type stubs for third-party packages	Run `mypy --install-types` or add stubs with `uv pip install types-<package>`
mypy reports `Skipping analyzing`	Module is not in the mypy search path	Add the source directory to `mypy.ini` or `pyproject.toml` under `[tool.mypy]` with `mypy_path`
ruff ignores some files	Files are excluded in `pyproject.toml` or `ruff.toml`	Check `[tool.ruff]` exclude patterns in your config file
Too many issues reported	No config file limiting rule set	Create a `ruff.toml` or `[tool.ruff]` section in `pyproject.toml` to select specific rule sets
bandit reports false positives	Some rules are too strict for your codebase	Use `# nosec` inline comments or configure exclusions in `.bandit` or `pyproject.toml`
`ruff check --fix` did not fix all issues	Some violations require manual intervention	Review the remaining issues and fix them by hand; ruff marks auto-fixable rules in its output

python_lint_fix

Python Lint Fix

When to Use

Prerequisites

Workflow

Troubleshooting