Python

What the source does

• FilesystemNone observedNo reads or writes in the source
• NetworkNone observedNo outbound calls in the source
• ShellNone observedNo commands run in the source
• DependenciesPinnedNothing floats
• SecretsNone foundNo keys in source

Five audit layers

Gates applied: no behavioural pass.

Audit 0.4.1 · source sha ea59a0c53d79 · 14 Oct 2026Report an issue or request a re-scan

• Publisheralinaqi GitHub userOwner of the repository this skill is read from
• Source folderalinaqi/claude-bootstrap/skills/pythonThe exact folder we audited
• LicenceMITAs the repository states it
• Commit pinned for this verdictea59a0c53d79A new audit runs when the source changes
• Repository statusNot archivedPushed today
• Sandboxed runNot runSkills are read, not executed; layer L4 is skipped

Its description: Python development with ruff, mypy, pytest - TDD and type safety

---
name: python
description: Python development with ruff, mypy, pytest - TDD and type safety
when-to-use: When working on Python files
user-invocable: false
paths: ["**/*.py", "pyproject.toml", "setup.py", "requirements*.txt"]
effort: medium
---

# Python Skill


---

## Type Hints

- Use type hints on all function signatures
- Use `typing` module for complex types
- Run `mypy --strict` in CI

```python
def process_user(user_id: int, options: dict[str, Any] | None = None) -> User:
    ...
```

---

## Project Structure

```
project/
├── src/
│   └── package_name/
│       ├── __init__.py
│       ├── core/           # Pure business logic
│       │   ├── __init__.py
│       │   ├── models.py   # Pydantic models / dataclasses
│       │   └── services.py # Pure functions
│       ├── infra/          # Side effects
│       │   ├── __init__.py
│       │   ├── api.py      # FastAPI routes
│       │   └── db.py       # Database operations
│       └── utils/          # Shared utilities
├── tests/
│   ├── unit/
│   └── integration/
├── pyproject.toml
└── CLAUDE.md
```

---

## Tooling (Required)

```toml
# pyproject.toml
[tool.ruff]
line-length = 100
select = ["E", "F", "I", "N", "W", "UP"]

[tool.mypy]
strict = true

[tool.pytest.ini_options]
testpaths = ["tests"]
addopts = "--cov=src --cov-report=term-missing --cov-fail-under=80"
```

---

## Testing with Pytest

```python
# tests/unit/test_services.py
import pytest
from package_name.core.services import calculate_total

class TestCalculateTotal:
    def test_returns_sum_of_items(self):
        # Arrange
        items = [{"price": 10}, {"price": 20}]
        
        # Act
        result = calculate_total(items)
        
        # Assert
        assert result == 30

    def test_returns_zero_for_empty_list(self):
        assert calculate_total([]) == 0

    def test_raises_on_invalid_item(self):
        with pytest.raises(ValueError):
            calculate_total([{"invalid": "item"}])
```

---

## GitHub Actions

```yaml
name: Python Quality Gate

on: [push, pull_request]

jobs:
  quality:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      
      - name: Setup Python
        uses: actions/setup-python@v5
        with:
          python-version: '3.12'
          
      - name: Install dependencies
        run: |
          pip install -e ".[dev]"
          
      - name: Lint (Ruff)
        run: ruff check .
        
      - name: Format Check (Ruff)
        run: ruff format --check .
        
      - name: Type Check (mypy)
        run: mypy src/
        
      - name: Test with Coverage
        run: pytest
```

---

## Pre-Commit Hooks

```yaml
# .pre-commit-config.yaml
repos:
  - repo: https://github.com/astral-sh/ruff-pre-commit
    rev: v0.8.0
    hooks:
      - id: ruff
        args: [--fix]
      - id: ruff-format

  - repo: https://github.com/pre-commit/mirrors-mypy
    rev: v1.13.0
    hooks:
      - id: mypy
        additional_dependencies: [pydantic]
        args: [--strict]

  - repo: local
    hooks:
      - id: pytest
        name: pytest
        entry: pytest tests/unit -x --tb=short
        language: system
        pass_filenames: false
        always_run: true
```

Install and setup:
```bash
pip install pre-commit
pre-commit install
```

---

## Patterns

### Pydantic for Data Validation
```python
from pydantic import BaseModel, Field

class CreateUserRequest(BaseModel):
    email: str = Field(..., min_length=5)
    name: str = Field(..., max_length=100)
```

### Dependency Injection
```python
# Don't import dependencies directly in business logic
# Pass them in

# Bad
from .db import database
def get_user(user_id: int) -> User:
    return database.fetch(user_id)

# Good
def get_user(user_id: int, db: Database) -> User:
    return db.fetch(user_id)
```

### Result Pattern (No Exceptions in Core)
```python
from dataclasses import dataclass

@dataclass
class Result[T]:
    value: T | None
    error: str | None
    
    @property
    def is_ok(self) -> bool:
        return self.error is None
```

---

## Python Anti-Patterns

- ❌ `from module import *`
- ❌ Mutable default arguments
- ❌ Bare `except:` clauses
- ❌ Using `type: ignore` without explanation
- ❌ Global variables for state
- ❌ Classes when functions suffice

Excerpt, first 4,275 characters of SKILL.md, verbatim from the audited commit. It is text from someone else’s repository, quoted so you can judge it before your agent reads it.

pip install -e ".[dev]"
pip install pre-commit

git clone https://github.com/alinaqi/claude-bootstrap
git -C claude-bootstrap checkout ea59a0c53d79

Works in

1. 2026-10-14
   ✓SAFE B 89 / 100

   first audit · source ea59a0c53d79

Questions about Python

• github.com/alinaqi/claude-bootstrap/tree/main/skills/python — the audited source at commit ea59a0c53d79 and every finding aboveObserved · 14 Oct 2026

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