ascii-guard 2.2.0

A minimal-dependency Python linter for detecting and fixing misaligned ASCII art boxes in documentation

ascii-guard

Zero-dependency Python linter for detecting and fixing misaligned ASCII art boxes in documentation.

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🎯 Why ascii-guard?

AI-generated ASCII flowcharts and diagrams often have subtle formatting errors where box borders are misaligned by 1-2 characters. This breaks visual integrity and makes documentation harder to read.

ascii-guard automatically detects and fixes these alignment issues, ensuring your ASCII art looks perfect.

✨ Key Features

• 🚀 Minimal dependencies - Zero for Python 3.11+, one tiny dep for Python 3.10 (tomli)
• 💾 Tiny footprint - Lightweight and fast
• 🔒 Minimal supply chain risk - Pure stdlib on 3.11+
• ⚡ Quick startup - No import overhead
• 📦 Simple installation - One command, automatic dependency handling
• 🛡️ Type-safe - Full mypy strict mode
• ✅ Well tested - Comprehensive test coverage

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📦 Installation

For Users (AI Agents)

pip install ascii-guard

That's it! No other dependencies needed.

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🚀 Quick Start

Check files for ASCII art issues

ascii-guard lint README.md
ascii-guard lint docs/**/*.md

Auto-fix alignment issues

ascii-guard fix README.md
ascii-guard fix --dry-run docs/guide.md  # Preview changes first

Example

Before (misaligned):

┌─────────────────────┐
│ Box Content         │
└────────────────────┘   ← Missing one character!

After (fixed):

┌─────────────────────┐
│ Box Content         │
└─────────────────────┘  ← Perfect alignment ✓

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🎭 Ignore Markers

Need to show intentionally broken boxes in your docs? Use ignore markers:

**❌ Common Mistake (don't do this):**

<!-- ascii-guard-ignore-next -->
┌─────────────────────┐
│ Box Content         │
└────────────────────┘   ← Misaligned on purpose for demonstration

**✅ Correct Way:**

┌─────────────────────┐
│ Box Content         │
└─────────────────────┘  ← Perfect alignment

The ignore markers are invisible in rendered markdown but tell ascii-guard to skip validation. Perfect for:

• Before/after comparisons
• Tutorial examples showing common mistakes
• Documentation with intentionally broken examples

See USAGE.md for complete syntax and examples.

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🎨 Supported Box-Drawing Characters

ascii-guard supports Unicode box-drawing characters:

Type	Characters	Description
Horizontal	─ (U+2500)	Horizontal line
Vertical	│ (U+2502)	Vertical line
Corners	┌ ┐ └ ┘	Standard corners
T-junctions	├ ┤ ┬ ┴	Connection points
Cross	┼	Four-way intersection
Heavy lines	━ ┃ ┏ ┓ ┗ ┛	Bold variants
Double lines	═ ║ ╔ ╗ ╚ ╝	Double-line variants

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📋 Validation Rules

ascii-guard checks for:

1. Vertical alignment - All │ characters in a column align
2. Horizontal alignment - All ─ characters connect properly
3. Corner correctness - Corner characters match adjacent lines
4. Width consistency - Top, middle, and bottom borders match
5. Content fit - Content stays within box borders

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🤝 Contributing

We welcome contributions! Here's how to get started:

Prerequisites:

• Python 3.10+
• uv - Fast Python package manager

# Install uv
curl -LsSf https://astral.sh/uv/install.sh | sh

# Fork and clone the repository
git clone https://github.com/YOUR-USERNAME/ascii-guard.git
cd ascii-guard

# One-step setup (creates venv, installs deps, configures hooks)
./setup.sh

# Use uv run for commands
uv run pytest              # Run tests
uv run ruff check .        # Lint code
uv run mypy src/           # Type check

# Make your changes and submit a PR

For detailed development guide, see docs/DEVELOPMENT.md

For contribution guidelines, see CONTRIBUTING.md

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📄 License

Apache License 2.0 - see LICENSE for details.

Copyright 2025 Oliver Ratzesberger

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🔗 Links

• Repository: https://github.com/fxstein/ascii-guard
• Issues: https://github.com/fxstein/ascii-guard/issues
• PyPI: https://pypi.org/project/ascii-guard/
• Documentation:
  • User Guide - Complete usage documentation
  • Python API Reference - Complete API documentation
  • Development Guide - Setup, workflow, architecture
  • FAQ - Frequently asked questions

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🙏 Acknowledgments

Inspired by the need for better ASCII art formatting in AI-generated documentation.

Built with ❤️ using only Python's standard library.

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Note: ascii-guard is stable and actively maintained. Contributions and feedback are welcome!