Add CLAUDE.md for Claude Code context

Provides guidance for future Claude Code instances working with this repository,
including repository structure, content characteristics, and maintenance guidelines.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: DavidLiedle

CLAUDE.md

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+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Repository Purpose
+
+This is a comprehensive book about the Io programming language, written entirely in Markdown. The book targets experienced programmers as a second or third language resource, focusing on prototype-based object-oriented programming concepts with comparisons to mainstream languages (JavaScript, Python, Ruby, Java).
+
+## Content Structure
+
+The repository contains 19 numbered chapter files (00-preface.md through 18-conclusion.md) that form a complete technical book. Each chapter builds on previous concepts while maintaining standalone value. The `examples/` directory contains runnable Io code organized by chapter.
+
+## Working with Content
+
+### Running Examples
+```bash
+io examples/chapter-02/hello.io
+```
+Note: The Io interpreter may not be installed on all systems. Installation:
+- macOS: `brew install io`
+- Linux: Build from source at https://github.com/IoLanguage/io
+- Windows: Use WSL or Docker
+
+### Key Content Characteristics
+
+1. **Technical Comparisons**: Examples frequently compare Io concepts to JavaScript, Python, Ruby, and Java equivalents
+2. **Code Examples**: All code blocks are meant to be runnable in the Io REPL
+3. **Benchmark Outputs**: Performance comparisons include representative timing outputs (e.g., Chapter 5 benchmarks)
+4. **Progressive Complexity**: Early chapters introduce fundamentals, later chapters cover advanced topics like metaprogramming and concurrency
+
+## Maintenance Guidelines
+
+### When Adding Content
+- Maintain consistent comparison style with other languages
+- Include runnable code examples with expected outputs
+- Place example files in appropriate `examples/chapter-XX/` directories
+- Follow the established chapter numbering scheme
+
+### When Reviewing Feedback
+- The book has been reviewed by Steve Dekorte (Io's creator) - his feedback focused on adding outputs for benchmarks and expanding explanations for operator messages and common patterns
+
+### Version Control
+- The repository uses semantic versioning with tags (current: v1.1.0)
+- Major content improvements warrant version bumps
+- Include acknowledgments for technical reviewers in README.md
+
+## Important Context
+
+This book was generated by Claude (Opus 4.1) in collaboration with a human developer. The entire 400+ page book was created in a single conversation session, demonstrating AI-assisted technical writing capabilities. The content is released under CC0 1.0 Universal license, encouraging community contributions and corrections.