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CONTRIBUTING.md

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+# Contributing to Attributes Validation Extension
+
+Thank you for considering contributing to Attributes Validation Extension! This document provides guidelines for contributing to the project.
+
+## Table of Contents
+
+- [Getting Started](#getting-started)
+- [Development Setup](#development-setup)
+- [Running Tests](#running-tests)
+- [Code Style](#code-style)
+- [Pull Request Guidelines](#pull-request-guidelines)
+- [Reporting Issues](#reporting-issues)
+
+## Getting Started
+
+Attributes Validation Extension is a PHP C extension that provides Pydantic-inspired data validation using PHP 8.2+ attributes and type hints.
+
+## Development Setup
+
+### Prerequisites
+
+- PHP 8.2 or later (8.3+ recommended for full attribute support)
+- PHP development headers and tools (`phpize`, `php-config`)
+- Git
+- Composer
+- Make
+- GCC or Clang
+
+### Install Dependencies
+
+```bash
+# Clone the repository
+git clone https://github.com/Attributes-PHP/validation-ext.git
+cd validation-ext
+
+# Install PHP dependencies
+composer install
+```
+
+### Build the Extension
+
+```bash
+# Generate configure script
+phpize
+
+# Configure the extension
+./configure --enable-attributes-validation
+
+# Build the extension
+make
+
+# Install the extension (optional)
+sudo make install
+```
+
+### Enable the Extension
+
+Add the following line to your `php.ini`:
+
+```ini
+extension=attributes_validation.so
+```
+
+Or load it dynamically in your PHP scripts:
+
+```php
+<?php
+dl('attributes_validation.so');
+```
+
+## Running Tests
+
+### PHP Tests (Pest)
+
+The project uses [Pest](https://pestphp.com/) for PHP testing.
+
+```bash
+# Run all PHP tests
+composer test:integration
+
+# Run with coverage
+composer test:coverage
+
+# Run linting
+composer lint
+```
+
+### C Tests (Ceedling)
+
+The project uses [Ceedling](https://www.throwtheswitch.org/ceedling) for C testing.
+
+```bash
+# Run all C tests
+composer test:unit
+
+# Run specific test
+ceedling test:test_validate_function
+
+# Clean build artifacts
+composer clean:test
+```
+
+### Full Test Suite
+
+```bash
+# Run all tests (PHP + C)
+composer test
+```
+
+## Code Style
+
+### PHP Code
+
+- Follow [PSR-12](https://www.php-fig.org/psr/psr-12/) coding standard
+- Use Laravel Pint for code style checking:
+
+```bash
+composer lint
+```
+
+### C Code
+
+- Use `zend_always_inline` for performance-critical functions
+- Use `static inline` for less critical inline functions
+- Prefix internal functions with `av_` (e.g., `av_validate_type`)
+- Use Zend Engine memory management functions (`emalloc`, `efree`, etc.)
+- Always check for exceptions after Zend API calls using `EG(exception)`
+- Use `UNEXPECTED()` macro for error conditions
+
+### Naming Conventions
+
+| Type | Convention | Example |
+|------|------------|---------|
+| PHP Classes | PascalCase | `BaseModel`, `ValidationException` |
+| PHP Methods | camelCase | `beforeValidation()`, `afterValidation()` |
+| PHP Properties | camelCase or snake_case | `$age`, `$first_name` |
+| C Functions | snake_case with `av_` prefix | `av_validate_type()`, `av_get_property_name()` |
+| C Macros | UPPER_SNAKE_CASE | `AV_PASCAL_CASE`, `AV_BaseModel_ce` |
+| C Types | snake_case with `av_` prefix | `av_model_configs_properties` |
+
+## Pull Request Guidelines
+
+1. **Fork the repository** and create a feature branch from `main`
+2. **Use descriptive branch names**: `feature/xxx`, `fix/xxx`, `docs/xxx`, etc.
+3. **Keep PRs focused**: One feature or fix per PR
+4. **Write tests**: Add tests for new functionality or bug fixes
+5. **Update documentation**: Update README, docs, or comments as needed
+6. **Follow code style**: Ensure your code follows the project's style guidelines
+7. **Write clear commit messages**: Use imperative mood, keep first line under 50 chars
+8. **Reference issues**: Use `Closes #xxx` or `Fixes #xxx` in PR description
+
+### Commit Message Format
+
+```
+Type: Short description (50 chars or less)
+
+Longer description if needed (72 chars per line)
+
+- Bullet points for additional details
+- Use imperative mood ("Fix" not "Fixed")
+
+Closes #123
+```
+
+Types: `feat`, `fix`, `docs`, `style`, `refactor`, `test`, `chore`
+
+### PR Title Format
+
+- Use imperative mood
+- Keep under 72 characters
+- Capitalize first letter
+- No period at the end
+
+Examples:
+- "Fix memory leaks in validate_function.c"
+- "Add comprehensive C unit tests"
+- "Implement core validation logic"
+
+## Reporting Issues
+
+When reporting issues, please include:
+
+1. **PHP version** (`php -v`)
+2. **Operating system**
+3. **Steps to reproduce**
+4. **Expected behavior**
+5. **Actual behavior**
+6. **Code examples** (if applicable)
+7. **Error messages** (if any)
+
+### Issue Template
+
+```markdown
+## Description
+
+[Describe the issue]
+
+## Environment
+
+- PHP Version: [e.g., 8.2.32]
+- OS: [e.g., Ubuntu 22.04, macOS 14]
+- Extension Version: [if known]
+
+## Steps to Reproduce
+
+1. [First step]
+2. [Second step]
+3. [Third step]
+
+## Expected Behavior
+
+[What should happen]
+
+## Actual Behavior
+
+[What actually happens]
+
+## Additional Context
+
+[Any other relevant information]
+```
+
+## Code of Conduct
+
+By participating in this project, you agree to abide by the [Code of Conduct](CODE_OF_CONDUCT.md).
+
+## License
+
+By contributing to this project, you agree that your contributions will be licensed under the [MIT License](LICENSE).