Add CLAUDE.md file

Author: borkweb

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.
+
+## Commands
+
+### Development
+```bash
+# Install dependencies
+composer install
+
+# Run static analysis
+composer phpstan
+
+# Generate PHPStan baseline for new violations
+composer phpstan:baseline
+
+# Run tests locally (requires vendor directory)
+vendor/bin/codecept run unit
+
+# Run specific test
+vendor/bin/codecept run unit ValidatorTest.php
+
+# Run tests with SLIC (if available)
+slic use validation
+slic composer install --ignore-platform-reqs
+slic run unit --ext DotReporter
+```
+
+## Architecture Overview
+
+### Core Components
+
+1. **Config** (`src/Config.php`): Static configuration manager
+   - Must call `Config::setServiceContainer()` before use
+   - Initialize with `Config::initialize()` to register rules
+
+2. **Validator** (`src/Validator.php`): Main validation engine
+   - Takes rules array, values array, and labels array
+   - Key methods: `passes()`, `fails()`, `validated()`, `errors()`
+   - Returns sanitized data via `validated()`
+
+3. **ValidationRulesRegistrar**: Rule registry accessed via service container
+   - Prevents duplicate rule registration
+   - Maps rule IDs to class implementations
+
+### Design Patterns
+
+- **Strategy Pattern**: Each rule implements `ValidationRule` interface
+- **Command Pattern**: Rules can return `ExcludeValue` or `SkipValidationRules` commands
+- **Abstract Factory**: Rules created from strings via `fromString()` method
+- **Registry Pattern**: Rules registered in `ValidationRulesRegistrar`
+- **Trait**: `HasValidationRules` adds validation to value objects
+
+### Rule System
+
+Rules can be specified as:
+- Strings: `'required'`, `'max:255'`, `'email'`
+- Instances: `new Max(255)`, `new Required()`
+- Closures: Custom validation logic
+
+Built-in rule categories:
+- Basic: Required, Optional, Nullable, Exclude
+- Type: Boolean, Integer, Numeric, Email, Currency, DateTime
+- Comparison: Min, Max, Size, In, InStrict
+- Conditional: ExcludeIf, NullableIf, OptionalIf (with Unless variants)
+
+### Key Interfaces
+
+- `ValidationRule`: Core rule interface with `__invoke()` method
+- `Sanitizer`: Rules that modify values during validation
+- `ValidatesOnFrontEnd`: Rules that can serialize to JSON for client-side validation
+- `ConditionalRule`: Abstract base for conditional validation rules
+
+### WordPress Integration
+
+- Uses `__()` for internationalization with `%TEXTDOMAIN%` placeholder
+- Hook system via configurable prefix: `{prefix}register_validation_rules`
+- Compatible with WordPress coding standards and PHPStan WordPress rules
+
+### Testing
+
+Tests use custom assertions in `TestCase`:
+- `assertValidationRulePassed($rule, $value, $values = [])`
+- `assertValidationRuleFailed($rule, $value, $values = [])`
+
+Mock rules available for testing validators (e.g., `MockRequiredRule`).
+
+### Extension Points
+
+1. Create custom rules by implementing `ValidationRule`
+2. Register rules via WordPress action hook
+3. Custom exceptions via `Config::setValidationExceptionClass()`
+4. Extend `ConditionalRule` for conditional validation logic