# Validators
## Purpose
Comprehensive input validation and sanitization providing defense-in-depth against security threats.
## Key Components
- **input.py**: Multi-layer input validation with pattern matching, content filtering, and sanitization for all external data
- **filesystem.py**: Filesystem security enforcement with path validation, boundary checking, and resource monitoring
## Architecture & Dependencies
**External**: re for pattern matching, html for HTML escaping, pathlib for secure path operations
**Internal**: Security contracts for validation enforcement, boundaries module for filesystem security
**Patterns**: Strategy pattern for validation algorithms, Chain of Responsibility for validation layers
## Critical Considerations
- **Security**: Whitelist-based validation with comprehensive attack pattern detection and prevention
- **Performance**: O(n) input processing with compiled regex patterns for efficient validation
- **Integration**: Seamless integration with contract system for automatic security boundary enforcement
## Related Documentation
- [Security Framework Documentation](../../docs/security/SECURITY_FRAMEWORK.md)
- [Input Validation Guide](input.py)
- [Filesystem Security Guide](filesystem.py)
