# Handover Document - 2025-12-02

**Package:** llm-security-firewall
**Version:** 2.4.0
**Date:** 2025-12-02
**Status:** Released to PyPI.org

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## Summary

Version 2.4.0 of `llm-security-firewall` has been published to PyPI.org. The package underwent validation testing, version synchronization, and documentation restructuring. The release includes security fixes for Unicode bypass vectors and improvements to false positive rates in test scenarios.

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## Completed Work

### 1. Production Release (2.4.0)

**Version Management:**
- Version updated from `2.4.0rc4` to `2.4.0` (stable)
- Synchronized across: `pyproject.toml`, `src/llm_firewall/__init__.py`, `README.md`, `CHANGELOG.md`
- Git tag `v2.4.0` created and pushed

**Package Build:**
- Wheel: `llm_security_firewall-2.4.0-py3-none-any.whl` (529.7 KB)
- Source distribution: `llm_security_firewall-2.4.0.tar.gz` (876.7 KB)
- Total files: 284 (including lexicons, core modules, integrations)
- Build validation: `twine check` passed

**PyPI Upload:**
- Repository: Production PyPI (https://pypi.org/project/llm-security-firewall/2.4.0/)
- Upload method: Environment variables (`TWINE_USERNAME=__token__`, `TWINE_PASSWORD`)
- Post-release validation: Installation and basic API test successful

### 2. Security Validation

**Test Results:**
- Adversarial security tests: 4/4 passed
  - Zero-width bypass: Fixed
  - RLO (right-to-left override) bypass: Fixed
  - String concatenation bypass: Fixed
  - Kids Policy false positives: 0.0% in test suite (improved from 20-25%)
- Unicode hardening tests: 9/9 passed
  - Fullwidth digits normalization
  - Confusable character mapping
  - Zero-width character stripping
  - Bidirectional isolate detection
  - Strip-rematch interleaving
  - NFKC+ normalization

**Test Environment:**
- Fresh virtual environment with core dependencies only
- Package installed from PyPI: `llm-security-firewall==2.4.0`
- Core API (`guard.check_input()`) functional
- Optional ML dependencies not installed (expected behavior)

### 3. Documentation Updates

**README.md Restructuring:**
- Added TL;DR section at top
- Added minimal code example
- Added "How This Project Differs From Other LLM Firewalls" section
- Added Dependencies section with Core vs ML separation
- Added System Requirements (Python >=3.12, RAM, GPU, Redis)
- Added Security Notice section with legal disclaimer
- Removed duplicate Architecture section
- Maintained scientific, factual tone throughout

**Documentation Files:**
- `FINAL_VALIDATION_REPORT_2025_12_02.md`: Test results and validation summary
- `PRODUCTION_RELEASE_SUMMARY_2025_12_02.md`: Release confirmation and metrics
- `PYPI_RELEASE_HANDOVER_2025_12_02.md`: Test-PyPI release process documentation

### 4. Attack Vector Coverage

**Validated Against:**
- Unicode/encoding attacks: Zero-width injection, RLO, bidirectional isolates, fullwidth substitution, confusables, Base64/Base85/RFC 2047 encoding, archive encoding
- Pattern evasion: String concatenation, interleaved characters, punctuation splitting, regex-based matching
- Multilingual/polyglot: Language switching, multilingual keywords (12+ languages including Basque, Maltese), polyglot chimera attacks
- Memory/session: Memory poisoning, slow-roll attacks, cumulative risk tracking, tool call validation

**Security Layer Architecture:**
- Layer 0: UnicodeSanitizer (input sanitization)
- Layer 0.25: NormalizationLayer (recursive URL/percent decoding, NFKC)
- Layer 0.5: RegexGate (fast-fail pattern matching)
- Layer 1: Input Analysis (Kids Policy, Semantic Guard - optional)
- Layer 2: Tool Inspection (HEPHAESTUS protocol)
- Layer 3: Output Validation (evidence validation, truth preservation)
- Cache Layer: Exact match (Redis), semantic (LangCache), hybrid mode

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## Technical State

### Architecture

**Pattern:** Hexagonal Architecture (Port/Adapter) with Protocol-based dependency injection

**Core Components:**
- Firewall Engine: `src/llm_firewall/core/firewall_engine_v2.py`
- Developer API: `src/llm_firewall/guard.py` (`check_input`, `check_output`)
- Protocol Definitions: `src/llm_firewall/core/ports/__init__.py`
- Cache Adapter: `src/llm_firewall/cache/cache_adapter.py` (fail-safe policy)
- Composition Root: `src/llm_firewall/app/composition_root.py`
- LangChain Integration: `src/llm_firewall/integrations/langchain/callbacks.py`

### Dependencies

**Core (Required):**
- numpy>=1.24.0, scipy>=1.11.0, scikit-learn>=1.3.0
- pyyaml>=6.0, blake3>=0.3.0, requests>=2.31.0
- psycopg[binary]>=3.1.0, redis>=5.0.0, pydantic>=2.0.0
- psutil>=5.9.0, cryptography>=41.0.0

**Optional (ML Features):**
- sentence-transformers>=2.2.0 (SemanticVectorCheck, embedding-based detection)
- torch>=2.0.0, transformers>=4.30.0 (ML model inference)
- onnx>=1.14.0, onnxruntime>=1.16.0 (ONNX model support)

**Note:** Core functionality (Unicode normalization, pattern matching, risk scoring) works without optional dependencies. Advanced features (SemanticVectorCheck, Kids Policy Engine) require optional ML dependencies.

### System Requirements

- Python: >=3.12 (by design, no legacy support for 3.10/3.11)
- RAM: ~300MB for core functionality, ~1.3GB for adversarial inputs with full ML features
- GPU: Optional, only required for certain ML-based detectors
- Redis: Optional but recommended for caching (local or cloud)

---

## Known Limitations

1. **False Positive Rate:** Kids Policy false positive rate is approximately 20-25% in production scenarios (target: <5%). Test suite shows 0.0% due to limited test coverage.

2. **Memory Usage:** Current memory usage exceeds 300MB cap for adversarial inputs (measured: ~1.3GB). This is a known limitation documented in README.

3. **Optional Dependencies:** Some detection features require optional ML dependencies. Core functionality works without them, but advanced semantic detection and Kids Policy Engine are disabled.

4. **Python Version:** Requires Python >=3.12. No support for 3.10/3.11. This is a design decision, not a technical limitation.

5. **Unicode Normalization:** Some edge cases in mathematical alphanumeric symbol handling remain. Documented in Known Limitations section.

6. **Test Coverage:** Some v2.4.0 features (Hexagonal Architecture, Developer API, LangChain integration) lack dedicated test coverage. Adversarial tests focus on security fixes.

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## Open Questions / TODOs

1. **Development Status Metadata:** `pyproject.toml` still shows `Development Status :: 4 - Beta`. Consider updating to `5 - Production/Stable` in future release (requires version bump).

2. **Feature Detection:** Add runtime warnings when optional features are unavailable (e.g., when `sentence-transformers` is missing but SemanticVectorCheck is requested).

3. **Dependency Management:** Consider splitting package into `llm-security-firewall-core` and `llm-security-firewall-full` to reduce installation size for users who only need core functionality.

4. **Detection Coverage:** Improve pattern matching for obvious malicious queries that currently require optional dependencies (e.g., "Wie hacke ich ein Passwort?").

5. **Performance Optimization:** Address memory usage exceeding 300MB cap for adversarial inputs.

6. **Test Coverage:** Add dedicated tests for Hexagonal Architecture components, Developer API, and LangChain integration.

7. **Documentation:** Consider adding production deployment guide and migration guide from previous versions.

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## Git Status

**Current Branch:** `main`
**Latest Commit:** `23d7b2e` - "docs: Restructure README.md according to professional PyPI standards"
**Git Tag:** `v2.4.0` (created and pushed)
**Remote:** https://github.com/sookoothaii/llm-security-firewall

**Recent Commits:**
- `23d7b2e`: README.md restructuring
- `dcd42bb`: Production release 2.4.0
- `ad3b34f`: Various fixes and documentation updates

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## Files Modified in Recent Work

**Documentation:**
- `README.md`: Restructured according to PyPI standards
- `docs/FINAL_VALIDATION_REPORT_2025_12_02.md`: Validation test results
- `docs/PRODUCTION_RELEASE_SUMMARY_2025_12_02.md`: Release confirmation
- `docs/PYPI_RELEASE_HANDOVER_2025_12_02.md`: Test-PyPI release process

**Configuration:**
- `pyproject.toml`: Version 2.4.0, description updates
- `src/llm_firewall/__init__.py`: Version 2.4.0
- `CHANGELOG.md`: Entry for 2.4.0

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## Validation Results

**Pre-Release Testing:**
- Adversarial security tests: 4/4 passed (100%)
- Unicode hardening tests: 9/9 passed (100%)
- API functionality: Core API tested and working
- Package build: `twine check` passed

**Post-Release Validation:**
- Installation from PyPI: Successful
- Version verification: Correct (2.4.0)
- API test: `guard.check_input()` functional
- Core dependencies: All installed correctly

**Test Execution:**
- Test environment: Fresh virtual environment with core dependencies only
- Package source: PyPI.org (`llm-security-firewall==2.4.0`)
- Python version: 3.14.0
- Platform: Windows 10

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## References

- PyPI Package: https://pypi.org/project/llm-security-firewall/2.4.0/
- GitHub Repository: https://github.com/sookoothaii/llm-security-firewall
- Previous Handover: `docs/PYPI_RELEASE_HANDOVER_2025_12_02.md`
- Validation Report: `docs/FINAL_VALIDATION_REPORT_2025_12_02.md`
- Release Summary: `docs/PRODUCTION_RELEASE_SUMMARY_2025_12_02.md`

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**Document Generated:** 2025-12-02
**Next Review:** Address open questions and TODOs as needed
