LightGuard-Agent v0.4.0: Enterprise RAG Shield, DLP PII Redaction & Prometheus Telemetry

What's New in v0.4.0 🚀

1. 📚 RAG Context Poisoning Shield (lightguard.rag)

• Chunk Sanitization: Inspects retrieved text chunks for indirect prompt injection directives.
• XML Context Fencing: Encapsulates retrieved knowledge in tamper-evident boundaries.
• Poisoned Chunk Dropping: Automatically drops poisoned documents before LLM context construction.
• Retriever Proxy: Drop-in wrapping for LangChain and LlamaIndex retrievers (shield.protect_retriever(retriever)).

2. 🔒 Zero-Dependency DLP & PII Redaction (lightguard.privacy)

• Financial Validation: Luhn checksum validation for Visa, MasterCard, Amex, Discover.
• Secrets Scanning: Auto-redacts OpenAI keys (sk-...), Anthropic keys, AWS Access Keys, GitHub tokens.
• Contact & PII: Redacts emails, phone numbers, SSNs, and IPv4 addresses.
• Reversible Anonymization: Restore original sensitive entities before executing secure local database operations.

3. ⚙️ Enterprise Security Policy Profiles (lightguard.policy)

• Out-of-the-box security postures: STRICT, BALANCED, and PERMISSIVE.
• Granular per-tool permissions and custom high-stakes registries.

4. 📈 Prometheus Telemetry & Observability (lightguard.telemetry)

• Real-time thread-safe telemetry collector.
• Exposes standard Prometheus text metrics (export_prometheus()) with rolling latency percentiles (P95, mean).

5. 💻 CLI Subcommand Expansion

• lightguard redact <text>
• lightguard rag-scan <chunk>
• lightguard metrics

📊 Verification & Tests

• 60/60 unit tests passing (0.50s)
• 100% defense rate against 26 red-team attack vectors
• Zero external runtime dependencies
• Published to PyPI: pip install lightguard-agent==0.4.0