The Sentinel Release (With upgraded layer and risk tier)

[Harshit-J004]

Version 5.0.0 brought the worlds first security proxy for AI agents. Today, Version 6.0.0 builds the Absolute Zero firewall. We shipped the most requested feature -- a Schema Drift Detection Engine -- and surgically hardened every single layer of the interceptor pipeline against real-world evasion vectors.

This is NOT an incremental update. This is a new security layer AND a total hardening of every existing one.

--- NEW: Schema Drift Detection Engine (Layer 6) ---
The crown jewel of v6.0.0. LLM providers silently update their models. A payload that historically returned integers might suddenly return strings, instantly crashing your type-strict backend. ToolGuard now solves this at the infrastructure level:

• Cryptographic Fingerprinting: The engine infers JSON Schema from raw Python dicts, freezes them into SHA-256 cryptographic fingerprints, and violently rejects structural deviations (like renaming temperature to temp) before they reach your network edge.
• SQLite WAL Concurrency: The Fingerprint Store is backed by a pristine SQLite backend configured with PRAGMA WAL mode, synchronous=NORMAL, and a 30-Second busy_timeout. This allows 200+ concurrent LangGraph agent connections to read/write fingerprints without a single database lock crash.
• False-Positive Guard: Missing optional fields (those not in required[]) are silently allowed. Only missing required fields or unauthorized field additions trigger CRITICAL drift alerts. This prevents alert fatigue from harmless structural variance.
• Pydantic Bridge: create_fingerprint_from_model() generates baselines directly from Python classes. Includes a recursive resolver (depth-capped at 10) and anyOf union flattener for Optional types.
• SchemaDriftError: First-class catchable exception in the error hierarchy for programmatic pipeline control.
• Drift CLI Suite: toolguard drift snapshot, toolguard drift check --fail-on-drift, toolguard drift list, toolguard drift clear, toolguard drift snapshot-pydantic. Run drift check in your CI/CD pipeline and fail the build if the model drifts from your frozen baseline.

--- The 7-Layer Interceptor Pipeline (Upgraded from 6) ---
Every layer has been individually hardened against real-world attack vectors:

1. L1 Policy: Immutable Allow/Deny list with absolute casing normalization. Stop dangerous tools from ever being contacted.
2. L2 Risk-Tier (Production 4-Tier IAM): Transformed from a basic prompt into a military-grade access matrix. Tier 1 auto-approves. Tier 2 requires human approval with an auto-deny Timeout (prevents hanging unattended pipelines) and TTL Caching (reduces prompt fatigue for agent loops). Tier 3 (Critical) enforces absolute intent by requiring the user to type out the tool name. Tier 4 permanently forbids execution with full forensic tracing. Headless sub-TTY evasion (SSH-T/Pod) is neutralized with OS-level fstat() capability detection.
3. L3 Injection (Stack-Buster Protected): Recursive DFS parser that natively decodes binary streams (bytes/bytearray). Now features strict recursion depth limits to neutralize nested-payload DoS exhaustion attacks.
4. L4 Rate-Limit (Reboot-Resilient): Sliding-window per-tool cap. Now backed by thread-safe atomic JSON disk-persistence so rate-limit state survives volatile container restarts and server wipes.
5. L5 Semantic (Obfuscation Unrolling): Catches DROP TABLE and path traversal. Now powered by a recursive decoder pipeline (base64/urllib) that automatically intercepts URL-encoded and Base64-masked payloads (e.g., L2V0Yy9wYXNzd2Q= decodes to /etc/passwd) prior to canonical evaluation.
6. L6 Schema Drift (NEW): Compares live LLM tool payloads against frozen structural fingerprints. Blocks unauthorized field additions (Major Severity) to prevent data exfiltration and shadow agent behavior.
7. L7 Trace: Full DAG instrumentation with per-tool latency metrics. Asynchronous JSON dumps are pushed locally to power live SSE observability dashboards without blocking proxy execution.

--- Sentinel Dashboard V6.0 (Forensic Observability) ---

• Nano-Latency Forensics: Per-tool overhead tracking with 0.001ms precision.
• Identity Spoof Detection: Automated FAKE flags for casing-based spoofing (e.g., execute_sql vs Execute_SQL).
• L1-L7 Sentinel HUD: Real-time LED indicators show exactly which security layer fired on every tool call.
• CRT Visuals: High-contrast terminal overhaul for mission-critical security monitoring.
• Dynamic Versioning: Dashboard dynamically pulls the current ToolGuard version from init.py.

--- Verified (E2E Adversarial Swarm -- Live Gemini 2.0 Flash) ---
We launched a 3-agent concurrent attack using live Google Gemini 2.0 Flash API instances against the 7-layer mesh:

• ROGUE ARCHITECT: Tried //etc/passwd bypass -- Blocked (L5 Semantic + Obfuscation Unrolling).
• DESTRUCTIVE DBA: Tried DROP TABLE CASCADE -- Blocked (L3 Injection).
• CHAOS ENGINEER: Tried Shadow JSON schema mutations -- Blocked (L6 Drift + Cryptographic Fingerprint Mismatch).

Total Interception. Zero Leakage. Absolute Zero vulnerability.

The execution-layer firewall for the intelligence boom is here.

Credits: Architected and Hardened by Harshit-J004.
Repository: https://github.com/Harshit-J004/toolguard
Documentation: https://github.com/Harshit-J004/toolguard#readme
Install: pip install py-toolguard

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