Open-source prompt injection defense library for AI agents that detects and blocks indirect prompt injection attacks in tool results using a tiered approach: Tier 1 pattern-based detection, Tier 2 ML classification with a fine-tuned MiniLM model (~22MB bundled), and optional Tier 3 LLM-based verification. Returns sanitized content and an allow/block verdict to gate untrusted data before it reaches the LLM.