Missing technique: injection detection before the LLM retrieval step

[ZentricProtocol]

Hey Nir,

RAG_Techniques is one of the best structured resources for the community.

One technique I don't see covered: injection detection as a pre-LLM layer. It's the gap between advanced retrieval and production safety — you can have perfect recall and still have a poisoned chunk hijack the model's output.

I built Zentric Protocol for this: one POST, 23ms, CLEARED/BLOCKED. Would fit naturally as a "Production Security" notebook alongside the advanced retrieval techniques.

Happy to contribute a notebook. 100k free to test:
https://zentricprotocol.com/quickstart

Abel

[vgudur-dev]

Abel raises a great point — injection detection as a pre-LLM layer is a real gap in most RAG implementations.

One additional dimension worth covering alongside real-time detection: memory-persistent injection, where poisoned chunks survive the initial retrieval call and get written into agent memory (vector DB, markdown files, SQLite). The attack then re-surfaces in future turns without triggering the initial retrieval guard.

This is categorized as ASI06 in the OWASP Agentic AI Top 10 and is distinct from standard RAG injection because the attack vector is the write path to persistent memory, not the retrieval step.

A notebook covering this could include:

# Pattern: write-path validation before memory persistence
def validate_before_store(chunk: str, source_trust: str = "external") -> bool:
    """Validate retrieved chunk before writing to agent memory."""
    injection_patterns = [
        r"ignore previous instructions",
        r"you are now",
        r"system:\s*override",
        r"<\|.*?\|>",  # delimiter injection
    ]
    for pattern in injection_patterns:
        if re.search(pattern, chunk, re.IGNORECASE):
            return False  # Block write to memory
    return True

References for the notebook:

• OWASP Agentic AI Top 10 ASI06: https://owasp.org/www-project-top-10-for-large-language-model-applications/
• OWASP Agent Memory Guard — reference implementation
• AgentThreatBench — benchmark with 847 labeled attack scenarios across injection categories

Happy to contribute a notebook covering both retrieval-time and write-path injection detection if that would be useful.

[ZentricProtocol]

Great point, and an important distinction. Retrieval-time detection and write-path validation are two separate trust boundaries. Most implementations only guard the first one.
The memory-persistent vector is particularly nasty because it survives session boundaries. A chunk that passes the initial retrieval check can still poison long-term context if nothing validates before the write step. The source_trust parameter in your sketch is a clean way to flag external vs. internal origin.
Zentric Protocol currently runs detection at the retrieval layer. Adding validate_before_store as a second checkpoint would complete the picture.
Happy to contribute a notebook covering both layers: retrieval-time detection, then write-path validation, then a combined pipeline showing how they interact in a real RAG loop. Let me know if that scope works.
Abel