Guardrails & Safety for Production LLM Agents: Input, Output, Tool & Memory Defense Layers
Engineering Implementation
A production engineering guide to LLM guardrails: layered input/output/tool/memory defenses, PII and prompt-injection detection, Guardrails AI validators, a policy-enforcer agent, and LangGraph guardrail nodes with human-in-the-loop.
- Treats safety as a layered pipeline — input, tool, output, and memory guardrails each blocking a different failure class before it reaches the user
- Deterministic detectors (PII, secrets, injection, SQL) handle the cheap cases; an LLM policy-enforcer handles the semantic ones pattern matching can't
- Full Guardrails AI integration: validators, RAIL guards, OnFailAction (reask/fix/filter/refrain), and Pydantic-backed structured validation
- Runnable LangGraph guardrail nodes — input screening, output redaction, human-approval interrupts, and bounded retry with routing
- Grounded in NeMo Guardrails and Llama Guard, the two reference designs for programmable rails and LLM-based input/output safeguards
Guardrails
AI Safety
LLM Security
Prompt Injection
PII Detection
Guardrails AI
LangGraph
Policy Enforcement
Human-in-the-Loop