The Four Gates: A Practical Threat Model for Agentic AI Systems

A diagnostic framework for evaluating the security posture of AI agents that act on your behalf—covering threat layers, attack surfaces, access boundaries, and governance. The Problem Nobody Ships a Fix For AI agents are shipping fast. They browse the web for you, execute code, read your files, manage your calendar, send emails, and chain tool calls across services—often in a single prompt. The convenience is real. So is the attack surface. Most security conversations about agentic systems focus on prompt injection and call it a day. That's one vector out of many. If you're building, deploying, or even just using an agentic system, you need a broader diagnostic lens. This post walks through four evaluation gates—a lightweight framework for assessing where your exposure actually lives when you hand operational access to a non-human agent. Gate 1: The Five-Layer Threat Model Every agentic interaction involves five layers. Most people only think about two of them. Layer What It Is What It