Agent Hooks: The Secret to Controlling AI Agents in Your Codebase

Instructions alone are NOT enforcement. That's the hard lesson I learned watching AI agents cheerfully ignore my carefully crafted guidelines and pollute my clean architecture with cross-layer imports. You can write the most detailed agent instructions in the world. You can create custom agents with specific knowledge. You can even build elaborate context engineering systems. But here's the truth: what happens when the agent just... doesn't follow them? I recently refactored one of my projects into a strict hierarchical layer system—L0 through L7, each with explicit import rules. Without enforcement, it lasted about three commits before an AI agent decided that directly importing infrastructure code into a pure type layer was perfectly reasonable. That's when I built agent hooks. The Layer System That Needed Protection Before we talk about hooks, let me explain what I was trying to protect. I restructured my application into eight strict layers: L0: Pure Types — No dependencies on anyt