Your LLM Is Not an Agent. Your Framework Is Not Enough. You Need a Harness.

Introduction Every team building with AI agents hits the same wall. The demo works beautifully. The agent answers questions, calls tools, produces results. Then you ship it and the cracks appear it loses track of what it was doing, burns through API calls in circles, ignores boundaries it should respect, forgets context from five minutes ago. Users lose trust. Engineers lose sleep. This is not a model problem. The LLM is capable. It's an infrastructure problem. The agent has a brain but no op...