What an "Agent Harness" Actually Is - and Why Raw Model Calls Don't Survive Production
There's a demo that convinces every engineering team that agents are ready: someone gives a model a goal, it calls a couple of tools, and it produces a result that would have taken a person an hour. The gap between that demo and a system real users depend on is enormous, and most of that gap is not the model. It's everything around the model - the layer that decides what to do next, calls tools safely, remembers what happened, asks for help when it should, and records the whole run so you can debug it. That layer has a name: the agent harness.