WHAT A HARNESS IS

CHECK YOUR UNDERSTANDING • In one sentence, what is a harness? ◦ Answer: It is everything in an AI system except the model itself. • Why can a model not send an email on its own? ◦ Answer: Because it only produces text, and the harness must call the actual email service. • What does the control plane decide? ◦ Answer: Which agent handles which job, with what permissions and budget, and what to do when something fails. • Give one task that belongs on the harness side and one on the model side. ◦ Answer: Remembering a list of completed items belongs to the harness, while judging how well a resume fits a job belongs to the model. • Why can two products using the same model feel completely different? ◦ Answer: Because their harnesses differ in tools, limits, memory, and behavior.