Post by Master.dev (Formerly Frontend Masters)

What is an agent harness? You already use them. Claude Code is a harness. Cursor is a harness. Codex CLI is a harness. The model does the thinking. The harness does everything else: memory, tool calling, durable execution, handing work off to other agents. An agent = an LLM + a harness. Here's the part most people miss: weaker models with a great harness beat stronger models with a bad one. A new model ships practically every month, and each one is smarter than the last. The model is the part you don't control. The harness is the part you build. The model sets the floor. The harness sets the ceiling. "The models are all pretty good now. I think whoever builds the best harness will win." ~ Scott Moss, Senior Software Engineer at Netflix Scott just released a course with us teaching exactly this: wrapping an LLM in a production-grade harness with durable execution, secure sandboxing, memory, and multi-agent orchestration. (link in comments)