What is a Harness
In short This article builds a framework that defines what a Harness is and where its boundaries lie, based on existing definitions. The framework separates the layers of an agent system: prompt, context, LLM agent, and Harness. Within the Harness, it defines a core of three parts: environment, turn lifecycle, and verification. Beyond that core, the framework can be extended with cross-session memory, interfaces, and observability. Additionally, a self-improving harness and the loop can operate on the framework. The framework is then validated against existing harness implementations (coding agents, harness SDKs, and personal assistants) by analyzing their code. ...