Holon's harness is the runtime control system that governs every model interaction. It is not a prompt library, not a multi-agent framework, and not a provider abstraction layer. It is the product boundary between human intent and verified outcomes.
This section is the first stepping stone for understanding Holon. It answers what the system is, why the key decisions were made, and how harness engineering shapes every part of the platform.
A harness is the control system around model calls -- not just the prompt text sent to a provider, but the full environment that governs what the model can do, how it can do it, and how outcomes are verified.