Comment by songrenchu

The router sits between application layer and the harness layer. HarnessRouter is the spec translation layer that translates the unified interface into each harness's own api format. Each harness is treating somehow like a blackbox, and they talk to the models as is. For routing across harnesses, think about it as an aggregator, like OpenRouter. The application layer have multiple use cases and each function could backed by a different harness. We do have smart routing feature on our roadmap to support use cases of harness fallback, cost optimization, etc