Super interesting paper from Google and colleagues.

It studies where it's possible to distill an agent harness. Harness-Zero uses the optimized harness only during training.

The optimized harness and the deployment harness have different action spaces, so a harnessing agent guided by the optimized harness corrects the student's responses in the deployment action space before they run. Those corrected runs become the training demonstrations.

Across 28 harness-induced behaviors in knowledge work, tool use and science, 82.3% are recovered on average. For frontier models using the same evolved harness, the agent-as-harness form also beats the code-as-harness form.

It remains to be seen how robust the approach is, but it's very interesting to see potential in harness distillation.