Harness-1, a 20B retrieval subagent trained with reinforcement learning, reaches 0.730 curated recall

Summary

UIUC and Chroma released Harness-1, a 20-billion-parameter retrieval subagent trained with reinforcement learning inside a stateful search harness. It achieves 0.730 average curated recall across eight benchmarks, beating the next open subagent by 11.4 points and trailing only Opus-4.6.