test-time training

SIA: Self-Improving AI via Joint Harness and Weight Updates

SIA proposes a self-improving loop in which a Feedback-Agent simultaneously updates both the scaffold (harness) and model weights of a task-specific agent, unifying two previously disjoint research lines: meta-agent scaffold rewriting and test-time training. The system is evaluated on three diverse benchmarks—Chinese legal charge classification, GPU kernel optimization, and single-cell RNA denoising—achieving gains of 56.6%, 91.9% runtime reduction, and 502% respectively over baselines. The paper argues that harness updates shape agentic behavior while weight updates instill domain intuition that prompting alone cannot provide, and that combining both levers consistently outperforms either alone.