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A coding model rewrote a robot's control harness and took success from 9.7% to 43.3% without touching the model

AspireAI community · arXiv
A frozen robot policy performs far better inside a good agent harness - control code that decides when to query the policy, consult vision tools or command the arm directly - but those harnesses are still hand-built for each robot and benchmark. RoboArchitect makes a coding model observe a robot's rollouts, diagnose failures and iteratively revise the harness around the frozen policy, evolving on one set of episodes and evaluating on held-out scenes and tasks. Without updating any model weights it raised average success from 9.7% to 43.3% on unseen scenes (4.5x) and from 12.7% to 40.2% on unseen tasks (3.2x) across multiple benchmarks and policies. The gains were largest where the benchmark sat furthest from the policy's training data, and in that regime the evolved harness sometimes beat the finetuned version, while also inventing concrete strategies such as lifting a jammed arm clear or reaching in horizontally when an obstacle blocks the way from above. The harness evolves its own persistent memory, carrying things like effective grasp depths into later decisions, and the authors read this as substantial headroom in robotic manipulation living in the harness rather than the weights.
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