arXiv AI By Yuxiao Lee, Zherui Yang, Fan Liu, Hao Liu

Predict the Reward, Not the World: World Reward Models for ML Agents

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The paper introduces World Reward Models (WRMs), a new approach for machine‑learning agents that selects the best candidate program directly from execution results instead of predicting intermediate outcomes. WRMs, exemplified by the ForeCritic model, are trained on thousands of executed program pairs and achieve a 79.4% success rate in choosing the better program, outperforming general‑purpose LLM judges. When integrated into systems like AIDE, ML‑Master, and ForeAgent, ForeCritic reduces mean task time by 4.4–7.5× while maintaining or improving overall performance.

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arXiv AI
5d ago

MLE-World: Predicting Machine Learning Experiment Outcomes with a Learned World Model

MLE-World is a world model fine‑tuned from Qwen3.5‑4B that predicts the terminal output of a machine learning program—such as error traces, training logs, and validation scores—directly from its code and data description, without executing the program. It also provides a confidence score indicating the likelihood that the prediction is correct. Using these predictions, the authors design five test‑time‑scaling policies that compare multiple candidate programs per step, executing only those with low confidence, and demonstrate that MLE‑World matches real outputs on 77.9% of held‑out programs and improves agent performance by up to 22.1% with fewer real executions.

By Brian Ko, Han Wang, Hejia Geng, Li Erran Li, Sherry Yang
arXiv AI
Oct 9

StoreBench: A Live-Commerce Environment for Evaluating and Training Autonomous Operator Agents

StoreBench is a live‑commerce environment where an autonomous agent runs a mid‑size online apparel store on a production‑grade backend, facing continuous customer orders, supplier price changes, and market shocks. The agent uses the same 29 merchant tools as a human operator, with a windowed operation budget that ties simulated time to actions, ensuring that model latency does not affect the simulation. Seven large language models were evaluated across 11 scenarios of 30–45 days and a full simulated year, but none matched the scripted smart‑triage policy, and human experts outperformed all models.

By Daksh Raghuvanshi, Ved Vedere, Yifan Wang