Scaling Automatic Research Agents via World Models
WMRL replaces environment execution with a world model in RL, accelerating research-agent post-training 3-4x and letting 4B/9B agents beat 48B/120B open-weight agents.
The paper identifies that environment execution dominates RL training cost for automatic research agents because each execution occupies an exclusive sandbox while generation batches efficiently. World Model RL (WMRL) substitutes a learned world model for execution, with Online Debiasing and Inverse-Variance Denoising to handle reward bias and noise, and the paper proves both improve convergence guarantees. WMRL accelerates training 3-4x across tasks and outperforms standard RL baselines; post-trained 4B and 9B agents beat 48B and 120B open-weight agents on held-out benchmarks. WMRL also transfers to post-training embodied VLA policies.