Policy-Conditioned Counterfactual Credit for Verifiable Reinforcement Learning of Long-Horizon Language Agents
Researchers present CVT-RL, a reinforcement learning algorithm that addresses the problem of long-horizon language agents learning shortcuts and unsupported reasoning chains by introducing policy-conditioned counterfactual credit estimation and intervention-validity gating. The method achieves 78.9% task success and reduces measured hacking attempts from 7.2% to 3.9%, demonstrating measurable improvements in agent reliability and verifiability.