AttnSR: Attention Step Reward for Long-Horizon Agentic RL
AttnSR is a step-level reward augmentation method for long-horizon LLM agents that derives reward allocations directly from policy attention during training replay, eliminating the need for a separate reward model or additional rollouts. By tracing backward through the policy model's attention graph, it estimates the relevance of earlier steps to the final response and uses a running baseline to determine whether rewards reinforce or penalize selected steps. In experiments with Qwen2.5-7B-Instruct, AttnSR improved ALFWorld success from 91.2% to 97.1% and consistently outperformed PPO on ScienceWorld while reducing environment interactions by 29.9%.