SEED: Self-Evolving On-Policy Distillation for Agentic Reinforcement Learning
arXiv · HuggingFace · ▲90
Abstract (verbatim)
Large language models are increasingly trained as interactive agents for long-horizon tasks involving multi-turn interaction, tool use, and environment feedback. Outcome-based reinforcement learning (RL) provides a practical optimization paradigm, but its sparse trajectory-level rewards offer limited guidance on intermediate decisions, leaving a supervision gap between episode-level outcomes and token-level policy learning. We propose SEED (SElf-Evolving On-Policy Distillation), a self-evolving framework that converts completed on-policy trajectories into training-time hindsight skills and distills their behavioral effect back into the policy model. SEED first fine-tunes the policy to analyze completed trajectories and generate natural-language skills that capture reusable workflows, decisive observations, or failure-avoidance rules. During RL, the current policy both collects trajectories and serves as the analyzer that extracts hindsight skills from them. Policy updates therefore improve subsequent decision making and skill analysis together, allowing hindsight supervision to evolve with the policy. SEED then re-scores the sampled actions under ordinary and skill-augmented contexts, converting the skill-induced probability shift into a dense token-level on-policy distillation signal. This signal is jointly optimized with outcome-based RL, keeping the auxiliary supervision aligned with the current trajectory distribution. Extensive experiments on text-based and vision-based agentic tasks show that SEED consistently improves performance and sample efficiency, exhibiting robust generalization to unseen scenarios. Our code is available at https://github.com/jinyangwu/SEED.
Background
Background Analysis
1. Technical Context and Real-world Needs
Recent large language models (LLMs) are increasingly applied to multi-turn agentic tasks, such as tool use, environmental feedback processing, and long-horizon planning. These scenarios require models to learn how to collect information, call tools, interpret feedback, and adjust strategies over multiple steps. Reinforcement learning (RL) has become a key paradigm for optimizing such agent behaviors because it directly adjusts policies based on environmental feedback. However, in real-world settings, reward signals are often sparse and delayed (e.g., given only at task completion), making it difficult for models to learn effective behaviors from intermediate steps, thus limiting their decision-making capability and sample efficiency.
2. Limitations of Previous Methods
Traditional RL methods rely on trajectory-level rewards but fail to guide intermediate decisions (e.g., a failed trajectory may contain partially correct behaviors, while a successful trajectory may hide reusable strategies). Although some studies have attempted to extract experience from trajectories using "hindsight learning" (e.g., summarizing success patterns or failure reasons), these methods typically treat hindsight as static data or external memory, unable to adapt dynamically as the model's capabilities improve. Additionally, existing approaches either depend on a fixed teacher model for supervision or require extra reasoning traces or prompts, leading to a disconnect between the supervision signal and the model's current behavior.
3. Solution Proposed in This Paper
The SEED framework addresses this issue through "self-evolving on-policy distillation." Its core idea is to let the model play two roles simultaneously during reinforcement learning:
- Analyzer Role: The model extracts natural-language describable reusable skills (e.g., key observations, decision rules, or error-avoidance strategies) from completed trajectories.
- Decision-maker Role: The model improves subsequent decisions based on these skills and converts the behavioral guidance from skills into fine-grained token-level supervision signals through distillation.
Through this self-evolving loop, the model can dynamically optimize both its behavioral analysis and decision-making capabilities without relying on external memory or static data.
4. Key Differences from Previous Work
The uniqueness of SEED lies in:
- Dynamic Supervision: The hindsight signal is not fixed but evolves with the model's policy improvements.
- Dense Supervision: It converts trajectory-level hindsight into token-level distillation signals, directly guiding intermediate decisions.
- Self-consistency: The model performs both decision-making and reflection during reinforcement learning, avoiding the disconnect between the teacher model and the environment in traditional methods.
This approach enables SEED to achieve higher sample efficiency and robustness in long-horizon agentic tasks.
















