On-Policy Distillation with Curriculum Turn-level Guidance for Multi-turn Agents

Gengsheng Li, Mao Zheng, Mingyang Song, Ruiqi Liu, Tianyu Yang, Jie Sun, Qiyong Zhong, Dan Zhang, Haiyun Guo, Junfeng Fang, Jinqiao Wang


Abstract
Multi-turn agents that plan, invoke tools, and interact with environments offer a promising paradigm for solving complex tasks, yet their capabilities typically rely on very large models whose inference cost is prohibitive in practice. On-Policy Distillation (OPD) is a natural recipe for transferring such capabilities to smaller students, but we find that it suffers a characteristic failure mode in this setting: small student errors compound across turns and push the trajectory out of the teacher’s familiar state distribution, so the teacher’s supervision becomes least reliable precisely where the student needs it most. We propose Guided On-Policy Distillation (Guided-OPD), a simple yet effective algorithm that mixes teacher- and student-generated turns within each rollout and schedules the teacher’s intervention probability along a curriculum that decays to zero. Strong guidance keeps early trajectories close to the teacher distribution and is then gradually withdrawn to recover the purely on-policy regime used at inference. On ALFWorld, ScienceWorld, and WebShop, distilling Qwen3 students from a Qwen3-30B-A3B teacher, Guided-OPD yields average relative gains of 21.1% in Score and 25.5% in Success Rate over vanilla OPD, with larger gains on smaller students.
Anthology ID:
2026.emnlp-main.1424
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
32539–32555
Language:
URL:
https://aclanthology.org/2026.emnlp-main.1424/
DOI:
Bibkey:
Cite (ACL):
Gengsheng Li, Mao Zheng, Mingyang Song, Ruiqi Liu, Tianyu Yang, Jie Sun, Qiyong Zhong, Dan Zhang, Haiyun Guo, Junfeng Fang, and Jinqiao Wang. 2026. On-Policy Distillation with Curriculum Turn-level Guidance for Multi-turn Agents. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 32539–32555, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
On-Policy Distillation with Curriculum Turn-level Guidance for Multi-turn Agents (Li et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.1424.pdf