ARM: Role-Conditioned Neuron Transplantation for Training-Free Generalist LLM Agent Merging

Zhuoka Feng, Kang Chen, Sihan Zhao, Kai Xiong, Yaoning Wang, Yu Minshen, Junjie Nian, Changyi Xiao, Yixin Cao, Yu-Gang Jiang


Abstract
Interactive large language model agents are often specialized to a single environment and transfer poorly across others. We study training-free consolidation of such specialists into a single generalist checkpoint. A key difficulty in this setting is that, in multi-turn agents, small merge errors on role-critical outputs can trigger long-horizon failure cascades. We therefore propose Agent-Role Merging (ARM), a neuron-level training-free framework that selects a merged backbone with an answer-free activation-overlap signal and then repairs residual gaps through conflict-aware transplantation of a small set of role-salient neurons. Our analyses further show that role-conditioned tracing yields more benchmark-specific neuron sets, enabling more localized repair. Across Qwen3-8B and Qwen2.5-7B expert pools, ARM produces the strongest balanced merged generalist among compared training-free baselines, improving both average performance and worst-suite robustness while preserving out-of-domain generalization. These results suggest that targeted neuron-level edits offer a practical route to robust multi-turn agent merging without end-to-end retraining.
Anthology ID:
2026.emnlp-main.2115
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
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Pages:
48104–48118
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URL:
https://aclanthology.org/2026.emnlp-main.2115/
DOI:
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Cite (ACL):
Zhuoka Feng, Kang Chen, Sihan Zhao, Kai Xiong, Yaoning Wang, Yu Minshen, Junjie Nian, Changyi Xiao, Yixin Cao, and Yu-Gang Jiang. 2026. ARM: Role-Conditioned Neuron Transplantation for Training-Free Generalist LLM Agent Merging. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 48104–48118, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
ARM: Role-Conditioned Neuron Transplantation for Training-Free Generalist LLM Agent Merging (Feng et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.2115.pdf