MENTOR: Mitigating Identity Drift in Dynamic Role-Playing via Dual-Chain Structured Memory

Zhu Zhuoning, Xingyu Gao, Hailong Shi


Abstract
Long-context LLM agents increasingly serve multiple users or personas within a single session, requiring stable identity and knowledge boundaries under frequent switching. We identify a common failure mode, identity drift, where models conflate user-specific states and leak information across roles. On BEAM-SWITCH, a benchmark for controlled multi-user switching, performance consistently degrades as switching intensifies, even when responses remain fluent and locally coherent. We propose MENTOR, a cognitive architecture that mitigates identity drift without fine-tuning. MENTOR uses a Dual-Chain Memory Mechanism: a Global Chain (𝒢) for long-term event logging and isolated Role Chains (r) as per-role working memories, supported by a semantic Knowledge Graph (𝒦) that filters and verifies role-admissible information before generation. Across six LLM families, MENTOR improves the overall score (Avg) from 0.46 to 0.75 on average (+0.29 absolute), with substantial gains in identity adherence and knowledge fidelity.
Anthology ID:
2026.findings-acl.1046
Volume:
Findings of the Association for Computational Linguistics: ACL 2026
Month:
July
Year:
2026
Address:
San Diego, California, United States
Editors:
Maria Liakata, Viviane P. Moreira, Jiajun Zhang, David Jurgens
Venue:
Findings
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
20865–20882
Language:
URL:
https://aclanthology.org/2026.findings-acl.1046/
DOI:
10.18653/v1/2026.findings-acl.1046
Bibkey:
Cite (ACL):
Zhu Zhuoning, Xingyu Gao, and Hailong Shi. 2026. MENTOR: Mitigating Identity Drift in Dynamic Role-Playing via Dual-Chain Structured Memory. In Findings of the Association for Computational Linguistics: ACL 2026, pages 20865–20882, San Diego, California, United States. Association for Computational Linguistics.
Cite (Informal):
MENTOR: Mitigating Identity Drift in Dynamic Role-Playing via Dual-Chain Structured Memory (Zhuoning et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-acl.1046.pdf
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