MemGuard: Preventing Memory Contamination in Long-Term Memory-Augmented Large Language Models

Fuente: arXiv
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Main Authors: Ha, Hyeonjeong, Kim, Jeonghwan, Qian, Cheng, Liu, Jiayu, Campbell, William M., Wu, Yue, Zhang, Yuji, McKeown, Kathleen, Hakkani-Tur, Dilek, Ji, Heng
Format: Preprint
Published: 2026
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author Ha, Hyeonjeong
Kim, Jeonghwan
Qian, Cheng
Liu, Jiayu
Campbell, William M.
Wu, Yue
Zhang, Yuji
McKeown, Kathleen
Hakkani-Tur, Dilek
Ji, Heng
author_facet Ha, Hyeonjeong
Kim, Jeonghwan
Qian, Cheng
Liu, Jiayu
Campbell, William M.
Wu, Yue
Zhang, Yuji
McKeown, Kathleen
Hakkani-Tur, Dilek
Ji, Heng
contents Memory-augmented large language models extend reasoning beyond a fixed context window by maintaining long-term memory across interactions. However, existing memory systems often collapse stable user facts, episodic events, and behavioral rules into a shared space, allowing functionally distinct memories to be retrieved and used as interchangeable evidence. We identify this failure mode as heterogeneous memory contamination, where context-specific events become overgeneralized claims, or semantically relevant but functionally incompatible memories mislead generation. To this end, we introduce MemGuard, a type-aware memory framework that preserves functional memory boundaries during memory construction and retrieval. It assigns each memory an explicit functional role at write time, maintains relations across type-isolated memories, and selectively composes evidence only from necessary memory types, reducing contamination from irrelevant or functionally incompatible evidence. Across hallucination and long-horizon conversation benchmarks, MemGuard improves memory reliability by up to 28.27% while retrieving up to 5.8x fewer memory tokens than prior methods. These results suggest that reliable long-term reasoning depends on principled organization and selective use of heterogeneous memory.
format Preprint
id arxiv_https___arxiv_org_abs_2605_28009
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle MemGuard: Preventing Memory Contamination in Long-Term Memory-Augmented Large Language Models
Ha, Hyeonjeong
Kim, Jeonghwan
Qian, Cheng
Liu, Jiayu
Campbell, William M.
Wu, Yue
Zhang, Yuji
McKeown, Kathleen
Hakkani-Tur, Dilek
Ji, Heng
Computation and Language
Artificial Intelligence
Machine Learning
Memory-augmented large language models extend reasoning beyond a fixed context window by maintaining long-term memory across interactions. However, existing memory systems often collapse stable user facts, episodic events, and behavioral rules into a shared space, allowing functionally distinct memories to be retrieved and used as interchangeable evidence. We identify this failure mode as heterogeneous memory contamination, where context-specific events become overgeneralized claims, or semantically relevant but functionally incompatible memories mislead generation. To this end, we introduce MemGuard, a type-aware memory framework that preserves functional memory boundaries during memory construction and retrieval. It assigns each memory an explicit functional role at write time, maintains relations across type-isolated memories, and selectively composes evidence only from necessary memory types, reducing contamination from irrelevant or functionally incompatible evidence. Across hallucination and long-horizon conversation benchmarks, MemGuard improves memory reliability by up to 28.27% while retrieving up to 5.8x fewer memory tokens than prior methods. These results suggest that reliable long-term reasoning depends on principled organization and selective use of heterogeneous memory.
title MemGuard: Preventing Memory Contamination in Long-Term Memory-Augmented Large Language Models
topic Computation and Language
Artificial Intelligence
Machine Learning
url https://arxiv.org/abs/2605.28009