MemReranker: Reasoning-Aware Reranking for Agent Memory Retrieval

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Main Authors: Li, Chunyu, Zhang, Mengyuan, Kang, Jingyi, Chen, Ding, Shen, Jiajun, Tang, Bo, Zhou, Xuanhe, Xiong, Feiyu, Li, Zhiyu
Format: Preprint
Published: 2026
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author Li, Chunyu
Zhang, Mengyuan
Kang, Jingyi
Chen, Ding
Shen, Jiajun
Tang, Bo
Zhou, Xuanhe
Xiong, Feiyu
Li, Zhiyu
author_facet Li, Chunyu
Zhang, Mengyuan
Kang, Jingyi
Chen, Ding
Shen, Jiajun
Tang, Bo
Zhou, Xuanhe
Xiong, Feiyu
Li, Zhiyu
contents In agent memory systems, the reranking model serves as the critical bridge connecting user queries with long-term memory. Most systems adopt the "retrieve-then-rerank" two-stage paradigm, but generic reranking models rely on semantic similarity matching and lack genuine reasoning capabilities, leading to a problem where recalled results are semantically highly relevant yet do not contain the key information needed to answer the question. This deficiency manifests in memory scenarios as three specific problems. First, relevance scores are miscalibrated, making threshold-based filtering difficult. Second, ranking degrades when facing temporal constraints, causal reasoning, and other complex queries. Third, the model cannot leverage dialogue context for semantic disambiguation. This report introduces MemReranker, a reranking model family (0.6B/4B) built on Qwen3-Reranker through multi-stage LLM knowledge distillation. Multi-teacher pairwise comparisons generate calibrated soft labels, BCE pointwise distillation establishes well-distributed scores, and InfoNCE contrastive learning enhances hard-sample discrimination. Training data combines general corpora with memory-specific multi-turn dialogue data covering temporal constraints, causal reasoning, and coreference resolution. On the memory retrieval benchmark, MemReranker-0.6B substantially outperforms BGE-Reranker and matches open-source 4B/8B models as well as GPT-4o-mini on key metrics. MemReranker-4B further achieves 0.737 MAP, with several metrics on par with Gemini-3-Flash, while maintaining inference latency at only 10--20% of large models. On finance and healthcare vertical-domain benchmarks, the models preserve generalization capabilities on par with mainstream large-parameter rerankers.
format Preprint
id arxiv_https___arxiv_org_abs_2605_06132
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle MemReranker: Reasoning-Aware Reranking for Agent Memory Retrieval
Li, Chunyu
Zhang, Mengyuan
Kang, Jingyi
Chen, Ding
Shen, Jiajun
Tang, Bo
Zhou, Xuanhe
Xiong, Feiyu
Li, Zhiyu
Computation and Language
In agent memory systems, the reranking model serves as the critical bridge connecting user queries with long-term memory. Most systems adopt the "retrieve-then-rerank" two-stage paradigm, but generic reranking models rely on semantic similarity matching and lack genuine reasoning capabilities, leading to a problem where recalled results are semantically highly relevant yet do not contain the key information needed to answer the question. This deficiency manifests in memory scenarios as three specific problems. First, relevance scores are miscalibrated, making threshold-based filtering difficult. Second, ranking degrades when facing temporal constraints, causal reasoning, and other complex queries. Third, the model cannot leverage dialogue context for semantic disambiguation. This report introduces MemReranker, a reranking model family (0.6B/4B) built on Qwen3-Reranker through multi-stage LLM knowledge distillation. Multi-teacher pairwise comparisons generate calibrated soft labels, BCE pointwise distillation establishes well-distributed scores, and InfoNCE contrastive learning enhances hard-sample discrimination. Training data combines general corpora with memory-specific multi-turn dialogue data covering temporal constraints, causal reasoning, and coreference resolution. On the memory retrieval benchmark, MemReranker-0.6B substantially outperforms BGE-Reranker and matches open-source 4B/8B models as well as GPT-4o-mini on key metrics. MemReranker-4B further achieves 0.737 MAP, with several metrics on par with Gemini-3-Flash, while maintaining inference latency at only 10--20% of large models. On finance and healthcare vertical-domain benchmarks, the models preserve generalization capabilities on par with mainstream large-parameter rerankers.
title MemReranker: Reasoning-Aware Reranking for Agent Memory Retrieval
topic Computation and Language
url https://arxiv.org/abs/2605.06132