Memory Grafting: Scaling Language Model Pre-training via Offline Conditional Memory

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Hauptverfasser: Cheng, Runxi, Guan, Yuchen, Wei, Yongxian, Sun, Qianpu, Li, Qixiu, Du, Sinan, Xiong, Feng, Yuan, Chun, Lu, Yan, Gong, Yeyun
Format: Preprint
Veröffentlicht: 2026
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author Cheng, Runxi
Guan, Yuchen
Wei, Yongxian
Sun, Qianpu
Li, Qixiu
Du, Sinan
Xiong, Feng
Yuan, Chun
Lu, Yan
Gong, Yeyun
author_facet Cheng, Runxi
Guan, Yuchen
Wei, Yongxian
Sun, Qianpu
Li, Qixiu
Du, Sinan
Xiong, Feng
Yuan, Chun
Lu, Yan
Gong, Yeyun
contents Scaling conditional memory offers a promising way to increase language-model capacity, but existing methods such as Engram learn large memory tables from scratch during pre-training, making memory scaling expensive and sometimes ineffective. We propose Memory Grafting, a conditional memory scaling method that utilizes frozen hidden states from a grafting model as conditional n-gram memory. Given frequent local n-grams, we run the grafting model offline, store final-token hidden representations as memory values, and let the recipient model retrieve them through exact longest-match suffix lookup. Retrieved memories are adapted by lightweight projections and gates, while a hash-based Engram fallback preserves coverage for unmatched contexts. Since the grafting model is only run offline and exact lookup has expected O(1) complexity with respect to memory-bank size, Memory Grafting expands external latent capacity with limited training and inference overhead. Experiments under matched recipient architectures and pre-training budgets show that Memory Grafting improves over both MoE and vanilla Engram baselines. In the 2.8B-scale setting, it improves the average benchmark score from 51.95 for MoE and 52.43 for vanilla Engram to 53.86. In the 0.92B-scale setting, all grafting-model variants improve over the baselines, with Qwen3.5-35B-A3B giving the strongest gains. These results suggest that pretrained models can serve as reusable constructors of external latent memory, providing a practical step toward scaling future language models beyond trainable parameters alone.
format Preprint
id arxiv_https___arxiv_org_abs_2605_20948
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Memory Grafting: Scaling Language Model Pre-training via Offline Conditional Memory
Cheng, Runxi
Guan, Yuchen
Wei, Yongxian
Sun, Qianpu
Li, Qixiu
Du, Sinan
Xiong, Feng
Yuan, Chun
Lu, Yan
Gong, Yeyun
Computation and Language
Scaling conditional memory offers a promising way to increase language-model capacity, but existing methods such as Engram learn large memory tables from scratch during pre-training, making memory scaling expensive and sometimes ineffective. We propose Memory Grafting, a conditional memory scaling method that utilizes frozen hidden states from a grafting model as conditional n-gram memory. Given frequent local n-grams, we run the grafting model offline, store final-token hidden representations as memory values, and let the recipient model retrieve them through exact longest-match suffix lookup. Retrieved memories are adapted by lightweight projections and gates, while a hash-based Engram fallback preserves coverage for unmatched contexts. Since the grafting model is only run offline and exact lookup has expected O(1) complexity with respect to memory-bank size, Memory Grafting expands external latent capacity with limited training and inference overhead. Experiments under matched recipient architectures and pre-training budgets show that Memory Grafting improves over both MoE and vanilla Engram baselines. In the 2.8B-scale setting, it improves the average benchmark score from 51.95 for MoE and 52.43 for vanilla Engram to 53.86. In the 0.92B-scale setting, all grafting-model variants improve over the baselines, with Qwen3.5-35B-A3B giving the strongest gains. These results suggest that pretrained models can serve as reusable constructors of external latent memory, providing a practical step toward scaling future language models beyond trainable parameters alone.
title Memory Grafting: Scaling Language Model Pre-training via Offline Conditional Memory
topic Computation and Language
url https://arxiv.org/abs/2605.20948