NExT-Guard: Training-Free Streaming Safeguard without Token-Level Labels

Fuente: arXiv
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Autores principales: Fang, Junfeng, Chen, Nachuan, Jiang, Houcheng, Zhang, Dan, Shen, Fei, Wang, Xiang, He, Xiangnan, Chua, Tat-Seng
Formato: Preprint
Publicado: 2026
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author Fang, Junfeng
Chen, Nachuan
Jiang, Houcheng
Zhang, Dan
Shen, Fei
Wang, Xiang
He, Xiangnan
Chua, Tat-Seng
author_facet Fang, Junfeng
Chen, Nachuan
Jiang, Houcheng
Zhang, Dan
Shen, Fei
Wang, Xiang
He, Xiangnan
Chua, Tat-Seng
contents Large language models are increasingly deployed in streaming scenarios, rendering conventional post-hoc safeguards ineffective as they fail to interdict unsafe content in real-time. While streaming safeguards based on token-level supervised training could address this, they necessitate expensive annotations and suffer from severe overfitting. In this work, we challenge the paradigm that streaming safety must rely on token-level supervised training. Instead, it is an inherent capability of well-trained post-hoc safeguards, as they already encode token-level risk signals in hidden representations. Hence, we introduce NExT-Guard, a training-free framework that achieves streaming safeguards by monitoring interpretable latent features from Sparse Autoencoders (SAEs). It uses pretrained SAEs from publicly available base LLMs, enabling flexible, low-cost deployment without token-level supervision. Experimental results show that NExT-Guard outperforms both post-hoc and streaming safeguards based on supervised training, with superior robustness across models, SAE variants, and risk scenarios. These results make NExT-Guard a universal and scalable paradigm for real-time safety, accelerating the practical deployment of streaming safeguards.
format Preprint
id arxiv_https___arxiv_org_abs_2603_02219
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle NExT-Guard: Training-Free Streaming Safeguard without Token-Level Labels
Fang, Junfeng
Chen, Nachuan
Jiang, Houcheng
Zhang, Dan
Shen, Fei
Wang, Xiang
He, Xiangnan
Chua, Tat-Seng
Machine Learning
Artificial Intelligence
Large language models are increasingly deployed in streaming scenarios, rendering conventional post-hoc safeguards ineffective as they fail to interdict unsafe content in real-time. While streaming safeguards based on token-level supervised training could address this, they necessitate expensive annotations and suffer from severe overfitting. In this work, we challenge the paradigm that streaming safety must rely on token-level supervised training. Instead, it is an inherent capability of well-trained post-hoc safeguards, as they already encode token-level risk signals in hidden representations. Hence, we introduce NExT-Guard, a training-free framework that achieves streaming safeguards by monitoring interpretable latent features from Sparse Autoencoders (SAEs). It uses pretrained SAEs from publicly available base LLMs, enabling flexible, low-cost deployment without token-level supervision. Experimental results show that NExT-Guard outperforms both post-hoc and streaming safeguards based on supervised training, with superior robustness across models, SAE variants, and risk scenarios. These results make NExT-Guard a universal and scalable paradigm for real-time safety, accelerating the practical deployment of streaming safeguards.
title NExT-Guard: Training-Free Streaming Safeguard without Token-Level Labels
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2603.02219