ReProF: Residual Prototype Fusion for Continual LLM Attribution

Yujie Wang, Zhendong Mao, Quan Wang


Abstract
Continual LLM attribution aims to identify the source of generated text amid the ongoing emergence of new models. While existing training-free, prototype-based methods excel at this task, they rely solely on the final-layer features of a frozen extractor, overlooking rich hierarchical stylistic cues. Moreover, naive multi-layer fusion yields suboptimal results. To address these limitations, we propose ReProF (Residual Prototype Fusion), a training-free framework that partitions the feature extractor’s hierarchy into layer blocks and derives depth-aware analytic prototypes via shallow-to-deep residual fitting: deeper prototypes model the residuals of shallower ones. By fusing predictions across these blocks, ReProF captures multi-granular stylistic cues without requiring parameter tuning or data rehearsal, thereby intrinsically eliminating catastrophic forgetting. Extensive experiments across 19 LLMs and 8 domains demonstrate that ReProF establishes a new state-of-the-art, consistently outperforming existing approaches by a wide margin. Code is available at: https://github.com/wyj-hb/ReProF.
Anthology ID:
2026.emnlp-main.2051
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
46709–46724
Language:
URL:
https://aclanthology.org/2026.emnlp-main.2051/
DOI:
Bibkey:
Cite (ACL):
Yujie Wang, Zhendong Mao, and Quan Wang. 2026. ReProF: Residual Prototype Fusion for Continual LLM Attribution. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 46709–46724, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
ReProF: Residual Prototype Fusion for Continual LLM Attribution (Wang et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.2051.pdf