ICICLE: Expanding Retrieval with In-Context Documents

Yu-Chen Den, Yung-Yu Shih, Zhi Rui Tam, Kuan-Yu Chen, Pu-Jen Cheng, Yun-Nung Chen, Eugene Yang


Abstract
Generative retrieval (GR) maps queries directly to document identifiers (docids) using parametric knowledge. However, this design makes corpus expansion costly: adding new documents requires updating model parameters to encode new document-docid associations incurs repeated training and catastrophic forgetting of previously indexed documents. In this work, we revisit incremental GR as an in-context retrieval problem, where newly added documents are supplied as inference-time document-docid evidence. We propose ICICLE, an in-context indexing framework that performs source-aware docid generation over both parametric memory and context-provided document-docid pairs. ICICLE combines a ‘[COPY]‘-based routing mechanism, preference-based calibration, and large context adaptation to distinguish context-grounded retrieval from parametric retrieval. Experiments on MS MARCO and NQ320K show that ICICLE improves retrieval of newly introduced documents while preserving seen-document retention without corpus-specific retraining. Our analysis further shows that high-shot degradation is mainly caused by routing failure, highlighting source-selection calibration as a key bottleneck for scaling in-context generative retrieval.
Anthology ID:
2026.findings-emnlp.213
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
4449–4466
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.213/
DOI:
Bibkey:
Cite (ACL):
Yu-Chen Den, Yung-Yu Shih, Zhi Rui Tam, Kuan-Yu Chen, Pu-Jen Cheng, Yun-Nung Chen, and Eugene Yang. 2026. ICICLE: Expanding Retrieval with In-Context Documents. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 4449–4466, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
ICICLE: Expanding Retrieval with In-Context Documents (Den et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.213.pdf