RACA-PODS: Reasoning-Informed First-Token Prediction for Query-Document Relevance in WeChat Search

Yupeng Hu, Dongliang Liao, Changxing Ding, Mengchuan Qiu, Huasheng Liang, Qiang Yan, Junhong Wang


Abstract
Applying LLMs to query-document relevance estimation in industrial document retrieval faces two key challenges: the complexity and heterogeneity of Web content, and stringent latency and resource constraints. To address them, we propose an automated framework with two components: **R**eflection-**A**ware **C**ollaborative **A**gent (**RACA**) and **P**rogressive **O**ptimization **D**istillation **S**trategy (**PODS**). RACA uses collaborative reasoning and reflection to produce relevance labels and structured rationales. PODS stratifies training data by difficulty and combines supervised fine-tuning with Reasoning-Informed GRPO. Rationale supervision improves the student’s first-token relevance decision, while deployment stops after that token and avoids explicit rationale generation. Together, these mechanisms enable reasoning-informed first-token prediction that preserves the benefits of structured rationale supervision under stringent latency and resource constraints. Extensive offline experiments and a 10-day online A/B test in WeChat Search demonstrate the resulting accuracy–efficiency trade-off.
Anthology ID:
2026.emnlp-industry.209
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing: Industry Track
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Pepa Atanasova, Gholamreza Haffari, Minghan Wang
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
3520–3534
Language:
URL:
https://aclanthology.org/2026.emnlp-industry.209/
DOI:
Bibkey:
Cite (ACL):
Yupeng Hu, Dongliang Liao, Changxing Ding, Mengchuan Qiu, Huasheng Liang, Qiang Yan, and Junhong Wang. 2026. RACA-PODS: Reasoning-Informed First-Token Prediction for Query-Document Relevance in WeChat Search. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing: Industry Track, pages 3520–3534, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
RACA-PODS: Reasoning-Informed First-Token Prediction for Query-Document Relevance in WeChat Search (Hu et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-industry.209.pdf