TAP-RAG: Task-Aware Policy Control for Long-Document Multimodal Question Answering

Zhong Ji, Keqi Jin, Yan Zhang, Jiasheng Li


Abstract
Long-document multimodal question answering requires more than retrieving relevant chunks from a large document. Different queries require different evidence behavior. Existing multimodal RAG systems improve evidence access through text chunks, page images, graph links, or heterogeneous document elements, but they often apply a largely query-agnostic evidence-use strategy. We present TAP-RAG, a task-aware policy-controlled RAG framework for long-document multimodal QA. TAP-RAG contains a main controller, the Task-Aware Policy Controller (TAPC), and two policy-guided evidence executors: Task-Aware Query-Guided Flow Diffusion (TA-QFD) and Task-Aware Visual Enhancement (TAVE). For each query, TAPC predicts the task prior, estimates visual/local/global evidence signals, and produces an executable policy. TA-QFD then expands textual and structural evidence over the multimodal document graph, while TAVE selectively inspects page images when visual or layout evidence is needed. A guarded synthesis stage fuses text, visual, and structural evidence and abstains when support is insufficient. On DocBench and MMLongBench-Doc, TAP-RAG achieves the best overall accuracy among the compared systems, improving over a matched multimodal-RAG baseline by +9.1 points (61.1 to 70.2) and +4.5 points (42.2 to 46.7), respectively.
Anthology ID:
2026.findings-emnlp.1685
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
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SIGDAT
Publisher:
Association for Computational Linguistics
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Pages:
35966–35980
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URL:
https://aclanthology.org/2026.findings-emnlp.1685/
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Cite (ACL):
Zhong Ji, Keqi Jin, Yan Zhang, and Jiasheng Li. 2026. TAP-RAG: Task-Aware Policy Control for Long-Document Multimodal Question Answering. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 35966–35980, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
TAP-RAG: Task-Aware Policy Control for Long-Document Multimodal Question Answering (Ji et al., Findings 2026)
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https://aclanthology.org/2026.findings-emnlp.1685.pdf