Safe Adaptive Context and TACER: Task-Aware Evidence Routing for Token-Efficient Retrieval-Augmented Generation

Joel Vazquez Lopez, Andreia Alexa, Kārlis Mārtiņš Auce, Simon Backhaus Brudzewski, Sheraz Ahmad


Abstract
Retrieval-Augmented Generation (RAG) pipelines often pass a fixed number of retrieved documents to the generator, even though evidence needs vary by query. We study context selection as a post-retrieval control problem: given the same candidate list, how much evidence should enter the prompt, and in what form? We present Safe Adaptive Context, a lightweight controller that starts with limited evidence and expands when the generated answer appears weak, and TACER, a task-aware extension that routes between compact evidence and safer broader context using retrieval-side and evidence-coverage signals. Across five datasets, two generators, and stronger retriever settings, the controllers substantially reduce provider-reported token use while preserving most Fixed Top-10 answer quality. In a five-dataset, 500-query external-baseline stress test, Safe Adaptive Context retains 99.8% of Fixed Top-10 F1 with 55.0% token reduction, while TACER retains 99.4% with 60.4% token reduction. The contribution is not universal quality improvement, but practical quality-preserving efficiency through task-aware context control.
Anthology ID:
2026.groundlm-1.33
Volume:
Proceedings of the 1st Workshop on Grounding Language Models: Learning Faithfully and Efficiently (GroundLM 2026)
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Yimu Wang, Yee Man Choi, Di Wu, Siqi Ouyang, Mozhgan Nasr Azadani, Yi R. (May) Fung
Venues:
GroundLM | WS
SIG:
Publisher:
Association for Computational Linguistics
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Pages:
418–433
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URL:
https://aclanthology.org/2026.groundlm-1.33/
DOI:
Bibkey:
Cite (ACL):
Joel Vazquez Lopez, Andreia Alexa, Kārlis Mārtiņš Auce, Simon Backhaus Brudzewski, and Sheraz Ahmad. 2026. Safe Adaptive Context and TACER: Task-Aware Evidence Routing for Token-Efficient Retrieval-Augmented Generation. In Proceedings of the 1st Workshop on Grounding Language Models: Learning Faithfully and Efficiently (GroundLM 2026), pages 418–433, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Safe Adaptive Context and TACER: Task-Aware Evidence Routing for Token-Efficient Retrieval-Augmented Generation (Lopez et al., GroundLM 2026)
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https://aclanthology.org/2026.groundlm-1.33.pdf
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