Fake It Till You Make It: Training Deep-Search Agents in Synthetic Search Environments

Yibo Xue, Pin Zheng, Chengyu Wang, Yukun Kang, Yuanjie Lyu, Ming Wang, Jian Peng, Jun Huang, Changliang Xu


Abstract
Deep-search agents are commonly trained via repeated interaction with real-world search APIs and browser environments. While realistic, this paradigm is expensive, difficult to reproduce, and sensitive to external drift. Existing simulator-based alternatives reduce dependence on live retrieval, but they largely inherit task distributions from pre-existing QA datasets, limiting their alignment with the behaviors required for deep search. We introduce SynSearch, a framework for training deep-search agents entirely within a synthetic search–browse environment. Our core idea is to jointly design the environment and the training-task distribution, enabling the synthesis of environment-aligned tasks and reinforcement learning of compact language models in multi-turn search settings. By grounding task validity in executable environment trajectories rather than surface-level plausibility alone, SynSearch unifies task generation, trajectory verification, and policy optimization within a low-marginal-cost and reproducible framework. Experiments on multi-hop QA and deep-search benchmarks show that SynSearch consistently improves both answer accuracy and search behavior, with especially large gains on deep-search tasks. Moreover, SynSearch offers low marginal cost, reproducibility, controllability, and strong performance under real-search evaluation, highlighting synthetic environments as an effective substrate for training deep-search agents.
Anthology ID:
2026.emnlp-main.928
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:
21347–21372
Language:
URL:
https://aclanthology.org/2026.emnlp-main.928/
DOI:
Bibkey:
Cite (ACL):
Yibo Xue, Pin Zheng, Chengyu Wang, Yukun Kang, Yuanjie Lyu, Ming Wang, Jian Peng, Jun Huang, and Changliang Xu. 2026. Fake It Till You Make It: Training Deep-Search Agents in Synthetic Search Environments. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 21347–21372, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Fake It Till You Make It: Training Deep-Search Agents in Synthetic Search Environments (Xue et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.928.pdf