Imagine-then-Plan: Agent Learning from Adaptive Lookahead with World Models

Fuente: arXiv
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Autores principales: Liu, Youwei, Wang, Jian, Wang, Hanlin, Guo, Beichen, Li, Wenjie
Formato: Preprint
Publicado: 2026
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author Liu, Youwei
Wang, Jian
Wang, Hanlin
Guo, Beichen
Li, Wenjie
author_facet Liu, Youwei
Wang, Jian
Wang, Hanlin
Guo, Beichen
Li, Wenjie
contents Recent advances in world models have shown promise for modeling future dynamics of environmental states, enabling agents to reason and act without accessing real environments. Current methods mainly perform single-step or fixed-horizon rollouts, leaving their potential for complex task planning under-exploited. We propose Imagine-then-Plan (\texttt{ITP}), a unified framework for agent learning via lookahead imagination, where an agent's policy model interacts with the learned world model, yielding multi-step ``imagined'' trajectories. Since the imagination horizon may vary by tasks and stages, we introduce a novel adaptive lookahead mechanism by trading off the ultimate goal and task progress. The resulting imagined trajectories provide rich signals about future consequences, such as achieved progress and potential conflicts, which are fused with current observations, formulating a partially \textit{observable} and \textit{imaginable} Markov decision process to guide policy learning. We instantiate \texttt{ITP} with both training-free and reinforcement-trained variants. Extensive experiments across representative agent benchmarks demonstrate that \texttt{ITP} significantly outperforms competitive baselines. Further analyses validate that our adaptive lookahead largely enhances agents' reasoning capability, providing valuable insights into addressing broader, complex tasks. Our code and data will be publicly available at https://github.com/loyiv/ITP.
format Preprint
id arxiv_https___arxiv_org_abs_2601_08955
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Imagine-then-Plan: Agent Learning from Adaptive Lookahead with World Models
Liu, Youwei
Wang, Jian
Wang, Hanlin
Guo, Beichen
Li, Wenjie
Computation and Language
Artificial Intelligence
Machine Learning
Recent advances in world models have shown promise for modeling future dynamics of environmental states, enabling agents to reason and act without accessing real environments. Current methods mainly perform single-step or fixed-horizon rollouts, leaving their potential for complex task planning under-exploited. We propose Imagine-then-Plan (\texttt{ITP}), a unified framework for agent learning via lookahead imagination, where an agent's policy model interacts with the learned world model, yielding multi-step ``imagined'' trajectories. Since the imagination horizon may vary by tasks and stages, we introduce a novel adaptive lookahead mechanism by trading off the ultimate goal and task progress. The resulting imagined trajectories provide rich signals about future consequences, such as achieved progress and potential conflicts, which are fused with current observations, formulating a partially \textit{observable} and \textit{imaginable} Markov decision process to guide policy learning. We instantiate \texttt{ITP} with both training-free and reinforcement-trained variants. Extensive experiments across representative agent benchmarks demonstrate that \texttt{ITP} significantly outperforms competitive baselines. Further analyses validate that our adaptive lookahead largely enhances agents' reasoning capability, providing valuable insights into addressing broader, complex tasks. Our code and data will be publicly available at https://github.com/loyiv/ITP.
title Imagine-then-Plan: Agent Learning from Adaptive Lookahead with World Models
topic Computation and Language
Artificial Intelligence
Machine Learning
url https://arxiv.org/abs/2601.08955