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Main Authors: Liu, Xuanzhang, Feng, Jianglun, Zhuang, Zhuoran, Zhao, Junzhe, Que, Maofei, Li, Jieting, Wang, Dianlei, Tong, Hao, Chen, Ye, Li, Pan
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2512.12716
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author Liu, Xuanzhang
Feng, Jianglun
Zhuang, Zhuoran
Zhao, Junzhe
Que, Maofei
Li, Jieting
Wang, Dianlei
Tong, Hao
Chen, Ye
Li, Pan
author_facet Liu, Xuanzhang
Feng, Jianglun
Zhuang, Zhuoran
Zhao, Junzhe
Que, Maofei
Li, Jieting
Wang, Dianlei
Tong, Hao
Chen, Ye
Li, Pan
contents Large Language Model (LLM) agents trained with reinforcement learning (RL) show great promise for solving complex, multi-step tasks. However, their performance is often crippled by "Context Explosion", where the accumulation of long text outputs overwhelms the model's context window and leads to reasoning failures. To address this, we introduce CoDA, a Context-Decoupled hierarchical Agent, a simple but effective reinforcement learning framework that decouples high-level planning from low-level execution. It employs a single, shared LLM backbone that learns to operate in two distinct, contextually isolated roles: a high-level Planner that decomposes tasks within a concise strategic context, and a low-level Executor that handles tool interactions in an ephemeral, isolated workspace. We train this unified agent end-to-end using PECO (Planner-Executor Co-Optimization), a reinforcement learning methodology that applies a trajectory-level reward to jointly optimize both roles, fostering seamless collaboration through context-dependent policy updates. Extensive experiments demonstrate that CoDA achieves significant performance improvements over state-of-the-art baselines on complex multi-hop question-answering benchmarks, and it exhibits strong robustness in long-context scenarios, maintaining stable performance while all other baselines suffer severe degradation, thus further validating the effectiveness of our hierarchical design in mitigating context overload.
format Preprint
id arxiv_https___arxiv_org_abs_2512_12716
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle CoDA: A Context-Decoupled Hierarchical Agent with Reinforcement Learning
Liu, Xuanzhang
Feng, Jianglun
Zhuang, Zhuoran
Zhao, Junzhe
Que, Maofei
Li, Jieting
Wang, Dianlei
Tong, Hao
Chen, Ye
Li, Pan
Computation and Language
Large Language Model (LLM) agents trained with reinforcement learning (RL) show great promise for solving complex, multi-step tasks. However, their performance is often crippled by "Context Explosion", where the accumulation of long text outputs overwhelms the model's context window and leads to reasoning failures. To address this, we introduce CoDA, a Context-Decoupled hierarchical Agent, a simple but effective reinforcement learning framework that decouples high-level planning from low-level execution. It employs a single, shared LLM backbone that learns to operate in two distinct, contextually isolated roles: a high-level Planner that decomposes tasks within a concise strategic context, and a low-level Executor that handles tool interactions in an ephemeral, isolated workspace. We train this unified agent end-to-end using PECO (Planner-Executor Co-Optimization), a reinforcement learning methodology that applies a trajectory-level reward to jointly optimize both roles, fostering seamless collaboration through context-dependent policy updates. Extensive experiments demonstrate that CoDA achieves significant performance improvements over state-of-the-art baselines on complex multi-hop question-answering benchmarks, and it exhibits strong robustness in long-context scenarios, maintaining stable performance while all other baselines suffer severe degradation, thus further validating the effectiveness of our hierarchical design in mitigating context overload.
title CoDA: A Context-Decoupled Hierarchical Agent with Reinforcement Learning
topic Computation and Language
url https://arxiv.org/abs/2512.12716