CodeGraphVLP: Code-as-Planner Meets Semantic-Graph State for Non-Markovian Vision-Language-Action Models

Khoa Vo; Sieu Tran; Taisei Hanyu; Yuki Ikebe; Duy Nguyen; Nghi D. Q. Bui; Minh Vu; Anthony Gunderman; Chase Rainwater; Anh Nguyen; Ngan Le

arXiv · 2604.22238

CodeGraphVLP: Code-as-Planner Meets Semantic-Graph State for Non-Markovian Vision-Language-Action Models

Khoa Vo·Sieu Tran·Taisei Hanyu·Yuki Ikebe·Duy Nguyen·Nghi D. Q. Bui·Minh Vu·Anthony Gunderman·Chase Rainwater·Anh Nguyen·Ngan Le

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Abstract

Vision-Language-Action (VLA) models promise generalist robot manipulation, but are typically trained and deployed as short-horizon policies that assume the latest observation is sufficient for action reasoning. This assumption breaks in non-Markovian long-horizon tasks, where task-relevant evidence can be occluded or appear only earlier in the trajectory, and where clutter and distractors make fine-grained visual grounding brittle. We present CodeGraphVLP, a hierarchical framework that enables reliable long-horizon manipulation by combining a persistent semantic-graph state with an executable code-based planner and progress-guided visual-language prompting. The semantic-graph maintains task-relevant entities and relations under partial observability. The synthesized planner executes over this semantic-graph to perform efficient progress checks and outputs a subtask instruction together with subtask-relevant objects. We use these outputs to construct clutter-suppressed observations that focus the VLA executor on critical evidence. On real-world non-Markovian tasks, CodeGraphVLP improves task completion over strong VLA baselines and history-enabled variants while substantially lowering planning latency compared to VLM-in-the-loop planning. We also conduct extensive ablation studies to confirm the contributions of each component.

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Khoa Vo, Sieu Tran, Taisei Hanyu, Yuki Ikebe, Duy Nguyen, Nghi D. Q. Bui, Minh Vu, Anthony Gunderman, Chase Rainwater, Anh Nguyen, Ngan Le. 2026-04-24. CodeGraphVLP: Code-as-Planner Meets Semantic-Graph State for Non-Markovian Vision-Language-Action Models. https://arxiv.org/abs/2604.22238

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