ContractSkill: Repairable Contract-Based Skills for Multimodal Web Agents

Fuente: arXiv
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Main Authors: Lu, Zijian, Zuo, Yiping, Nie, Yupeng, He, Xin, Fan, Weibei, Qi, Lianyong, Jin, Shi
Format: Preprint
Published: 2026
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author Lu, Zijian
Zuo, Yiping
Nie, Yupeng
He, Xin
Fan, Weibei
Qi, Lianyong
Jin, Shi
author_facet Lu, Zijian
Zuo, Yiping
Nie, Yupeng
He, Xin
Fan, Weibei
Qi, Lianyong
Jin, Shi
contents Self-generated skills for web agents are often unstable and can even hurt performance relative to direct acting. We argue that the key bottleneck is not only skill generation quality, but the fact that web skills remain implicit and therefore cannot be checked or locally repaired. To address this, we present ContractSkill, a framework that converts a draft skill into an executable artifact with explicit procedural structure, enabling deterministic verifica tion, fault localization, and minimal local repair. This turns skill refinement from full rewriting into localized editing of a single skill artifact. Experiments on VisualWebArena show that Contract Skill is effective in realistic web environments, while MiniWoB provides a controlled test of the mechanism behind the gain. Under matched transfer layers, repaired artifacts also remain reusable after removing the source model from the loop, providing evi dence of portability within the same benchmark family rather than full-benchmark generalization. These results suggest that the central challenge is not merely generating skills, but mak ing them explicit, executable, and repairable. Code is available at https://github.com/underfitting-lu/contractskill.git.
format Preprint
id arxiv_https___arxiv_org_abs_2603_20340
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle ContractSkill: Repairable Contract-Based Skills for Multimodal Web Agents
Lu, Zijian
Zuo, Yiping
Nie, Yupeng
He, Xin
Fan, Weibei
Qi, Lianyong
Jin, Shi
Software Engineering
Artificial Intelligence
Self-generated skills for web agents are often unstable and can even hurt performance relative to direct acting. We argue that the key bottleneck is not only skill generation quality, but the fact that web skills remain implicit and therefore cannot be checked or locally repaired. To address this, we present ContractSkill, a framework that converts a draft skill into an executable artifact with explicit procedural structure, enabling deterministic verifica tion, fault localization, and minimal local repair. This turns skill refinement from full rewriting into localized editing of a single skill artifact. Experiments on VisualWebArena show that Contract Skill is effective in realistic web environments, while MiniWoB provides a controlled test of the mechanism behind the gain. Under matched transfer layers, repaired artifacts also remain reusable after removing the source model from the loop, providing evi dence of portability within the same benchmark family rather than full-benchmark generalization. These results suggest that the central challenge is not merely generating skills, but mak ing them explicit, executable, and repairable. Code is available at https://github.com/underfitting-lu/contractskill.git.
title ContractSkill: Repairable Contract-Based Skills for Multimodal Web Agents
topic Software Engineering
Artificial Intelligence
url https://arxiv.org/abs/2603.20340