\newblock Where did it go wrong? capability-oriented failure attribution for vision-and-language navigation agents.
\newblock In \emph{Findings of the Association for Computational Linguistics: ACL 2026}, pp.\ 28132--28150, San Diego, California, United States, July 2026. Association for Computational Linguistics.
Lichang Chen, Shiyang Li, Jun Yan, Hai Wang, Kalpa Gunaratna, Vikas Yadav, Zheng Tang, Vijay Srinivasan, Tianyi Zhou, Heng Huang, and Hongxia Jin.
\newblock Alpagasus: Training a better alpaca with fewer data.
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@@ -450,6 +457,12 @@ Mingjie Sun, Zhuang Liu, Anna Bair, and J.~Zico Kolter.
\newblock In \emph{The Twelfth International Conference on Learning Representations, {ICLR} 2024, Vienna, Austria, May 7-11, 2024}. OpenReview.net, 2024.
@@ -280,7 +280,7 @@ This process is illustrated in Figure~\ref{fig:agent-environment-scaling}. It ty
\item\textbf{Scenario Generation.} Based on the environment specification, we generate diverse initial states and user tasks. The tasks should cover different goals, constraints, and difficulty levels. For example, in a shopping environment, a simple task may ask the agent to purchase a single item, while a more difficult task may require it to compare multiple products.
\item\textbf{Agent--Environment Interaction.} The agent interacts with the generated environment through multiple rounds of actions and observations. At each step, the agent selects a tool and provides the required arguments. The environment executes the action and returns an observation.
\item\textbf{Outcome Verification.} After the interaction is completed, a verifier checks whether the task has been successfully solved. The verifier may inspect tool execution results, database states, or other structured records.
\item\textbf{Agent Learning.} Finally, the verified trajectories are used to improve the agent. Successful trajectories can serve as demonstrations for SFT, while task-level or step-level feedback can support RL training. Note that failed interactions are also useful because they reveal weaknesses in the current policy or gaps in the task distribution. For example, repeated failures on invalid API arguments may motivate the generation of additional scenarios involving parameter constraints. In this way, learning results can further guide scenario generation and form an iterative environment--agent improvement loop.
\item\textbf{Agent Learning.} Finally, the verified trajectories are used to improve the agent. On the one hand, successful trajectories can serve as demonstrations for SFT, while task-level or step-level feedback can support RL training. On the other hand, failed interactions are also valuable because they reveal weaknesses in the current policy and gaps in the task distribution. This can guide the generation of targeted scenarios that exercise the agent's weak capabilities and provide more informative experience for subsequent training \citep{chen-etal:failure-attribution,sun-etal:learning-from-failure}.
\end{itemize}
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@@ -301,11 +301,24 @@ Scaling environments also introduces substantial heterogeneity. Different enviro