fix: ensure getExplanation uses the settled MODEL

[songlairui]

The getExplanation method is currently defaulting to the standard model instead of the custom model specified in the initial step.

This PR corrects the issue by ensuring that the getExplanation method correctly uses the custom model, maintaining the intended functionality.

in the screnshot, I am using custom model, but it trying the default model during the second step

[steve8708]

thanks @songlairui !

[bytemain]

@steve8708 could you release a new version for this? I also meet this problem.

[steve8708]

published!