That's great, but can you do it that easily from inside a Custom HTML Prompt action? I see how to set dictionary keys from inside the Custom HTML Prompt action, but I don't see a way to delete the whole dictionary. Perhaps KM is missing a way to set a JSON variable from its list of Javascript functions near the bottom of this page:
https://wiki.keyboardmaestro.com/action/Custom_HTML_Prompt
It also seems to be missing a way to Append and Prepend text variables.