Welcome to Meta!Edit
The Editing team has scheduled a major update to mw:Extension:DiscussionTools (the new Reply tool) for next week's deployment train. Since you invoke the feature from a script (I do, too), you're probably going to see that update next week, before it's officially released in the mw:Beta Feature system. The new update will use a similar system for starting a ==New discussion==. As before, full-page wikitext editing will not be affected. There is more information on the project page at mw:Talk pages project/New discussion.