I had always assumed that when you delete the contents of the Transcript, by selecting everything in it and deleting it ,it was all deleted. Or when running
Or one of the "clean up" methods like those above.
Anyway. It seems like the stream should clear more often than it does (looks like it may never empty itself? I don't think there is code in the image that does that though.
WriteStream>>#reset & WriteStream>>#close do not empty the #collection or #stepContents inst vars. And it doesn't look like there is a method to empty/re-initailze those inst vars defined in the Stream hierarchy in 7.1 or 8.0.