Actually, I just checked and an active text thread is added to the inline prompt context (you may need to click on the box at the bottom of the inline prompt to include it, but then it is added by default for the next). So it looks fine to me (and it is nicer that it is more explicit this way).
There is also the "+" button to add files, threads etc, though it would be nice if it could also be done through slash commands.
Yes, and it followed the instructions in my text thread.
I opened a previous agent thread and it gave me the option to include both threads to the context of the inline prompt (the old text thread was included and I had to click to exclude it, the new thread was grayed out and I had to click to include it).
There is also the "+" button to add files, threads etc, though it would be nice if it could also be done through slash commands.