/add-dir with no argument should list the currently included directories

The problem

There's no way to see which directories are currently part of a session. That's the primary working directory plus anything I added with /add-dir or --add-dir. /status doesn't list them, and no other command does either. So I can add directories, but I can never check what's already there.

What I'd like

Running /add-dir on its own, with no path, should just print the directories that are currently included. That's the obvious place for it: the command I use to add a directory is also where I'd look to see what's already added.

Alternatives

A section in /status that lists the directories would work too. Or a separate /dirs command.

Extra context

Right now the only reliable way to find out is to ask the model, since it can see the directories in its session environment but they show up nowhere in the UI.