Plumb runs on my own Google account, and the app can reach my files and send mail as me. Opening that to the public would hand strangers a door into my own workspace, so I did not do it.

This is the real interface instead, running on invented data inside your browser. Nothing you type here leaves this page, there is nothing to sign in to, and refreshing keeps your changes until you press Reset.

Switch the role above to see the same app from a different seat. That is the part worth looking at: an administrator sees every site, regional staff see one region, and site staff see one site.