When opening multiple projects with Zed, they can be spread
across separate instances (windows), but Zed's preference is that all projects
are within the same window. Both File > Open and zed path/to/project will
open that project as part of the existing Zed window.
Once I'm working with multiple projects, I need to toggle between them. This can be done from the Threads sidebar by Cmd-clicking the project I want to focus. I, however, prefer to use the keybinding that opens a picker menu.
Cmd+Opt+o
Hitting that keybinding with the editor area focused will open a Command Palette specifically for interacting with open projects.
I can navigate to the one I want to open either with the arrow keys or Ctrl-n
/ Ctrl-p and then hit enter to open it.