HammerSpoon menu bar item to show active Mission Control space.

Built-in and external display names are shown. Spaces are listed in order per display. Active space is square bracketed.

Example config:

ActiveSpace = hs.loadSpoon("ActiveSpace")
ActiveSpace:start()

Click the menubar to switch to a compact view without display names.

Or, set ActiveSpace.compact = true in the HammerSpoon config. The default is false.