Versioned city-block modules. A blueprint book in the game blueprint library is the source of truth; every placement of a module is re-pasted as ghosts when its blueprint changes.
Side-by-side comparison variant of Ghost Scanner 4. Adds a separate 'Ghost Scanner (Ignore Assigned)' combinator with an option to ignore ghosts that already have a construction robot dispatched. Can run alongside the original Ghost Scanner 4.
Drag over crafting machines to get a lamp board in the same layout: each lamp shows whether its machine is working. The machines are set to read working and wired together, so one wire to the board is all that's left.