Maintain allocation of windows to spaces on restart and external monitor unplugging
After some experimentation, I've been able to keep all windows in the proper spaces across unplug/replug by adding 1 extra blank space on my laptop screen.
While plugged in to external monitor, I have #1 on monitor and #2 &amp; 3 on the laptop (call these 1a, 2a, 3a).  #2a is kept blank.
Upon unplugging, there is some merging and rearranging of the Spaces happening:

1a + 2a -&gt; 1b   (This is why I left 2a blank)
3a -&gt; 2b

End result when unplugged is my original stuff which was separated is still separated, I just don't have the extra blank display.
There's probably some way to extrapolate this merging behavior with more than 3 displays.