We had a conflict here: archive history is used to resolve new
patches. However, they were saved with delay and after that were
cleared. We should save archive immediately and immediately clear it
in mvar so it's ready for new patches.

This is used to save when quitting the server. Previous, debounce
save, didn't work properly on exit.

This is not the optimal solution since it duplicates so much
data. Best would be to add "children" in the node directly.