I gave a possibly relevant talk at JupyterCon last week: "CoCalc:
Real-time collaboration with Jupyter notebooks"
--
https://tinyurl.com/yb9yvash
Chris Colbert and Jason Grout also told me about some awesome work
they are doing related to realtime sync for JupyterLab, which would
probably be a useful foundation for multiple checkpoints.
--
William (
http://wstein.org)