Hacker News Reader

This is only a change in the interface. I don't think there is any underlying change in the notebook format. Your old notebooks are completely safe.

P.S. Juptext is a pretty cool extension https://pypi.org/project/jupytext/

nbformat is reference implementation of the notebook format: https://github.com/jupyter/nbformat No recent major releases.

jupytext is great, you can also review your notebooks as `.ipynb` files using GitNotebooks [https://gitnotebooks.com]. (I'm the solo dev)

I would think of JupyterLab as more of an IDE, and the major version bump need not affect their notebook format.

I think if they made breaking changes to the notebook format, they'd mention this right away.