Thanks for the feedback Max!
I’m personally not so worried that this isn’t obvious behaviour. In Observable, for example, the UI makes it clear how things are structured:
This associative left-margin pictured above is something that I think we miss in JupyterLab. It might be that just adding something like this (that visually related the cell source and output more distinctly) would be enough to scratch this itch of mine, although I suspect not entirely!
RE mix-and-match of the notebook, I think you’re right on core development needs — it was non-trivial to build-out the prototype for inline markdown variables for this reason!