Splitting notebook cells to have comments persist on the line

[JulianVJacobs]

It's good practice to explain code with comments and it helps with comment readability if they're all justified to a common margin and are next to the line of code they are intended to explain. This is complicated when you need to edit the line because changing the length of the code before ruins the justification and if something needs to be added in between 2 lines, going to a new line causes the comment to migrate. Moreover, to have every comment justified, several space characters need to be added between the line of code and the comment and these would add up over time in terms of file size.

I suggest a collapsible vertical split on a cell that can only hold comments which persist on the line they're written and migrate with the code only if the cursor is not at the end of the line when the line break is added.