Undo removes the partial output of currently running cell; cannot redo changes undone when other cell produces outputs

[krassowski]

Description

The new system of storing history of changes in 3.1 introduced with Real Time Collaboration (RTC) has some peculiarities which do not work great with my workflow. The synchronization of outputs and inputs might be neat in some cases, but it can be disruptive for live-editing code while the cell is already running.

Reproduce

Demo isolated to a single cell

1. Open notebook using JupyterLab 3.1rc2
2. Execute following code:

   from time import sleep
   
   for i in range(20):
       print(i)
       sleep(1)

3. Try pressing Ctrl + Z while the code is running
4. See that the last bit of output gets removed
5. Try to make a change in the code and undo it with Ctrl + Z
6. See that it will be only undone after removing the bits of output that showed up since making the change in the code

The real problems

1. I cannot work in other cell when I use a progress reporting in an earlier cell or I will loose bits of output:

2. I cannot redo changes that I undo:

Expected behavior

I was able to get used to the undo being document-wide rather than cells-specific, but it still can be annoying from time to time.

I think that there are two issues:
a) allowing users to disable the document-wide history tracking when not in RTC mode
b) separating history of outputs from history of inputs, at least when not in RTC mode

Context

• Browser and version: Chrome
• JupyterLab version: 3.1.0rc2

[goanpeca]

Thoughts on this one @dmonad ?

Pinging @hbcarlos :)

[hbcarlos]

Actually, there is a way of preventing Yjs from capturing operations.
see: https://docs.yjs.dev/api/undo-manager#example-stop-capturing

I'm working on this. I'll open a PR.

[mlucool]

a) allowing users to disable the document-wide history tracking when not in RTC mode

This would be great to do. To some users, this behavior is detrimental to their workflow.

[vidartf]

b) separating history of outputs from history of inputs, at least when not in RTC mode

I don't think having undo/redo of outputs makes sense. While it might make sense to keep the history, I think it should be marked in some way to not be included in the undo/redo stream.

[krassowski]

Closing as fixed in #10756 (released in 3.1.2). I opened #10791 to track allowing to disable the history tracking entirely.