jupyterlab-myst breaks navigating from the TOC outline

[parmentelat]

Description

the outline TOC is no longer usable to navigate across the notebook once jupyterlab-myst is installed

to reproduce:

• install a fresh jupyterlab environment
  • open a notebook whose height is a few viewports
  • make sure that one of the headers ends up below the bottom of the viewport
  • in the jlab outline, click that header, the corresponding cell gets selected and the notebook scrolls so this cell becomes visible
• on top of that, install jupyterlab-myst
  • restart jlab and reproduce the same
  • the header cell gets selected, but the notebook does not scroll

Proposed solution

I have not yet been able to investigate this issue, but am willing to, with a little guidance :)

Additional notes

initially posted in https://github.com/jupyterlab/jupyterlab/issues/14897 before I could pinpoint this to jupyterlab-myst

[parmentelat]

duplicated from the original issue, hopefully makes things clearer

[rowanc1]

It looks like this has changed in JupyterLab 4 and this is no longer a simple anchor link as the notebook has become virtualized.

I think we need to add a new factory or something similar to this:

https://github.com/jupyterlab/jupyterlab/blob/1d989bad87e89307a336d2f671c9cc98ec37f5e9/packages/markdownviewer/src/toc.ts#L90

[parmentelat]

a little surprisingly, I have just noticed that the feature starts working again, apparently if I create an artificial delay in the notebook loading phase

more specifically:

• I add a breakpoint, for example in the activate part of the myst plugin (but it does not seem to matter, just pick something that is called once at load-time)
• then, upon reloading a notebook that otherwise exhibits the faulty behaviour, I immediately click on the 'proceed' button of the debugger,
• and bingo, the TOC works again..

in my limited understanding of the system, this could suggest some asynchronous function that is not properly awaited, or some similar flaw that would occur at load time

I'm still puzzled that the issue clearly relates to jupyterlab-myst though, since without this extension everything works fine...

[parmentelat]

let me add that I am much impeded by this issue, and that am quite willing to spend more time investigating it

as part of my attempts I have tried to follow-up on @rowanc1's idea to register my own brew of a MarkdownViewerTableOfContentsFactory in the tocRegistry, but could not go very far down this road, mostly because I could not figure out

1. which registered factory is supposed to trigger in what context
2. nor how exactly to customize such a factory - short of redefining _createNew which looked like too big a chump to swallow so I gave up when I realized the above

[parmentelat]

finally I'd like to report that the issue happens also in the "Markdown Preview" and the "Editor" document views, and in both cases apparently adding an artificial delay as explained above makes the feature working again

[parmentelat]

looks like this might very well be an issue on jupyterlab proper after all, and that it is being addressed here

https://github.com/jupyterlab/jupyterlab/pull/14884

[parmentelat]

to be more explicit, the referenced PR does fix the issue that I have when using the TOC with the jupyterlab-myst extension loaded clearly a workaround because there obviously are deeper issues in the jlab loading phase that create the conditions for the issue regardless, this is currently a major productivity impediment, at least as far as I am concerned, so if the PR makes it to being merged, whether it's a clean fix or not, it would be a great relief already...

[parmentelat]

quite obviously, as per both https://github.com/jupyterlab/jupyterlab/issues/14897 and https://github.com/jupyterlab/jupyterlab/issues/14591 the issue is totally a jupyterlab one after all

am closing this one

[rowanc1]

Thanks for following up @parmentelat!