In general though this problem seems like potentially a lot of work for an uncommon edge case.

Another example is a row/col deletion that results a colspan/rowspan change:

Here 7,8,10 is deleted which makes 9 shorter:

The output is still more legible than wikitext though.

We also need to decide how we'd like table (un)merges to appear.

Unmergres can simple be shown as the insertion of all but the top left cell:

Going the other way is a little more complex, to be discussed?

Agree on un-merges. Not sure what you're showing in "the other way" – is that adding things to an already merged cell?

In T149851#3165016, @Jdforrester-WMF wrote:

Agree on un-merges. Not sure what you're showing in "the other way" – is that adding things to an already merged cell?

It shows merging 4 cells (in red) into 1 cell (green). The easier solution is just to not show the removed content.

Change 455321 had a related patch set uploaded (by Esanders; author: Tchanders):

[VisualEditor/VisualEditor@master] Daff table diffing

https://gerrit.wikimedia.org/r/455321

	Before patch	After patch	Comments
A+E merge			Layout less broken visually, but the removed content is not shown
Merge			As above
Unmerge			Almost no change
Row removal			Both quite broken. Displaying removed cells will always cause problems when colspan/rowspan is involved

I think not showing the remove content in cell merges is better than breaking the layout, and we can iterate towards the design shown above:

In T149851#3164988, @Esanders wrote: