Change 419081 had a related patch set uploaded (by Petar.petkovic; owner: Petar.petkovic):
[mediawiki/extensions/ContentTranslation@master] Add category mapping support

https://gerrit.wikimedia.org/r/419081

Changes done in https://gerrit.wikimedia.org/r/419081

Remaining:

• Need styling as per the ticket.
• Hightlighting the pairs on hover
• A heading for the category listing, which will have the tag icon
• Categories are the last item in the column, but since they don't have equal height, the background color differs. And as per design in this ticket, insead of white background is light gray and has a border
• If the target category has one autoadapted item, the category count lable at top of the target column shows 'one category'. But when we add or remove items to the target category list, that label is not updated.

I think we need to change the behavior of mw.cx.ui.Categories. Instead of accepting the categories list as constructor, let this class act as a ui component, exposing a public method to add category list after initialization. Any addition, deletion to the category listing of this instance at any point in the lifecycle of instance will update the UI elements. That means, count label get automatically updated. This also means, we can start painting the containers for the UI early if needed. Also, this will make the restoring categories ( T188238: Adapted categories are not saved along with translation ) feature easy.

Thank you @santhosh for creating the list of things that are still to be done. Most of the things listed were in my plans for future patches.
I will remind that this ticket has clear scope. Some of items listed in comment above require separate tickets to be created.

In T188614#4045536, @santhosh wrote:

• Need styling as per the ticket.

This requires separate ticket. I don't think this ticket specifies design, there is only one screenshot from mockup to illustrate idea. Design details should be created in separate ticket. @Pginer-WMF, can you provide ticket with design specifics around categories UI?

• Hightlighting the pairs on hover

I have added highlighting support in my latest patch set.

• A heading for the category listing, which will have the tag icon

I will do this when implementing eventual designs.

• Categories are the last item in the column, but since they don't have equal height, the background color differs. And as per design in this ticket, insead of white background is light gray and has a border

I have created ticket to track this issue - T189632.

• If the target category has one autoadapted item, the category count lable at top of the target column shows 'one category'. But when we add or remove items to the target category list, that label is not updated.

Number of target categories label is getting updated after my latest patchset.

I think we need to change the behavior of mw.cx.ui.Categories. Instead of accepting the categories list as constructor, let this class act as a ui component, exposing a public method to add category list after initialization. Any addition, deletion to the category listing of this instance at any point in the lifecycle of instance will update the UI elements. That means, count label get automatically updated. This also means, we can start painting the containers for the UI early if needed. Also, this will make the restoring categories ( T188238: Adapted categories are not saved along with translation ) feature easy.

Making mw.cx.ui.Categories into UI component is exactly what I wanted to do and was keeping that for future patches. But, in efforts to add highlight support and cover all requirements listed in this ticket with one patch, I have done that sooner.

Change 419081 merged by jenkins-bot:
[mediawiki/extensions/ContentTranslation@master] Add category mapping support

https://gerrit.wikimedia.org/r/419081