There are two test stubs that need completing. Notes in patch description of https://gerrit.wikimedia.org/r/c/mediawiki/extensions/WikiLambda/+/872977/

As per https://phabricator.wikimedia.org/T322132, we are no longer showing example links for names & aliases.

This copy no longer shows as it was replaced by the Publish Component.

The z-object-selector is more generic and can handle any kind of change in its parent (eg a changeType, adding a language etc). However, how z-object-selector is implemented in ZImplementation it is indeed the same as a z-reference update (updating setZObjectValue). So it could be refactored, and then yes I agree even further refactored as per your suggestion above.
@JKieserman to confirm all please!

This has been solved by https://gerrit.wikimedia.org/r/c/mediawiki/extensions/WikiLambda/+/861917

And to answer your question @Teleosteen, yes this is a duplicate of T323381

So sorry @Teleosteen , didn't see you had claimed this before I worked on it! I have a patch attached above, hope there wasn't double work done. Feel free to share if you had come up with something else, it might be cleaner than mine.. :) was a bit of a messy problem. If not, then I will add some tests to the above, or you may!

I have created the above patch if we are happy to move forward with the space bar not opening the menu.
If it's preferred to go the other route of additional logic to handle the edge case, I can update the patch.

I'm assuming a codex component is preferable? I only currently see a progress bar available for loading. @AAlhazwani-WMF any thoughts?

I was unable to reproduce in local, as was jkieserman@.

Do you mean the z-object editor? I believe the function-editor Publish button is reactive as soon as you start typing in any box. The "labels" boxes on the z-object editor however are not, but that appears to be true for the value appearing in the "Current ZObject" tree on the right too - it only appears once you click out of the box. I'm assuming the preferred behavior is for it to appear as it is typed? I can look into that.

Resolved in https://gerrit.wikimedia.org/r/c/mediawiki/extensions/WikiLambda/+/859553

I believe this is due to the implemented functionality of the Codex Lookup.vue component [1]. For accessibility, the space bar will open the the dropdown menu if it is not already open, otherwise it will act as a regular space bar. This means when you try to add a space in your text in the short time between beginning to type and results populating the dropdown, the space bar won't add a space into the text, but will open the menu.

Document: Displaying zObject revision diffs
(Not a full design, but laying out some findings and high-level proposal)

Thank you all for the input! I am going to go ahead and mark this ticket as resolved.

I have handled 2. It seems it was accidentally removed in a previous patch.

@JKieserman this appears to be the current behavior. Please could you check on your end, and confirm if it is/isn't behaving as such?

This was fixed by https://gerrit.wikimedia.org/r/c/mediawiki/extensions/WikiLambda/+/858385.

Not sure this is possible with needing the string to be internationalized

This is true of testers with no labels too, and should be implemented similarly.

Also as part of this, we should allow for the deletion of the first argument since we allow no argument functions. Currently (on mobile), only deletion of the second+ argument is possible.

An additional issue with the no label, is how the implementation shows in the testers table. (Displays the class)

This has been implemented for the Special: Evaluate Function Call page but not for where it is embedded in other pages.