As of v0.21.0 [[ https://doc.wikimedia.org/oojs-ui/master/demos/#widgets-mediawiki-ltr-desktop | TagMultiselectWidget ]] has landed in OOjs UI.
Current variants/options have oriented on requirements of new RCFilters, existing CapsuleMultiselectWidget and it's usage in production like [[ https://en.wikipedia.org/wiki/Special:ApiSandbox#action=query&format=json&prop=revisions&rvlimit=99999 | API:Sandbox ]].
With CapsuleMultiselectWidget there's already existing a tracking task, {T119044}, with several shortcomings that need to be considered for the new TagMultiselectWidget, if applicable.
Issues at point of filing:
[] Add TagMultiselectWidget to comparison table at {T158400} and identify shortcomings
[] Aligning padding, min-height and text input position of the widget(s) to all other widgets (last two missing ones)
[] Replacing remove icon with normal remove icon and add breathing space https://gerrit.wikimedia.org/r/#/c/341494/
[x] TagMultiselectWidget inputPosition:outline resembles TextInputWidget, although it's just a readonly container. Also not perfect connection to input. ⇒T163126
[] Is appearance of invalid tags clear?
[] Appearance of remove indicator and spacing around it
[] Define clear (visual) indication of draggable tags
[] PopupTagMultiselectWidget a good idea from UX standpoint?
[] If tags are editable in single-line input, make it easily understandable for users