Have you tried the "Improved Syntax Highlighting" beta feature? All extension tags should already be foldable.

I was chatting with Novem when he wrote this task. I think he was basically asking for the "especially refs" part of T381574: Collapse tags, especially refs in CodeMirror :)

See also T384908: Highlight reference contents differently than other extension tags which I hope to complete soon.

There's plenty of room for CodeMirror preferences to grow, but I'll need to finish up that dialog that I started at the Hackathon. I've filed T393664: The CodeMirror preferences panel can obstruct the editor and expanded on the idea.

Keyboard shortcuts for folding templates also work for extension tags. I do not like the idea of an extra set of shortcuts.

The use-case is that they want to read prose, but hide references. Some prose is in templates (such as blockquotes, or pretty much all of Wikisource – though they don't use references as much). There's now two requests for this, and I know I'd use it as well. Do we think it is technically complex, or are your concerns purely product-related?

At any rate, I think T384908 will help the situation, once I get around to it. Perhaps once that's done, this task will be of lesser importance.

Change #1156280 had a related patch set uploaded (by Bhsd; author: Bhsd):

[mediawiki/extensions/CodeMirror@master] foldKeymap: `Ctrl-Shift-,` to fold all <ref> tags only

https://gerrit.wikimedia.org/r/1156280

Change #1156280 merged by jenkins-bot:

[mediawiki/extensions/CodeMirror@master] foldKeymap: `Ctrl-Shift-,` to fold all <ref> tags only

https://gerrit.wikimedia.org/r/1156280