I’ve reactivated the Discourse Phabricator project (and added some more notes to its description), and will start working through the deployment checklist.
I feel like the caching of Discourse data on the MediaWiki side might be the tricky stuff; we have to find a balance between it staying up to date, and it not making too many requests to Discourse. Currently, it allows any URL path, and caches the response for an hour. But anyway, that can be discussed elsewhere.
I think the basic extension functionality is done. Probably T215053 can be closed, and we’ve got T313375 for tracking work to be done for deployment.
Deploying to Wikimedia wikis is unlikely at the moment, I think, but we could perhaps look at connecting Wikispore, if that’s a good idea? So that we can start experimenting with how Discourse can best work alongside MediaWiki.