What Ember.js version does Discourse use?

I’ve started going through the plugin guide, which links to the Ember 2.13 docs.

Ember is currently up to version 3.26, so I’m a bit confused. In /app/assets/javascripts/discourse/package.json I see this:

"ember": {
    "edition": "default"
}

But in some of other places like discourse-common, I see this:

"ember": {
    "edition": "octane"
}

So, is the plugin guide outdated or can I use either version?

Discourse is currently on 3.12.2, however we are about to start rapidly upgrading towards octane. Those JSON files you are seeing are sub projects from our Ember CLI build