JSComments Configuration with Discourse

I think I must be missing something incredibly simple: how do I associate a particular post in Grav with a particular thread in Discourse?

The twig to enable comments is in my template theme (a customized Antimatter child), comments are enabled, and the provider is set to Discourse with the appropriate URL. My pages load the URL stating comments are powered by Discourse.

I tried overriding the URL on a blog post with a thread, but there is nothing appearing.

What else do I need to feed the plugin so the appropriate thread’s comments are loaded?