What query to award a badge for liking or replying to a particular topic?

[satonotdead]

That should help:

A badge granted when someone posts a reply in a single specified topic

SELECT DISTINCT ON (p.user_id) p.user_id, p.id post_id, p.created_at granted_at FROM badge_posts p WHERE p.topic_id = 32 AND -- 32 is the "please introduce yourself" topic (:backfill OR p.id IN (:post_ids) ) Triggered on “edit/create a post”.