Index: src/routes/posts.js
===================================================================
--- src/routes/posts.js	(revision c74565987caf12d910b2fb8dd439042dd0e2f94f)
+++ src/routes/posts.js	(revision 3289a6433bf12cccc844824d53d4f353853ef2f0)
@@ -1022,6 +1022,9 @@
       ActivityPubService.setInteractionBoosted(parent.id, on);
     } else {
-      ActivityPubService.sendInteraction(site, 'like', parent.object_uri, parent.actor_uri)
+      // Toggle: like an unliked comment, or un-favourite (Undo Like) if already liked.
+      const on = !parent.acted_like;
+      ActivityPubService.sendInteraction(site, on ? 'like' : 'unlike', parent.object_uri, parent.actor_uri)
         .catch((e) => console.warn('[AP] reaction failed:', e.message));
+      ActivityPubService.setInteractionLiked(parent.id, on);
     }
   }