Show categories on the user streams for topics.

app/assets/javascripts/discourse/models/user_action.js

@@ -30,6 +30,13 @@ _.each(UserActionTypes, function (k, v) {
 
 Discourse.UserAction = Discourse.Model.extend({
 
+  _attachCategory: function() {
+    var categoryId = this.get('category_id');
+    if (categoryId) {
+      this.set('category', Discourse.Category.findById(categoryId));
+    }
+  }.on('init'),
+
   /**
     Return an i18n key we will use for the description text of a user action.
 

app/assets/javascripts/discourse/templates/user/stream.js.handlebars

@@ -5,6 +5,7 @@
       <span class='time'>{{unboundDate path="created_at" leaveAgo="true"}}</span>
       <span class="title">
         <a href="{{unbound postUrl}}">{{unbound title}}</a>
+        {{categoryLink category}}
       </span>
       <span class="type">{{unbound descriptionHtml}}</span>
     </div>

app/models/user_action.rb

@@ -116,7 +116,8 @@ SELECT
   CASE WHEN coalesce(p.deleted_at, p2.deleted_at, t.deleted_at) IS NULL THEN false ELSE true END deleted,
   p.hidden,
   p.post_type,
-  p.edit_reason
+  p.edit_reason,
+  t.category_id
 FROM user_actions as a
 JOIN topics t on t.id = a.target_topic_id
 LEFT JOIN posts p on p.id = a.target_post_id

app/serializers/user_action_serializer.rb

@@ -22,7 +22,8 @@ class UserActionSerializer < ApplicationSerializer
              :deleted,
              :hidden,
              :moderator_action,
-             :edit_reason
+             :edit_reason,
+             :category_id
 
   def excerpt
     PrettyText.excerpt(object.cooked, 300) if object.cooked