API for syncing added/removed posts after a discussion is updated

js/forum/src/utils/post-stream.js

@@ -131,6 +131,18 @@ export default class PostStream {
     });
   }
 
+  sync() {
+    var discussion = this.discussion;
+
+    var addedPosts = discussion.addedPosts();
+    addedPosts && addedPosts.forEach(this.addPostToEnd.bind(this));
+    discussion.pushData({links: {addedPosts: null}});
+
+    var removedPosts = discussion.removedPosts();
+    removedPosts && removedPosts.forEach(this.removePost.bind(this));
+    discussion.pushData({removedPosts: null});
+  }
+
   makeItem(start, end, post) {
     var item = {start, end}
     if (post) {

js/lib/models/discussion.js

@@ -78,8 +78,8 @@ class Discussion extends Model {
     var title = prompt('Enter a new title for this discussion:', currentTitle);
     if (title && title !== currentTitle) {
       this.save({title}).then(discussion => {
-        if (app.current.discussion && app.current.discussion().id() === discussion.id()) {
+        if (app.current instanceof DiscussionPage) {
-          discussion.addedPosts().forEach(post => app.current.stream().addPostToEnd(post));
+          app.current.stream().sync();
         }
         m.redraw();
       });