Handle groups being joined and left

src/components/structures/TagPanel.js

@@ -60,6 +60,7 @@ const TagPanel = React.createClass({
 
             const orderedTags = TagOrderStore.getOrderedTags() || [];
             const orderedGroupTags = orderedTags.filter((t) => t[0] === '+');
+            // XXX: One profile lookup failing will bring the whole lot down
             Promise.all(orderedGroupTags.map(
                 (groupId) => FlairStore.getGroupProfileCached(this.context.matrixClient, groupId),
             )).then((orderedGroupTagProfiles) => {

src/stores/TagOrderStore.js

@@ -97,11 +97,28 @@ class TagOrderStore extends Store {
 
     _updateOrderedTags() {
         this._setState({
-            orderedTags: this._state.hasSynced && this._state.hasFetchedJoinedGroups ?
+            orderedTags:
-                this._state.orderedTagsAccountData || this._state.joinedGroupIds : null,
+                this._state.hasSynced &&
+                this._state.hasFetchedJoinedGroups ?
+                    this._mergeGroupsAndTags() : null,
         });
     }
 
+    _mergeGroupsAndTags() {
+        const groupIds = this._state.joinedGroupIds || [];
+        const tags = this._state.orderedTagsAccountData || [];
+
+        const tagsToKeep = tags.filter(
+            (t) => t[0] !== '+' || groupIds.includes(t),
+        );
+
+        const groupIdsToAdd = groupIds.filter(
+            (groupId) => !tags.includes(groupId),
+        );
+
+        return tagsToKeep.concat(groupIdsToAdd);
+    }
+
     getOrderedTags() {
         return this._state.orderedTags;
     }