restore topic subscription after a reconnect

src/views/messages-view.jsx

@@ -326,6 +326,9 @@ class MessagesView extends React.Component {
       } else if (topic.isSubscribed() && this.state.isReader && !prevState.isReader) {
         // If reader status has changed and data became available.
         topic.getMeta(topic.startMetaQuery().withLaterData().build());
+      } else if (!topic.isSubscribed() && this.props.ready && !prevProps.ready) {
+        // Connection restored (e.g. wake from sleep): resubscribe to the currently open topic.
+        this.subscribe(topic);
       }
     }
   }

src/views/tinode-web.jsx

@@ -853,7 +853,9 @@ class TinodeWeb extends React.Component {
       LocalStorageUtil.setObject('auth-token', this.tinode.getAuthToken());
     }
 
-    const goToTopic = this.state.requestedTopic;
+    // On reconnect, requestedTopic is undefined but topicSelected may still be set.
+    // Preserve the open topic so it gets restored after re-login.
+    const goToTopic = this.state.requestedTopic || this.state.topicSelected;
     // Logged in fine, subscribe to 'me' attaching callbacks from the contacts view.
     const me = this.tinode.getMeTopic();
     me.onMetaDesc = this.tnMeMetaDesc;