feat(project-subscribers): implement project subscriber management and loading state

- Added `getProjectSubscribers` method in `TasksControllerV2` to retrieve project subscribers with user details.
- Updated socket command to handle project subscription changes, ensuring no duplicate entries on conflict.
- Enhanced `ProjectViewHeader` to manage subscription loading state, providing user feedback during subscription updates.
- Implemented error handling and timeout for subscription requests to improve user experience.

worklenz-backend/src/controllers/tasks-controller-v2.ts

@@ -610,6 +610,21 @@ export default class TasksControllerV2 extends TasksControllerBase {
     return this.createTagList(result.rows);
   }
 
+  public static async getProjectSubscribers(projectId: string) {
+    const q = `
+      SELECT u.name, u.avatar_url, ps.user_id, ps.team_member_id, ps.project_id
+      FROM project_subscribers ps
+             LEFT JOIN users u ON ps.user_id = u.id
+      WHERE ps.project_id = $1;
+    `;
+    const result = await db.query(q, [projectId]);
+
+    for (const member of result.rows)
+      member.color_code = getColor(member.name);
+
+    return this.createTagList(result.rows);
+  }
+
   public static async checkUserAssignedToTask(taskId: string, userId: string, teamId: string) {
     const q = `
     SELECT EXISTS(

worklenz-backend/src/socket.io/commands/on-project-subscriber-change.ts

@@ -19,7 +19,8 @@ export async function on_project_subscriber_change(_io: Server, socket: Socket,
     const isSubscribe = data.mode == 0;
     const q = isSubscribe
       ? `INSERT INTO project_subscribers (user_id, project_id, team_member_id)
-         VALUES ($1, $2, $3);`
+         VALUES ($1, $2, $3)
+         ON CONFLICT (user_id, project_id, team_member_id) DO NOTHING;`
       : `DELETE
          FROM project_subscribers
          WHERE user_id = $1
@@ -27,7 +28,7 @@ export async function on_project_subscriber_change(_io: Server, socket: Socket,
            AND team_member_id = $3;`;
     await db.query(q, [data.user_id, data.project_id, data.team_member_id]);
 
-    const subscribers = await TasksControllerV2.getTaskSubscribers(data.project_id);
+    const subscribers = await TasksControllerV2.getProjectSubscribers(data.project_id);
     socket.emit(SocketEvents.PROJECT_SUBSCRIBERS_CHANGE.toString(), subscribers);
 
     return;

worklenz-frontend/src/pages/projects/projectView/project-view-header.tsx

@@ -67,6 +67,7 @@ const ProjectViewHeader = () => {
   const { loadingGroups, groupBy } = useAppSelector(state => state.taskReducer);
 
   const [creatingTask, setCreatingTask] = useState(false);
+  const [subscriptionLoading, setSubscriptionLoading] = useState(false);
 
   const handleRefresh = () => {
     if (!projectId) return;
@@ -98,17 +99,51 @@ const ProjectViewHeader = () => {
   };
 
   const handleSubscribe = () => {
-    if (selectedProject?.id) {
+    if (!selectedProject?.id || !socket || subscriptionLoading) return;
+    
+    try {
+      setSubscriptionLoading(true);
       const newSubscriptionState = !selectedProject.subscribed;
 
-      dispatch(setProject({ ...selectedProject, subscribed: newSubscriptionState }));
-
-      socket?.emit(SocketEvents.PROJECT_SUBSCRIBERS_CHANGE.toString(), {
+      // Emit socket event first, then update state based on response
+      socket.emit(SocketEvents.PROJECT_SUBSCRIBERS_CHANGE.toString(), {
         project_id: selectedProject.id,
         user_id: currentSession?.id,
         team_member_id: currentSession?.team_member_id,
-        mode: newSubscriptionState ? 1 : 0,
+        mode: newSubscriptionState ? 0 : 1, // Fixed: 0 for subscribe, 1 for unsubscribe
       });
+
+      // Listen for the response to confirm the operation
+      socket.once(SocketEvents.PROJECT_SUBSCRIBERS_CHANGE.toString(), (response) => {
+        try {
+          // Update the project state with the confirmed subscription status
+          dispatch(setProject({ 
+            ...selectedProject, 
+            subscribed: newSubscriptionState 
+          }));
+        } catch (error) {
+          logger.error('Error handling project subscription response:', error);
+          // Revert optimistic update on error
+          dispatch(setProject({ 
+            ...selectedProject, 
+            subscribed: selectedProject.subscribed 
+          }));
+        } finally {
+          setSubscriptionLoading(false);
+        }
+      });
+
+      // Add timeout in case socket response never comes
+      setTimeout(() => {
+        if (subscriptionLoading) {
+          setSubscriptionLoading(false);
+          logger.error('Project subscription timeout - no response from server');
+        }
+      }, 5000);
+
+    } catch (error) {
+      logger.error('Error updating project subscription:', error);
+      setSubscriptionLoading(false);
     }
   };
 
@@ -239,6 +274,7 @@ const ProjectViewHeader = () => {
       <Tooltip title={t('subscribe')}>
         <Button
           shape="round"
+          loading={subscriptionLoading}
           icon={selectedProject?.subscribed ? <BellFilled /> : <BellOutlined />}
           onClick={handleSubscribe}
         >