Don't block desktop app on backend starting up (#5041)

# Description of Changes
Start bundled backend instantly on startup of app and don't wait on it
being fully up to spawn app. This is techincally wasteful curently on
self-hosted mode where everything runs remotely, but in the future we'll
probably route simple operations to the local machine regardless of
connection, and it stops unnecessary waiting in the offline mode.

frontend/src-tauri/src/commands/backend.rs

@@ -398,10 +398,6 @@ pub async fn start_backend(
         e
     })?;
 
-    // Wait for the backend to start
-    println!("⏳ Waiting for backend startup...");
-    tokio::time::sleep(std::time::Duration::from_millis(10000)).await;
-
     // Reset the starting flag since startup is complete
     reset_starting_flag();
     add_log("✅ Backend startup sequence completed, starting flag cleared".to_string());

frontend/src-tauri/src/lib.rs

@@ -66,7 +66,7 @@ pub fn run() {
       // Emit a generic notification that files were added (frontend will re-read storage)
       let _ = app.emit("files-changed", ());
     }))
-    .setup(|_app| {
+    .setup(|app| {
       add_log("🚀 Tauri app setup started".to_string());
 
       // Process command line arguments on first launch
@@ -78,6 +78,17 @@ pub fn run() {
         }
       }
 
+      // Start backend immediately, non-blocking
+      let app_handle = app.handle().clone();
+
+      tauri::async_runtime::spawn(async move {
+        add_log("🚀 Starting bundled backend in background".to_string());
+        let connection_state = app_handle.state::<AppConnectionState>();
+        if let Err(e) = commands::backend::start_backend(app_handle.clone(), connection_state).await {
+          add_log(format!("⚠️ Backend start failed: {}", e));
+        }
+      });
+
       add_log("🔍 DEBUG: Setup completed".to_string());
       Ok(())
     })

frontend/src/desktop/components/AppProviders.tsx

@@ -31,10 +31,10 @@ export function AppProviders({ children }: { children: ReactNode }) {
     }
   }, [setupComplete, isFirstLaunch, connectionMode]);
 
-  // Only start bundled backend if in SaaS mode (local backend) and setup is complete
-  // Self-hosted mode connects to remote server so doesn't need local backend
-  const shouldStartBackend = setupComplete && !isFirstLaunch && connectionMode === 'saas';
-  useBackendInitializer(shouldStartBackend);
+  // Initialize monitoring for bundled backend (already started in Rust)
+  // This sets up port detection and health checks
+  const shouldMonitorBackend = setupComplete && !isFirstLaunch && connectionMode === 'saas';
+  useBackendInitializer(shouldMonitorBackend);
 
   // Show setup wizard on first launch
   if (isFirstLaunch && !setupComplete) {
@@ -51,23 +51,7 @@ export function AppProviders({ children }: { children: ReactNode }) {
         }}
       >
         <SetupWizard
-          onComplete={async () => {
-            // Wait for backend to become healthy before reloading
-            // This prevents reloading mid-startup which would interrupt the backend
-            const maxWaitTime = 60000; // 60 seconds max
-            const checkInterval = 1000; // Check every second
-            const startTime = Date.now();
-
-            while (Date.now() - startTime < maxWaitTime) {
-              if (tauriBackendService.isBackendHealthy()) {
-                window.location.reload();
-                return;
-              }
-              await new Promise(resolve => setTimeout(resolve, checkInterval));
-            }
-
-            // If we timeout, reload anyway
-            console.warn('[AppProviders] Backend health check timeout, reloading anyway...');
+          onComplete={() => {
             window.location.reload();
           }}
         />

frontend/src/desktop/components/SetupWizard/index.tsx

@@ -61,7 +61,7 @@ export const SetupWizard: React.FC<SetupWizardProps> = ({ onComplete }) => {
       }
 
       await connectionModeService.switchToSaaS(serverConfig.url);
-      await tauriBackendService.startBackend();
+      tauriBackendService.startBackend().catch(console.error);
       onComplete();
     } catch (err) {
       console.error('SaaS login failed:', err);