fix: langfuse MockObservation crash, mobile preview mockup overflow, and early preview loading

- Fix MockObservation.start_span/start_generation using positional param that
  mismatched callers using name= keyword arg (crashed all agent runs when
  Langfuse disabled)
- Reduce iPhone/Android mockup screenWidth from 300→250 and tighten padding
  so the phone frame fits within the viewport without bottom cutoff
- Show mobile preview (QR code + phone mockup) while agent is still running
  so Expo bundler can start loading earlier
- Add Inngest dev server to docker-compose.dev.yml for local development

Author: iamjr15

backend/services/langfuse.py

@@ -25,10 +25,10 @@ def update(self, **_kwargs) -> "MockObservation":
     def end(self, **kwargs) -> None:
         pass
 
-    def start_span(self, _name: str, **_kwargs) -> "MockObservation":
+    def start_span(self, name: str = "", **_kwargs) -> "MockObservation":
         return MockObservation()
 
-    def start_generation(self, _name: str, **_kwargs) -> "MockObservation":
+    def start_generation(self, name: str = "", **_kwargs) -> "MockObservation":
         return MockObservation()
 
     def event(self, name: str, **kwargs) -> None:

docker-compose.dev.yml

@@ -15,9 +15,14 @@ services:
       - ENV_MODE=local
       - REDIS_URL=redis://redis:6379
       - PYTHONUNBUFFERED=1
+      - INNGEST_DEV=1
+      - INNGEST_BASE_URL=http://inngest:8288
+      - INNGEST_SERVE_ORIGIN=http://backend:8000
     depends_on:
       redis:
         condition: service_healthy
+      inngest:
+        condition: service_started
     networks:
       - dev-network
     dns:
@@ -47,6 +52,17 @@ services:
       - 8.8.8.8
       - 8.8.4.4
 
+  # Inngest Dev Server (local function invocation)
+  inngest:
+    image: inngest/inngest:latest
+    ports:
+      - "8288:8288"
+    environment:
+      - INNGEST_LOG_LEVEL=info
+    networks:
+      - dev-network
+    command: inngest dev -u http://backend:8000/api/inngest
+
   # Redis
   redis:
     image: redis:8-alpine

frontend/src/components/thread/app-preview-side-panel.tsx

@@ -87,11 +87,13 @@ export function AppPreviewSidePanel({
   const { onOpen } = useModal();
 
   // Show loading screen when agent is actively building OR no preview URL available
-  // But prioritize showing preview if URL exists and agent isn't actively modifying code
+  // For mobile: show preview early (QR code + phone mockup) even while agent runs,
+  // since Expo bundler needs time and the QR code is useful immediately
+  const isMobileApp = project?.app_type === 'mobile';
   const shouldShowLoadingScreen =
     (!previewUrl.previewUrl ||
-      agentStatus === 'running' ||
-      agentStatus === 'connecting') &&
+      (agentStatus === 'running' && !isMobileApp) ||
+      (agentStatus === 'connecting' && !isMobileApp)) &&
     (activeMainTab === 'preview' || !previewUrl.previewUrl);
 
   // Switch to preview tab when loading starts if user is on code tab

frontend/src/components/thread/components/MobilePreviewTab.tsx

@@ -101,17 +101,17 @@ export const MobilePreviewTab: React.FC<MobilePreviewTabProps> = ({
   return (
     <div className="h-full overflow-y-auto flex flex-col lg:flex-row bg-zinc-50 dark:bg-background">
       {/* Phone Preview Area */}
-      <div className="flex-1 flex items-center justify-center p-8 lg:p-12 relative">
+      <div className="flex-1 flex items-center justify-center p-4 lg:p-6 relative min-h-0">
         {/* Background Pattern */}
         <div className="absolute inset-0 bg-grid-zinc-200/50 dark:bg-grid-zinc-800/20 [mask-image:radial-gradient(ellipse_at_center,black,transparent_75%)] pointer-events-none" />
 
         <div className="relative z-10 transform transition-transform duration-500 hover:scale-[1.02]">
           {selectedPlatform === 'ios' ? (
-            <IPhoneMockup screenWidth={300} screenType="island">
+            <IPhoneMockup screenWidth={250} screenType="island">
               {renderMockupContent()}
             </IPhoneMockup>
           ) : (
-            <AndroidMockup screenWidth={300}>
+            <AndroidMockup screenWidth={250}>
               {renderMockupContent()}
             </AndroidMockup>
           )}