diff --git a/.env.example b/.env.example
index ff37fbbad..faf548e0c 100644
--- a/.env.example
+++ b/.env.example
@@ -18,7 +18,7 @@ API_PORT=8000
 # Supported languages: en_US, en_GB, zh-Hans, zh-Hant  
 # You can interact with the agent in your preferred language.  
 # This variable is mainly intended for frontend use; setting LANG is not required.
-LANG=en-US
+LANG=en_US
 TIMEZONE=America/New_York
 PYTHONIOENCODING=utf-8
 
diff --git a/frontend/biome.json b/frontend/biome.json
index af0c2fafd..477e5fa44 100644
--- a/frontend/biome.json
+++ b/frontend/biome.json
@@ -58,12 +58,8 @@
           "fix": "safe",
           "level": "error",
           "options": {
-            "attributes": [
-              "className"
-            ],
-            "functions": [
-              "cn"
-            ]
+            "attributes": ["className"],
+            "functions": ["cn"]
           }
         }
       },
@@ -84,4 +80,4 @@
     "enabled": true,
     "useIgnoreFile": true
   }
-}
\ No newline at end of file
+}
diff --git a/frontend/src/root.tsx b/frontend/src/root.tsx
index d97966193..46e301c09 100644
--- a/frontend/src/root.tsx
+++ b/frontend/src/root.tsx
@@ -1,5 +1,7 @@
+import { useEffect, useRef } from "react";
 import { QueryClient, QueryClientProvider } from "@tanstack/react-query";
 import { Links, Meta, Outlet, Scripts, ScrollRestoration } from "react-router";
+import { toast } from "sonner";
 import AppSidebar from "@/components/valuecell/app-sidebar";
 import { Toaster } from "./components/ui/sonner";
 
@@ -42,6 +44,69 @@ const queryClient = new QueryClient({
 });
 
 export default function Root() {
+  const bannerShownRef = useRef(false);
+
+  useEffect(() => {
+    const checkApiConfig = async () => {
+      if (bannerShownRef.current) {
+        return;
+      }
+
+      try {
+        const baseUrl =
+          import.meta.env.VITE_API_BASE_URL || "http://localhost:8000/api/v1";
+
+        const response = await fetch(`${baseUrl}/system/health`, {
+          method: "GET",
+          headers: {
+            "Content-Type": "application/json",
+          },
+        });
+
+        if (!response.ok) {
+          bannerShownRef.current = true;
+          toast.error(
+            "⚠️ No LLM APIs configured. Please set up API keys in your .env file",
+            {
+              duration: Infinity,
+              description:
+                "Add API keys for OpenRouter, SiliconFlow, Google, or OpenAI",
+            }
+          );
+          return;
+        }
+
+        const data = await response.json();
+
+        if (data?.data?.api_configured === false) {
+          bannerShownRef.current = true;
+          toast.error(
+            "⚠️ No LLM APIs configured. Please set up API keys in your .env file",
+            {
+              duration: Infinity,
+              description:
+                "Add API keys for OpenRouter, SiliconFlow, Google, or OpenAI",
+            }
+          );
+        } else if (data?.data?.api_configured === true) {
+          bannerShownRef.current = true;
+        }
+      } catch (_error) {
+        bannerShownRef.current = true;
+        toast.error(
+          "⚠️ No LLM APIs configured. Please set up API keys in your .env file",
+          {
+            duration: Infinity,
+            description:
+              "Add API keys for OpenRouter, SiliconFlow, Google, or OpenAI",
+          }
+        );
+      }
+    };
+
+    checkApiConfig();
+  }, []);
+
   return (
     <QueryClientProvider client={queryClient}>
       <SidebarProvider>
diff --git a/frontend/vite.config.ts b/frontend/vite.config.ts
index bd174d41c..452f47459 100644
--- a/frontend/vite.config.ts
+++ b/frontend/vite.config.ts
@@ -7,7 +7,10 @@ import tsconfigPaths from "vite-tsconfig-paths";
 const host = process.env.TAURI_DEV_HOST;
 
 // https://vite.dev/config/
+
+
 export default defineConfig(async () => ({
+  
   plugins: [
     tailwindcss(),
     reactRouter(),
diff --git a/python/valuecell/server/api/routers/system.py b/python/valuecell/server/api/routers/system.py
index 820a34330..9258ad756 100644
--- a/python/valuecell/server/api/routers/system.py
+++ b/python/valuecell/server/api/routers/system.py
@@ -4,6 +4,8 @@
 
 from fastapi import APIRouter
 
+from valuecell.config.manager import ConfigManager
+
 from ...config.settings import get_settings
 from ..schemas import AppInfoData, HealthCheckData, SuccessResponse
 
@@ -38,8 +40,15 @@ async def get_app_info():
     )
     async def health_check():
         """Service health status check."""
+        config_manager = ConfigManager()
+        enabled_providers = config_manager.get_enabled_providers()
+
         health_data = HealthCheckData(
-            status="healthy", version=settings.APP_VERSION, timestamp=datetime.now()
+            status="healthy",
+            version=settings.APP_VERSION,
+            timestamp=datetime.now(),
+            api_configured=len(enabled_providers) > 0,
+            available_providers=enabled_providers,
         )
         return SuccessResponse.create(
             data=health_data, msg="Service is running normally"
diff --git a/python/valuecell/server/api/schemas/base.py b/python/valuecell/server/api/schemas/base.py
index 6449a5845..b5d4e9c70 100644
--- a/python/valuecell/server/api/schemas/base.py
+++ b/python/valuecell/server/api/schemas/base.py
@@ -2,7 +2,7 @@
 
 from datetime import datetime
 from enum import IntEnum
-from typing import Generic, Optional, TypeVar
+from typing import Generic, List, Optional, TypeVar
 
 from pydantic import BaseModel, Field
 
@@ -73,3 +73,7 @@ class HealthCheckData(BaseModel):
     status: str = Field(..., description="Service status")
     version: str = Field(..., description="Service version")
     timestamp: Optional[datetime] = Field(None, description="Check timestamp")
+    api_configured: bool = Field(..., description="Whether LLM APIs are configured")
+    available_providers: List[str] = Field(
+        default_factory=list, description="List of available LLM providers"
+    )