diff --git a/packages/web/vite.config.ts b/packages/web/vite.config.ts
index ecc3db7e..49c30e3c 100644
--- a/packages/web/vite.config.ts
+++ b/packages/web/vite.config.ts
@@ -1,40 +1,60 @@
-import { defineConfig } from 'vite'
+import { defineConfig, loadEnv } from 'vite'
 import vue from '@vitejs/plugin-vue'
 import { resolve } from 'path'
 import path from 'path'
+import { DEFAULT_VITE_ENV } from '../core/src/utils/default-env'
 
 // https://vitejs.dev/config/
-export default defineConfig({
-  plugins: [vue()],
-  server: {
-    port: 18181,
-    host: true,
-    fs: {
-      // 允许为工作区依赖提供服务
-      allow: ['..']
-    },
-    hmr: true,
-    watch: {
-      // 确保监视monorepo中其他包的变化
-      ignored: ['!**/node_modules/@prompt-optimizer/**']
-    }
-  },
-  build: {
-    rollupOptions: {
-      input: {
-        main: resolve(__dirname, 'index.html')
+export default defineConfig(({ mode }) => {
+  const monorepoRoot = resolve(__dirname, '../..')
+  const env = loadEnv(mode, monorepoRoot)
+  const processEnv = {
+    ...DEFAULT_VITE_ENV,
+    ...env,
+  }
+
+  return {
+    envDir: monorepoRoot,
+    plugins: [vue()],
+    server: {
+      port: 18181,
+      host: true,
+      fs: {
+        // 允许为工作区依赖提供服务
+        allow: ['..']
+      },
+      hmr: true,
+      watch: {
+        // 确保监视monorepo中其他包的变化
+        ignored: ['!**/node_modules/@prompt-optimizer/**']
+      }
+    },
+    build: {
+      rollupOptions: {
+        input: {
+          main: resolve(__dirname, 'index.html')
+        }
+      }
+    },
+    publicDir: 'public',
+    resolve: {
+      preserveSymlinks: true,
+      alias: {
+        '@': resolve(__dirname, 'src'),
+        '@prompt-optimizer/core': path.resolve(__dirname, '../core'),
+        '@prompt-optimizer/ui': path.resolve(__dirname, '../ui'),
+        '@prompt-optimizer/web': path.resolve(__dirname, '../web'),
+        '@prompt-optimizer/extension': path.resolve(__dirname, '../extension')
+      }
+    },
+    define: {
+      'process.env': {
+        NODE_ENV: JSON.stringify(process.env.NODE_ENV || 'development'),
+        ...Object.keys(processEnv).reduce((acc, key) => {
+          acc[key] = processEnv[key as keyof typeof processEnv]
+          return acc
+        }, {} as Record<string, string>)
       }
-    }
-  },
-  publicDir: 'public',
-  resolve: {
-    preserveSymlinks: true,
-    alias: {
-      '@': resolve(__dirname, 'src'),
-      '@prompt-optimizer/core': path.resolve(__dirname, '../core'),
-      '@prompt-optimizer/ui': path.resolve(__dirname, '../ui'),
-      '@prompt-optimizer/web': path.resolve(__dirname, '../web'),
-      '@prompt-optimizer/extension': path.resolve(__dirname, '../extension')
     }
   }
 })
diff --git a/scripts/package-scripts.test.mjs b/scripts/package-scripts.test.mjs
index 947884de..64ecd219 100644
--- a/scripts/package-scripts.test.mjs
+++ b/scripts/package-scripts.test.mjs
@@ -61,6 +61,21 @@ test('web and extension package typecheck scripts use isolated tsconfig files',
   assert.match(extensionTypecheckConfig.include.join(' '), /\benv\.d\.ts\b/)
 })
 
+test('web dev loads root env while extension build stays isolated from root env', () => {
+  const webViteConfig = fs.readFileSync(path.join(process.cwd(), 'packages', 'web', 'vite.config.ts'), 'utf8')
+  const extensionViteConfig = fs.readFileSync(path.join(process.cwd(), 'packages', 'extension', 'vite.config.ts'), 'utf8')
+
+  assert.match(webViteConfig, /loadEnv\(mode,\s*monorepoRoot\)/)
+  assert.match(webViteConfig, /envDir:\s*monorepoRoot/)
+  assert.match(webViteConfig, /DEFAULT_VITE_ENV/)
+  assert.match(webViteConfig, /'process\.env'/)
+
+  assert.doesNotMatch(extensionViteConfig, /loadEnv\(mode,\s*monorepoRoot\)/)
+  assert.doesNotMatch(extensionViteConfig, /envDir:\s*monorepoRoot/)
+  assert.doesNotMatch(extensionViteConfig, /DEFAULT_VITE_ENV/)
+  assert.doesNotMatch(extensionViteConfig, /'process\.env'/)
+})
+
 test('mcp-server bin points to a file that exists before build output is generated', () => {
   const mcpPackagePath = path.join('packages', 'mcp-server', 'package.json')
   const mcpPackage = readJson(mcpPackagePath)