feat: add dotenv-flow for environment variable management in serve command

Author: hotlong

.gitignore

@@ -87,3 +87,7 @@ next-env.d.ts
 apps/*/. source/
 apps/*/.next/docs/
 .turbo
+
+# Local env overrides (may contain secrets)
+.env.local
+.env.*.local

packages/cli/package.json

@@ -49,6 +49,7 @@
     "@oclif/core": "^4.9.0",
     "bundle-require": "^5.1.0",
     "chalk": "^5.3.0",
+    "dotenv-flow": "^4.1.0",
     "tsx": "^4.7.1",
     "zod": "^4.3.6"
   },

packages/cli/src/commands/serve.ts

@@ -23,6 +23,7 @@ import {
   hasStudioDist,
   createStudioStaticPlugin,
 } from '../utils/studio.js';
+import dotenvFlow from 'dotenv-flow';
 
 // Helper to find available port
 const getAvailablePort = async (startPort: number): Promise<number> => {
@@ -76,6 +77,12 @@ export default class Serve extends Command {
       // Ignore error and try with original port
     }
 
+    // Load .env files following Vite/Next.js convention
+    const mode = flags.dev ? 'development'
+      : (process.env.NODE_ENV === 'test' ? 'test'
+        : (process.env.NODE_ENV || 'production'));
+    dotenvFlow.config({ node_env: mode, silent: true });
+
     const isDev = flags.dev || process.env.NODE_ENV === 'development';
 
     const absolutePath = path.resolve(process.cwd(), args.config!);