[mcp-ui-server]: fix env variable loading in vite-node dev mode

Author: eliotjlee

demo/mcp-ui-server/package.json

@@ -1,13 +1,13 @@
 {
-  "name": "option-selector-mcp",
+  "name": "acp-mcp-ui-server",
   "version": "1.0.0",
   "type": "module",
-  "description": "MCP-UI server with interactive option selection",
+  "description": "MCP-UI server for ACP demo",
   "main": "dist/index.js",
   "scripts": {
     "build": "tsc",
     "start": "node dist/index.js",
-    "dev": "vite-node src/index.ts"
+    "dev": "NODE_OPTIONS='-r dotenv/config' vite-node src/index.ts"
   },
   "keywords": ["mcp", "mcp-ui", "commerce", "acp"],
   "author": "Locus <info@paywithlocus.com>",

demo/mcp-ui-server/src/routes/payment.ts

@@ -2,7 +2,7 @@ import { Express } from 'express';
 import { MerchantSessionService } from '../services/MerchantSessionService.js';
 import { Logger } from '../utils/logger.js';
 
-const MERCHANT_URL = process.env.MERCHANT_BASE_URL || 'http://localhost:3000';
+const MERCHANT_URL = process.env.MERCHANT_BASE_URL || 'http://localhost:4001';
 const PSP_URL = process.env.PSP_BASE_URL || 'http://localhost:4000';
 const MERCHANT_API_KEY = process.env.MERCHANT_API_KEY || 'test_api_key_123';
 const MERCHANT_API_VERSION = process.env.MERCHANT_API_VERSION || '2025-09-29';