Make vite work out-of-the-box for simple-host (#33)

examples/simple-host/index.html

@@ -0,0 +1 @@
+<meta http-equiv="refresh" content="0; url=/example-host-react.html">

examples/simple-host/package.json

@@ -4,9 +4,9 @@
   "version": "1.0.0",
   "type": "module",
   "scripts": {
-    "start": "NODE_ENV=development npm run build && concurrently 'npm run start:server'",
+    "start": "vite dev",
-    "start:server": "bun serve.ts",
+    "start:server": "vite preview",
-    "build": "concurrently 'INPUT=example-host-vanilla.html vite build' 'INPUT=example-host-react.html vite build' 'INPUT=sandbox.html vite build'"
+    "build": "vite build"
   },
   "dependencies": {
     "@modelcontextprotocol/ext-apps": "../..",

examples/simple-host/serve.ts

@@ -1,80 +0,0 @@
-#!/usr/bin/env npx tsx
-/**
- * HTTP servers for the MCP UI example:
- * - Host server (port 8080): serves host HTML files (React and Vanilla examples)
- * - Sandbox server (port 8081): serves sandbox.html with permissive CSP
- *
- * Running on separate ports ensures proper origin isolation for security.
- */
-
-import express from "express";
-import cors from "cors";
-import { fileURLToPath } from "url";
-import { dirname, join } from "path";
-
-const __filename = fileURLToPath(import.meta.url);
-const __dirname = dirname(__filename);
-
-const HOST_PORT = parseInt(process.env.HOST_PORT || "8080", 10);
-const SANDBOX_PORT = parseInt(process.env.SANDBOX_PORT || "8081", 10);
-const DIRECTORY = join(__dirname, "dist");
-
-// ============ Host Server (port 8080) ============
-const hostApp = express();
-hostApp.use(cors());
-
-// Exclude sandbox.html from host server
-hostApp.use((req, res, next) => {
-  if (req.path === "/sandbox.html") {
-    res.status(404).send("Sandbox is served on a different port");
-    return;
-  }
-  next();
-});
-
-hostApp.use(express.static(DIRECTORY));
-
-hostApp.get("/", (_req, res) => {
-  res.redirect("/example-host-react.html");
-});
-
-// ============ Sandbox Server (port 8081) ============
-const sandboxApp = express();
-sandboxApp.use(cors());
-
-// Permissive CSP for sandbox content
-sandboxApp.use((_req, res, next) => {
-  const csp = [
-    "default-src 'self'",
-    "img-src * data: blob: 'unsafe-inline'",
-    "style-src * blob: data: 'unsafe-inline'",
-    "script-src * blob: data: 'unsafe-inline' 'unsafe-eval'",
-    "connect-src *",
-    "font-src * blob: data:",
-    "media-src * blob: data:",
-    "frame-src * blob: data:",
-  ].join("; ");
-  res.setHeader("Content-Security-Policy", csp);
-  res.setHeader("Cache-Control", "no-cache, no-store, must-revalidate");
-  res.setHeader("Pragma", "no-cache");
-  res.setHeader("Expires", "0");
-  next();
-});
-
-sandboxApp.get(["/", "/sandbox.html"], (_req, res) => {
-  res.sendFile(join(DIRECTORY, "sandbox.html"));
-});
-
-sandboxApp.use((_req, res) => {
-  res.status(404).send("Only sandbox.html is served on this port");
-});
-
-// ============ Start both servers ============
-hostApp.listen(HOST_PORT, () => {
-  console.log(`Host server:    http://localhost:${HOST_PORT}`);
-});
-
-sandboxApp.listen(SANDBOX_PORT, () => {
-  console.log(`Sandbox server: http://localhost:${SANDBOX_PORT}`);
-  console.log("\nPress Ctrl+C to stop\n");
-});

examples/simple-host/src/example-host-react.tsx

@@ -8,7 +8,11 @@ import { Tool } from "@modelcontextprotocol/sdk/types.js";
 import { AppRenderer, AppRendererProps } from "../src/AppRenderer";
 import { AppBridge } from "../../../dist/src/app-bridge";
 
-const SANDBOX_PROXY_URL = new URL("http://localhost:8081/sandbox.html");
+// We use '[::1]' for the sandbox to ensure it's a different origin from 'localhost'.
+const SANDBOX_PROXY_URL = new URL(
+  "/sandbox.html",
+  location.href.replace("localhost:", "[::1]:"),
+);
 
 /**
  * Example React application demonstrating the AppRenderer component.

examples/simple-host/src/example-host-vanilla.ts

@@ -18,7 +18,11 @@ import {
   McpUiSizeChangeNotificationSchema,
 } from "@modelcontextprotocol/ext-apps";
 
-const SANDBOX_PROXY_URL = new URL("http://localhost:8081/sandbox.html");
+// We use '[::1]' for the sandbox to ensure it's a different origin from 'localhost'.
+const SANDBOX_PROXY_URL = new URL(
+  "/sandbox.html",
+  location.href.replace("localhost:", "[::1]:"),
+);
 
 window.addEventListener("load", async () => {
   const client = new Client({

examples/simple-host/vite.config.ts

@@ -1,24 +1,24 @@
 import { defineConfig } from "vite";
 import react from "@vitejs/plugin-react";
-import { viteSingleFile } from "vite-plugin-singlefile";
 
-const INPUT = process.env.INPUT;
+export default defineConfig(({ mode }) => {
-if (!INPUT) {
+  const isDevelopment = mode === "development";
-  throw new Error("INPUT environment variable is not set");
+  return {
-}
+    plugins: [react()],
-
+    build: {
-const isDevelopment = process.env.NODE_ENV === "development";
+      sourcemap: isDevelopment ? "inline" : undefined,
-
+      cssMinify: !isDevelopment,
-export default defineConfig({
+      minify: !isDevelopment,
-  plugins: [react(), viteSingleFile()],
+      rollupOptions: {
-  build: {
+        input: [
-    sourcemap: isDevelopment ? "inline" : undefined,
+          "index.html",
-    cssMinify: !isDevelopment,
+          "example-host-vanilla.html",
-    minify: !isDevelopment,
+          "example-host-react.html",
-    rollupOptions: {
+          "sandbox.html",
-      input: INPUT,
+        ],
+      },
+      outDir: `dist`,
+      emptyOutDir: false,
     },
-    outDir: `dist`,
+  };
-    emptyOutDir: false,
-  },
 });