chore: import upstream snapshot with attribution

examples/integrations/mcp-apps/threejs-server/server-utils.ts

@@ -0,0 +1,72 @@
+/**
+ * Shared utilities for running MCP servers with Streamable HTTP transport.
+ */
+
+import { createMcpExpressApp } from "@modelcontextprotocol/sdk/server/express.js";
+import type { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
+import { StreamableHTTPServerTransport } from "@modelcontextprotocol/sdk/server/streamableHttp.js";
+import cors from "cors";
+import type { Request, Response } from "express";
+
+export interface ServerOptions {
+  port: number;
+  name?: string;
+}
+
+/**
+ * Starts an MCP server with Streamable HTTP transport in stateless mode.
+ *
+ * @param createServer - Factory function that creates a new McpServer instance per request.
+ * @param options - Server configuration options.
+ */
+export async function startServer(
+  createServer: () => McpServer,
+  options: ServerOptions,
+): Promise<void> {
+  const { port, name = "MCP Server" } = options;
+
+  const app = createMcpExpressApp({ host: "0.0.0.0" });
+  app.use(cors());
+
+  app.all("/mcp", async (req: Request, res: Response) => {
+    const server = createServer();
+    const transport = new StreamableHTTPServerTransport({
+      sessionIdGenerator: undefined,
+    });
+
+    res.on("close", () => {
+      transport.close().catch(() => {});
+      server.close().catch(() => {});
+    });
+
+    try {
+      await server.connect(transport);
+      await transport.handleRequest(req, res, req.body);
+    } catch (error) {
+      console.error("MCP error:", error);
+      if (!res.headersSent) {
+        res.status(500).json({
+          jsonrpc: "2.0",
+          error: { code: -32603, message: "Internal server error" },
+          id: null,
+        });
+      }
+    }
+  });
+
+  const httpServer = app.listen(port, (err) => {
+    if (err) {
+      console.error("Failed to start server:", err);
+      process.exit(1);
+    }
+    console.log(`${name} listening on http://localhost:${port}/mcp`);
+  });
+
+  const shutdown = () => {
+    console.log("\nShutting down...");
+    httpServer.close(() => process.exit(0));
+  };
+
+  process.on("SIGINT", shutdown);
+  process.on("SIGTERM", shutdown);
+}