fix: update MCP add-on

Author: jherr

frameworks/react-cra/add-ons/mcp/assets/src/utils/mcp-handler.ts

@@ -1,61 +1,63 @@
-import { StreamableHTTPServerTransport } from "@modelcontextprotocol/sdk/server/streamableHttp.js";
-import { getEvent } from "@tanstack/react-start/server";
-import type { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
-
-export async function handleMcpRequest(request: Request, server: McpServer) {
-  const body = await request.json();
-  const event = getEvent();
-  const res = event.node.res;
-  const req = event.node.req;
-
-  return new Promise<Response>((resolve, reject) => {
-    const transport = new StreamableHTTPServerTransport({
-      sessionIdGenerator: undefined,
-    });
-
-    const cleanup = () => {
-      transport.close();
-      server.close();
-    };
-
-    let settled = false;
-    const safeResolve = (response: Response) => {
-      if (!settled) {
-        settled = true;
-        cleanup();
-        resolve(response);
-      }
-    };
-
-    const safeReject = (error: any) => {
-      if (!settled) {
-        settled = true;
-        cleanup();
-        reject(error);
-      }
-    };
-
-    res.on("finish", () => safeResolve(new Response(null, { status: 200 })));
-    res.on("close", () => safeResolve(new Response(null, { status: 200 })));
-    res.on("error", safeReject);
-
-    server
-      .connect(transport)
-      .then(() => transport.handleRequest(req, res, body))
-      .catch((error) => {
-        console.error("Transport error:", error);
-        cleanup();
-        if (!res.headersSent) {
-          res.writeHead(500, { "Content-Type": "application/json" });
-          res.end(
-            JSON.stringify({
-              jsonrpc: "2.0",
-              error: { code: -32603, message: "Internal server error" },
-              id: null,
-            })
-          );
-        }
-        safeReject(error);
-      });
-  });
+import { InMemoryTransport } from '@modelcontextprotocol/sdk/inMemory.js'
+
+import type { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js'
+import type { JSONRPCMessage } from '@modelcontextprotocol/sdk/types.js'
+
+export async function handleMcpRequest(
+  request: Request,
+  server: McpServer,
+): Promise<Response> {
+  try {
+    const jsonRpcRequest = (await request.json()) as JSONRPCMessage
+
+    const [clientTransport, serverTransport] =
+      InMemoryTransport.createLinkedPair()
+
+    let responseData: JSONRPCMessage | null = null
+
+    clientTransport.onmessage = (message: JSONRPCMessage) => {
+      responseData = message
+    }
+
+    await server.connect(serverTransport)
+
+    await clientTransport.start()
+    await serverTransport.start()
+
+    await clientTransport.send(jsonRpcRequest)
+
+    await new Promise((resolve) => setTimeout(resolve, 10))
+
+    await clientTransport.close()
+    await serverTransport.close()
+
+    console.log('responseData', JSON.stringify(responseData, null, 2))
+
+    return Response.json(responseData, {
+      headers: {
+        'Content-Type': 'application/json',
+      },
+    })
+  } catch (error) {
+    console.error('MCP handler error:', error)
+
+    // Return a JSON-RPC error response
+    return Response.json(
+      {
+        jsonrpc: '2.0',
+        error: {
+          code: -32603,
+          message: 'Internal server error',
+          data: error instanceof Error ? error.message : String(error),
+        },
+        id: null,
+      },
+      {
+        status: 500,
+        headers: {
+          'Content-Type': 'application/json',
+        },
+      },
+    )
+  }
 }

packages/cta-engine/src/create-app.ts

@@ -234,7 +234,7 @@ Use the following commands to start your app:
       getPackageManagerScriptCommand(options.packageManager, ['dev']),
     )}
 
-Please check the README.md for information on testing, styling, adding routes, etc.${errorStatement}`,
+Please read the README.md for information on testing, styling, adding routes, etc.${errorStatement}`,
   )
 }