add isInitializeRequest and isInitializedNotification utility

src/client/streamableHttp.ts

@@ -1,5 +1,5 @@
 import { Transport } from "../shared/transport.js";
-import { isJSONRPCNotification, isJSONRPCRequest, isJSONRPCResponse, JSONRPCMessage, JSONRPCMessageSchema } from "../types.js";
+import { isInitializedNotification, isJSONRPCNotification, isJSONRPCRequest, isJSONRPCResponse, JSONRPCMessage, JSONRPCMessageSchema } from "../types.js";
 import { auth, AuthResult, OAuthClientProvider, UnauthorizedError } from "./auth.js";
 import { EventSourceParserStream } from "eventsource-parser/stream";
 
@@ -420,7 +420,7 @@ export class StreamableHTTPClientTransport implements Transport {
       if (response.status === 202) {
         // if the accepted notification is initialized, we start the SSE stream
         // if it's supported by the server
-        if (isJSONRPCNotification(message) && message.method === "notifications/initialized") {
+        if (isInitializedNotification(message)) {
           // Start without a lastEventId since this is a fresh connection
           this._startOrAuthSse({ resumptionToken: undefined }).catch(err => this.onerror?.(err));
         }

src/examples/server/jsonResponseStreamableHttp.ts

@@ -3,7 +3,7 @@ import { randomUUID } from 'node:crypto';
 import { McpServer } from '../../server/mcp.js';
 import { StreamableHTTPServerTransport } from '../../server/streamableHttp.js';
 import { z } from 'zod';
-import { CallToolResult } from '../../types.js';
+import { CallToolResult, isInitializeRequest } from '../../types.js';
 
 // Create an MCP server with implementation details
 const server = new McpServer({
@@ -145,14 +145,6 @@ app.get('/mcp', async (req: Request, res: Response) => {
   res.status(405).set('Allow', 'POST').send('Method Not Allowed');
 });
 
-// Helper function to detect initialize requests
-function isInitializeRequest(body: unknown): boolean {
-  if (Array.isArray(body)) {
-    return body.some(msg => typeof msg === 'object' && msg !== null && 'method' in msg && msg.method === 'initialize');
-  }
-  return typeof body === 'object' && body !== null && 'method' in body && body.method === 'initialize';
-}
-
 // Start the server
 const PORT = 3000;
 app.listen(PORT, () => {

src/examples/server/simpleStreamableHttp.ts

@@ -3,7 +3,7 @@ import { randomUUID } from 'node:crypto';
 import { McpServer } from '../../server/mcp.js';
 import { EventStore, StreamableHTTPServerTransport } from '../../server/streamableHttp.js';
 import { z } from 'zod';
-import { CallToolResult, GetPromptResult, JSONRPCMessage, ReadResourceResult } from '../../types.js';
+import { CallToolResult, GetPromptResult, isInitializeRequest, JSONRPCMessage, ReadResourceResult } from '../../types.js';
 
 // Create a simple in-memory EventStore for resumability
 class InMemoryEventStore implements EventStore {
@@ -36,7 +36,7 @@ class InMemoryEventStore implements EventStore {
    * Replays events that occurred after a specific event ID
    * Implements EventStore.replayEventsAfter
    */
-  async replayEventsAfter(lastEventId: string, 
+  async replayEventsAfter(lastEventId: string,
     { send }: { send: (eventId: string, message: JSONRPCMessage) => Promise<void> }
   ): Promise<string> {
     if (!lastEventId || !this.events.has(lastEventId)) {
@@ -312,14 +312,6 @@ app.get('/mcp', async (req: Request, res: Response) => {
   await transport.handleRequest(req, res);
 });
 
-// Helper function to detect initialize requests
-function isInitializeRequest(body: unknown): boolean {
-  if (Array.isArray(body)) {
-    return body.some(msg => typeof msg === 'object' && msg !== null && 'method' in msg && msg.method === 'initialize');
-  }
-  return typeof body === 'object' && body !== null && 'method' in body && body.method === 'initialize';
-}
-
 // Start the server
 const PORT = 3000;
 app.listen(PORT, () => {

src/examples/server/standaloneSseWithGetStreamableHttp.ts

@@ -2,7 +2,7 @@ import express, { Request, Response } from 'express';
 import { randomUUID } from 'node:crypto';
 import { McpServer } from '../../server/mcp.js';
 import { StreamableHTTPServerTransport } from '../../server/streamableHttp.js';
-import { ReadResourceResult } from '../../types.js';
+import { isInitializeRequest, ReadResourceResult } from '../../types.js';
 
 // Create an MCP server with implementation details
 const server = new McpServer({
@@ -107,13 +107,6 @@ app.get('/mcp', async (req: Request, res: Response) => {
   await transport.handleRequest(req, res);
 });
 
-// Helper function to detect initialize requests
-function isInitializeRequest(body: unknown): boolean {
-  if (Array.isArray(body)) {
-    return body.some(msg => typeof msg === 'object' && msg !== null && 'method' in msg && msg.method === 'initialize');
-  }
-  return typeof body === 'object' && body !== null && 'method' in body && body.method === 'initialize';
-}
 
 // Start the server
 const PORT = 3000;

src/types.ts

@@ -248,6 +248,10 @@ export const InitializeRequestSchema = RequestSchema.extend({
   }),
 });
 
+export const isInitializeRequest = (value: unknown): value is InitializeRequest =>
+  InitializeRequestSchema.safeParse(value).success;
+
+
 /**
  * Capabilities that a server may support. Known capabilities are defined here, in this schema, but this is not a closed set: any server can define its own, additional capabilities.
  */
@@ -337,6 +341,9 @@ export const InitializedNotificationSchema = NotificationSchema.extend({
   method: z.literal("notifications/initialized"),
 });
 
+export const isInitializedNotification = (value: unknown): value is InitializedNotification =>
+  InitializedNotificationSchema.safeParse(value).success;
+
 /* Ping */
 /**
  * A ping, issued by either the server or the client, to check that the other party is still alive. The receiver must promptly respond, or else may be disconnected.