From 24e663b53be5a1482ea7573d3d0ac2ddebde198d Mon Sep 17 00:00:00 2001
From: luxp <luxianpo@gmail.com>
Date: Wed, 16 Apr 2025 16:17:16 +0800
Subject: [PATCH] StreamableHTTPServerTransport should support multiple
initializations in stateless mode
---
src/server/streamableHttp.test.ts | 7 +++++++
src/server/streamableHttp.ts | 3 ++-
2 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/src/server/streamableHttp.test.ts b/src/server/streamableHttp.test.ts
index efd5de1c..730d42ab 100644
--- a/src/server/streamableHttp.test.ts
+++ b/src/server/streamableHttp.test.ts
@@ -1077,6 +1077,13 @@ describe("StreamableHTTPServerTransport in stateless mode", () => {
await stopTestServer({ server, transport });
});
+ it("should support multiple initializations in stateless mode", async () => {
+ await sendPostRequest(baseUrl, TEST_MESSAGES.initialize);
+ const initResponse = await sendPostRequest(baseUrl, TEST_MESSAGES.initialize);
+ expect(initResponse.status).toBe(200);
+ expect(initResponse.headers.get("mcp-session-id")).toBeNull();
+ });
+
it("should operate without session ID validation", async () => {
// Initialize the server first
const initResponse = await sendPostRequest(baseUrl, TEST_MESSAGES.initialize);
diff --git a/src/server/streamableHttp.ts b/src/server/streamableHttp.ts
index 31aad09c..3f19e1b2 100644
--- a/src/server/streamableHttp.ts
+++ b/src/server/streamableHttp.ts
@@ -334,7 +334,8 @@ export class StreamableHTTPServerTransport implements Transport {
if (isInitializationRequest) {
// If it's a server with session management and the session ID is already set we should reject the request
// to avoid re-initialization.
- if (this._initialized) {
+ // sessionId undefined means stateless mode, so we don't need to check for re-initialization
+ if (this._initialized && this.sessionId !== undefined) {
res.writeHead(400).end(JSON.stringify({
jsonrpc: "2.0",
error: {