naming is hard

Author: kev-flex

packages/core/src/shared/transport.ts

@@ -128,7 +128,7 @@ export interface Transport {
      * {@linkcode @modelcontextprotocol/server!server/server.Server.connect | connect()} to
      * seed client capabilities and version info.
      */
-    oninitialized?: ((data: { clientCapabilities: ClientCapabilities; clientVersion: Implementation }) => void) | undefined;
+    oninitializationreplay?: ((data: { clientCapabilities: ClientCapabilities; clientVersion: Implementation }) => void) | undefined;
 
     /**
      * The session ID generated for this connection.

packages/core/src/util/inMemory.ts

@@ -18,7 +18,7 @@ export class InMemoryTransport implements Transport {
     onclose?: () => void;
     onerror?: (error: Error) => void;
     onmessage?: (message: JSONRPCMessage, extra?: { authInfo?: AuthInfo }) => void;
-    oninitialized?: (data: { clientCapabilities: ClientCapabilities; clientVersion: Implementation }) => void;
+    oninitializationreplay?: (data: { clientCapabilities: ClientCapabilities; clientVersion: Implementation }) => void;
     sessionId?: string;
 
     /**

packages/middleware/node/src/streamableHttp.ts

@@ -141,12 +141,14 @@ export class NodeStreamableHTTPServerTransport implements Transport {
     /**
      * Sets callback for session initialization replay.
      */
-    set oninitialized(handler: ((data: { clientCapabilities: ClientCapabilities; clientVersion: Implementation }) => void) | undefined) {
-        this._webStandardTransport.oninitialized = handler;
+    set oninitializationreplay(
+        handler: ((data: { clientCapabilities: ClientCapabilities; clientVersion: Implementation }) => void) | undefined
+    ) {
+        this._webStandardTransport.oninitializationreplay = handler;
     }
 
-    get oninitialized(): ((data: { clientCapabilities: ClientCapabilities; clientVersion: Implementation }) => void) | undefined {
-        return this._webStandardTransport.oninitialized;
+    get oninitializationreplay(): ((data: { clientCapabilities: ClientCapabilities; clientVersion: Implementation }) => void) | undefined {
+        return this._webStandardTransport.oninitializationreplay;
     }
 
     /**

packages/server/src/server/server.ts

@@ -142,13 +142,13 @@ export class Server extends Protocol<ServerContext> {
     }
 
     /**
-     * Attaches to the given transport, hooking the `oninitialized` callback
+     * Attaches to the given transport, hooking the `oninitializationreplay` callback
      * to seed client capabilities and version info from replayed sessions.
      */
     override async connect(transport: Transport): Promise<void> {
-        const _oninitialized = transport.oninitialized;
-        transport.oninitialized = data => {
-            _oninitialized?.(data);
+        const _oninitializationreplay = transport.oninitializationreplay;
+        transport.oninitializationreplay = data => {
+            _oninitializationreplay?.(data);
             this._clientCapabilities ??= data.clientCapabilities;
             this._clientVersion ??= data.clientVersion;
         };

packages/server/src/server/streamableHttp.ts

@@ -279,7 +279,7 @@ export class WebStandardStreamableHTTPServerTransport implements Transport {
     onclose?: () => void;
     onerror?: (error: Error) => void;
     onmessage?: (message: JSONRPCMessage, extra?: MessageExtraInfo) => void;
-    oninitialized?: (data: { clientCapabilities: ClientCapabilities; clientVersion: Implementation }) => void;
+    oninitializationreplay?: (data: { clientCapabilities: ClientCapabilities; clientVersion: Implementation }) => void;
 
     constructor(options: WebStandardStreamableHTTPServerTransportOptions = {}) {
         this.sessionIdGenerator = options.sessionIdGenerator;
@@ -892,7 +892,7 @@ export class WebStandardStreamableHTTPServerTransport implements Transport {
      * Called once in `handleRequest()` before method dispatch.
      *
      * No-op when already initialized, no callback provided, or no session ID header.
-     * On success, sets `sessionId` and `_initialized`, then invokes `oninitialized`
+     * On success, sets `sessionId` and `_initialized`, then invokes `oninitializationreplay`
      * so the server can seed client capabilities and version info.
      */
     private async _tryReplayInitialization(req: Request): Promise<Response | undefined> {
@@ -912,7 +912,7 @@ export class WebStandardStreamableHTTPServerTransport implements Transport {
 
             this.sessionId = sessionId;
             this._initialized = true;
-            this.oninitialized?.(result);
+            this.oninitializationreplay?.(result);
             return undefined;
         } finally {
             this._replayInProgress = false;

packages/server/test/server/server.test.ts

@@ -40,18 +40,18 @@ describe('Server', () => {
         });
     });
 
-    describe('connect — oninitialized hook', () => {
+    describe('connect — oninitializationreplay hook', () => {
         const testCapabilities: ClientCapabilities = { sampling: {} };
         const testVersion: Implementation = { name: 'test-client', version: '2.0.0' };
 
-        it('should seed getClientCapabilities() when transport.oninitialized is called', async () => {
+        it('should seed getClientCapabilities() when transport.oninitializationreplay is called', async () => {
             const server = new Server({ name: 'test', version: '1.0.0' }, { capabilities: {} });
 
             const [, serverTransport] = InMemoryTransport.createLinkedPair();
             await server.connect(serverTransport);
 
-            // Simulate transport calling oninitialized (as _tryReplayInitialization would)
-            serverTransport.oninitialized?.({
+            // Simulate transport calling oninitializationreplay (as _tryReplayInitialization would)
+            serverTransport.oninitializationreplay?.({
                 clientCapabilities: testCapabilities,
                 clientVersion: testVersion
             });
@@ -62,7 +62,7 @@ describe('Server', () => {
             await server.close();
         });
 
-        it('should return undefined for getClientCapabilities() when oninitialized is not called', async () => {
+        it('should return undefined for getClientCapabilities() when oninitializationreplay is not called', async () => {
             const server = new Server({ name: 'test', version: '1.0.0' }, { capabilities: {} });
 
             const [, serverTransport] = InMemoryTransport.createLinkedPair();
@@ -80,8 +80,8 @@ describe('Server', () => {
             const [clientTransport, serverTransport] = InMemoryTransport.createLinkedPair();
             await server.connect(serverTransport);
 
-            // First: seed via oninitialized
-            serverTransport.oninitialized?.({
+            // First: seed via oninitializationreplay
+            serverTransport.oninitializationreplay?.({
                 clientCapabilities: testCapabilities,
                 clientVersion: testVersion
             });
@@ -116,18 +116,18 @@ describe('Server', () => {
             await server.close();
         });
 
-        it('should chain with an existing transport.oninitialized callback', async () => {
+        it('should chain with an existing transport.oninitializationreplay callback', async () => {
             const server = new Server({ name: 'test', version: '1.0.0' }, { capabilities: {} });
 
             const [, serverTransport] = InMemoryTransport.createLinkedPair();
 
             const existingCallback = vi.fn();
-            serverTransport.oninitialized = existingCallback;
+            serverTransport.oninitializationreplay = existingCallback;
 
             await server.connect(serverTransport);
 
             const data = { clientCapabilities: testCapabilities, clientVersion: testVersion };
-            serverTransport.oninitialized?.(data);
+            serverTransport.oninitializationreplay?.(data);
 
             // Both the existing callback and the server's hook should have fired
             expect(existingCallback).toHaveBeenCalledWith(data);

packages/server/test/server/streamableHttp.test.ts

@@ -1038,13 +1038,13 @@ describe('Zod v4', () => {
             expect(transport.sessionId).toBe(REPLAY_SESSION_ID);
         });
 
-        it('should invoke oninitialized with replayed data', async () => {
+        it('should invoke oninitializationreplay with replayed data', async () => {
             const transport = new WebStandardStreamableHTTPServerTransport({
                 replayInitialization: () => REPLAY_DATA
             });
 
-            const oninitializedSpy = vi.fn();
-            transport.oninitialized = oninitializedSpy;
+            const oninitializationreplaySpy = vi.fn();
+            transport.oninitializationreplay = oninitializationreplaySpy;
 
             const mcpServer = new McpServer({ name: 'test', version: '1.0.0' });
             await mcpServer.connect(transport);
@@ -1055,10 +1055,10 @@ describe('Zod v4', () => {
             await transport.handleRequest(request);
 
             // The server's connect() chains its own hook, so verify the original was also called
-            expect(oninitializedSpy).toHaveBeenCalledWith(REPLAY_DATA);
+            expect(oninitializationreplaySpy).toHaveBeenCalledWith(REPLAY_DATA);
         });
 
-        it('should seed server capabilities via oninitialized hook', async () => {
+        it('should seed server capabilities via oninitializationreplay hook', async () => {
             const transport = new WebStandardStreamableHTTPServerTransport({
                 replayInitialization: () => REPLAY_DATA
             });