Skip to content

fix(core): handle stateless MCP wrapper transport correlation #20293

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
logaretm wants to merge 2 commits into
base: develop
Choose a base branch
from
+98 −9
Open

fix(core): handle stateless MCP wrapper transport correlation #20293

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
c4271fc
fix(core): handle stateless MCP wrapper transport correlation
logaretm Apr 14, 2026
5c60a74
fix(core): align MCP session metadata lookup for wrappers
logaretm Apr 14, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
18 changes: 9 additions & 9 deletions packages/core/src/integrations/mcp-server/transport.ts
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -43,7 +43,7 @@ export function wrapTransportOnMessage(transport: MCPTransport, options: Resolve
if (isInitialize) {
try {
initSessionData = extractSessionDataFromInitializeRequest(message);
storeSessionDataForTransport(this, initSessionData);
storeSessionDataForTransport(transport, initSessionData);
Comment thread
logaretm marked this conversation as resolved.
Comment thread
cursor[bot] marked this conversation as resolved.
} catch {
// noop
}
Expand All @@ -52,7 +52,7 @@ export function wrapTransportOnMessage(transport: MCPTransport, options: Resolve
const isolationScope = getIsolationScope().clone();

return withIsolationScope(isolationScope, () => {
const spanConfig = buildMcpServerSpanConfig(message, this, extra as ExtraHandlerData, options);
const spanConfig = buildMcpServerSpanConfig(message, transport, extra as ExtraHandlerData, options);
const span = startInactiveSpan(spanConfig);

// For initialize requests, add client info directly to span (works even for stateless transports)
Expand All @@ -65,7 +65,7 @@ export function wrapTransportOnMessage(transport: MCPTransport, options: Resolve
});
}

storeSpanForRequest(this, message.id, span, message.method);
storeSpanForRequest(transport, message.id, span, message.method);

return withActiveSpan(span, () => {
return (originalOnMessage as (...args: unknown[]) => unknown).call(this, message, extra);
Expand All @@ -74,7 +74,7 @@ export function wrapTransportOnMessage(transport: MCPTransport, options: Resolve
}

if (isJsonRpcNotification(message)) {
return createMcpNotificationSpan(message, this, extra as ExtraHandlerData, options, () => {
return createMcpNotificationSpan(message, transport, extra as ExtraHandlerData, options, () => {
return (originalOnMessage as (...args: unknown[]) => unknown).call(this, message, extra);
});
}
Expand All @@ -99,7 +99,7 @@ export function wrapTransportSend(transport: MCPTransport, options: ResolvedMcpO
const [message] = args;

if (isJsonRpcNotification(message)) {
return createMcpOutgoingNotificationSpan(message, this, options, () => {
return createMcpOutgoingNotificationSpan(message, transport, options, () => {
return (originalSend as (...args: unknown[]) => unknown).call(this, ...args);
});
}
Expand All @@ -114,14 +114,14 @@ export function wrapTransportSend(transport: MCPTransport, options: ResolvedMcpO
if (message.result.protocolVersion || message.result.serverInfo) {
try {
const serverData = extractSessionDataFromInitializeResponse(message.result);
updateSessionDataForTransport(this, serverData);
updateSessionDataForTransport(transport, serverData);
Comment thread
logaretm marked this conversation as resolved.
} catch {
// noop
}
}
}

completeSpanWithResults(this, message.id, message.result, options, !!message.error);
completeSpanWithResults(transport, message.id, message.result, options, !!message.error);
}
}

Expand All @@ -139,8 +139,8 @@ export function wrapTransportOnClose(transport: MCPTransport): void {
if (transport.onclose) {
fill(transport, 'onclose', originalOnClose => {
return function (this: MCPTransport, ...args: unknown[]) {
cleanupPendingSpansForTransport(this);
cleanupSessionDataForTransport(this);
cleanupPendingSpansForTransport(transport);
cleanupSessionDataForTransport(transport);
return (originalOnClose as (...args: unknown[]) => unknown).call(this, ...args);
};
});
Expand Down
89 changes: 89 additions & 0 deletions packages/core/test/lib/integrations/mcp-server/transportInstrumentation.test.ts
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -880,6 +880,95 @@ describe('MCP Server Transport Instrumentation', () => {
expect(mockSpan.end).toHaveBeenCalled();
});

it('should correlate spans correctly for stateless wrapper transports', async () => {
const { wrapper, inner } = createMockWrapperTransport('stateless-wrapper-session');
inner.sessionId = undefined;

const mockMcpServer = createMockMcpServer();
const wrappedMcpServer = wrapMcpServerWithSentry(mockMcpServer);

await wrappedMcpServer.connect(wrapper);

const mockSpan = { setAttributes: vi.fn(), end: vi.fn() };
startInactiveSpanSpy.mockReturnValue(mockSpan as any);

inner.onmessage?.call(
inner,
{
jsonrpc: '2.0',
method: 'tools/call',
id: 'stateless-wrapper-req-1',
params: { name: 'test-tool' },
},
{},
);

await wrapper.send({
jsonrpc: '2.0',
id: 'stateless-wrapper-req-1',
result: { content: [{ type: 'text', text: 'success' }] },
});

expect(mockSpan.end).toHaveBeenCalled();
});

it('should preserve session metadata for later stateless wrapper spans', async () => {
const { wrapper, inner } = createMockWrapperTransport('stateless-wrapper-session');
inner.sessionId = undefined;

const mockMcpServer = createMockMcpServer();
const wrappedMcpServer = wrapMcpServerWithSentry(mockMcpServer);

await wrappedMcpServer.connect(wrapper);

inner.onmessage?.call(
inner,
{
jsonrpc: '2.0',
method: 'initialize',
id: 'init-stateless',
params: {
protocolVersion: '2025-06-18',
clientInfo: { name: 'test-client', version: '1.0.0' },
},
},
{},
);

await wrapper.send({
jsonrpc: '2.0',
id: 'init-stateless',
result: {
protocolVersion: '2025-06-18',
serverInfo: { name: 'test-server', version: '2.0.0' },
capabilities: {},
},
});

inner.onmessage?.call(
inner,
{
jsonrpc: '2.0',
method: 'tools/call',
id: 'stateless-wrapper-req-2',
params: { name: 'test-tool' },
},
{},
);

expect(startInactiveSpanSpy).toHaveBeenCalledWith(
expect.objectContaining({
attributes: expect.objectContaining({
'mcp.client.name': 'test-client',
'mcp.client.version': '1.0.0',
'mcp.protocol.version': '2025-06-18',
'mcp.server.name': 'test-server',
'mcp.server.version': '2.0.0',
}),
}),
);
});

it('should handle initialize request/response with wrapper transport', async () => {
const { wrapper } = createMockWrapperTransport('init-wrapper-session');
const mockMcpServer = createMockMcpServer();
Expand Down
Loading