feat: add agentName to Langfuse trace metadata

src/run.ts

@@ -305,9 +305,13 @@ export class Run<_T extends t.BaseGraphState> {
     ) {
       const userId = config.configurable?.user_id;
       const sessionId = config.configurable?.thread_id;
+      const primaryContext = this.Graph.agentContexts.get(
+        this.Graph.defaultAgentId
+      );
       const traceMetadata = {
         messageId: this.id,
         parentMessageId: config.configurable?.requestBody?.parentMessageId,
+        agentName: primaryContext?.name,
       };
       const handler = new CallbackHandler({
         userId,
@@ -453,8 +457,12 @@ export class Run<_T extends t.BaseGraphState> {
     ) {
       const userId = chainOptions.configurable?.user_id;
       const sessionId = chainOptions.configurable?.thread_id;
+      const titleContext = this.Graph?.agentContexts.get(
+        this.Graph.defaultAgentId
+      );
       const traceMetadata = {
         messageId: 'title-' + this.id,
+        agentName: titleContext?.name,
       };
       const handler = new CallbackHandler({
         userId,

src/specs/langfuse-metadata.test.ts

@@ -0,0 +1,91 @@
+import { CallbackHandler } from '@langfuse/langchain';
+import { Providers } from '@/common';
+import { Run } from '@/run';
+
+jest.mock('@langfuse/langchain', () => ({
+  CallbackHandler: jest.fn().mockImplementation(() => ({})),
+}));
+
+const MockedCallbackHandler = CallbackHandler as jest.MockedClass<
+  typeof CallbackHandler
+>;
+
+async function createTestRun(agentName?: string): Promise<Run<never>> {
+  const run = await Run.create({
+    runId: 'test-run-id',
+    graphConfig: {
+      type: 'standard',
+      agents: [
+        {
+          agentId: 'agent_abc123',
+          ...(agentName != null && { name: agentName }),
+          provider: Providers.OPENAI,
+          clientOptions: { model: 'gpt-4' },
+          tools: [],
+        },
+      ],
+    },
+  });
+
+  const emptyStream = (async function* (): AsyncGenerator {
+    /* no events */
+  })();
+  run.graphRunnable = { streamEvents: () => emptyStream } as never;
+
+  return run;
+}
+
+describe('Langfuse trace metadata includes agentName', () => {
+  const originalEnv = process.env;
+
+  beforeEach(() => {
+    jest.clearAllMocks();
+    process.env = {
+      ...originalEnv,
+      LANGFUSE_SECRET_KEY: 'sk-test',
+      LANGFUSE_PUBLIC_KEY: 'pk-test',
+      LANGFUSE_BASE_URL: 'https://langfuse.test',
+    };
+  });
+
+  afterEach(() => {
+    process.env = originalEnv;
+  });
+
+  it('passes agentName in processStream traceMetadata when agent has a name', async () => {
+    const run = await createTestRun('DWAINE');
+    await run.processStream(
+      { messages: [] },
+      { configurable: { thread_id: 't1', user_id: 'u1' }, version: 'v2' }
+    );
+
+    expect(MockedCallbackHandler).toHaveBeenCalledTimes(1);
+    const ctorArgs = MockedCallbackHandler.mock.calls[0][0];
+    expect(ctorArgs?.traceMetadata).toMatchObject({ agentName: 'DWAINE' });
+  });
+
+  it('falls back to agentId when agent has no explicit name', async () => {
+    const run = await createTestRun();
+    await run.processStream(
+      { messages: [] },
+      { configurable: { thread_id: 't1', user_id: 'u1' }, version: 'v2' }
+    );
+
+    expect(MockedCallbackHandler).toHaveBeenCalledTimes(1);
+    const ctorArgs = MockedCallbackHandler.mock.calls[0][0];
+    expect(ctorArgs?.traceMetadata).toMatchObject({
+      agentName: 'agent_abc123',
+    });
+  });
+
+  it('does not create CallbackHandler when Langfuse env vars are missing', async () => {
+    delete process.env.LANGFUSE_SECRET_KEY;
+    const run = await createTestRun('MAIA');
+    await run.processStream(
+      { messages: [] },
+      { configurable: { thread_id: 't1', user_id: 'u1' }, version: 'v2' }
+    );
+
+    expect(MockedCallbackHandler).not.toHaveBeenCalled();
+  });
+});