fix(core): Set conversation_id only on gen_ai spans (#20274)

We should only set the `conversation_id` for `gen_ai` spans. These are
the only spans for which this attribute is relevant and setting it on
other spans can lead to unnecessarily slow queries in the product.

This works fine for all our AI integrations except Vercel. This is
because the Vercel ai integration also registers a `spanStart` hook that
transforms Vercel spans to sentry `gen_ai` spans. The conversation id
integration fires before that happens, so we have to special case the
Vercel ai spans here for this to work properly.

Closes #20272

Author: nicohrubec

.size-limit.js

@@ -234,7 +234,7 @@ module.exports = [
     path: createCDNPath('bundle.min.js'),
     gzip: false,
     brotli: false,
-    limit: '83 KB',
+    limit: '83.5 KB',
   },
   {
     name: 'CDN Bundle (incl. Tracing) - uncompressed',

packages/core/src/integrations/conversationId.ts

@@ -4,6 +4,7 @@ import { defineIntegration } from '../integration';
 import { GEN_AI_CONVERSATION_ID_ATTRIBUTE } from '../semanticAttributes';
 import type { IntegrationFn } from '../types-hoist/integration';
 import type { Span } from '../types-hoist/span';
+import { spanToJSON } from '../utils/spanUtils';
 
 const INTEGRATION_NAME = 'ConversationId';
 
@@ -18,6 +19,16 @@ const _conversationIdIntegration = (() => {
         const conversationId = scopeData.conversationId || isolationScopeData.conversationId;
 
         if (conversationId) {
+          const { op, data: attributes, description: name } = spanToJSON(span);
+
+          // Only apply conversation ID to gen_ai spans.
+          // We also check for Vercel AI spans (ai.operationId attribute or ai.* span name)
+          // because the Vercel AI integration sets the gen_ai.* op in its own spanStart handler
+          // which fires after this, so the op is not yet available at this point.
+          if (!op?.startsWith('gen_ai.') && !attributes['ai.operationId'] && !name?.startsWith('ai.')) {
+            return;
+          }
+
           span.setAttribute(GEN_AI_CONVERSATION_ID_ATTRIBUTE, conversationId);
         }
       });

packages/core/test/lib/integrations/conversationId.test.ts

@@ -26,7 +26,7 @@ describe('ConversationId', () => {
   it('applies conversation ID from current scope to span', () => {
     getCurrentScope().setConversationId('conv_test_123');
 
-    startSpan({ name: 'test-span' }, span => {
+    startSpan({ name: 'test-span', op: 'gen_ai.chat' }, span => {
       const spanJSON = spanToJSON(span);
       expect(spanJSON.data[GEN_AI_CONVERSATION_ID_ATTRIBUTE]).toBe('conv_test_123');
     });
@@ -35,7 +35,7 @@ describe('ConversationId', () => {
   it('applies conversation ID from isolation scope when current scope does not have one', () => {
     getIsolationScope().setConversationId('conv_isolation_456');
 
-    startSpan({ name: 'test-span' }, span => {
+    startSpan({ name: 'test-span', op: 'gen_ai.chat' }, span => {
       const spanJSON = spanToJSON(span);
       expect(spanJSON.data[GEN_AI_CONVERSATION_ID_ATTRIBUTE]).toBe('conv_isolation_456');
     });
@@ -45,14 +45,14 @@ describe('ConversationId', () => {
     getCurrentScope().setConversationId('conv_current_789');
     getIsolationScope().setConversationId('conv_isolation_999');
 
-    startSpan({ name: 'test-span' }, span => {
+    startSpan({ name: 'test-span', op: 'gen_ai.chat' }, span => {
       const spanJSON = spanToJSON(span);
       expect(spanJSON.data[GEN_AI_CONVERSATION_ID_ATTRIBUTE]).toBe('conv_current_789');
     });
   });
 
   it('does not apply conversation ID when not set in scope', () => {
-    startSpan({ name: 'test-span' }, span => {
+    startSpan({ name: 'test-span', op: 'gen_ai.chat' }, span => {
       const spanJSON = spanToJSON(span);
       expect(spanJSON.data[GEN_AI_CONVERSATION_ID_ATTRIBUTE]).toBeUndefined();
     });
@@ -62,7 +62,7 @@ describe('ConversationId', () => {
     getCurrentScope().setConversationId('conv_test_123');
     getCurrentScope().setConversationId(null);
 
-    startSpan({ name: 'test-span' }, span => {
+    startSpan({ name: 'test-span', op: 'gen_ai.chat' }, span => {
       const spanJSON = spanToJSON(span);
       expect(spanJSON.data[GEN_AI_CONVERSATION_ID_ATTRIBUTE]).toBeUndefined();
     });
@@ -71,8 +71,8 @@ describe('ConversationId', () => {
   it('applies conversation ID to nested spans', () => {
     getCurrentScope().setConversationId('conv_nested_abc');
 
-    startSpan({ name: 'parent-span' }, () => {
-      startSpan({ name: 'child-span' }, childSpan => {
+    startSpan({ name: 'parent-span', op: 'gen_ai.invoke_agent' }, () => {
+      startSpan({ name: 'child-span', op: 'gen_ai.chat' }, childSpan => {
         const childJSON = spanToJSON(childSpan);
         expect(childJSON.data[GEN_AI_CONVERSATION_ID_ATTRIBUTE]).toBe('conv_nested_abc');
       });
@@ -85,6 +85,7 @@ describe('ConversationId', () => {
     startSpan(
       {
         name: 'test-span',
+        op: 'gen_ai.chat',
         attributes: {
           [GEN_AI_CONVERSATION_ID_ATTRIBUTE]: 'conv_explicit',
         },
@@ -95,4 +96,13 @@ describe('ConversationId', () => {
       },
     );
   });
+
+  it('does not apply conversation ID to non-gen_ai spans', () => {
+    getCurrentScope().setConversationId('conv_test_123');
+
+    startSpan({ name: 'db-query', op: 'db.query' }, span => {
+      const spanJSON = spanToJSON(span);
+      expect(spanJSON.data[GEN_AI_CONVERSATION_ID_ATTRIBUTE]).toBeUndefined();
+    });
+  });
 });