guard profiling data attachment; add tests

Author: s1gr1d

dev-packages/browser-integration-tests/suites/feedback/captureFeedbackWithProfiling/test.ts

@@ -39,8 +39,8 @@ sentryTest(
 
     await page.goto(url);
 
-    // Wait for the idle span to finish
-    await pageloadRequestPromise;
+    // Wait for the idle page load span to finish
+    const pageLoadEvent = envelopeRequestParser(await pageloadRequestPromise);
 
     // Submit feedback after idle span ended — no active span
     await page.getByText('Report a Bug').click();
@@ -51,10 +51,14 @@ sentryTest(
 
     const feedbackEvent = envelopeRequestParser((await feedbackRequestPromise).request());
 
-    // BUG: With profiling enabled and no active span, attachProfiledThreadToEvent
-    // creates a partial trace context { data: { thread.id, thread.name } } that
-    // overwrites the real trace context (with trace_id/span_id) via spread in _prepareEvent.
     expect(feedbackEvent.contexts?.trace?.trace_id).toMatch(/\w{32}/);
     expect(feedbackEvent.contexts?.trace?.span_id).toMatch(/\w{16}/);
+
+    // contexts.trace.data must include thread.id to identify which thread is associated with the transaction
+    expect(pageLoadEvent.contexts?.trace?.data?.['thread.id']).toBe('0');
+    expect(pageLoadEvent.contexts?.trace?.data?.['thread.name']).toBe('main');
+
+    // fixme: figure out why profiler_id is set on feedback and not on pageload transaction
+    expect(feedbackEvent.contexts?.profile?.profiler_id).toMatch(/^[a-f\d]{32}$/);
   },
 );

packages/browser/src/profiling/utils.ts

@@ -798,16 +798,18 @@ export function attachProfiledThreadToEvent(event: Event): Event {
     return event;
   }
 
-  // @ts-expect-error the trace fallback value is wrong, though it should never happen
-  // and in case it does, we dont want to override whatever was passed initially.
-  event.contexts.trace = {
-    ...(event.contexts?.trace ?? {}),
-    data: {
-      ...(event.contexts?.trace?.data ?? {}),
-      ['thread.id']: PROFILER_THREAD_ID_STRING,
-      ['thread.name']: PROFILER_THREAD_NAME,
-    },
-  };
+  // Only mutate the trace context when it already has a trace_id — that
+  // guarantees `applySpanToEvent` has already run, and we are not creating a partial trace context from scratch.
+  if (event.contexts.trace?.trace_id) {
+    event.contexts.trace = {
+      ...event.contexts.trace,
+      data: {
+        ...(event.contexts.trace.data ?? {}),
+        ['thread.id']: PROFILER_THREAD_ID_STRING,
+        ['thread.name']: PROFILER_THREAD_NAME,
+      },
+    };
+  }
 
   // Attach thread info to individual spans so that spans can be associated with the profiled thread on the UI even if contexts are missing.
   event.spans?.forEach(span => {