fix(tanstackstart-react): Set code.function.name in both trace lifecycles

The span starts with a `serverFn` placeholder because the function's name
is not known until the global function middleware runs. That middleware
only replaced the placeholder under span streaming, so static-lifecycle
spans kept `serverFn` even though the real name was available.

Resolve the attribute in both lifecycles and gate only `sentry.description`,
which exists solely to carry the request path past Relay's streaming
description template. This matches the ember and sveltekit `function` spans,
which both set `code.function.name` unconditionally.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: Lms24

packages/tanstackstart-react/src/server/globalMiddleware.ts

@@ -56,12 +56,10 @@ function createSentryFunctionMiddlewareHandler(mechanismType: string) {
 
         // With span streaming, a `function` span is named after the function it wraps.
         updateSpanName(activeSpan, hasSpanStreaming ? serverFnMeta.name : description);
+        activeSpan.setAttribute(CODE_FUNCTION_NAME, serverFnMeta.name);
         if (hasSpanStreaming) {
           // Relay infers a `function` span's description from `code.function.name` alone.
-          activeSpan.setAttributes({
-            [CODE_FUNCTION_NAME]: serverFnMeta.name,
-            [SENTRY_DESCRIPTION]: description,
-          });
+          activeSpan.setAttribute(SENTRY_DESCRIPTION, description);
         }
         activeSpan.setAttribute(SENTRY_SEGMENT_NAME_SOURCE, 'route');
       }

packages/tanstackstart-react/test/server/globalMiddleware.test.ts

@@ -79,8 +79,8 @@ describe('sentryGlobalFunctionMiddleware', () => {
   });
 
   describe('server function span naming', () => {
-    const setUpActiveSpan = (): { setAttribute: ReturnType<typeof vi.fn>; setAttributes: ReturnType<typeof vi.fn> } => {
-      const span = { setAttribute: vi.fn(), setAttributes: vi.fn() };
+    const setUpActiveSpan = (): { setAttribute: ReturnType<typeof vi.fn> } => {
+      const span = { setAttribute: vi.fn() };
       getActiveSpanSpy.mockReturnValue(span);
       spanToJSONSpy.mockReturnValue({
         name: 'GET /_serverFn/abc123',
@@ -102,10 +102,8 @@ describe('sentryGlobalFunctionMiddleware', () => {
       await serverFn({ next: vi.fn().mockResolvedValue('ok'), serverFnMeta: { name: 'testLog' } });
 
       expect(updateSpanNameSpy).toHaveBeenCalledWith(span, 'testLog');
-      expect(span.setAttributes).toHaveBeenCalledWith({
-        'code.function.name': 'testLog',
-        'sentry.description': 'GET /_serverFn/testLog',
-      });
+      expect(span.setAttribute).toHaveBeenCalledWith('code.function.name', 'testLog');
+      expect(span.setAttribute).toHaveBeenCalledWith('sentry.description', 'GET /_serverFn/testLog');
     });
 
     it('keeps the request path in the span name without span streaming', async () => {
@@ -116,7 +114,9 @@ describe('sentryGlobalFunctionMiddleware', () => {
       await serverFn({ next: vi.fn().mockResolvedValue('ok'), serverFnMeta: { name: 'testLog' } });
 
       expect(updateSpanNameSpy).toHaveBeenCalledWith(span, 'GET /_serverFn/testLog');
-      expect(span.setAttributes).not.toHaveBeenCalled();
+      // The resolved function name is useful in both lifecycles; only the description is a streaming workaround.
+      expect(span.setAttribute).toHaveBeenCalledWith('code.function.name', 'testLog');
+      expect(span.setAttribute).not.toHaveBeenCalledWith('sentry.description', expect.anything());
     });
   });
 });