fix(core): fix startup stats to use int values for timestamps and durations (#22201)

Co-authored-by: Yuna Seol <yunaseol@google.com>

packages/core/src/telemetry/startupProfiler.test.ts

@@ -388,5 +388,32 @@ describe('StartupProfiler', () => {
         }),
       );
     });
+
+    it('should log startup stats timestamps as rounded integers', () => {
+      const handle = profiler.start('test_phase');
+      handle?.end();
+
+      profiler.flush(mockConfig);
+
+      const statsEvent = logStartupStats.mock.calls[0][1];
+      const phase = statsEvent.phases[0];
+
+      // Verify they are integers
+      expect(Number.isInteger(phase.start_time_usec)).toBe(true);
+      expect(Number.isInteger(phase.end_time_usec)).toBe(true);
+    });
+
+    it('should log startup stats duration as rounded integers', () => {
+      const handle = profiler.start('test_phase');
+      handle?.end();
+
+      profiler.flush(mockConfig);
+
+      const statsEvent = logStartupStats.mock.calls[0][1];
+      const phase = statsEvent.phases[0];
+
+      // Verify they are integers
+      expect(Number.isInteger(phase.duration_ms)).toBe(true);
+    });
   });
 });

packages/core/src/telemetry/startupProfiler.ts

@@ -207,13 +207,16 @@ export class StartupProfiler {
       if (measure && phase.cpuUsage) {
         startupPhases.push({
           name: phase.name,
-          duration_ms: measure.duration,
+          duration_ms: Math.round(measure.duration),
           cpu_usage_user_usec: phase.cpuUsage.user,
           cpu_usage_system_usec: phase.cpuUsage.system,
-          start_time_usec: (performance.timeOrigin + measure.startTime) * 1000,
-          end_time_usec:
+          start_time_usec: Math.round(
+            (performance.timeOrigin + measure.startTime) * 1000,
+          ),
+          end_time_usec: Math.round(
             (performance.timeOrigin + measure.startTime + measure.duration) *
-            1000,
+              1000,
+          ),
         });
       }
     }