fix(tracing): Use actual span end timestamp for frames.delay in TTID/TTFD

Pass the intended span end timestamp into captureEndFramesAndAttachToSpan
instead of falling back to Date.now(). The function runs before span.end()
is called, so spanToJSON(span).timestamp is always undefined, causing the
delay calculation to include frame data after the span semantically ended.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: antonis

packages/core/src/js/tracing/timetodisplay.tsx

@@ -203,9 +203,10 @@ export function startTimeToFullDisplaySpan(
     }
     fullDisplaySpan.setStatus({ code: SPAN_STATUS_ERROR, message: 'deadline_exceeded' });
 
-    captureEndFramesAndAttachToSpan(fullDisplaySpan).then(() => {
+    const fullDisplayEndTimestamp = spanToJSON(initialDisplaySpan).timestamp;
+    captureEndFramesAndAttachToSpan(fullDisplaySpan, fullDisplayEndTimestamp).then(() => {
       debug.log(`[TimeToDisplay] span ${fullDisplaySpan.spanContext().spanId} updated with frame data.`);
-      fullDisplaySpan.end(spanToJSON(initialDisplaySpan).timestamp);
+      fullDisplaySpan.end(fullDisplayEndTimestamp);
       setSpanDurationAsMeasurement('time_to_full_display', fullDisplaySpan);
     }).catch(() => {
       debug.warn(`[TimeToDisplay] Failed to capture end frames for full display span (${fullDisplaySpan.spanContext().spanId}).`);
@@ -265,7 +266,7 @@ export function updateInitialDisplaySpan(
     return;
   }
 
-  captureEndFramesAndAttachToSpan(span).then(() => {
+  captureEndFramesAndAttachToSpan(span, frameTimestampSeconds).then(() => {
     span.end(frameTimestampSeconds);
     span.setStatus({ code: SPAN_STATUS_OK });
     debug.log(`[TimeToDisplay] ${spanToJSON(span).description} span updated with end timestamp and frame data.`);
@@ -322,8 +323,8 @@ function updateFullDisplaySpan(frameTimestampSeconds: number, passedInitialDispl
     return;
   }
 
-  captureEndFramesAndAttachToSpan(span).then(() => {
-    const endTimestamp = initialDisplayEndTimestamp > frameTimestampSeconds ? initialDisplayEndTimestamp : frameTimestampSeconds;
+  const endTimestamp = initialDisplayEndTimestamp > frameTimestampSeconds ? initialDisplayEndTimestamp : frameTimestampSeconds;
+  captureEndFramesAndAttachToSpan(span, endTimestamp).then(() => {
 
     if (initialDisplayEndTimestamp > frameTimestampSeconds) {
       debug.warn('[TimeToDisplay] Using initial display end. Full display end frame timestamp is before initial display end.');
@@ -466,7 +467,7 @@ async function captureStartFramesForSpan(spanId: string): Promise<void> {
 /**
  * Captures end frames and attaches frame data to span
  */
-async function captureEndFramesAndAttachToSpan(span: Span): Promise<void> {
+async function captureEndFramesAndAttachToSpan(span: Span, spanEndTimestampSeconds?: number): Promise<void> {
   if (!NATIVE.enableNative) {
     return;
   }
@@ -488,7 +489,7 @@ async function captureEndFramesAndAttachToSpan(span: Span): Promise<void> {
     const spanStartTimestamp = spanToJSON(span).start_timestamp;
     if (spanStartTimestamp) {
       try {
-        const endTimestamp = spanToJSON(span).timestamp || Date.now() / 1000;
+        const endTimestamp = spanEndTimestampSeconds || spanToJSON(span).timestamp || Date.now() / 1000;
         const framesDelay = await NATIVE.fetchNativeFramesDelay(spanStartTimestamp, endTimestamp);
         if (framesDelay != null) {
           span.setAttribute('frames.delay', framesDelay);