Add Sentry span for JS bundle parse time

Uses native `runJsBundleStart`/`runJsBundleEnd` performance marks to
create a `ManualJsParseTime` span parented to `ManualAppStartup`,
making pre-JS startup time visible in Sentry traces.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: elirangoshen

src/CONST/index.ts

@@ -1777,6 +1777,7 @@ const CONST = {
         // Span names
         SPAN_OPEN_REPORT: 'ManualOpenReport',
         SPAN_APP_STARTUP: 'ManualAppStartup',
+        SPAN_JS_PARSE_TIME: 'ManualJsParseTime',
         SPAN_NAVIGATE_TO_REPORTS_TAB: 'ManualNavigateToReportsTab',
         SPAN_NAVIGATE_TO_REPORTS_TAB_RENDER: 'ManualNavigateToReportsTabRender',
         SPAN_ON_LAYOUT_SKELETON_REPORTS: 'ManualOnLayoutSkeletonReports',

src/libs/telemetry/activeSpans.ts

@@ -1,4 +1,4 @@
-import type {StartSpanOptions} from '@sentry/core';
+import type {SpanTimeInput, StartSpanOptions} from '@sentry/core';
 import * as Sentry from '@sentry/react-native';
 import CONST from '@src/CONST';
 
@@ -25,15 +25,15 @@ function startSpan(spanId: string, options: StartSpanOptions, extraOptions: Star
     return span;
 }
 
-function endSpan(spanId: string) {
+function endSpan(spanId: string, endTime?: SpanTimeInput) {
     const span = activeSpans.get(spanId);
 
     if (!span) {
         return;
     }
     span.setStatus({code: 1});
     span.setAttribute(CONST.TELEMETRY.ATTRIBUTE_FINISHED_MANUALLY, true);
-    span.end();
+    span.end(endTime);
     activeSpans.delete(spanId);
 }
 

src/setup/telemetry/index.ts

@@ -1,7 +1,8 @@
 import * as Sentry from '@sentry/react-native';
 import {Platform} from 'react-native';
+import performance, {PerformanceObserver} from 'react-native-performance';
 import {isDevelopment} from '@libs/Environment/Environment';
-import {startSpan} from '@libs/telemetry/activeSpans';
+import {endSpan, getSpan, startSpan} from '@libs/telemetry/activeSpans';
 import {breadcrumbsIntegration, browserProfilingIntegration, consoleIntegration, navigationIntegration, tracingIntegration} from '@libs/telemetry/integrations';
 import processBeforeSendTransactions from '@libs/telemetry/middlewares';
 import CONFIG from '@src/CONFIG';
@@ -39,4 +40,34 @@ export default function (): void {
         name: CONST.TELEMETRY.SPAN_APP_STARTUP,
         op: CONST.TELEMETRY.SPAN_APP_STARTUP,
     });
+
+    const runJsBundleStartEntries = performance.getEntriesByName('runJsBundleStart');
+    if (runJsBundleStartEntries.length > 0) {
+        const jsParseStartSecs = (runJsBundleStartEntries.at(0)?.startTime ?? 0) / 1000;
+
+        startSpan(CONST.TELEMETRY.SPAN_JS_PARSE_TIME, {
+            name: CONST.TELEMETRY.SPAN_JS_PARSE_TIME,
+            op: CONST.TELEMETRY.SPAN_JS_PARSE_TIME,
+            startTime: jsParseStartSecs,
+            parentSpan: getSpan(CONST.TELEMETRY.SPAN_APP_STARTUP),
+        });
+
+        const finishJsParseSpan = (endTimeSecs: number) => {
+            endSpan(CONST.TELEMETRY.SPAN_JS_PARSE_TIME, endTimeSecs);
+        };
+
+        const runJsBundleEndEntries = performance.getEntriesByName('runJsBundleEnd');
+        if (runJsBundleEndEntries.length > 0) {
+            finishJsParseSpan((runJsBundleEndEntries.at(0)?.startTime ?? 0) / 1000);
+        } else {
+            const observer = new PerformanceObserver((list) => {
+                const entries = list.getEntriesByName('runJsBundleEnd');
+                if (entries.length > 0) {
+                    finishJsParseSpan((entries.at(0)?.startTime ?? 0) / 1000);
+                    observer.disconnect();
+                }
+            });
+            observer.observe({type: 'mark', buffered: true});
+        }
+    }
 }