From 25c1b289aba80004085736aedeaa54bc6edc1914 Mon Sep 17 00:00:00 2001
From: Lukas Stracke <lukas.stracke@sentry.io>
Date: Wed, 5 Aug 2026 18:30:27 +0200
Subject: [PATCH] fix(browser): Use drift-corrected time origin for INP, replay
 and profiling

`timestampInSeconds` re-derives its time origin when it detects clock drift,
but `browserPerformanceTimeOrigin` caches the origin resolved at SDK init and
never revisits it. Consumers that convert a `PerformanceEntry`'s monotonic
`startTime` to wall clock time therefore end up on a different timeline than
span and event timestamps once a correction has happened.

Exposes the corrected origin as `correctedPerformanceTimeOrigin` and uses it
for the consumers that outlive a span timeout: INP (reports on pagehide) and
replay (sessions run up to an hour). Profiling already compensated for the SDK
changing its time origin, but computed the adjustment against the stale cached
value.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
---
 .../src/metrics/webVitalSpans.ts              |  5 +-
 .../test/metrics/webVitalSpans.test.ts        |  3 +
 packages/browser/src/profiling/utils.ts       |  6 +-
 packages/core/src/shared-exports.ts           |  7 +-
 packages/core/src/utils/time.ts               | 24 +++++-
 packages/core/test/lib/utils/time.test.ts     | 81 ++++++++++++++++++-
 .../src/util/createPerformanceEntries.ts      |  6 +-
 7 files changed, 119 insertions(+), 13 deletions(-)

diff --git a/packages/browser-utils/src/metrics/webVitalSpans.ts b/packages/browser-utils/src/metrics/webVitalSpans.ts
index 9c4f82249874..89024148865c 100644
--- a/packages/browser-utils/src/metrics/webVitalSpans.ts
+++ b/packages/browser-utils/src/metrics/webVitalSpans.ts
@@ -1,6 +1,7 @@
 import type { Client, Integration, Span, SpanAttributes } from '@sentry/core';
 import {
   browserPerformanceTimeOrigin,
+  correctedPerformanceTimeOrigin,
   debug,
   getActiveSpan,
   getClient,
@@ -329,7 +330,9 @@ export function trackInpAsSpan(client: Client): void {
 export function _sendInpSpan(inpValue: number, entry: PerformanceEventTiming, standalone = false): void {
   DEBUG_BUILD && debug.log(`Sending INP span (${inpValue})`);
 
-  const startTime = msToSec((browserPerformanceTimeOrigin() as number) + entry.startTime);
+  // INP reports on pagehide, potentially hours after the origin cached at init, so the corrected origin is used to stay
+  // on the same timeline as span and event timestamps.
+  const startTime = msToSec((correctedPerformanceTimeOrigin() as number) + entry.startTime);
   const duration = msToSec(inpValue);
   const interactionType = INP_ENTRY_MAP[entry.name];
 
diff --git a/packages/browser-utils/test/metrics/webVitalSpans.test.ts b/packages/browser-utils/test/metrics/webVitalSpans.test.ts
index ef938d7017f0..95fc1494447e 100644
--- a/packages/browser-utils/test/metrics/webVitalSpans.test.ts
+++ b/packages/browser-utils/test/metrics/webVitalSpans.test.ts
@@ -17,6 +17,7 @@ vi.mock('@sentry/core', async () => {
   return {
     ...actual,
     browserPerformanceTimeOrigin: vi.fn(),
+    correctedPerformanceTimeOrigin: vi.fn(),
     timestampInSeconds: vi.fn(),
     getCurrentScope: vi.fn(),
     getClient: vi.fn(),
@@ -475,6 +476,7 @@ describe('_sendInpSpan', () => {
   beforeEach(() => {
     vi.mocked(SentryCore.getCurrentScope).mockReturnValue(mockScope as any);
     vi.mocked(SentryCore.browserPerformanceTimeOrigin).mockReturnValue(1000);
+    vi.mocked(SentryCore.correctedPerformanceTimeOrigin).mockReturnValue(1000);
     vi.mocked(htmlTreeAsString).mockReturnValue('<button>');
     vi.mocked(SentryCore.startInactiveSpan).mockReturnValue(mockSpan as any);
     vi.mocked(SentryCore.getActiveSpan).mockReturnValue(undefined);
@@ -592,6 +594,7 @@ describe('trackInpAsSpan', () => {
 
   beforeEach(() => {
     vi.mocked(SentryCore.browserPerformanceTimeOrigin).mockReturnValue(1000);
+    vi.mocked(SentryCore.correctedPerformanceTimeOrigin).mockReturnValue(1000);
     vi.mocked(SentryCore.getCurrentScope).mockReturnValue(mockScope as any);
     vi.mocked(SentryCore.getActiveSpan).mockReturnValue(undefined);
     vi.mocked(SentryCore.startInactiveSpan).mockReturnValue({ end: vi.fn() } as any);
diff --git a/packages/browser/src/profiling/utils.ts b/packages/browser/src/profiling/utils.ts
index 938b7eadb784..d8be3d17f9db 100644
--- a/packages/browser/src/profiling/utils.ts
+++ b/packages/browser/src/profiling/utils.ts
@@ -12,7 +12,7 @@ import type {
   ThreadCpuProfile,
 } from '@sentry/core/browser';
 import {
-  browserPerformanceTimeOrigin,
+  correctedPerformanceTimeOrigin,
   debug,
   DEFAULT_ENVIRONMENT,
   forEachEnvelopeItem,
@@ -339,7 +339,7 @@ function convertToContinuousProfile(input: {
   }
 
   // Align timestamps to SDK time origin to match span/event timelines
-  const perfOrigin = browserPerformanceTimeOrigin();
+  const perfOrigin = correctedPerformanceTimeOrigin();
   const origin = typeof performance.timeOrigin === 'number' ? performance.timeOrigin : perfOrigin || 0;
   const adjustForOriginChange = origin - (perfOrigin || origin);
 
@@ -412,7 +412,7 @@ export function convertJSSelfProfileToSampledFormat(input: JSSelfProfile): Profi
   // when that happens, we need to ensure we are correcting the profile timings so the two timelines stay in sync.
   // Since JS self profiling time origin is always initialized to performance.timeOrigin, we need to adjust for
   // the drift between the SDK selected value and our profile time origin.
-  const perfOrigin = browserPerformanceTimeOrigin();
+  const perfOrigin = correctedPerformanceTimeOrigin();
   const origin = typeof performance.timeOrigin === 'number' ? performance.timeOrigin : perfOrigin || 0;
   const adjustForOriginChange = origin - (perfOrigin || origin);
 
diff --git a/packages/core/src/shared-exports.ts b/packages/core/src/shared-exports.ts
index 057d70a37e47..c63283b4203d 100644
--- a/packages/core/src/shared-exports.ts
+++ b/packages/core/src/shared-exports.ts
@@ -274,7 +274,12 @@ export {
   supportsReferrerPolicy,
 } from './utils/supports';
 export { SyncPromise, rejectedSyncPromise, resolvedSyncPromise } from './utils/syncpromise';
-export { browserPerformanceTimeOrigin, dateTimestampInSeconds, timestampInSeconds } from './utils/time';
+export {
+  browserPerformanceTimeOrigin,
+  correctedPerformanceTimeOrigin,
+  dateTimestampInSeconds,
+  timestampInSeconds,
+} from './utils/time';
 export {
   TRACEPARENT_REGEXP,
   extractTraceparentData,
diff --git a/packages/core/src/utils/time.ts b/packages/core/src/utils/time.ts
index 00283bc6e48f..9f841ef6f2c9 100644
--- a/packages/core/src/utils/time.ts
+++ b/packages/core/src/utils/time.ts
@@ -31,6 +31,12 @@ export function dateTimestampInSeconds(): number {
   return safeDateNow() / ONE_SECOND_IN_MS;
 }
 
+/**
+ * The time origin `timestampInSeconds` currently maps the monotonic clock against, kept in sync with the corrections it
+ * applies. `undefined` until the first `timestampInSeconds` call, and whenever the Performance API is unavailable.
+ */
+let _correctedTimeOrigin: number | undefined;
+
 /**
  * Returns a wrapper around the native Performance API browser implementation, or undefined for browsers that do not
  * support the API.
@@ -47,7 +53,7 @@ function createUnixTimestampInSecondsFunc(): () => number {
 
   // performance.now() is a monotonic clock, which means it starts at 0 when the process begins. To get the current
   // wall clock time (actual UNIX timestamp), we need to add the starting time origin and the current time elapsed.
-  let timeOrigin = performance.timeOrigin;
+  let timeOrigin = (_correctedTimeOrigin = performance.timeOrigin);
 
   return () => {
     return withRandomSafeContext(() => {
@@ -66,7 +72,7 @@ function createUnixTimestampInSecondsFunc(): () => number {
       // See: https://github.com/mdn/content/issues/4713
       // See: https://dev.to/noamr/when-a-millisecond-is-not-a-millisecond-3h6
       if (Math.abs(timeOrigin + performanceNow - dateNow) > CLOCK_DRIFT_THRESHOLD_MS) {
-        timeOrigin = dateNow - performanceNow;
+        timeOrigin = _correctedTimeOrigin = dateNow - performanceNow;
       }
 
       return (timeOrigin + performanceNow) / ONE_SECOND_IN_MS;
@@ -76,6 +82,20 @@ function createUnixTimestampInSecondsFunc(): () => number {
 
 let _cachedTimestampInSeconds: (() => number) | undefined;
 
+/**
+ * Returns the time origin (in milliseconds since the UNIX epoch) that {@link timestampInSeconds} currently maps
+ * `performance.now()` against, including any correction it has applied for clock drift.
+ *
+ * Use this over {@link browserPerformanceTimeOrigin} when converting a `PerformanceEntry`'s monotonic `startTime` to
+ * wall clock time at the moment the entry is observed, so the result shares a timeline with span and event timestamps.
+ * Returns `undefined` if the Performance API is unavailable, in which case monotonic timestamps cannot be converted.
+ */
+export function correctedPerformanceTimeOrigin(): number | undefined {
+  // The origin is only populated once `timestampInSeconds` has resolved which clock source to use.
+  timestampInSeconds();
+  return _correctedTimeOrigin;
+}
+
 /**
  * Returns a timestamp in seconds since the UNIX epoch using either the Performance or Date APIs, depending on the
  * availability of the Performance API.
diff --git a/packages/core/test/lib/utils/time.test.ts b/packages/core/test/lib/utils/time.test.ts
index 70fc7e5c0243..20cd71dd22ae 100644
--- a/packages/core/test/lib/utils/time.test.ts
+++ b/packages/core/test/lib/utils/time.test.ts
@@ -9,11 +9,17 @@ async function getFreshPerformanceTimeOrigin() {
 
 let freshImportCounter = 0;
 
-async function getFreshTimestampInSeconds(): Promise<() => number> {
+async function getFreshTimeModule(): Promise<{
+  timestampInSeconds: () => number;
+  correctedPerformanceTimeOrigin: () => number | undefined;
+}> {
   // A counter rather than `Date.now()`: these tests run under fake timers, which freeze the wall clock and would
   // otherwise hand out a cached module.
-  const timeModule = await import(`../../../src/utils/time?update=${freshImportCounter++}`);
-  return timeModule.timestampInSeconds;
+  return import(`../../../src/utils/time?update=${freshImportCounter++}`);
+}
+
+async function getFreshTimestampInSeconds(): Promise<() => number> {
+  return (await getFreshTimeModule()).timestampInSeconds;
 }
 
 const RELIABLE_THRESHOLD_MS = 300_000;
@@ -180,6 +186,75 @@ describe('timestampInSeconds', () => {
   });
 });
 
+describe('correctedPerformanceTimeOrigin', () => {
+  afterEach(() => {
+    vi.useRealTimers();
+    vi.unstubAllGlobals();
+  });
+
+  it('returns `performance.timeOrigin` while the clocks agree', async () => {
+    const currentTimeMs = 1767778040866;
+    const timeSincePageloadMs = 1_000;
+    const timeOrigin = currentTimeMs - timeSincePageloadMs;
+
+    vi.useFakeTimers();
+    vi.setSystemTime(new Date(currentTimeMs));
+    vi.stubGlobal('performance', { timeOrigin, now: () => timeSincePageloadMs });
+
+    const { correctedPerformanceTimeOrigin } = await getFreshTimeModule();
+
+    expect(correctedPerformanceTimeOrigin()).toBe(timeOrigin);
+  });
+
+  it('returns the corrected origin after clock drift, without a prior `timestampInSeconds` call', async () => {
+    const currentTimeMs = 1767778040866;
+    const timeSincePageloadMs = 1_000;
+    const sleepDurationMs = RELIABLE_THRESHOLD_MS + 60_000;
+
+    vi.useFakeTimers();
+    vi.setSystemTime(new Date(currentTimeMs));
+    vi.stubGlobal('performance', {
+      timeOrigin: currentTimeMs - timeSincePageloadMs,
+      now: () => timeSincePageloadMs,
+    });
+
+    const { correctedPerformanceTimeOrigin } = await getFreshTimeModule();
+
+    vi.setSystemTime(new Date(currentTimeMs + sleepDurationMs));
+
+    expect(correctedPerformanceTimeOrigin()).toBe(currentTimeMs + sleepDurationMs - timeSincePageloadMs);
+  });
+
+  it('stays on the same timeline as `timestampInSeconds`', async () => {
+    const currentTimeMs = 1767778040866;
+    const timeSincePageloadMs = 1_000;
+    const sleepDurationMs = RELIABLE_THRESHOLD_MS + 60_000;
+
+    vi.useFakeTimers();
+    vi.setSystemTime(new Date(currentTimeMs));
+    vi.stubGlobal('performance', {
+      timeOrigin: currentTimeMs - timeSincePageloadMs,
+      now: () => timeSincePageloadMs,
+    });
+
+    const { correctedPerformanceTimeOrigin, timestampInSeconds } = await getFreshTimeModule();
+
+    vi.setSystemTime(new Date(currentTimeMs + sleepDurationMs));
+
+    // Converting the current `performance.now()` against the origin must yield the same wall clock time that
+    // `timestampInSeconds` reports, otherwise perf entries and spans land on diverging timelines.
+    expect((correctedPerformanceTimeOrigin() as number) + timeSincePageloadMs).toBe(timestampInSeconds() * 1000);
+  });
+
+  it('returns `undefined` if the performance API is unavailable', async () => {
+    vi.stubGlobal('performance', undefined);
+
+    const { correctedPerformanceTimeOrigin } = await getFreshTimeModule();
+
+    expect(correctedPerformanceTimeOrigin()).toBeUndefined();
+  });
+});
+
 describe('browserPerformanceTimeOrigin', () => {
   it('returns `performance.timeOrigin` if it is available and reliable', async () => {
     const timeOrigin = await getFreshPerformanceTimeOrigin();
diff --git a/packages/replay-internal/src/util/createPerformanceEntries.ts b/packages/replay-internal/src/util/createPerformanceEntries.ts
index 5d3435b7efbc..2f4e45e9b600 100644
--- a/packages/replay-internal/src/util/createPerformanceEntries.ts
+++ b/packages/replay-internal/src/util/createPerformanceEntries.ts
@@ -1,4 +1,4 @@
-import { browserPerformanceTimeOrigin } from '@sentry/core';
+import { correctedPerformanceTimeOrigin } from '@sentry/core';
 import { record } from '@sentry/rrweb';
 import { WINDOW } from '../constants';
 import type {
@@ -87,9 +87,9 @@ function createPerformanceEntry(entry: AllPerformanceEntry): ReplayPerformanceEn
 }
 
 function getAbsoluteTime(time: number): number {
-  // browserPerformanceTimeOrigin can be undefined if `performance` or
+  // correctedPerformanceTimeOrigin can be undefined if `performance` or
   // `performance.now` doesn't exist, but this is already checked by this integration
-  return ((browserPerformanceTimeOrigin() || WINDOW.performance.timeOrigin) + time) / 1000;
+  return ((correctedPerformanceTimeOrigin() || WINDOW.performance.timeOrigin) + time) / 1000;
 }
 
 function createPaintEntry(entry: PerformancePaintTiming): ReplayPerformanceEntry<PaintData> {