From fd7ccbbb52d1c7c62b003795066191bbc1d717ad 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>
---
 .../browser-utils/src/web-vitals/spans.ts     |  5 +-
 .../test/web-vitals/spans.test.ts             |  4 +
 packages/browser/src/profiling/utils.ts       |  4 +-
 packages/core/src/index.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(+), 12 deletions(-)

diff --git a/packages/browser-utils/src/web-vitals/spans.ts b/packages/browser-utils/src/web-vitals/spans.ts
index 424180427141..8167978c5f9e 100644
--- a/packages/browser-utils/src/web-vitals/spans.ts
+++ b/packages/browser-utils/src/web-vitals/spans.ts
@@ -2,6 +2,7 @@
 import type { Client, Span, SpanAttributes } from '@sentry/core';
 import {
   browserPerformanceTimeOrigin,
+  correctedPerformanceTimeOrigin,
   debug,
   getActiveSpan,
   getClient,
@@ -409,8 +410,10 @@ export function _sendInpSpan(
   // A web vital span carries the metric, not a real interaction timing, so an INP without an entry
   // is still worth reporting. It just has no element or interaction type to describe, and is placed
   // at the start of the navigation it belongs to rather than at the interaction.
+  // 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(
-    (browserPerformanceTimeOrigin() as number) + (entry?.startTime ?? metric?.navigationStartTime ?? 0),
+    (correctedPerformanceTimeOrigin() as number) + (entry?.startTime ?? metric?.navigationStartTime ?? 0),
   );
   const duration = msToSec(inpValue);
   // An INP without an entry has no interaction type to report. It still has to land inside the
diff --git a/packages/browser-utils/test/web-vitals/spans.test.ts b/packages/browser-utils/test/web-vitals/spans.test.ts
index f9182b52d153..be18908676ff 100644
--- a/packages/browser-utils/test/web-vitals/spans.test.ts
+++ b/packages/browser-utils/test/web-vitals/spans.test.ts
@@ -22,6 +22,7 @@ vi.mock('@sentry/core', async () => {
   return {
     ...actual,
     browserPerformanceTimeOrigin: vi.fn(),
+    correctedPerformanceTimeOrigin: vi.fn(),
     timestampInSeconds: vi.fn(),
     getCurrentScope: vi.fn(),
     getClient: vi.fn(),
@@ -612,6 +613,7 @@ 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(SentryCoreBrowser.startInactiveSpan).mockReturnValue(mockSpan as any);
     vi.mocked(SentryCore.getActiveSpan).mockReturnValue(undefined);
@@ -792,6 +794,7 @@ 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(SentryCoreBrowser.startInactiveSpan).mockReturnValue({ end: vi.fn() } as any);
@@ -890,6 +893,7 @@ describe('soft navigation web vitals', () => {
       supportedEntryTypes: ['largest-contentful-paint', 'layout-shift', 'soft-navigation'],
     });
     vi.mocked(SentryCore.browserPerformanceTimeOrigin).mockReturnValue(1000);
+    vi.mocked(SentryCore.correctedPerformanceTimeOrigin).mockReturnValue(1000);
     vi.mocked(SentryCore.getCurrentScope).mockReturnValue(mockScope as any);
     vi.mocked(SentryCoreBrowser.startInactiveSpan).mockReturnValue({ end: vi.fn() } as any);
     vi.mocked(SentryCore.spanToJSON).mockImplementation(
diff --git a/packages/browser/src/profiling/utils.ts b/packages/browser/src/profiling/utils.ts
index 2669e121ac97..cdc35a1649cb 100644
--- a/packages/browser/src/profiling/utils.ts
+++ b/packages/browser/src/profiling/utils.ts
@@ -1,7 +1,7 @@
 /* eslint-disable max-lines */
 import type { Client, ContinuousThreadCpuProfile, DebugImage, ProfileChunk, Span } from '@sentry/core';
 import {
-  browserPerformanceTimeOrigin,
+  correctedPerformanceTimeOrigin,
   debug,
   getClient,
   getDebugImagesForResources,
@@ -148,7 +148,7 @@ 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);
 
diff --git a/packages/core/src/index.ts b/packages/core/src/index.ts
index 20b52be30603..a8d889fc4c0f 100644
--- a/packages/core/src/index.ts
+++ b/packages/core/src/index.ts
@@ -276,7 +276,12 @@ 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> {