fix(replay): Ignore old events when manually starting replay

packages/replay-internal/src/replay.ts

@@ -100,6 +100,9 @@ export class ReplayContainer implements ReplayContainerInterface {
    */
   public readonly timeouts: Timeouts;
 
+  /** The replay has to be manually started, because no sample rate (neither session or error) was provided. */
+  private _requiresManualStart: boolean;
+
   private _throttledAddEvent: (
     event: RecordingEvent,
     isCheckout?: boolean,
@@ -170,6 +173,7 @@ export class ReplayContainer implements ReplayContainerInterface {
     this._lastActivity = Date.now();
     this._isEnabled = false;
     this._isPaused = false;
+    this._requiresManualStart = false;
     this._hasInitializedCoreListeners = false;
     this._context = {
       errorIds: new Set(),
@@ -246,7 +250,11 @@ export class ReplayContainer implements ReplayContainerInterface {
 
     // If neither sample rate is > 0, then do nothing - user will need to call one of
     // `start()` or `startBuffering` themselves.
-    if (errorSampleRate <= 0 && sessionSampleRate <= 0) {
+    const requiresManualStart = errorSampleRate <= 0 && sessionSampleRate <= 0;
+
+    this._requiresManualStart = requiresManualStart;
+
+    if (requiresManualStart) {
       return;
     }
 
@@ -1049,7 +1057,9 @@ export class ReplayContainer implements ReplayContainerInterface {
   /** Update the initial timestamp based on the buffer content. */
   private _updateInitialTimestampFromEventBuffer(): void {
     const { session, eventBuffer } = this;
-    if (!session || !eventBuffer) {
+    // If replay was started manually (=no sample rate was given),
+    // We do not want to back-port the initial timestamp
+    if (!session || !eventBuffer || this._requiresManualStart) {
       return;
     }
 

packages/replay-internal/test/integration/earlyEvents.test.ts

@@ -0,0 +1,107 @@
+import { BASE_TIMESTAMP } from '..';
+import { resetSdkMock } from '../mocks/resetSdkMock';
+import { useFakeTimers } from '../utils/use-fake-timers';
+
+useFakeTimers();
+
+describe('Integration | early events', () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it('updates initialTimestamp for early performance entries', async () => {
+    const earlyTimeStampSeconds = BASE_TIMESTAMP / 1000 - 10;
+
+    const { replay } = await resetSdkMock({
+      replayOptions: {
+        stickySession: true,
+      },
+      sentryOptions: {
+        replaysSessionSampleRate: 0,
+        replaysOnErrorSampleRate: 1.0,
+      },
+    });
+
+    expect(replay.session).toBeDefined();
+    expect(replay['_requiresManualStart']).toBe(false);
+
+    const initialTimestamp = replay.getContext().initialTimestamp;
+
+    expect(initialTimestamp).not.toEqual(earlyTimeStampSeconds * 1000);
+
+    // A performance entry that happend before should not extend the session when we manually started
+    replay.replayPerformanceEntries.push({
+      type: 'largest-contentful-paint',
+      name: 'largest-contentful-paint',
+      start: earlyTimeStampSeconds,
+      end: earlyTimeStampSeconds,
+      data: {
+        value: 100,
+        size: 100,
+        nodeId: undefined,
+      },
+    });
+
+    // _too_ early events are always thrown away
+    replay.replayPerformanceEntries.push({
+      type: 'largest-contentful-paint',
+      name: 'largest-contentful-paint',
+      start: earlyTimeStampSeconds - 999999,
+      end: earlyTimeStampSeconds - 99999,
+      data: {
+        value: 100,
+        size: 100,
+        nodeId: undefined,
+      },
+    });
+
+    await replay.flushImmediate();
+    vi.runAllTimers();
+
+    expect(replay.getContext().initialTimestamp).toEqual(earlyTimeStampSeconds * 1000);
+  });
+
+  it('does not change initialTimestamp when replay is manually started', async () => {
+    const earlyTimeStampSeconds = Date.now() / 1000 - 5;
+
+    const { replay } = await resetSdkMock({
+      replayOptions: {
+        stickySession: true,
+      },
+      sentryOptions: {
+        replaysSessionSampleRate: 0.0,
+        replaysOnErrorSampleRate: 0.0,
+      },
+    });
+
+    expect(replay.session).toBe(undefined);
+    expect(replay['_requiresManualStart']).toBe(true);
+
+    replay.start();
+    vi.runAllTimers();
+
+    const initialTimestamp = replay.getContext().initialTimestamp;
+
+    expect(initialTimestamp).not.toEqual(earlyTimeStampSeconds * 1000);
+    expect(replay.session).toBeDefined();
+    expect(replay['_requiresManualStart']).toBe(true);
+
+    // A performance entry that happened before should not extend the session when we manually started
+    replay.replayPerformanceEntries.push({
+      type: 'largest-contentful-paint',
+      name: 'largest-contentful-paint',
+      start: earlyTimeStampSeconds,
+      end: earlyTimeStampSeconds,
+      data: {
+        value: 100,
+        size: 100,
+        nodeId: undefined,
+      },
+    });
+
+    await replay.flushImmediate();
+    vi.runAllTimers();
+
+    expect(replay.getContext().initialTimestamp).toEqual(initialTimestamp);
+  });
+});