fix(replay): Defer buffered replay upload until after error sampling

CHANGELOG.md

@@ -20,6 +20,7 @@
 - Time to initial display is no longer understated on Android in optimized release builds ([#6692](https://github.com/getsentry/sentry-react-native/pull/6692))
 - Fix visionOS compilation ([#6676](https://github.com/getsentry/sentry-react-native/pull/6676))
 - A throwing `beforeBreadcrumb` now drops the breadcrumb, and a throwing `tracesSampler` now falls back to the configured `tracesSampleRate` ([#6675](https://github.com/getsentry/sentry-react-native/pull/6675))
+- Stop uploading on-error Session Replays for errors dropped by `sampleRate` ([#6685](https://github.com/getsentry/sentry-react-native/pull/6685))
 
 ### Internal
 

packages/core/android/src/main/java/io/sentry/react/RNSentryModuleImpl.java

@@ -482,17 +482,36 @@ public void fetchNativeFramesDelay(
 
   public void captureReplay(boolean isHardCrash, Promise promise) {
     Sentry.getCurrentScopes().getOptions().getReplayController().captureReplay(isHardCrash);
-    promise.resolve(getCurrentReplayId());
+    // Resolve with the scope's replayId, which is populated only when a replay
+    // was actually sent. Returning the controller's buffered id here would make
+    // JS treat an on-error sampling miss as a successful flush, diverging from
+    // iOS (which resolves nil unless a replay was captured).
+    promise.resolve(getReplayIdFromScope());
   }
 
   public @Nullable String getCurrentReplayId() {
+    // Prefer the replay controller's id: it is assigned when recording starts
+    // (buffer or session) and is therefore available BEFORE a replay is
+    // flushed, so a buffered (on-error) replay can be linked to the event in
+    // `beforeSend`. The scope's replayId is only populated once a replay is
+    // sent, so it stays empty while a buffer replay is recording (issue #6598).
+    final @NotNull SentryId controllerId =
+        Sentry.getCurrentScopes().getOptions().getReplayController().getReplayId();
+    if (!SentryId.EMPTY_ID.equals(controllerId)) {
+      return controllerId.toString();
+    }
+
+    return getReplayIdFromScope();
+  }
+
+  private @Nullable String getReplayIdFromScope() {
     final @Nullable IScope scope = InternalSentrySdk.getCurrentScope();
     if (scope == null) {
       return null;
     }
 
     final @NotNull SentryId id = scope.getReplayId();
-    if (id == SentryId.EMPTY_ID) {
+    if (SentryId.EMPTY_ID.equals(id)) {
       return null;
     }
     return id.toString();

packages/core/android/src/test/java/io/sentry/react/RNSentryReplayIdTest.java

@@ -0,0 +1,166 @@
+package io.sentry.react;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+import static org.mockito.ArgumentMatchers.anyInt;
+import static org.mockito.ArgumentMatchers.anyString;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.mockStatic;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import android.content.pm.PackageInfo;
+import android.content.pm.PackageManager;
+import com.facebook.react.bridge.Promise;
+import com.facebook.react.bridge.ReactApplicationContext;
+import io.sentry.IScope;
+import io.sentry.IScopes;
+import io.sentry.ReplayController;
+import io.sentry.Sentry;
+import io.sentry.SentryOptions;
+import io.sentry.android.core.InternalSentrySdk;
+import io.sentry.protocol.SentryId;
+import org.junit.Before;
+import org.junit.Test;
+import org.mockito.MockedStatic;
+
+/**
+ * Coverage for {@link RNSentryModuleImpl#getCurrentReplayId()} and its buffer (on-error) replay
+ * lookup added for https://github.com/getsentry/sentry-react-native/issues/6598.
+ *
+ * <p>A buffer replay's id is assigned by the {@link ReplayController} when recording starts, but
+ * the scope's replayId is only populated once a replay is sent. The JS mobile replay integration
+ * must be able to read the buffered id BEFORE the replay is flushed, so {@code
+ * getCurrentReplayId()} prefers the controller's id and only falls back to the scope.
+ */
+public class RNSentryReplayIdTest {
+
+  private RNSentryModuleImpl module;
+
+  @Before
+  public void setUp() throws Exception {
+    ReactApplicationContext reactContext = mock(ReactApplicationContext.class);
+    PackageManager packageManager = mock(PackageManager.class);
+    when(packageManager.getPackageInfo(anyString(), anyInt())).thenReturn(new PackageInfo());
+    when(reactContext.getPackageManager()).thenReturn(packageManager);
+    when(reactContext.getPackageName()).thenReturn("com.test.app");
+    module = new RNSentryModuleImpl(reactContext);
+  }
+
+  /**
+   * Wires {@code Sentry.getCurrentScopes().getOptions().getReplayController()} to return the id and
+   * hands back the mocked controller so callers can verify interactions with it.
+   */
+  private ReplayController stubControllerReplayId(
+      final MockedStatic<Sentry> sentry, final SentryId id) {
+    final ReplayController replayController = mock(ReplayController.class);
+    when(replayController.getReplayId()).thenReturn(id);
+    final SentryOptions options = mock(SentryOptions.class);
+    when(options.getReplayController()).thenReturn(replayController);
+    final IScopes scopes = mock(IScopes.class);
+    when(scopes.getOptions()).thenReturn(options);
+    sentry.when(Sentry::getCurrentScopes).thenReturn(scopes);
+    return replayController;
+  }
+
+  @Test
+  public void prefersReplayControllerIdWhenBuffering() {
+    // A buffer replay is recording: the controller exposes its id even though the scope has none.
+    final SentryId bufferedId = new SentryId();
+
+    try (MockedStatic<Sentry> sentry = mockStatic(Sentry.class);
+        MockedStatic<InternalSentrySdk> internal = mockStatic(InternalSentrySdk.class)) {
+      stubControllerReplayId(sentry, bufferedId);
+      // Scope has no replay id yet — the fix must not depend on it.
+      final IScope scope = mock(IScope.class);
+      when(scope.getReplayId()).thenReturn(SentryId.EMPTY_ID);
+      internal.when(InternalSentrySdk::getCurrentScope).thenReturn(scope);
+
+      assertEquals(bufferedId.toString(), module.getCurrentReplayId());
+    }
+  }
+
+  @Test
+  public void fallsBackToScopeIdWhenControllerEmpty() {
+    // A full-session replay was sent: the controller reports empty, the id lives on the scope.
+    final SentryId scopeId = new SentryId();
+
+    try (MockedStatic<Sentry> sentry = mockStatic(Sentry.class);
+        MockedStatic<InternalSentrySdk> internal = mockStatic(InternalSentrySdk.class)) {
+      stubControllerReplayId(sentry, SentryId.EMPTY_ID);
+      final IScope scope = mock(IScope.class);
+      when(scope.getReplayId()).thenReturn(scopeId);
+      internal.when(InternalSentrySdk::getCurrentScope).thenReturn(scope);
+
+      assertEquals(scopeId.toString(), module.getCurrentReplayId());
+    }
+  }
+
+  @Test
+  public void returnsNullWhenControllerEmptyAndScopeEmpty() {
+    try (MockedStatic<Sentry> sentry = mockStatic(Sentry.class);
+        MockedStatic<InternalSentrySdk> internal = mockStatic(InternalSentrySdk.class)) {
+      stubControllerReplayId(sentry, SentryId.EMPTY_ID);
+      final IScope scope = mock(IScope.class);
+      when(scope.getReplayId()).thenReturn(SentryId.EMPTY_ID);
+      internal.when(InternalSentrySdk::getCurrentScope).thenReturn(scope);
+
+      assertNull(module.getCurrentReplayId());
+    }
+  }
+
+  @Test
+  public void returnsNullWhenControllerEmptyAndScopeNull() {
+    try (MockedStatic<Sentry> sentry = mockStatic(Sentry.class);
+        MockedStatic<InternalSentrySdk> internal = mockStatic(InternalSentrySdk.class)) {
+      stubControllerReplayId(sentry, SentryId.EMPTY_ID);
+      internal.when(InternalSentrySdk::getCurrentScope).thenReturn(null);
+
+      assertNull(module.getCurrentReplayId());
+    }
+  }
+
+  @Test
+  public void captureReplayResolvesNullOnSamplingMissEvenWhileBuffering() {
+    // On an on-error sampling miss the controller still holds the buffered id, but the scope has
+    // none because nothing was uploaded. captureReplay must resolve null (matching iOS), rather
+    // than leak the buffered id as if a replay had been sent.
+    final SentryId bufferedId = new SentryId();
+
+    try (MockedStatic<Sentry> sentry = mockStatic(Sentry.class);
+        MockedStatic<InternalSentrySdk> internal = mockStatic(InternalSentrySdk.class)) {
+      final ReplayController replayController = stubControllerReplayId(sentry, bufferedId);
+      final IScope scope = mock(IScope.class);
+      when(scope.getReplayId()).thenReturn(SentryId.EMPTY_ID);
+      internal.when(InternalSentrySdk::getCurrentScope).thenReturn(scope);
+
+      final Promise promise = mock(Promise.class);
+      module.captureReplay(true, promise);
+
+      verify(replayController).captureReplay(true);
+      verify(promise).resolve(null);
+    }
+  }
+
+  @Test
+  public void captureReplayResolvesScopeIdWhenReplayWasSent() {
+    // When a replay is actually sent the scope carries its id; captureReplay resolves that, not the
+    // controller's id, so JS learns the real uploaded replay id.
+    final SentryId bufferedId = new SentryId();
+    final SentryId scopeId = new SentryId();
+
+    try (MockedStatic<Sentry> sentry = mockStatic(Sentry.class);
+        MockedStatic<InternalSentrySdk> internal = mockStatic(InternalSentrySdk.class)) {
+      final ReplayController replayController = stubControllerReplayId(sentry, bufferedId);
+      final IScope scope = mock(IScope.class);
+      when(scope.getReplayId()).thenReturn(scopeId);
+      internal.when(InternalSentrySdk::getCurrentScope).thenReturn(scope);
+
+      final Promise promise = mock(Promise.class);
+      module.captureReplay(false, promise);
+
+      verify(replayController).captureReplay(false);
+      verify(promise).resolve(scopeId.toString());
+    }
+  }
+}

packages/core/src/js/replay/mobilereplay.ts

@@ -345,7 +345,25 @@ export const mobileReplayIntegration = (initOptions: MobileReplayOptions = defau
     return nativeReplayId;
   }
 
-  async function processEvent(event: ErrorEvent, hint: EventHint): Promise<ErrorEvent> {
+  // Error `sampleRate` sampling runs AFTER `beforeSend` in `@sentry/core`
+  // (since 10.70.0, getsentry/sentry-javascript#22819). Flushing the buffered
+  // replay inside `beforeSend` therefore uploads a replay even for errors that
+  // are then dropped by `sampleRate`, orphaning the replay (issue #6598).
+  //
+  // The work is split in two:
+  //   1. `tagEventWithReplayId` runs in the `beforeSend` wrapper and only links
+  //      the event to the buffered replay id (no flush).
+  //   2. `flushReplayForSentEvent` runs in `afterSendEvent`, which fires only
+  //      for events that survive sampling and are actually sent, and performs
+  //      the native flush there.
+  //
+  // Trade-off: the link is tagged optimistically from the buffered id before the
+  // native `replaysOnErrorSampleRate` roll (which still happens at flush time in
+  // `captureReplay`). If that roll misses, the event carries a `replay_id` for a
+  // replay that is never uploaded. A fully-correct fix requires the native SDKs
+  // to decouple the on-error sampling decision from the buffer upload.
+
+  function tagEventWithReplayId(event: ErrorEvent, hint: EventHint): ErrorEvent {
     const hasException = event.exception?.values && event.exception.values.length > 0;
     if (!hasException) {
       // Event is not an error, will not capture replay
@@ -370,39 +388,58 @@ export const mobileReplayIntegration = (initOptions: MobileReplayOptions = defau
       }
     }
 
-    const replayId = await NATIVE.captureReplay(isHardCrash(event));
+    // Read the buffered replay id WITHOUT flushing. The native bridge returns
+    // the id assigned when recording started (buffer or full session), so the
+    // event can be linked to the replay that will be flushed after sampling.
+    const replayId = NATIVE.getCurrentReplayId();
     if (replayId) {
       updateCachedReplayId(replayId);
-      debug.log(
-        `[Sentry] ${MOBILE_REPLAY_INTEGRATION_NAME} Captured recording replay ${replayId} for event ${event.event_id}.`,
-      );
       // Add replay_id to error event contexts to link replays to events/traces
       event.contexts = event.contexts || {};
       event.contexts.replay = {
         ...event.contexts.replay,
         replay_id: replayId,
       };
+      debug.log(
+        `[Sentry] ${MOBILE_REPLAY_INTEGRATION_NAME} linked replay ${replayId} to event ${event.event_id}; flush deferred until after sampling.`,
+      );
     } else {
-      // Check if there's an ongoing recording and update cache if found
-      const recordingReplayId = NATIVE.getCurrentReplayId();
-      if (recordingReplayId) {
-        updateCachedReplayId(recordingReplayId);
+      updateCachedReplayId(null);
+      debug.log(`[Sentry] ${MOBILE_REPLAY_INTEGRATION_NAME} no active recording for event ${event.event_id}.`);
+    }
+
+    return event;
+  }
+
+  async function flushReplayForSentEvent(event: Event): Promise<void> {
+    const eventId = event.event_id;
+    // Only flush for events that were linked to a buffered replay in
+    // `beforeSend`. The link lives on the event itself, so no shared bookkeeping
+    // is needed: events dropped by sampling never reach this hook and cannot
+    // affect the flush decision for other events.
+    if (!eventId || !event.contexts?.replay?.replay_id) {
+      return;
+    }
+
+    try {
+      const replayId = await NATIVE.captureReplay(isHardCrash(event));
+      if (replayId) {
+        updateCachedReplayId(replayId);
         debug.log(
-          `[Sentry] ${MOBILE_REPLAY_INTEGRATION_NAME} assign already recording replay ${recordingReplayId} for event ${event.event_id}.`,
+          `[Sentry] ${MOBILE_REPLAY_INTEGRATION_NAME} flushed recording replay ${replayId} for sent event ${eventId}.`,
         );
-        // Add replay_id to error event contexts to link replays to events/traces
-        event.contexts = event.contexts || {};
-        event.contexts.replay = {
-          ...event.contexts.replay,
-          replay_id: recordingReplayId,
-        };
       } else {
-        updateCachedReplayId(null);
-        debug.log(`[Sentry] ${MOBILE_REPLAY_INTEGRATION_NAME} not sampled for event ${event.event_id}.`);
+        // No replay was uploaded (e.g. an on-error sampling miss). Re-read the
+        // current recording id so the cache stops exposing an id that was never
+        // uploaded; it resolves to the still-active buffer id, or null.
+        updateCachedReplayId(NATIVE.getCurrentReplayId());
+        debug.log(
+          `[Sentry] ${MOBILE_REPLAY_INTEGRATION_NAME} not sampled for event ${eventId} (replaysOnErrorSampleRate).`,
+        );
       }
+    } catch (error) {
+      debug.error(`[Sentry] ${MOBILE_REPLAY_INTEGRATION_NAME} Failed to flush replay for sent event ${eventId}`, error);
     }
-
-    return event;
   }
 
   function setup(client: Client): void {
@@ -498,12 +535,21 @@ export const mobileReplayIntegration = (initOptions: MobileReplayOptions = defau
         }
       }
       try {
-        return await processEvent(result, hint);
+        return tagEventWithReplayId(result, hint);
       } catch (error) {
-        debug.error(`[Sentry] ${MOBILE_REPLAY_INTEGRATION_NAME} Failed to process event for replay`, error);
+        debug.error(`[Sentry] ${MOBILE_REPLAY_INTEGRATION_NAME} Failed to link event to replay`, error);
         return result;
       }
     };
+
+    // Flush the buffered replay only for events that survive sampling. This hook
+    // fires after the error `sampleRate` roll in `@sentry/core`, so an error
+    // dropped by sampling never triggers a replay upload (issue #6598).
+    client.on('afterSendEvent', (event: Event) => {
+      flushReplayForSentEvent(event).then(undefined, () => {
+        // errors are logged inside flushReplayForSentEvent
+      });
+    });
   }
 
   function getReplayId(): string | null {