fix(android): Prevent duplicated breadcrumbs on tombstone-merged events

CHANGELOG.md

@@ -8,6 +8,7 @@
 
 ### Fixes
 
+- Prevent duplicated breadcrumbs on tombstone-merged native crash events ([#5888](https://github.com/getsentry/sentry-java/pull/5888))
 - Clear contexts when calling `Scope.clear()` ([#5902](https://github.com/getsentry/sentry-java/pull/5902))
 - Preserve custom `Throwable` identities when R8 optimizes Android apps ([#5881](https://github.com/getsentry/sentry-java/pull/5881))
 - Report the correct cpu usage for the first performance sample of a transaction, which was measured against the time since device boot ([#5926](https://github.com/getsentry/sentry-java/pull/5926))

sentry-android-core/src/main/java/io/sentry/android/core/ApplicationExitInfoEventProcessor.java

@@ -349,16 +349,19 @@ private void setExtras(final @NotNull SentryBaseEvent event) {
 
   @SuppressWarnings("unchecked")
   private void setBreadcrumbs(final @NotNull SentryBaseEvent event) {
+    final List<Breadcrumb> eventBreadcrumbs = event.getBreadcrumbs();
+    if (eventBreadcrumbs != null && !eventBreadcrumbs.isEmpty()) {
+      // the event already carries its own breadcrumbs (e.g. a tombstone-merged native
+      // crash event), so appending the persisted ones here would duplicate entries. Skip the
+      // disk read altogether since the result would be discarded anyway.
+      return;
+    }
     final List<Breadcrumb> breadcrumbs =
         (List<Breadcrumb>) readFromDisk(options, BREADCRUMBS_FILENAME, List.class);
     if (breadcrumbs == null) {
       return;
     }
-    if (event.getBreadcrumbs() == null) {
-      event.setBreadcrumbs(breadcrumbs);
-    } else {
-      event.getBreadcrumbs().addAll(breadcrumbs);
-    }
+    event.setBreadcrumbs(breadcrumbs);
   }
 
   @SuppressWarnings("unchecked")

sentry-android-core/src/test/java/io/sentry/android/core/ApplicationExitInfoEventProcessorTest.kt

@@ -334,6 +334,21 @@ class ApplicationExitInfoEventProcessorTest {
     assertEquals("Google Chrome", processed.contexts.browser!!.name)
   }
 
+  @Test
+  fun `when backfillable event already has breadcrumbs, does not duplicate them with persisted ones`() {
+    // simulates a tombstone-merged native crash event, which already carries its own
+    // breadcrumb history captured at crash time, overlapping with what was persisted to disk
+    val hint = HintUtils.createWithTypeCheckHint(BackfillableHint())
+
+    val processed =
+      processEvent(hint, populateScopeCache = true) {
+        breadcrumbs = listOf(Breadcrumb.debug("own-crash-time-breadcrumb"))
+      }
+
+    assertEquals(1, processed.breadcrumbs!!.size)
+    assertEquals("own-crash-time-breadcrumb", processed.breadcrumbs!![0].message)
+  }
+
   @Test
   fun `when backfillable event is enrichable, does not backfill user ip`() {
     val hint = HintUtils.createWithTypeCheckHint(BackfillableHint())
@@ -670,10 +685,11 @@ class ApplicationExitInfoEventProcessorTest {
 
     assertEquals("MainActivity", processed.transaction)
     assertEquals(DEBUG, processed.level)
-    assertEquals(3, processed.breadcrumbs!!.size)
+    // breadcrumbs already set on the event are preserved as-is, not merged with the persisted
+    // ones, since the event already carries its own authoritative breadcrumb history
+    assertEquals(1, processed.breadcrumbs!!.size)
     assertEquals("debug", processed.breadcrumbs!![0].type)
-    assertEquals("debug", processed.breadcrumbs!![1].type)
-    assertEquals("navigation", processed.breadcrumbs!![2].type)
+    assertEquals("test", processed.breadcrumbs!![0].message)
 
     assertEquals("debug", processed.environment)
     assertEquals("io.sentry.samples@1.1.0+220", processed.release)

sentry/src/main/java/io/sentry/SentryClient.java

@@ -1618,7 +1618,8 @@ public void captureBatchedMetricsEvents(final @NotNull SentryMetricsEvents metri
           }
         }
       }
-      if (sentryBaseEvent.getBreadcrumbs() == null) {
+      final List<Breadcrumb> eventBreadcrumbs = sentryBaseEvent.getBreadcrumbs();
+      if (eventBreadcrumbs == null || eventBreadcrumbs.isEmpty()) {
         sentryBaseEvent.setBreadcrumbs(new ArrayList<>(scope.getBreadcrumbs()));
       } else if (!isCached) {
         // A Cached event comes from the outbox and already carries its own breadcrumbs (e.g. native