diff --git a/lib/sdk/server/build.gradle b/lib/sdk/server/build.gradle
index 67502ef8..49cc52a0 100644
--- a/lib/sdk/server/build.gradle
+++ b/lib/sdk/server/build.gradle
@@ -73,7 +73,7 @@ ext.versions = [
     "jackson": "2.11.2",
     "jsr305": "3.0.2",
     "launchdarklyJavaSdkCommon": "2.3.0",
-    "launchdarklyJavaSdkInternal": "1.12.2",
+    "launchdarklyJavaSdkInternal": "1.13.0",
     "launchdarklyLogging": "1.1.0",
     "okhttp": "4.12.0", // specify this for the SDK build instead of relying on the transitive dependency from okhttp-eventsource
     "okhttpEventsource": "5.0.1",
diff --git a/lib/sdk/server/contract-tests/service/src/main/java/sdktest/TestService.java b/lib/sdk/server/contract-tests/service/src/main/java/sdktest/TestService.java
index cbc0fab9..78c2329a 100644
--- a/lib/sdk/server/contract-tests/service/src/main/java/sdktest/TestService.java
+++ b/lib/sdk/server/contract-tests/service/src/main/java/sdktest/TestService.java
@@ -32,6 +32,7 @@ public class TestService {
     "context-comparison",
     "context-type",
     "evaluation-hooks",
+    "event-delivery-cooldown",
     "event-gzip",
     "event-sampling",
     "filtering",
diff --git a/lib/sdk/server/contract-tests/test-suppressions-fdv2.txt b/lib/sdk/server/contract-tests/test-suppressions-fdv2.txt
index 9765a098..67388ff5 100644
--- a/lib/sdk/server/contract-tests/test-suppressions-fdv2.txt
+++ b/lib/sdk/server/contract-tests/test-suppressions-fdv2.txt
@@ -1,3 +1,8 @@
 streaming/fdv2/recoverable fallback to secondary synchronizer
 streaming/fdv2/recoverable fallback with recovery
 streaming/fdv2/permanent fallback with recovery
+# launchdarkly-java-sdk-internal's HttpErrors.classifyHttpFailure treats a 413 as an unexpected
+# failure (it has no locally-unrecoverable classification), so a 413 opens a cooldown window
+# instead of only dropping the oversized payload (SDK-3513 owns the fix and the removal of this
+# suppression).
+events/delivery cooldown/413 is dropped without disabling delivery
diff --git a/lib/sdk/server/contract-tests/test-suppressions.txt b/lib/sdk/server/contract-tests/test-suppressions.txt
index 8b137891..f2bb348b 100644
--- a/lib/sdk/server/contract-tests/test-suppressions.txt
+++ b/lib/sdk/server/contract-tests/test-suppressions.txt
@@ -1 +1,5 @@
-
+# launchdarkly-java-sdk-internal's HttpErrors.classifyHttpFailure treats a 413 as an unexpected
+# failure (it has no locally-unrecoverable classification), so a 413 opens a cooldown window
+# instead of only dropping the oversized payload (SDK-3513 owns the fix and the removal of this
+# suppression).
+events/delivery cooldown/413 is dropped without disabling delivery
diff --git a/lib/sdk/server/src/main/java/com/launchdarkly/sdk/server/ComponentsImpl.java b/lib/sdk/server/src/main/java/com/launchdarkly/sdk/server/ComponentsImpl.java
index f808ebf7..56c6eccd 100644
--- a/lib/sdk/server/src/main/java/com/launchdarkly/sdk/server/ComponentsImpl.java
+++ b/lib/sdk/server/src/main/java/com/launchdarkly/sdk/server/ComponentsImpl.java
@@ -299,11 +299,11 @@ public Result sendDiagnosticEvent(byte[] data, URI eventsBaseUri) {
       private Result transformResult(com.launchdarkly.sdk.server.subsystems.EventSender.Result result) {
         switch (result) {
         case FAILURE:
-          return new Result(false, false, null);
+          return Result.failure();
         case STOP:
-          return new Result(false, true, null);
+          return Result.unexpectedFailure();
         default:
-          return new Result(true, false, null);
+          return Result.success(null);
         }
       }
     }
diff --git a/lib/sdk/server/src/main/java/com/launchdarkly/sdk/server/subsystems/EventSender.java b/lib/sdk/server/src/main/java/com/launchdarkly/sdk/server/subsystems/EventSender.java
index 20b4e29f..bac4725f 100644
--- a/lib/sdk/server/src/main/java/com/launchdarkly/sdk/server/subsystems/EventSender.java
+++ b/lib/sdk/server/src/main/java/com/launchdarkly/sdk/server/subsystems/EventSender.java
@@ -29,8 +29,19 @@ public enum Result {
     FAILURE,
     
     /**
-     * The EventSender was not able to deliver the events, and the nature of the error indicates that
-     * the SDK should not attempt to send any more events.
+     * The EventSender was not able to deliver the events, and the nature of the error (such as an
+     * HTTP 401 error, implying that the SDK key is invalid) indicates that the SDK should stop
+     * attempting delivery for a while.
+     * <p>
+     * The SDK responds by entering a bounded cooldown window. While the window is open, the SDK
+     * initiates no new analytics-event deliveries through this EventSender (a delivery already
+     * dispatched when the window opened still completes), and analytics events that would have
+     * been sent during the window are discarded rather than held. Diagnostic-event calls are not
+     * suppressed, and this result from one of them opens a window of its own. If delivery is
+     * still failing this way when a window elapses, the next window is longer, up to a ceiling;
+     * sustained successful delivery returns it to the initial length. Delivery resumes on its own
+     * once a window has elapsed; no application action is required, and event delivery is never
+     * disabled permanently. Returning {@link #FAILURE} instead never opens or lengthens a window.
      */
     STOP
   };
diff --git a/lib/sdk/server/src/test/java/com/launchdarkly/sdk/server/EventSenderWrapperTest.java b/lib/sdk/server/src/test/java/com/launchdarkly/sdk/server/EventSenderWrapperTest.java
new file mode 100644
index 00000000..8b3084c9
--- /dev/null
+++ b/lib/sdk/server/src/test/java/com/launchdarkly/sdk/server/EventSenderWrapperTest.java
@@ -0,0 +1,109 @@
+package com.launchdarkly.sdk.server;
+
+import com.launchdarkly.sdk.server.ComponentsImpl.EventProcessorBuilderImpl.EventSenderWrapper;
+import com.launchdarkly.sdk.server.subsystems.EventSender;
+
+import org.junit.Test;
+
+import java.io.IOException;
+import java.net.URI;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertSame;
+import static org.junit.Assert.assertTrue;
+
+@SuppressWarnings("javadoc")
+public class EventSenderWrapperTest {
+  private static final URI FAKE_URI = URI.create("http://fake");
+  private static final byte[] FAKE_DATA = new byte[] {1, 2, 3};
+
+  private static final class RecordingSender implements EventSender {
+    private final Result result;
+    String methodCalled;
+    byte[] receivedData;
+    int receivedEventCount = -1;
+    URI receivedUri;
+
+    RecordingSender(Result result) {
+      this.result = result;
+    }
+
+    @Override
+    public Result sendAnalyticsEvents(byte[] data, int eventCount, URI eventsBaseUri) {
+      methodCalled = "analytics";
+      receivedData = data;
+      receivedEventCount = eventCount;
+      receivedUri = eventsBaseUri;
+      return result;
+    }
+
+    @Override
+    public Result sendDiagnosticEvent(byte[] data, URI eventsBaseUri) {
+      methodCalled = "diagnostic";
+      receivedData = data;
+      receivedUri = eventsBaseUri;
+      return result;
+    }
+
+    @Override
+    public void close() throws IOException {}
+  }
+
+  @Test
+  public void successMapsToSuccessfulDelivery() {
+    RecordingSender sender = new RecordingSender(EventSender.Result.SUCCESS);
+    com.launchdarkly.sdk.internal.events.EventSender.Result result =
+        new EventSenderWrapper(sender).sendAnalyticsEvents(FAKE_DATA, 3, FAKE_URI);
+
+    assertTrue(result.isSuccess());
+    assertFalse(result.isUnexpectedFailure());
+    assertNull(result.getTimeFromServer());
+
+    // The wrapper routes to the analytics method with the arguments unchanged.
+    assertEquals("analytics", sender.methodCalled);
+    assertSame(FAKE_DATA, sender.receivedData);
+    assertEquals(3, sender.receivedEventCount);
+    assertSame(FAKE_URI, sender.receivedUri);
+  }
+
+  @Test
+  public void failureMapsToOrdinaryFailure() {
+    RecordingSender sender = new RecordingSender(EventSender.Result.FAILURE);
+    com.launchdarkly.sdk.internal.events.EventSender.Result result =
+        new EventSenderWrapper(sender).sendAnalyticsEvents(FAKE_DATA, 1, FAKE_URI);
+
+    assertFalse(result.isSuccess());
+    assertFalse(result.isUnexpectedFailure());
+  }
+
+  @SuppressWarnings("deprecation")
+  @Test
+  public void stopMapsToUnexpectedFailure() {
+    RecordingSender sender = new RecordingSender(EventSender.Result.STOP);
+    com.launchdarkly.sdk.internal.events.EventSender.Result result =
+        new EventSenderWrapper(sender).sendAnalyticsEvents(FAKE_DATA, 1, FAKE_URI);
+
+    assertFalse(result.isSuccess());
+    assertTrue(result.isUnexpectedFailure());
+    // The legacy flag stays written for consumers that have not migrated off it.
+    assertTrue(result.isMustShutDown());
+  }
+
+  @Test
+  public void diagnosticPathUsesTheSameMappingAndRouting() {
+    RecordingSender stopSender = new RecordingSender(EventSender.Result.STOP);
+    com.launchdarkly.sdk.internal.events.EventSender.Result stopResult =
+        new EventSenderWrapper(stopSender).sendDiagnosticEvent(FAKE_DATA, FAKE_URI);
+    assertTrue(stopResult.isUnexpectedFailure());
+    assertEquals("diagnostic", stopSender.methodCalled);
+    assertSame(FAKE_DATA, stopSender.receivedData);
+    assertSame(FAKE_URI, stopSender.receivedUri);
+
+    RecordingSender successSender = new RecordingSender(EventSender.Result.SUCCESS);
+    assertTrue(new EventSenderWrapper(successSender)
+        .sendDiagnosticEvent(FAKE_DATA, FAKE_URI).isSuccess());
+    assertEquals("diagnostic", successSender.methodCalled);
+  }
+}