diff --git a/PREUPLOAD.cfg b/PREUPLOAD.cfg
index 83619d6..39009cb 100644
--- a/PREUPLOAD.cfg
+++ b/PREUPLOAD.cfg
@@ -1,6 +1,15 @@
+[Builtin Hooks]
+bpfmt = true
+clang_format = true
+ktfmt = true
+
+[Builtin Hooks Options]
+clang_format = --commit ${PREUPLOAD_COMMIT} --style file --extensions c,h,cc,cpp,hpp
+ktfmt = --kotlinlang-style
+
 [Hook Scripts]
 checkstyle_hook = ${REPO_ROOT}/prebuilts/checkstyle/checkstyle.py --sha ${PREUPLOAD_COMMIT}
 
-ktlint_hook = ${REPO_ROOT}/prebuilts/ktlint/ktlint.py -f ${PREUPLOAD_FILES}
+ktlint_hook = ${REPO_ROOT}/prebuilts/ktlint/ktlint.py --no-verify-format -f ${PREUPLOAD_FILES}
 
 hidden_api_txt_checksorted_hook = ${REPO_ROOT}/tools/platform-compat/hiddenapi/checksorted_sha.sh ${PREUPLOAD_COMMIT} ${REPO_ROOT}
diff --git a/Tethering/common/TetheringLib/src/android/net/TetheringManager.java b/Tethering/common/TetheringLib/src/android/net/TetheringManager.java
index ae0161d..0f5a014 100644
--- a/Tethering/common/TetheringLib/src/android/net/TetheringManager.java
+++ b/Tethering/common/TetheringLib/src/android/net/TetheringManager.java
@@ -198,6 +198,10 @@
 
     /**
      * VIRTUAL tethering type.
+     *
+     * This tethering type is for providing external network to virtual machines
+     * running on top of Android devices, which are created and managed by
+     * AVF(Android Virtualization Framework).
      * @hide
      */
     @FlaggedApi(Flags.TETHERING_REQUEST_VIRTUAL)
diff --git a/framework/src/android/net/ConnectivityManager.java b/framework/src/android/net/ConnectivityManager.java
index 5e41dd9..a6a967b 100644
--- a/framework/src/android/net/ConnectivityManager.java
+++ b/framework/src/android/net/ConnectivityManager.java
@@ -4489,6 +4489,7 @@
     public static final int CALLBACK_BLK_CHANGED                = 11;
     /** @hide */
     public static final int CALLBACK_LOCAL_NETWORK_INFO_CHANGED = 12;
+    // When adding new IDs, note CallbackQueue assumes callback IDs are at most 16 bits.
 
 
     /** @hide */
diff --git a/service/src/com/android/server/CallbackQueue.java b/service/src/com/android/server/CallbackQueue.java
new file mode 100644
index 0000000..060a984
--- /dev/null
+++ b/service/src/com/android/server/CallbackQueue.java
@@ -0,0 +1,126 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server;
+
+import android.annotation.NonNull;
+import android.net.ConnectivityManager;
+import android.net.ConnectivityManager.NetworkCallback;
+
+import com.android.net.module.util.GrowingIntArray;
+
+/**
+ * A utility class to add/remove {@link NetworkCallback}s from a queue.
+ *
+ * <p>This is intended to be used as a temporary builder to create/modify callbacks stored in an int
+ * array for memory efficiency.
+ *
+ * <p>Intended usage:
+ * <pre>
+ *     final CallbackQueue queue = new CallbackQueue(storedCallbacks);
+ *     queue.forEach(netId, callbackId -> { [...] });
+ *     queue.addCallback(netId, callbackId);
+ *     [...]
+ *     queue.shrinkToLength();
+ *     storedCallbacks = queue.getBackingArray();
+ * </pre>
+ *
+ * <p>This class is not thread-safe.
+ */
+public class CallbackQueue extends GrowingIntArray {
+    public CallbackQueue(int[] initialCallbacks) {
+        super(initialCallbacks);
+    }
+
+    /**
+     * Get a callback int from netId and callbackId.
+     *
+     * <p>The first 16 bits of each int is the netId; the last 16 bits are the callback index.
+     */
+    private static int getCallbackInt(int netId, int callbackId) {
+        return (netId << 16) | (callbackId & 0xffff);
+    }
+
+    private static int getNetId(int callbackInt) {
+        return callbackInt >>> 16;
+    }
+
+    private static int getCallbackId(int callbackInt) {
+        return callbackInt & 0xffff;
+    }
+
+    /**
+     * A consumer interface for {@link #forEach(CallbackConsumer)}.
+     *
+     * <p>This is similar to a BiConsumer&lt;Integer, Integer&gt;, but avoids the boxing cost.
+     */
+    public interface CallbackConsumer {
+        /**
+         * Method called on each callback in the queue.
+         */
+        void accept(int netId, int callbackId);
+    }
+
+    /**
+     * Iterate over all callbacks in the queue.
+     */
+    public void forEach(@NonNull CallbackConsumer consumer) {
+        forEach(value -> {
+            final int netId = getNetId(value);
+            final int callbackId = getCallbackId(value);
+            consumer.accept(netId, callbackId);
+        });
+    }
+
+    /**
+     * Indicates whether the queue contains a callback for the given (netId, callbackId).
+     */
+    public boolean hasCallback(int netId, int callbackId) {
+        return contains(getCallbackInt(netId, callbackId));
+    }
+
+    /**
+     * Remove all callbacks for the given netId.
+     *
+     * @return true if at least one callback was removed.
+     */
+    public boolean removeCallbacksForNetId(int netId) {
+        return removeValues(cb -> getNetId(cb) == netId);
+    }
+
+    /**
+     * Remove all callbacks for the given netId and callbackId.
+     * @return true if at least one callback was removed.
+     */
+    public boolean removeCallbacks(int netId, int callbackId) {
+        final int cbInt = getCallbackInt(netId, callbackId);
+        return removeValues(cb -> cb == cbInt);
+    }
+
+    /**
+     * Add a callback at the end of the queue.
+     */
+    public void addCallback(int netId, int callbackId) {
+        add(getCallbackInt(netId, callbackId));
+    }
+
+    @Override
+    protected String valueToString(int item) {
+        final int callbackId = getCallbackId(item);
+        final int netId = getNetId(item);
+        return ConnectivityManager.getCallbackName(callbackId) + "(" + netId + ")";
+    }
+}
diff --git a/service/src/com/android/server/ConnectivityService.java b/service/src/com/android/server/ConnectivityService.java
index f015742..4d4dacf 100755
--- a/service/src/com/android/server/ConnectivityService.java
+++ b/service/src/com/android/server/ConnectivityService.java
@@ -145,6 +145,7 @@
 import static com.android.net.module.util.PermissionUtils.hasAnyPermissionOf;
 import static com.android.server.ConnectivityStatsLog.CONNECTIVITY_STATE_SAMPLE;
 import static com.android.server.connectivity.ConnectivityFlags.DELAY_DESTROY_SOCKETS;
+import static com.android.server.connectivity.ConnectivityFlags.QUEUE_CALLBACKS_FOR_FROZEN_APPS;
 import static com.android.server.connectivity.ConnectivityFlags.REQUEST_RESTRICTED_WIFI;
 import static com.android.server.connectivity.ConnectivityFlags.INGRESS_TO_VPN_ADDRESS_FILTERING;
 
@@ -329,9 +330,9 @@
 import com.android.net.module.util.LinkPropertiesUtils.CompareOrUpdateResult;
 import com.android.net.module.util.LinkPropertiesUtils.CompareResult;
 import com.android.net.module.util.LocationPermissionChecker;
-import com.android.net.module.util.RoutingCoordinatorService;
 import com.android.net.module.util.PerUidCounter;
 import com.android.net.module.util.PermissionUtils;
+import com.android.net.module.util.RoutingCoordinatorService;
 import com.android.net.module.util.TcUtils;
 import com.android.net.module.util.netlink.InetDiagMessage;
 import com.android.networkstack.apishim.BroadcastOptionsShimImpl;
@@ -510,6 +511,9 @@
 
     private final boolean mUseDeclaredMethodsForCallbacksEnabled;
 
+    // Flag to delay callbacks for frozen apps, suppressing duplicate and stale callbacks.
+    private final boolean mQueueCallbacksForFrozenApps;
+
     /**
      * Uids ConnectivityService tracks blocked status of to send blocked status callbacks.
      * Key is uid based on mAsUid of registered networkRequestInfo
@@ -1873,6 +1877,9 @@
                 context, ConnectivityFlags.BACKGROUND_FIREWALL_CHAIN);
         mUseDeclaredMethodsForCallbacksEnabled = mDeps.isFeatureEnabled(context,
                 ConnectivityFlags.USE_DECLARED_METHODS_FOR_CALLBACKS);
+        // registerUidFrozenStateChangedCallback is only available on U+
+        mQueueCallbacksForFrozenApps = mDeps.isAtLeastU()
+                && mDeps.isFeatureEnabled(context, QUEUE_CALLBACKS_FOR_FROZEN_APPS);
         mCarrierPrivilegeAuthenticator = mDeps.makeCarrierPrivilegeAuthenticator(
                 mContext, mTelephonyManager, mRequestRestrictedWifiEnabled,
                 this::handleUidCarrierPrivilegesLost, mHandler);
@@ -2028,7 +2035,7 @@
         mDelayDestroySockets = mDeps.isFeatureNotChickenedOut(context, DELAY_DESTROY_SOCKETS);
         mAllowSysUiConnectivityReports = mDeps.isFeatureNotChickenedOut(
                 mContext, ALLOW_SYSUI_CONNECTIVITY_REPORTS);
-        if (mDestroyFrozenSockets) {
+        if (mDestroyFrozenSockets || mQueueCallbacksForFrozenApps) {
             final UidFrozenStateChangedCallback frozenStateChangedCallback =
                     new UidFrozenStateChangedCallback() {
                 @Override
@@ -3464,6 +3471,14 @@
 
     private void handleFrozenUids(int[] uids, int[] frozenStates) {
         ensureRunningOnConnectivityServiceThread();
+        handleDestroyFrozenSockets(uids, frozenStates);
+        // TODO: handle freezing NetworkCallbacks
+    }
+
+    private void handleDestroyFrozenSockets(int[] uids, int[] frozenStates) {
+        if (!mDestroyFrozenSockets) {
+            return;
+        }
         for (int i = 0; i < uids.length; i++) {
             final int uid = uids[i];
             final boolean addReason = frozenStates[i] == UID_FROZEN_STATE_FROZEN;
@@ -7764,6 +7779,11 @@
             }
         }
 
+        boolean isCallbackOverridden(int callbackId) {
+            return !mUseDeclaredMethodsForCallbacksEnabled
+                    || (mDeclaredMethodsFlags & (1 << callbackId)) != 0;
+        }
+
         boolean hasHigherOrderThan(@NonNull final NetworkRequestInfo target) {
             // Compare two preference orders.
             return mPreferenceOrder < target.mPreferenceOrder;
@@ -10233,6 +10253,18 @@
         return new LocalNetworkInfo.Builder().setUpstreamNetwork(upstream).build();
     }
 
+    private Bundle makeCommonBundleForCallback(@NonNull final NetworkRequestInfo nri,
+            @Nullable Network network) {
+        final Bundle bundle = new Bundle();
+        // TODO b/177608132: make sure callbacks are indexed by NRIs and not NetworkRequest objects.
+        // TODO: check if defensive copies of data is needed.
+        putParcelable(bundle, nri.getNetworkRequestForCallback());
+        if (network != null) {
+            putParcelable(bundle, network);
+        }
+        return bundle;
+    }
+
     // networkAgent is only allowed to be null if notificationType is
     // CALLBACK_UNAVAIL. This is because UNAVAIL is about no network being
     // available, while all other cases are about some particular network.
@@ -10245,22 +10277,17 @@
             // are Type.LISTEN, but should not have NetworkCallbacks invoked.
             return;
         }
-        if (mUseDeclaredMethodsForCallbacksEnabled
-                && (nri.mDeclaredMethodsFlags & (1 << notificationType)) == 0) {
+        if (!nri.isCallbackOverridden(notificationType)) {
             // No need to send the notification as the recipient method is not overridden
             return;
         }
-        final Bundle bundle = new Bundle();
-        // TODO b/177608132: make sure callbacks are indexed by NRIs and not NetworkRequest objects.
-        // TODO: check if defensive copies of data is needed.
-        final NetworkRequest nrForCallback = nri.getNetworkRequestForCallback();
-        putParcelable(bundle, nrForCallback);
-        Message msg = Message.obtain();
-        if (notificationType != CALLBACK_UNAVAIL) {
-            putParcelable(bundle, networkAgent.network);
-        }
+        final Network bundleNetwork = notificationType == CALLBACK_UNAVAIL
+                ? null
+                : networkAgent.network;
+        final Bundle bundle = makeCommonBundleForCallback(nri, bundleNetwork);
         final boolean includeLocationSensitiveInfo =
                 (nri.mCallbackFlags & NetworkCallback.FLAG_INCLUDE_LOCATION_INFO) != 0;
+        final NetworkRequest nrForCallback = nri.getNetworkRequestForCallback();
         switch (notificationType) {
             case CALLBACK_AVAILABLE: {
                 final NetworkCapabilities nc =
@@ -10277,12 +10304,6 @@
                 // method here.
                 bundle.putParcelable(LocalNetworkInfo.class.getSimpleName(),
                         localNetworkInfoForNai(networkAgent));
-                // For this notification, arg1 contains the blocked status.
-                msg.arg1 = arg1;
-                break;
-            }
-            case CALLBACK_LOSING: {
-                msg.arg1 = arg1;
                 break;
             }
             case CALLBACK_CAP_CHANGED: {
@@ -10305,7 +10326,6 @@
             }
             case CALLBACK_BLK_CHANGED: {
                 maybeLogBlockedStatusChanged(nri, networkAgent.network, arg1);
-                msg.arg1 = arg1;
                 break;
             }
             case CALLBACK_LOCAL_NETWORK_INFO_CHANGED: {
@@ -10317,17 +10337,26 @@
                 break;
             }
         }
+        callCallbackForRequest(nri, notificationType, bundle, arg1);
+    }
+
+    private void callCallbackForRequest(@NonNull final NetworkRequestInfo nri, int notificationType,
+            Bundle bundle, int arg1) {
+        Message msg = Message.obtain();
+        msg.arg1 = arg1;
         msg.what = notificationType;
         msg.setData(bundle);
         try {
             if (VDBG) {
                 String notification = ConnectivityManager.getCallbackName(notificationType);
-                log("sending notification " + notification + " for " + nrForCallback);
+                log("sending notification " + notification + " for "
+                        + nri.getNetworkRequestForCallback());
             }
             nri.mMessenger.send(msg);
         } catch (RemoteException e) {
             // may occur naturally in the race of binder death.
-            loge("RemoteException caught trying to send a callback msg for " + nrForCallback);
+            loge("RemoteException caught trying to send a callback msg for "
+                    + nri.getNetworkRequestForCallback());
         }
     }
 
@@ -11416,11 +11445,7 @@
             return;
         }
 
-        final int blockedReasons = mUidBlockedReasons.get(nri.mAsUid, BLOCKED_REASON_NONE);
-        final boolean metered = nai.networkCapabilities.isMetered();
-        final boolean vpnBlocked = isUidBlockedByVpn(nri.mAsUid, mVpnBlockedUidRanges);
-        callCallbackForRequest(nri, nai, CALLBACK_AVAILABLE,
-                getBlockedState(nri.mAsUid, blockedReasons, metered, vpnBlocked));
+        callCallbackForRequest(nri, nai, CALLBACK_AVAILABLE, getBlockedState(nai, nri.mAsUid));
     }
 
     // Notify the requests on this NAI that the network is now lingered.
@@ -11450,6 +11475,13 @@
                 : reasons & ~BLOCKED_REASON_LOCKDOWN_VPN;
     }
 
+    private int getBlockedState(@NonNull NetworkAgentInfo nai, int uid) {
+        final boolean metered = nai.networkCapabilities.isMetered();
+        final boolean vpnBlocked = isUidBlockedByVpn(uid, mVpnBlockedUidRanges);
+        final int blockedReasons = mUidBlockedReasons.get(uid, BLOCKED_REASON_NONE);
+        return getBlockedState(uid, blockedReasons, metered, vpnBlocked);
+    }
+
     private void setUidBlockedReasons(int uid, @BlockedReason int blockedReasons) {
         if (blockedReasons == BLOCKED_REASON_NONE) {
             mUidBlockedReasons.delete(uid);
diff --git a/service/src/com/android/server/connectivity/ConnectivityFlags.java b/service/src/com/android/server/connectivity/ConnectivityFlags.java
index 1ee1ed7..df87316 100644
--- a/service/src/com/android/server/connectivity/ConnectivityFlags.java
+++ b/service/src/com/android/server/connectivity/ConnectivityFlags.java
@@ -49,6 +49,9 @@
     public static final String USE_DECLARED_METHODS_FOR_CALLBACKS =
             "use_declared_methods_for_callbacks";
 
+    public static final String QUEUE_CALLBACKS_FOR_FROZEN_APPS =
+            "queue_callbacks_for_frozen_apps";
+
     private boolean mNoRematchAllRequestsOnRegister;
 
     /**
diff --git a/staticlibs/device/com/android/net/module/util/GrowingIntArray.java b/staticlibs/device/com/android/net/module/util/GrowingIntArray.java
new file mode 100644
index 0000000..4a81c10
--- /dev/null
+++ b/staticlibs/device/com/android/net/module/util/GrowingIntArray.java
@@ -0,0 +1,190 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.net.module.util;
+
+import android.annotation.NonNull;
+
+import com.android.internal.annotations.VisibleForTesting;
+
+import java.util.Arrays;
+import java.util.StringJoiner;
+import java.util.function.IntConsumer;
+import java.util.function.IntPredicate;
+
+/**
+ * A growing array of primitive ints.
+ *
+ * <p>This is similar to ArrayList&lt;Integer&gt;, but avoids the cost of boxing (each Integer costs
+ * 16 bytes) and creation / garbage collection of individual Integer objects.
+ *
+ * <p>This class does not use any heuristic for growing capacity, so every call to
+ * {@link #add(int)} may reallocate the backing array. Callers should use
+ * {@link #ensureHasCapacity(int)} to minimize this behavior when they plan to add several values.
+ */
+public class GrowingIntArray {
+    private int[] mValues;
+    private int mLength;
+
+    /**
+     * Create an empty GrowingIntArray with the given capacity.
+     */
+    public GrowingIntArray(int initialCapacity) {
+        mValues = new int[initialCapacity];
+        mLength = 0;
+    }
+
+    /**
+     * Create a GrowingIntArray with an initial array of values.
+     *
+     * <p>The array will be used as-is and may be modified, so callers must stop using it after
+     * calling this constructor.
+     */
+    protected GrowingIntArray(int[] initialValues) {
+        mValues = initialValues;
+        mLength = initialValues.length;
+    }
+
+    /**
+     * Add a value to the array.
+     */
+    public void add(int value) {
+        ensureHasCapacity(1);
+        mValues[mLength] = value;
+        mLength++;
+    }
+
+    /**
+     * Get the current number of values in the array.
+     */
+    public int length() {
+        return mLength;
+    }
+
+    /**
+     * Get the value at a given index.
+     *
+     * @throws ArrayIndexOutOfBoundsException if the index is out of bounds.
+     */
+    public int get(int index) {
+        if (index < 0 || index >= mLength) {
+            throw new ArrayIndexOutOfBoundsException(index);
+        }
+        return mValues[index];
+    }
+
+    /**
+     * Iterate over all values in the array.
+     */
+    public void forEach(@NonNull IntConsumer consumer) {
+        for (int i = 0; i < mLength; i++) {
+            consumer.accept(mValues[i]);
+        }
+    }
+
+    /**
+     * Remove all values matching a predicate.
+     *
+     * @return true if at least one value was removed.
+     */
+    public boolean removeValues(@NonNull IntPredicate predicate) {
+        int newQueueLength = 0;
+        for (int i = 0; i < mLength; i++) {
+            final int cb = mValues[i];
+            if (!predicate.test(cb)) {
+                mValues[newQueueLength] = cb;
+                newQueueLength++;
+            }
+        }
+        if (mLength != newQueueLength) {
+            mLength = newQueueLength;
+            return true;
+        }
+        return false;
+    }
+
+    /**
+     * Indicates whether the array contains the given value.
+     */
+    public boolean contains(int value) {
+        for (int i = 0; i < mLength; i++) {
+            if (mValues[i] == value) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    /**
+     * Remove all values from the array.
+     */
+    public void clear() {
+        mLength = 0;
+    }
+
+    /**
+     * Ensure at least the given number of values can be added to the array without reallocating.
+     *
+     * @param capacity The minimum number of additional values the array must be able to hold.
+     */
+    public void ensureHasCapacity(int capacity) {
+        if (mValues.length >= mLength + capacity) {
+            return;
+        }
+        mValues = Arrays.copyOf(mValues, mLength + capacity);
+    }
+
+    @VisibleForTesting
+    int getBackingArrayLength() {
+        return mValues.length;
+    }
+
+    /**
+     * Shrink the array backing this class to the minimum required length.
+     */
+    public void shrinkToLength() {
+        if (mValues.length != mLength) {
+            mValues = Arrays.copyOf(mValues, mLength);
+        }
+    }
+
+    /**
+     * Get values as array by shrinking the internal array to length and returning it.
+     *
+     * <p>This avoids reallocations if the array is already the correct length, but callers should
+     * stop using this instance of {@link GrowingIntArray} if they use the array returned by this
+     * method.
+     */
+    public int[] getShrinkedBackingArray() {
+        shrinkToLength();
+        return mValues;
+    }
+
+    /**
+     * Get the String representation of an item in the array, for use by {@link #toString()}.
+     */
+    protected String valueToString(int item) {
+        return String.valueOf(item);
+    }
+
+    @NonNull
+    @Override
+    public String toString() {
+        final StringJoiner joiner = new StringJoiner(",", "[", "]");
+        forEach(item -> joiner.add(valueToString(item)));
+        return joiner.toString();
+    }
+}
diff --git a/staticlibs/framework/com/android/net/module/util/NetworkStackConstants.java b/staticlibs/framework/com/android/net/module/util/NetworkStackConstants.java
index a8c50d8..f1ff2e4 100644
--- a/staticlibs/framework/com/android/net/module/util/NetworkStackConstants.java
+++ b/staticlibs/framework/com/android/net/module/util/NetworkStackConstants.java
@@ -260,6 +260,18 @@
     public static final short DNS_OVER_TLS_PORT = 853;
 
     /**
+     * Dns query type constants.
+     *
+     * See also:
+     *    - https://datatracker.ietf.org/doc/html/rfc1035#section-3.2.2
+     */
+    public static final int TYPE_A = 1;
+    public static final int TYPE_PTR = 12;
+    public static final int TYPE_TXT = 16;
+    public static final int TYPE_AAAA = 28;
+    public static final int TYPE_SRV = 33;
+
+    /**
      * IEEE802.11 standard constants.
      *
      * See also:
diff --git a/staticlibs/tests/unit/src/com/android/net/module/util/GrowingIntArrayTest.kt b/staticlibs/tests/unit/src/com/android/net/module/util/GrowingIntArrayTest.kt
new file mode 100644
index 0000000..bdcb8c0
--- /dev/null
+++ b/staticlibs/tests/unit/src/com/android/net/module/util/GrowingIntArrayTest.kt
@@ -0,0 +1,129 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.net.module.util
+
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import androidx.test.filters.SmallTest
+import kotlin.test.assertContentEquals
+import kotlin.test.assertEquals
+import kotlin.test.assertFalse
+import kotlin.test.assertTrue
+import kotlin.test.fail
+import org.junit.Test
+import org.junit.runner.RunWith
+
+@RunWith(AndroidJUnit4::class)
+@SmallTest
+class GrowingIntArrayTest {
+    @Test
+    fun testAddAndGet() {
+        val array = GrowingIntArray(1)
+        array.add(-1)
+        array.add(0)
+        array.add(2)
+
+        assertEquals(-1, array.get(0))
+        assertEquals(0, array.get(1))
+        assertEquals(2, array.get(2))
+        assertEquals(3, array.length())
+    }
+
+    @Test
+    fun testForEach() {
+        val array = GrowingIntArray(10)
+        array.add(-1)
+        array.add(0)
+        array.add(2)
+
+        val actual = mutableListOf<Int>()
+        array.forEach { actual.add(it) }
+
+        val expected = listOf(-1, 0, 2)
+        assertEquals(expected, actual)
+    }
+
+    @Test
+    fun testForEach_EmptyArray() {
+        val array = GrowingIntArray(10)
+        array.forEach {
+            fail("This should not be called")
+        }
+    }
+
+    @Test
+    fun testRemoveValues() {
+        val array = GrowingIntArray(10)
+        array.add(-1)
+        array.add(0)
+        array.add(2)
+
+        array.removeValues { it <= 0 }
+        assertEquals(1, array.length())
+        assertEquals(2, array.get(0))
+    }
+
+    @Test
+    fun testContains() {
+        val array = GrowingIntArray(10)
+        array.add(-1)
+        array.add(2)
+
+        assertTrue(array.contains(-1))
+        assertTrue(array.contains(2))
+
+        assertFalse(array.contains(0))
+        assertFalse(array.contains(3))
+    }
+
+    @Test
+    fun testClear() {
+        val array = GrowingIntArray(10)
+        array.add(-1)
+        array.add(2)
+        array.clear()
+
+        assertEquals(0, array.length())
+    }
+
+    @Test
+    fun testEnsureHasCapacity() {
+        val array = GrowingIntArray(0)
+        array.add(42)
+        array.ensureHasCapacity(2)
+
+        assertEquals(3, array.backingArrayLength)
+    }
+
+    @Test
+    fun testGetShrinkedBackingArray() {
+        val array = GrowingIntArray(10)
+        array.add(-1)
+        array.add(2)
+
+        assertContentEquals(intArrayOf(-1, 2), array.shrinkedBackingArray)
+    }
+
+    @Test
+    fun testToString() {
+        assertEquals("[]", GrowingIntArray(10).toString())
+        assertEquals("[1,2,3]", GrowingIntArray(3).apply {
+            add(1)
+            add(2)
+            add(3)
+        }.toString())
+    }
+}
diff --git a/staticlibs/tests/unit/src/com/android/testutils/DefaultNetworkRestoreMonitorTest.kt b/staticlibs/tests/unit/src/com/android/testutils/DefaultNetworkRestoreMonitorTest.kt
new file mode 100644
index 0000000..7e508fb
--- /dev/null
+++ b/staticlibs/tests/unit/src/com/android/testutils/DefaultNetworkRestoreMonitorTest.kt
@@ -0,0 +1,167 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.testutils
+
+import android.content.Context
+import android.content.pm.PackageManager
+import android.net.ConnectivityManager
+import android.net.ConnectivityManager.NetworkCallback
+import android.net.Network
+import android.net.NetworkCapabilities
+import android.net.NetworkCapabilities.TRANSPORT_CELLULAR
+import android.net.NetworkCapabilities.TRANSPORT_WIFI
+import org.junit.Test
+import org.junit.runner.Description
+import org.junit.runner.notification.RunListener
+import org.junit.runner.notification.RunNotifier
+import org.mockito.ArgumentCaptor
+import org.mockito.ArgumentMatchers.any
+import org.mockito.ArgumentMatchers.anyString
+import org.mockito.ArgumentMatchers.argThat
+import org.mockito.Mockito.doAnswer
+import org.mockito.Mockito.doNothing
+import org.mockito.Mockito.doReturn
+import org.mockito.Mockito.inOrder
+import org.mockito.Mockito.mock
+import org.mockito.Mockito.never
+import org.mockito.Mockito.verify
+
+class DefaultNetworkRestoreMonitorTest {
+    private val restoreDefaultNetworkDesc =
+            Description.createSuiteDescription("RestoreDefaultNetwork")
+    private val testDesc = Description.createTestDescription("testClass", "testMethod")
+    private val wifiCap = NetworkCapabilities.Builder()
+            .addTransportType(TRANSPORT_WIFI)
+            .addCapability(NetworkCapabilities.NET_CAPABILITY_VALIDATED)
+            .build()
+    private val cellCap = NetworkCapabilities.Builder()
+            .addTransportType(TRANSPORT_CELLULAR)
+            .addCapability(NetworkCapabilities.NET_CAPABILITY_VALIDATED)
+            .build()
+    private val cm = mock(ConnectivityManager::class.java)
+    private val pm = mock(PackageManager::class.java).also {
+        doReturn(true).`when`(it).hasSystemFeature(anyString())
+    }
+    private val ctx = mock(Context::class.java).also {
+        doReturn(cm).`when`(it).getSystemService(ConnectivityManager::class.java)
+        doReturn(pm).`when`(it).getPackageManager()
+    }
+    private val notifier = mock(RunNotifier::class.java)
+    private val defaultNetworkMonitor = DefaultNetworkRestoreMonitor(
+        ctx,
+        notifier,
+        timeoutMs = 0
+    )
+
+    private fun getRunListener(): RunListener {
+        val captor = ArgumentCaptor.forClass(RunListener::class.java)
+        verify(notifier).addListener(captor.capture())
+        return captor.value
+    }
+
+    private fun mockDefaultNetworkCapabilities(cap: NetworkCapabilities?) {
+        if (cap == null) {
+            doNothing().`when`(cm).registerDefaultNetworkCallback(any())
+            return
+        }
+        doAnswer {
+            val callback = it.getArgument(0) as NetworkCallback
+            callback.onCapabilitiesChanged(Network(100), cap)
+        }.`when`(cm).registerDefaultNetworkCallback(any())
+    }
+
+    @Test
+    fun testDefaultNetworkRestoreMonitor_defaultNetworkRestored() {
+        mockDefaultNetworkCapabilities(wifiCap)
+        defaultNetworkMonitor.init(mock(ConnectUtil::class.java))
+
+        val listener = getRunListener()
+        listener.testFinished(testDesc)
+
+        defaultNetworkMonitor.reportResultAndCleanUp(restoreDefaultNetworkDesc)
+        val inOrder = inOrder(notifier)
+        inOrder.verify(notifier).fireTestStarted(restoreDefaultNetworkDesc)
+        inOrder.verify(notifier, never()).fireTestFailure(any())
+        inOrder.verify(notifier).fireTestFinished(restoreDefaultNetworkDesc)
+        inOrder.verify(notifier).removeListener(listener)
+    }
+
+    @Test
+    fun testDefaultNetworkRestoreMonitor_testStartWithoutDefaultNetwork() {
+        // There is no default network when the tests start
+        mockDefaultNetworkCapabilities(null)
+        defaultNetworkMonitor.init(mock(ConnectUtil::class.java))
+
+        mockDefaultNetworkCapabilities(wifiCap)
+        val listener = getRunListener()
+        listener.testFinished(testDesc)
+
+        defaultNetworkMonitor.reportResultAndCleanUp(restoreDefaultNetworkDesc)
+        val inOrder = inOrder(notifier)
+        inOrder.verify(notifier).fireTestStarted(restoreDefaultNetworkDesc)
+        // fireTestFailure is called
+        inOrder.verify(notifier).fireTestFailure(any())
+        inOrder.verify(notifier).fireTestFinished(restoreDefaultNetworkDesc)
+        inOrder.verify(notifier).removeListener(listener)
+    }
+
+    @Test
+    fun testDefaultNetworkRestoreMonitor_testEndWithoutDefaultNetwork() {
+        mockDefaultNetworkCapabilities(wifiCap)
+        defaultNetworkMonitor.init(mock(ConnectUtil::class.java))
+
+        // There is no default network after the test
+        mockDefaultNetworkCapabilities(null)
+        val listener = getRunListener()
+        listener.testFinished(testDesc)
+
+        defaultNetworkMonitor.reportResultAndCleanUp(restoreDefaultNetworkDesc)
+        val inOrder = inOrder(notifier)
+        inOrder.verify(notifier).fireTestStarted(restoreDefaultNetworkDesc)
+        // fireTestFailure is called with method name
+        inOrder.verify(
+                notifier
+        ).fireTestFailure(
+                argThat{failure -> failure.exception.message?.contains("testMethod") ?: false}
+        )
+        inOrder.verify(notifier).fireTestFinished(restoreDefaultNetworkDesc)
+        inOrder.verify(notifier).removeListener(listener)
+    }
+
+    @Test
+    fun testDefaultNetworkRestoreMonitor_testChangeDefaultNetwork() {
+        mockDefaultNetworkCapabilities(wifiCap)
+        defaultNetworkMonitor.init(mock(ConnectUtil::class.java))
+
+        // The default network transport types change after the test
+        mockDefaultNetworkCapabilities(cellCap)
+        val listener = getRunListener()
+        listener.testFinished(testDesc)
+
+        defaultNetworkMonitor.reportResultAndCleanUp(restoreDefaultNetworkDesc)
+        val inOrder = inOrder(notifier)
+        inOrder.verify(notifier).fireTestStarted(restoreDefaultNetworkDesc)
+        // fireTestFailure is called with method name
+        inOrder.verify(
+                notifier
+        ).fireTestFailure(
+                argThat{failure -> failure.exception.message?.contains("testMethod") ?: false}
+        )
+        inOrder.verify(notifier).fireTestFinished(restoreDefaultNetworkDesc)
+        inOrder.verify(notifier).removeListener(listener)
+    }
+}
diff --git a/staticlibs/testutils/devicetests/com/android/testutils/DefaultNetworkRestoreMonitor.kt b/staticlibs/testutils/devicetests/com/android/testutils/DefaultNetworkRestoreMonitor.kt
new file mode 100644
index 0000000..1b709b2
--- /dev/null
+++ b/staticlibs/testutils/devicetests/com/android/testutils/DefaultNetworkRestoreMonitor.kt
@@ -0,0 +1,113 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.testutils
+
+import android.content.Context
+import android.content.pm.PackageManager
+import android.net.ConnectivityManager
+import android.net.Network
+import android.net.NetworkCapabilities
+import com.android.internal.annotations.VisibleForTesting
+import com.android.net.module.util.BitUtils
+import java.util.concurrent.CompletableFuture
+import java.util.concurrent.TimeUnit
+import org.junit.runner.Description
+import org.junit.runner.notification.Failure
+import org.junit.runner.notification.RunListener
+import org.junit.runner.notification.RunNotifier
+
+@VisibleForTesting(visibility = VisibleForTesting.Visibility.PRIVATE)
+class DefaultNetworkRestoreMonitor(
+        ctx: Context,
+        private val notifier: RunNotifier,
+        private val timeoutMs: Long = 3000
+) {
+    var firstFailure: Exception? = null
+    var initialTransports = 0L
+    val cm = ctx.getSystemService(ConnectivityManager::class.java)!!
+    val pm = ctx.packageManager
+    val listener = object : RunListener() {
+        override fun testFinished(desc: Description) {
+            // Only the first method that does not restore the default network should be blamed.
+            if (firstFailure != null) {
+                return
+            }
+            val cb = TestableNetworkCallback()
+            cm.registerDefaultNetworkCallback(cb)
+            try {
+                cb.eventuallyExpect<RecorderCallback.CallbackEntry.CapabilitiesChanged>(
+                    timeoutMs = timeoutMs
+                ) {
+                    BitUtils.packBits(it.caps.transportTypes) == initialTransports &&
+                            it.caps.hasCapability(NetworkCapabilities.NET_CAPABILITY_VALIDATED)
+                }
+            } catch (e: AssertionError) {
+                firstFailure = IllegalStateException(desc.methodName +
+                        " does not restore the default network")
+            } finally {
+                cm.unregisterNetworkCallback(cb)
+            }
+        }
+    }
+
+    fun init(connectUtil: ConnectUtil) {
+        // Ensure Wi-Fi and cellular connection before running test to avoid starting test
+        // with unexpected default network.
+        // ConnectivityTestTargetPreparer does the same thing, but it's possible that previous tests
+        // don't enable DefaultNetworkRestoreMonitor and the default network is not restored.
+        // This can be removed if all tests enable DefaultNetworkRestoreMonitor
+        if (pm.hasSystemFeature(PackageManager.FEATURE_WIFI)) {
+            connectUtil.ensureWifiValidated()
+        }
+        if (pm.hasSystemFeature(PackageManager.FEATURE_TELEPHONY)) {
+            connectUtil.ensureCellularValidated()
+        }
+
+        val capFuture = CompletableFuture<NetworkCapabilities>()
+        val cb = object : ConnectivityManager.NetworkCallback() {
+            override fun onCapabilitiesChanged(
+                    network: Network,
+                    cap: NetworkCapabilities
+            ) {
+                capFuture.complete(cap)
+            }
+        }
+        cm.registerDefaultNetworkCallback(cb)
+        try {
+            val cap = capFuture.get(100, TimeUnit.MILLISECONDS)
+            initialTransports = BitUtils.packBits(cap.transportTypes)
+        } catch (e: Exception) {
+            firstFailure = IllegalStateException(
+                    "Failed to get default network status before starting tests", e
+            )
+        } finally {
+            cm.unregisterNetworkCallback(cb)
+        }
+        notifier.addListener(listener)
+    }
+
+    fun reportResultAndCleanUp(desc: Description) {
+        notifier.fireTestStarted(desc)
+        if (firstFailure != null) {
+            notifier.fireTestFailure(
+                    Failure(desc, firstFailure)
+            )
+        }
+        notifier.fireTestFinished(desc)
+        notifier.removeListener(listener)
+    }
+}
diff --git a/staticlibs/testutils/devicetests/com/android/testutils/DevSdkIgnoreRunner.kt b/staticlibs/testutils/devicetests/com/android/testutils/DevSdkIgnoreRunner.kt
index 8687ac7..a014834 100644
--- a/staticlibs/testutils/devicetests/com/android/testutils/DevSdkIgnoreRunner.kt
+++ b/staticlibs/testutils/devicetests/com/android/testutils/DevSdkIgnoreRunner.kt
@@ -16,6 +16,8 @@
 
 package com.android.testutils
 
+import android.content.Context
+import androidx.test.core.app.ApplicationProvider
 import androidx.test.ext.junit.runners.AndroidJUnit4
 import com.android.net.module.util.LinkPropertiesUtils.CompareOrUpdateResult
 import com.android.testutils.DevSdkIgnoreRule.IgnoreAfter
@@ -57,6 +59,10 @@
 class DevSdkIgnoreRunner(private val klass: Class<*>) : Runner(), Filterable, Sortable {
     private val leakMonitorDesc = Description.createTestDescription(klass, "ThreadLeakMonitor")
     private val shouldThreadLeakFailTest = klass.isAnnotationPresent(MonitorThreadLeak::class.java)
+    private val restoreDefaultNetworkDesc =
+            Description.createTestDescription(klass, "RestoreDefaultNetwork")
+    private val restoreDefaultNetwork = klass.isAnnotationPresent(RestoreDefaultNetwork::class.java)
+    val ctx = ApplicationProvider.getApplicationContext<Context>()
 
     // Inference correctly infers Runner & Filterable & Sortable for |baseRunner|, but the
     // Java bytecode doesn't have a way to express this. Give this type a name by wrapping it.
@@ -71,6 +77,10 @@
     // TODO(b/307693729): Remove this annotation and monitor thread leak by default.
     annotation class MonitorThreadLeak
 
+    // Annotation for test classes to indicate the test runner should verify the default network is
+    // restored after each test.
+    annotation class RestoreDefaultNetwork
+
     private val baseRunner: RunnerWrapper<*>? = klass.let {
         val ignoreAfter = it.getAnnotation(IgnoreAfter::class.java)
         val ignoreUpTo = it.getAnnotation(IgnoreUpTo::class.java)
@@ -125,6 +135,14 @@
             )
             return
         }
+
+        val networkRestoreMonitor = if (restoreDefaultNetwork) {
+            DefaultNetworkRestoreMonitor(ctx, notifier).apply{
+                init(ConnectUtil(ctx))
+            }
+        } else {
+            null
+        }
         val threadCountsBeforeTest = if (shouldThreadLeakFailTest) {
             // Dump threads as a baseline to monitor thread leaks.
             getAllThreadNameCounts()
@@ -137,6 +155,7 @@
         if (threadCountsBeforeTest != null) {
             checkThreadLeak(notifier, threadCountsBeforeTest)
         }
+        networkRestoreMonitor?.reportResultAndCleanUp(restoreDefaultNetworkDesc)
         // Clears up internal state of all inline mocks.
         // TODO: Call clearInlineMocks() at the end of each test.
         Mockito.framework().clearInlineMocks()
@@ -163,6 +182,9 @@
             if (shouldThreadLeakFailTest) {
                 it.addChild(leakMonitorDesc)
             }
+            if (restoreDefaultNetwork) {
+                it.addChild(restoreDefaultNetworkDesc)
+            }
         }
     }
 
@@ -173,7 +195,14 @@
         // When ignoring the tests, a skipped placeholder test is reported, so test count is 1.
         if (baseRunner == null) return 1
 
-        return baseRunner.testCount() + if (shouldThreadLeakFailTest) 1 else 0
+        var testCount = baseRunner.testCount()
+        if (shouldThreadLeakFailTest) {
+            testCount += 1
+        }
+        if (restoreDefaultNetwork) {
+            testCount += 1
+        }
+        return testCount
     }
 
     @Throws(NoTestsRemainException::class)
diff --git a/tests/cts/net/src/android/net/cts/MultinetworkApiTest.java b/tests/cts/net/src/android/net/cts/MultinetworkApiTest.java
index 06a827b..2c7d5c6 100644
--- a/tests/cts/net/src/android/net/cts/MultinetworkApiTest.java
+++ b/tests/cts/net/src/android/net/cts/MultinetworkApiTest.java
@@ -40,10 +40,10 @@
 import android.system.OsConstants;
 import android.util.ArraySet;
 
-import androidx.test.ext.junit.runners.AndroidJUnit4;
 import androidx.test.platform.app.InstrumentationRegistry;
 
 import com.android.testutils.AutoReleaseNetworkCallbackRule;
+import com.android.testutils.DevSdkIgnoreRunner;
 import com.android.testutils.DeviceConfigRule;
 
 import org.junit.Before;
@@ -53,7 +53,8 @@
 
 import java.util.Set;
 
-@RunWith(AndroidJUnit4.class)
+@DevSdkIgnoreRunner.RestoreDefaultNetwork
+@RunWith(DevSdkIgnoreRunner.class)
 public class MultinetworkApiTest {
     @Rule(order = 1)
     public final DeviceConfigRule mDeviceConfigRule = new DeviceConfigRule();
diff --git a/tests/cts/net/src/android/net/cts/NetworkAgentTest.kt b/tests/cts/net/src/android/net/cts/NetworkAgentTest.kt
index beb9274..60081d4 100644
--- a/tests/cts/net/src/android/net/cts/NetworkAgentTest.kt
+++ b/tests/cts/net/src/android/net/cts/NetworkAgentTest.kt
@@ -194,15 +194,16 @@
 // TODO : enable this in a Mainline update or in V.
 private const val SHOULD_CREATE_NETWORKS_IMMEDIATELY = false
 
-@RunWith(DevSdkIgnoreRunner::class)
-// NetworkAgent is not updatable in R-, so this test does not need to be compatible with older
-// versions. NetworkAgent was also based on AsyncChannel before S so cannot be tested the same way.
-@IgnoreUpTo(Build.VERSION_CODES.R)
+@AppModeFull(reason = "Instant apps can't use NetworkAgent because it needs NETWORK_FACTORY'.")
 // NetworkAgent is updated as part of the connectivity module, and running NetworkAgent tests in MTS
 // for modules other than Connectivity does not provide much value. Only run them in connectivity
 // module MTS, so the tests only need to cover the case of an updated NetworkAgent.
 @ConnectivityModuleTest
-@AppModeFull(reason = "Instant apps can't use NetworkAgent because it needs NETWORK_FACTORY'.")
+@DevSdkIgnoreRunner.RestoreDefaultNetwork
+// NetworkAgent is not updatable in R-, so this test does not need to be compatible with older
+// versions. NetworkAgent was also based on AsyncChannel before S so cannot be tested the same way.
+@IgnoreUpTo(Build.VERSION_CODES.R)
+@RunWith(DevSdkIgnoreRunner::class)
 class NetworkAgentTest {
     private val LOCAL_IPV4_ADDRESS = InetAddresses.parseNumericAddress("192.0.2.1")
     private val REMOTE_IPV4_ADDRESS = InetAddresses.parseNumericAddress("192.0.2.2")
diff --git a/tests/unit/java/com/android/server/CallbackQueueTest.kt b/tests/unit/java/com/android/server/CallbackQueueTest.kt
new file mode 100644
index 0000000..a6dd5c3
--- /dev/null
+++ b/tests/unit/java/com/android/server/CallbackQueueTest.kt
@@ -0,0 +1,181 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server
+
+import android.net.ConnectivityManager
+import android.net.ConnectivityManager.CALLBACK_AVAILABLE
+import android.net.ConnectivityManager.CALLBACK_CAP_CHANGED
+import android.net.ConnectivityManager.CALLBACK_IP_CHANGED
+import android.os.Build
+import androidx.test.filters.SmallTest
+import com.android.testutils.DevSdkIgnoreRule
+import com.android.testutils.DevSdkIgnoreRunner
+import java.lang.reflect.Modifier
+import kotlin.test.assertEquals
+import kotlin.test.assertFalse
+import kotlin.test.assertTrue
+import org.junit.Test
+import org.junit.runner.RunWith
+
+private const val TEST_NETID_1 = 123
+
+// Maximum 16 bits unsigned value
+private const val TEST_NETID_2 = 0xffff
+
+@RunWith(DevSdkIgnoreRunner::class)
+@SmallTest
+@DevSdkIgnoreRule.IgnoreUpTo(Build.VERSION_CODES.R)
+class CallbackQueueTest {
+    @Test
+    fun testAddCallback() {
+        val cbs = listOf(
+            TEST_NETID_1 to CALLBACK_AVAILABLE,
+            TEST_NETID_2 to CALLBACK_AVAILABLE,
+            TEST_NETID_1 to CALLBACK_CAP_CHANGED,
+            TEST_NETID_1 to CALLBACK_CAP_CHANGED
+        )
+        val queue = CallbackQueue(intArrayOf()).apply {
+            cbs.forEach { addCallback(it.first, it.second) }
+        }
+
+        assertQueueEquals(cbs, queue)
+    }
+
+    @Test
+    fun testHasCallback() {
+        val queue = CallbackQueue(intArrayOf()).apply {
+            addCallback(TEST_NETID_1, CALLBACK_AVAILABLE)
+            addCallback(TEST_NETID_2, CALLBACK_AVAILABLE)
+            addCallback(TEST_NETID_1, CALLBACK_CAP_CHANGED)
+            addCallback(TEST_NETID_1, CALLBACK_CAP_CHANGED)
+        }
+
+        assertTrue(queue.hasCallback(TEST_NETID_1, CALLBACK_AVAILABLE))
+        assertTrue(queue.hasCallback(TEST_NETID_2, CALLBACK_AVAILABLE))
+        assertTrue(queue.hasCallback(TEST_NETID_1, CALLBACK_CAP_CHANGED))
+
+        assertFalse(queue.hasCallback(TEST_NETID_2, CALLBACK_CAP_CHANGED))
+        assertFalse(queue.hasCallback(1234, CALLBACK_AVAILABLE))
+        assertFalse(queue.hasCallback(TEST_NETID_1, 5678))
+        assertFalse(queue.hasCallback(1234, 5678))
+    }
+
+    @Test
+    fun testRemoveCallbacks() {
+        val queue = CallbackQueue(intArrayOf()).apply {
+            assertFalse(removeCallbacks(TEST_NETID_1, CALLBACK_AVAILABLE))
+            addCallback(TEST_NETID_1, CALLBACK_AVAILABLE)
+            addCallback(TEST_NETID_1, CALLBACK_CAP_CHANGED)
+            addCallback(TEST_NETID_2, CALLBACK_AVAILABLE)
+            addCallback(TEST_NETID_1, CALLBACK_AVAILABLE)
+            assertTrue(removeCallbacks(TEST_NETID_1, CALLBACK_AVAILABLE))
+        }
+        assertQueueEquals(listOf(
+            TEST_NETID_1 to CALLBACK_CAP_CHANGED,
+            TEST_NETID_2 to CALLBACK_AVAILABLE
+        ), queue)
+    }
+
+    @Test
+    fun testRemoveCallbacksForNetId() {
+        val queue = CallbackQueue(intArrayOf()).apply {
+            assertFalse(removeCallbacksForNetId(TEST_NETID_2))
+            addCallback(TEST_NETID_2, CALLBACK_AVAILABLE)
+            assertFalse(removeCallbacksForNetId(TEST_NETID_1))
+            addCallback(TEST_NETID_1, CALLBACK_AVAILABLE)
+            addCallback(TEST_NETID_1, CALLBACK_CAP_CHANGED)
+            addCallback(TEST_NETID_2, CALLBACK_CAP_CHANGED)
+            addCallback(TEST_NETID_1, CALLBACK_AVAILABLE)
+            addCallback(TEST_NETID_2, CALLBACK_IP_CHANGED)
+            assertTrue(removeCallbacksForNetId(TEST_NETID_2))
+        }
+        assertQueueEquals(listOf(
+            TEST_NETID_1 to CALLBACK_AVAILABLE,
+            TEST_NETID_1 to CALLBACK_CAP_CHANGED,
+            TEST_NETID_1 to CALLBACK_AVAILABLE,
+        ), queue)
+    }
+
+    @Test
+    fun testConstructorFromExistingArray() {
+        val queue1 = CallbackQueue(intArrayOf()).apply {
+            addCallback(TEST_NETID_1, CALLBACK_AVAILABLE)
+            addCallback(TEST_NETID_2, CALLBACK_AVAILABLE)
+        }
+        val queue2 = CallbackQueue(queue1.shrinkedBackingArray)
+        assertQueueEquals(listOf(
+            TEST_NETID_1 to CALLBACK_AVAILABLE,
+            TEST_NETID_2 to CALLBACK_AVAILABLE
+        ), queue2)
+    }
+
+    @Test
+    fun testToString() {
+        assertEquals("[]", CallbackQueue(intArrayOf()).toString())
+        assertEquals(
+            "[CALLBACK_AVAILABLE($TEST_NETID_1)]",
+            CallbackQueue(intArrayOf()).apply {
+                addCallback(TEST_NETID_1, CALLBACK_AVAILABLE)
+            }.toString()
+        )
+        assertEquals(
+            "[CALLBACK_AVAILABLE($TEST_NETID_1),CALLBACK_CAP_CHANGED($TEST_NETID_2)]",
+            CallbackQueue(intArrayOf()).apply {
+                addCallback(TEST_NETID_1, CALLBACK_AVAILABLE)
+                addCallback(TEST_NETID_2, CALLBACK_CAP_CHANGED)
+            }.toString()
+        )
+    }
+
+    @Test
+    fun testMaxNetId() {
+        // CallbackQueue assumes netIds are at most 16 bits
+        assertTrue(NetIdManager.MAX_NET_ID <= 0xffff)
+    }
+
+    @Test
+    fun testMaxCallbackId() {
+        // CallbackQueue assumes callback IDs are at most 16 bits.
+        val constants = ConnectivityManager::class.java.declaredFields.filter {
+            Modifier.isStatic(it.modifiers) && Modifier.isFinal(it.modifiers) &&
+                    it.name.startsWith("CALLBACK_")
+        }
+        constants.forEach {
+            it.isAccessible = true
+            assertTrue(it.get(null) as Int <= 0xffff)
+        }
+    }
+}
+
+private fun assertQueueEquals(expected: List<Pair<Int, Int>>, actual: CallbackQueue) {
+    assertEquals(
+        expected.size,
+        actual.length(),
+        "Size mismatch between expected: $expected and actual: $actual"
+    )
+
+    var nextIndex = 0
+    actual.forEach { netId, cbId ->
+        val (expNetId, expCbId) = expected[nextIndex]
+        val msg = "$actual does not match $expected at index $nextIndex"
+        assertEquals(expNetId, netId, msg)
+        assertEquals(expCbId, cbId, msg)
+        nextIndex++
+    }
+    // Ensure forEach iterations and size are consistent
+    assertEquals(expected.size, nextIndex)
+}
diff --git a/tests/unit/java/com/android/server/ConnectivityServiceTest.java b/tests/unit/java/com/android/server/ConnectivityServiceTest.java
index be7f2a3..999d17d 100755
--- a/tests/unit/java/com/android/server/ConnectivityServiceTest.java
+++ b/tests/unit/java/com/android/server/ConnectivityServiceTest.java
@@ -2180,6 +2180,7 @@
                 case ConnectivityFlags.CARRIER_SERVICE_CHANGED_USE_CALLBACK:
                 case ConnectivityFlags.REQUEST_RESTRICTED_WIFI:
                 case ConnectivityFlags.USE_DECLARED_METHODS_FOR_CALLBACKS:
+                case ConnectivityFlags.QUEUE_CALLBACKS_FOR_FROZEN_APPS:
                 case KEY_DESTROY_FROZEN_SOCKETS_VERSION:
                     return true;
                 default:
diff --git a/tests/unit/java/com/android/server/connectivityservice/base/CSTest.kt b/tests/unit/java/com/android/server/connectivityservice/base/CSTest.kt
index ed72fd2..de56ae5 100644
--- a/tests/unit/java/com/android/server/connectivityservice/base/CSTest.kt
+++ b/tests/unit/java/com/android/server/connectivityservice/base/CSTest.kt
@@ -165,6 +165,7 @@
         it[ConnectivityFlags.BACKGROUND_FIREWALL_CHAIN] = true
         it[ConnectivityFlags.DELAY_DESTROY_SOCKETS] = true
         it[ConnectivityFlags.USE_DECLARED_METHODS_FOR_CALLBACKS] = true
+        it[ConnectivityFlags.QUEUE_CALLBACKS_FOR_FROZEN_APPS] = true
     }
     fun setFeatureEnabled(flag: String, enabled: Boolean) = enabledFeatures.set(flag, enabled)