diff --git a/core/api/current.txt b/core/api/current.txt
index 4df648c..56df8f3 100644
--- a/core/api/current.txt
+++ b/core/api/current.txt
@@ -39001,6 +39001,13 @@
 
 package android.service.voice {
 
+  public final class VisibleActivityInfo implements android.os.Parcelable {
+    method public int describeContents();
+    method @NonNull public android.service.voice.VoiceInteractionSession.ActivityId getActivityId();
+    method public void writeToParcel(@NonNull android.os.Parcel, int);
+    field @NonNull public static final android.os.Parcelable.Creator<android.service.voice.VisibleActivityInfo> CREATOR;
+  }
+
   public class VoiceInteractionService extends android.app.Service {
     ctor public VoiceInteractionService();
     method public int getDisabledShowContext();
@@ -39062,6 +39069,7 @@
     method public void onTaskStarted(android.content.Intent, int);
     method public void onTrimMemory(int);
     method public final void performDirectAction(@NonNull android.app.DirectAction, @Nullable android.os.Bundle, @Nullable android.os.CancellationSignal, @NonNull java.util.concurrent.Executor, @NonNull java.util.function.Consumer<android.os.Bundle>);
+    method public final void registerVisibleActivityCallback(@NonNull java.util.concurrent.Executor, @NonNull android.service.voice.VoiceInteractionSession.VisibleActivityCallback);
     method public final void requestDirectActions(@NonNull android.service.voice.VoiceInteractionSession.ActivityId, @Nullable android.os.CancellationSignal, @NonNull java.util.concurrent.Executor, @NonNull java.util.function.Consumer<java.util.List<android.app.DirectAction>>);
     method public void setContentView(android.view.View);
     method public void setDisabledShowContext(int);
@@ -39071,6 +39079,7 @@
     method public void show(android.os.Bundle, int);
     method public void startAssistantActivity(android.content.Intent);
     method public void startVoiceActivity(android.content.Intent);
+    method public final void unregisterVisibleActivityCallback(@NonNull android.service.voice.VoiceInteractionSession.VisibleActivityCallback);
     field public static final int SHOW_SOURCE_ACTIVITY = 16; // 0x10
     field public static final int SHOW_SOURCE_APPLICATION = 8; // 0x8
     field public static final int SHOW_SOURCE_ASSIST_GESTURE = 4; // 0x4
@@ -39144,6 +39153,11 @@
     method public boolean isActive();
   }
 
+  public static interface VoiceInteractionSession.VisibleActivityCallback {
+    method public default void onInvisible(@NonNull android.service.voice.VoiceInteractionSession.ActivityId);
+    method public default void onVisible(@NonNull android.service.voice.VisibleActivityInfo);
+  }
+
   public abstract class VoiceInteractionSessionService extends android.app.Service {
     ctor public VoiceInteractionSessionService();
     method public android.os.IBinder onBind(android.content.Intent);
diff --git a/core/api/test-current.txt b/core/api/test-current.txt
index 2ecf088..d484100 100644
--- a/core/api/test-current.txt
+++ b/core/api/test-current.txt
@@ -2391,6 +2391,10 @@
     method @RequiresPermission(allOf={android.Manifest.permission.RECORD_AUDIO, android.Manifest.permission.CAPTURE_AUDIO_HOTWORD}) public void triggerHardwareRecognitionEventForTest(int, int, boolean, int, int, int, boolean, @NonNull android.media.AudioFormat, @Nullable byte[]);
   }
 
+  public final class VisibleActivityInfo implements android.os.Parcelable {
+    ctor public VisibleActivityInfo(int, @NonNull android.os.IBinder);
+  }
+
 }
 
 package android.service.watchdog {
diff --git a/core/java/android/app/ActivityManagerInternal.java b/core/java/android/app/ActivityManagerInternal.java
index 70bb132..f8c8aa3 100644
--- a/core/java/android/app/ActivityManagerInternal.java
+++ b/core/java/android/app/ActivityManagerInternal.java
@@ -652,4 +652,23 @@
     public abstract int sendIntentSender(IIntentSender target, IBinder allowlistToken, int code,
             Intent intent, String resolvedType,
             IIntentReceiver finishedReceiver, String requiredPermission, Bundle options);
+
+    /**
+     * Sets the provider to communicate between voice interaction manager service and
+     * ActivityManagerService.
+     */
+    public abstract void setVoiceInteractionManagerProvider(
+            @Nullable VoiceInteractionManagerProvider provider);
+
+    /**
+     * Provides the interface to communicate between voice interaction manager service and
+     * ActivityManagerService.
+     */
+    public interface VoiceInteractionManagerProvider {
+        /**
+         * Notifies the service when a high-level activity event has been changed, for example,
+         * an activity was resumed or stopped.
+         */
+        void notifyActivityEventChanged();
+    }
 }
diff --git a/core/java/android/service/voice/IVoiceInteractionSession.aidl b/core/java/android/service/voice/IVoiceInteractionSession.aidl
index c142a53..59f1e8e 100644
--- a/core/java/android/service/voice/IVoiceInteractionSession.aidl
+++ b/core/java/android/service/voice/IVoiceInteractionSession.aidl
@@ -22,6 +22,7 @@
 import android.graphics.Bitmap;
 import android.os.Bundle;
 import android.os.IBinder;
+import android.service.voice.VisibleActivityInfo;
 
 import com.android.internal.app.IVoiceInteractionSessionShowCallback;
 
@@ -39,4 +40,5 @@
     void closeSystemDialogs();
     void onLockscreenShown();
     void destroy();
+    void updateVisibleActivityInfo(in VisibleActivityInfo visibleActivityInfo, int type);
 }
diff --git a/core/java/android/service/voice/VisibleActivityInfo.aidl b/core/java/android/service/voice/VisibleActivityInfo.aidl
new file mode 100644
index 0000000..34bd57c
--- /dev/null
+++ b/core/java/android/service/voice/VisibleActivityInfo.aidl
@@ -0,0 +1,19 @@
+/*
+ * Copyright (C) 2021 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 android.service.voice;
+
+parcelable VisibleActivityInfo;
diff --git a/core/java/android/service/voice/VisibleActivityInfo.java b/core/java/android/service/voice/VisibleActivityInfo.java
new file mode 100644
index 0000000..139544c
--- /dev/null
+++ b/core/java/android/service/voice/VisibleActivityInfo.java
@@ -0,0 +1,205 @@
+/*
+ * Copyright (C) 2021 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 android.service.voice;
+
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+import android.annotation.TestApi;
+import android.os.CancellationSignal;
+import android.os.IBinder;
+import android.os.Parcel;
+import android.os.Parcelable;
+
+import com.android.internal.util.DataClass;
+
+import java.util.Objects;
+import java.util.concurrent.Executor;
+import java.util.function.Consumer;
+
+/**
+ * The class is used to represent a visible activity information. The system provides this to
+ * services that need to know {@link android.service.voice.VoiceInteractionSession.ActivityId}.
+ */
+@DataClass(
+        genConstructor = false,
+        genEqualsHashCode = true,
+        genHiddenConstDefs = false,
+        genGetters = false,
+        genToString = true
+)
+public final class VisibleActivityInfo implements Parcelable {
+
+    /**
+     * Indicates that it is a new visible activity.
+     *
+     * @hide
+     */
+    public static final int TYPE_ACTIVITY_ADDED = 1;
+
+    /**
+     * Indicates that it has become a invisible activity.
+     *
+     * @hide
+     */
+    public static final int TYPE_ACTIVITY_REMOVED = 2;
+
+    /**
+     * The identifier of the task this activity is in.
+     */
+    private final int mTaskId;
+
+    /**
+     * Token for targeting this activity for assist purposes.
+     */
+    @NonNull
+    private final IBinder mAssistToken;
+
+    /** @hide */
+    @TestApi
+    public VisibleActivityInfo(
+            int taskId,
+            @NonNull IBinder assistToken) {
+        Objects.requireNonNull(assistToken);
+        mTaskId = taskId;
+        mAssistToken = assistToken;
+    }
+
+    /**
+     * Returns the {@link android.service.voice.VoiceInteractionSession.ActivityId} of this
+     * visible activity which can be used to interact with an activity, for example through
+     * {@link VoiceInteractionSession#requestDirectActions(VoiceInteractionSession.ActivityId,
+     * CancellationSignal, Executor, Consumer)}.
+     */
+    public @NonNull VoiceInteractionSession.ActivityId getActivityId() {
+        return new VoiceInteractionSession.ActivityId(mTaskId, mAssistToken);
+    }
+
+
+
+    // Code below generated by codegen v1.0.23.
+    //
+    // DO NOT MODIFY!
+    // CHECKSTYLE:OFF Generated code
+    //
+    // To regenerate run:
+    // $ codegen $ANDROID_BUILD_TOP/frameworks/base/core/java/android/service/voice/VisibleActivityInfo.java
+    //
+    // To exclude the generated code from IntelliJ auto-formatting enable (one-time):
+    //   Settings > Editor > Code Style > Formatter Control
+    //@formatter:off
+
+
+    @Override
+    @DataClass.Generated.Member
+    public String toString() {
+        // You can override field toString logic by defining methods like:
+        // String fieldNameToString() { ... }
+
+        return "VisibleActivityInfo { " +
+                "taskId = " + mTaskId + ", " +
+                "assistToken = " + mAssistToken +
+        " }";
+    }
+
+    @Override
+    @DataClass.Generated.Member
+    public boolean equals(@Nullable Object o) {
+        // You can override field equality logic by defining either of the methods like:
+        // boolean fieldNameEquals(VisibleActivityInfo other) { ... }
+        // boolean fieldNameEquals(FieldType otherValue) { ... }
+
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        @SuppressWarnings("unchecked")
+        VisibleActivityInfo that = (VisibleActivityInfo) o;
+        //noinspection PointlessBooleanExpression
+        return true
+                && mTaskId == that.mTaskId
+                && Objects.equals(mAssistToken, that.mAssistToken);
+    }
+
+    @Override
+    @DataClass.Generated.Member
+    public int hashCode() {
+        // You can override field hashCode logic by defining methods like:
+        // int fieldNameHashCode() { ... }
+
+        int _hash = 1;
+        _hash = 31 * _hash + mTaskId;
+        _hash = 31 * _hash + Objects.hashCode(mAssistToken);
+        return _hash;
+    }
+
+    @Override
+    @DataClass.Generated.Member
+    public void writeToParcel(@NonNull Parcel dest, int flags) {
+        // You can override field parcelling by defining methods like:
+        // void parcelFieldName(Parcel dest, int flags) { ... }
+
+        dest.writeInt(mTaskId);
+        dest.writeStrongBinder(mAssistToken);
+    }
+
+    @Override
+    @DataClass.Generated.Member
+    public int describeContents() { return 0; }
+
+    /** @hide */
+    @SuppressWarnings({"unchecked", "RedundantCast"})
+    @DataClass.Generated.Member
+    /* package-private */ VisibleActivityInfo(@NonNull Parcel in) {
+        // You can override field unparcelling by defining methods like:
+        // static FieldType unparcelFieldName(Parcel in) { ... }
+
+        int taskId = in.readInt();
+        IBinder assistToken = (IBinder) in.readStrongBinder();
+
+        this.mTaskId = taskId;
+        this.mAssistToken = assistToken;
+        com.android.internal.util.AnnotationValidations.validate(
+                NonNull.class, null, mAssistToken);
+
+        // onConstructed(); // You can define this method to get a callback
+    }
+
+    @DataClass.Generated.Member
+    public static final @NonNull Parcelable.Creator<VisibleActivityInfo> CREATOR
+            = new Parcelable.Creator<VisibleActivityInfo>() {
+        @Override
+        public VisibleActivityInfo[] newArray(int size) {
+            return new VisibleActivityInfo[size];
+        }
+
+        @Override
+        public VisibleActivityInfo createFromParcel(@NonNull Parcel in) {
+            return new VisibleActivityInfo(in);
+        }
+    };
+
+    @DataClass.Generated(
+            time = 1632383555284L,
+            codegenVersion = "1.0.23",
+            sourceFile = "frameworks/base/core/java/android/service/voice/VisibleActivityInfo.java",
+            inputSignatures = "public static final  int TYPE_ACTIVITY_ADDED\npublic static final  int TYPE_ACTIVITY_REMOVED\nprivate final  int mTaskId\nprivate final @android.annotation.NonNull android.os.IBinder mAssistToken\npublic @android.annotation.NonNull android.service.voice.VoiceInteractionSession.ActivityId getActivityId()\nclass VisibleActivityInfo extends java.lang.Object implements [android.os.Parcelable]\n@com.android.internal.util.DataClass(genConstructor=false, genEqualsHashCode=true, genHiddenConstDefs=false, genGetters=false, genToString=true)")
+    @Deprecated
+    private void __metadata() {}
+
+
+    //@formatter:on
+    // End of generated code
+
+}
diff --git a/core/java/android/service/voice/VoiceInteractionManagerInternal.java b/core/java/android/service/voice/VoiceInteractionManagerInternal.java
index c048286..c806409 100644
--- a/core/java/android/service/voice/VoiceInteractionManagerInternal.java
+++ b/core/java/android/service/voice/VoiceInteractionManagerInternal.java
@@ -22,7 +22,6 @@
 
 import com.android.internal.annotations.Immutable;
 
-
 /**
  * @hide
  * Private interface to the VoiceInteractionManagerService for use by ActivityManagerService.
diff --git a/core/java/android/service/voice/VoiceInteractionSession.java b/core/java/android/service/voice/VoiceInteractionSession.java
index 725e20f..9db856a 100644
--- a/core/java/android/service/voice/VoiceInteractionSession.java
+++ b/core/java/android/service/voice/VoiceInteractionSession.java
@@ -74,9 +74,11 @@
 import java.io.FileDescriptor;
 import java.io.PrintWriter;
 import java.lang.ref.WeakReference;
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.concurrent.Executor;
 import java.util.function.Consumer;
 
@@ -177,6 +179,10 @@
 
     ICancellationSignal mKillCallback;
 
+    private final Map<VisibleActivityCallback, Executor> mVisibleActivityCallbacks =
+            new ArrayMap<>();
+    private final List<VisibleActivityInfo> mVisibleActivityInfos = new ArrayList<>();
+
     final IVoiceInteractor mInteractor = new IVoiceInteractor.Stub() {
         @Override
         public IVoiceInteractorRequest startConfirmation(String callingPackage,
@@ -352,6 +358,13 @@
         public void destroy() {
             mHandlerCaller.sendMessage(mHandlerCaller.obtainMessage(MSG_DESTROY));
         }
+
+        @Override
+        public void updateVisibleActivityInfo(VisibleActivityInfo visibleActivityInfo, int type) {
+            mHandlerCaller.sendMessage(
+                    mHandlerCaller.obtainMessageIO(MSG_UPDATE_VISIBLE_ACTIVITY_INFO, type,
+                            visibleActivityInfo));
+        }
     };
 
     /**
@@ -843,6 +856,9 @@
     static final int MSG_SHOW = 106;
     static final int MSG_HIDE = 107;
     static final int MSG_ON_LOCKSCREEN_SHOWN = 108;
+    static final int MSG_UPDATE_VISIBLE_ACTIVITY_INFO = 109;
+    static final int MSG_REGISTER_VISIBLE_ACTIVITY_CALLBACK = 110;
+    static final int MSG_UNREGISTER_VISIBLE_ACTIVITY_CALLBACK = 111;
 
     class MyCallbacks implements HandlerCaller.Callback, SoftInputWindow.Callback {
         @Override
@@ -928,6 +944,27 @@
                     if (DEBUG) Log.d(TAG, "onLockscreenShown");
                     onLockscreenShown();
                     break;
+                case MSG_UPDATE_VISIBLE_ACTIVITY_INFO:
+                    if (DEBUG) {
+                        Log.d(TAG, "doUpdateVisibleActivityInfo: visibleActivityInfo=" + msg.obj
+                                + " type=" + msg.arg1);
+                    }
+                    doUpdateVisibleActivityInfo((VisibleActivityInfo) msg.obj, msg.arg1);
+                    break;
+                case MSG_REGISTER_VISIBLE_ACTIVITY_CALLBACK:
+                    if (DEBUG) {
+                        Log.d(TAG, "doRegisterVisibleActivityCallback");
+                    }
+                    args = (SomeArgs) msg.obj;
+                    doRegisterVisibleActivityCallback((Executor) args.arg1,
+                            (VisibleActivityCallback) args.arg2);
+                    break;
+                case MSG_UNREGISTER_VISIBLE_ACTIVITY_CALLBACK:
+                    if (DEBUG) {
+                        Log.d(TAG, "doUnregisterVisibleActivityCallback");
+                    }
+                    doUnregisterVisibleActivityCallback((VisibleActivityCallback) msg.obj);
+                    break;
             }
             if (args != null) {
                 args.recycle();
@@ -1122,6 +1159,86 @@
         }
     }
 
+    private void doUpdateVisibleActivityInfo(VisibleActivityInfo visibleActivityInfo, int type) {
+
+        if (mVisibleActivityCallbacks.isEmpty()) {
+            return;
+        }
+
+        switch (type) {
+            case VisibleActivityInfo.TYPE_ACTIVITY_ADDED:
+                informVisibleActivityChanged(visibleActivityInfo, type);
+                mVisibleActivityInfos.add(visibleActivityInfo);
+                break;
+            case VisibleActivityInfo.TYPE_ACTIVITY_REMOVED:
+                informVisibleActivityChanged(visibleActivityInfo, type);
+                mVisibleActivityInfos.remove(visibleActivityInfo);
+                break;
+        }
+    }
+
+    private void doRegisterVisibleActivityCallback(@NonNull @CallbackExecutor Executor executor,
+            @NonNull VisibleActivityCallback callback) {
+        if (mVisibleActivityCallbacks.containsKey(callback)) {
+            if (DEBUG) {
+                Log.d(TAG, "doRegisterVisibleActivityCallback: callback has registered");
+            }
+            return;
+        }
+
+        int preCallbackCount = mVisibleActivityCallbacks.size();
+        mVisibleActivityCallbacks.put(callback, executor);
+
+        if (preCallbackCount == 0) {
+            try {
+                mSystemService.startListeningVisibleActivityChanged(mToken);
+            } catch (RemoteException e) {
+                e.rethrowFromSystemServer();
+            }
+        } else {
+            for (int i = 0; i < mVisibleActivityInfos.size(); i++) {
+                final VisibleActivityInfo visibleActivityInfo = mVisibleActivityInfos.get(i);
+                executor.execute(() -> callback.onVisible(visibleActivityInfo));
+            }
+        }
+    }
+
+    private void doUnregisterVisibleActivityCallback(@NonNull VisibleActivityCallback callback) {
+        mVisibleActivityCallbacks.remove(callback);
+
+        if (mVisibleActivityCallbacks.size() == 0) {
+            mVisibleActivityInfos.clear();
+            try {
+                mSystemService.stopListeningVisibleActivityChanged(mToken);
+            } catch (RemoteException e) {
+                e.rethrowFromSystemServer();
+            }
+        }
+    }
+
+    private void informVisibleActivityChanged(VisibleActivityInfo visibleActivityInfo, int type) {
+        for (Map.Entry<VisibleActivityCallback, Executor> e :
+                mVisibleActivityCallbacks.entrySet()) {
+            final Executor executor = e.getValue();
+            final VisibleActivityCallback visibleActivityCallback = e.getKey();
+
+            switch (type) {
+                case VisibleActivityInfo.TYPE_ACTIVITY_ADDED:
+                    Binder.withCleanCallingIdentity(() -> {
+                        executor.execute(
+                                () -> visibleActivityCallback.onVisible(visibleActivityInfo));
+                    });
+                    break;
+                case VisibleActivityInfo.TYPE_ACTIVITY_REMOVED:
+                    Binder.withCleanCallingIdentity(() -> {
+                        executor.execute(() -> visibleActivityCallback.onInvisible(
+                                visibleActivityInfo.getActivityId()));
+                    });
+                    break;
+            }
+        }
+    }
+
     void ensureWindowCreated() {
         if (mInitialized) {
             return;
@@ -1926,6 +2043,45 @@
     }
 
     /**
+     * Registers a callback that will be notified when visible activities have been changed.
+     *
+     * @param executor The handler to receive the callback.
+     * @param callback The callback to receive the response.
+     *
+     * @throws IllegalStateException if calling this method before onCreate().
+     */
+    public final void registerVisibleActivityCallback(@NonNull @CallbackExecutor Executor executor,
+            @NonNull VisibleActivityCallback callback) {
+        if (DEBUG) {
+            Log.d(TAG, "registerVisibleActivityCallback");
+        }
+        if (mToken == null) {
+            throw new IllegalStateException("Can't call before onCreate()");
+        }
+        Objects.requireNonNull(executor);
+        Objects.requireNonNull(callback);
+
+        mHandlerCaller.sendMessage(
+                mHandlerCaller.obtainMessageOO(MSG_REGISTER_VISIBLE_ACTIVITY_CALLBACK, executor,
+                        callback));
+    }
+
+    /**
+     * Unregisters the callback.
+     *
+     * @param callback The callback to receive the response.
+     */
+    public final void unregisterVisibleActivityCallback(@NonNull VisibleActivityCallback callback) {
+        if (DEBUG) {
+            Log.d(TAG, "unregisterVisibleActivityCallback");
+        }
+        Objects.requireNonNull(callback);
+
+        mHandlerCaller.sendMessage(
+                mHandlerCaller.obtainMessageO(MSG_UNREGISTER_VISIBLE_ACTIVITY_CALLBACK, callback));
+    }
+
+    /**
      * Print the Service's state into the given stream.  This gets invoked by
      * {@link VoiceInteractionSessionService} when its Service
      * {@link android.app.Service#dump} method is called.
@@ -1975,6 +2131,17 @@
     }
 
     /**
+     * Callback interface for receiving visible activity changes used for assistant usage.
+     */
+    public interface VisibleActivityCallback {
+        /** Callback to inform that an activity has become visible. */
+        default void onVisible(@NonNull VisibleActivityInfo activityInfo) {}
+
+        /** Callback to inform that a visible activity has gone. */
+        default void onInvisible(@NonNull ActivityId activityId) {}
+    }
+
+    /**
      * Represents assist state captured when this session was started.
      * It contains the various assist data objects and a reference to
      * the source activity.
diff --git a/core/java/com/android/internal/app/IVoiceInteractionManagerService.aidl b/core/java/com/android/internal/app/IVoiceInteractionManagerService.aidl
index c8a4425..9985262 100644
--- a/core/java/com/android/internal/app/IVoiceInteractionManagerService.aidl
+++ b/core/java/com/android/internal/app/IVoiceInteractionManagerService.aidl
@@ -272,4 +272,14 @@
     void triggerHardwareRecognitionEventForTest(
             in SoundTrigger.KeyphraseRecognitionEvent event,
             in IHotwordRecognitionStatusCallback callback);
+
+    /**
+     * Starts to listen the status of visible activity.
+     */
+    void startListeningVisibleActivityChanged(in IBinder token);
+
+    /**
+     * Stops to listen the status of visible activity.
+     */
+    void stopListeningVisibleActivityChanged(in IBinder token);
 }
diff --git a/services/core/java/com/android/server/am/ActivityManagerService.java b/services/core/java/com/android/server/am/ActivityManagerService.java
index 2b1c695..18ed958 100644
--- a/services/core/java/com/android/server/am/ActivityManagerService.java
+++ b/services/core/java/com/android/server/am/ActivityManagerService.java
@@ -1550,6 +1550,13 @@
     private static final int INDEX_TOTAL_MEMTRACK_GL = 14;
     private static final int INDEX_LAST = 15;
 
+    /**
+     * Used to notify activity lifecycle events.
+     */
+    @Nullable
+    volatile ActivityManagerInternal.VoiceInteractionManagerProvider
+            mVoiceInteractionManagerProvider;
+
     final class UiHandler extends Handler {
         public UiHandler() {
             super(com.android.server.UiThread.get().getLooper(), null, true);
@@ -1886,6 +1893,14 @@
         return mAppOpsService;
     }
 
+    /**
+     * Sets the internal voice interaction manager service.
+     */
+    private void setVoiceInteractionManagerProvider(
+            @Nullable ActivityManagerInternal.VoiceInteractionManagerProvider provider) {
+        mVoiceInteractionManagerProvider = provider;
+    }
+
     static class MemBinder extends Binder {
         ActivityManagerService mActivityManagerService;
         private final PriorityDump.PriorityDumper mPriorityDumper =
@@ -2737,6 +2752,11 @@
                 || event == Event.ACTIVITY_DESTROYED)) {
             contentCaptureService.notifyActivityEvent(userId, activity, event);
         }
+        // TODO(b/201234353): Move the logic to client side.
+        if (mVoiceInteractionManagerProvider != null && (event == Event.ACTIVITY_PAUSED
+                || event == Event.ACTIVITY_RESUMED || event == Event.ACTIVITY_STOPPED)) {
+            mVoiceInteractionManagerProvider.notifyActivityEventChanged();
+        }
     }
 
     /**
@@ -16366,6 +16386,12 @@
             return ActivityManagerService.this.sendIntentSender(target, allowlistToken, code,
                     intent, resolvedType, finishedReceiver, requiredPermission, options);
         }
+
+        @Override
+        public void setVoiceInteractionManagerProvider(
+                @Nullable ActivityManagerInternal.VoiceInteractionManagerProvider provider) {
+            ActivityManagerService.this.setVoiceInteractionManagerProvider(provider);
+        }
     }
 
     long inputDispatchingTimedOut(int pid, final boolean aboveSystem, String reason) {
diff --git a/services/voiceinteraction/java/com/android/server/voiceinteraction/VoiceInteractionManagerService.java b/services/voiceinteraction/java/com/android/server/voiceinteraction/VoiceInteractionManagerService.java
index 9ea2b7b..8445ed4 100644
--- a/services/voiceinteraction/java/com/android/server/voiceinteraction/VoiceInteractionManagerService.java
+++ b/services/voiceinteraction/java/com/android/server/voiceinteraction/VoiceInteractionManagerService.java
@@ -167,6 +167,16 @@
     public void onStart() {
         publishBinderService(Context.VOICE_INTERACTION_MANAGER_SERVICE, mServiceStub);
         publishLocalService(VoiceInteractionManagerInternal.class, new LocalService());
+        mAmInternal.setVoiceInteractionManagerProvider(
+                new ActivityManagerInternal.VoiceInteractionManagerProvider() {
+                    @Override
+                    public void notifyActivityEventChanged() {
+                        if (DEBUG) {
+                            Slog.d(TAG, "call notifyActivityEventChanged");
+                        }
+                        mServiceStub.notifyActivityEventChanged();
+                    }
+                });
     }
 
     @Override
@@ -386,6 +396,14 @@
             return mImpl.supportsLocalVoiceInteraction();
         }
 
+        void notifyActivityEventChanged() {
+            synchronized (this) {
+                if (mImpl == null) return;
+
+                Binder.withCleanCallingIdentity(() -> mImpl.notifyActivityEventChangedLocked());
+            }
+        }
+
         @Override
         public boolean onTransact(int code, Parcel data, Parcel reply, int flags)
                 throws RemoteException {
@@ -1109,6 +1127,40 @@
             }
         }
 
+        @Override
+        public void startListeningVisibleActivityChanged(@NonNull IBinder token) {
+            synchronized (this) {
+                if (mImpl == null) {
+                    Slog.w(TAG, "startListeningVisibleActivityChanged without running"
+                            + " voice interaction service");
+                    return;
+                }
+                final long caller = Binder.clearCallingIdentity();
+                try {
+                    mImpl.startListeningVisibleActivityChangedLocked(token);
+                } finally {
+                    Binder.restoreCallingIdentity(caller);
+                }
+            }
+        }
+
+        @Override
+        public void stopListeningVisibleActivityChanged(@NonNull IBinder token) {
+            synchronized (this) {
+                if (mImpl == null) {
+                    Slog.w(TAG, "stopListeningVisibleActivityChanged without running"
+                            + " voice interaction service");
+                    return;
+                }
+                final long caller = Binder.clearCallingIdentity();
+                try {
+                    mImpl.stopListeningVisibleActivityChangedLocked(token);
+                } finally {
+                    Binder.restoreCallingIdentity(caller);
+                }
+            }
+        }
+
         //----------------- Hotword Detection/Validation APIs --------------------------------//
 
         @Override
diff --git a/services/voiceinteraction/java/com/android/server/voiceinteraction/VoiceInteractionManagerServiceImpl.java b/services/voiceinteraction/java/com/android/server/voiceinteraction/VoiceInteractionManagerServiceImpl.java
index 558a9ac..52c5b6bb 100644
--- a/services/voiceinteraction/java/com/android/server/voiceinteraction/VoiceInteractionManagerServiceImpl.java
+++ b/services/voiceinteraction/java/com/android/server/voiceinteraction/VoiceInteractionManagerServiceImpl.java
@@ -414,6 +414,44 @@
         return mInfo.getSupportsLocalInteraction();
     }
 
+    public void startListeningVisibleActivityChangedLocked(@NonNull IBinder token) {
+        if (DEBUG) {
+            Slog.d(TAG, "startListeningVisibleActivityChangedLocked: token=" + token);
+        }
+        if (mActiveSession == null || token != mActiveSession.mToken) {
+            Slog.w(TAG, "startListeningVisibleActivityChangedLocked does not match"
+                    + " active session");
+            return;
+        }
+        mActiveSession.startListeningVisibleActivityChangedLocked();
+    }
+
+    public void stopListeningVisibleActivityChangedLocked(@NonNull IBinder token) {
+        if (DEBUG) {
+            Slog.d(TAG, "stopListeningVisibleActivityChangedLocked: token=" + token);
+        }
+        if (mActiveSession == null || token != mActiveSession.mToken) {
+            Slog.w(TAG, "stopListeningVisibleActivityChangedLocked does not match"
+                    + " active session");
+            return;
+        }
+        mActiveSession.stopListeningVisibleActivityChangedLocked();
+    }
+
+    public void notifyActivityEventChangedLocked() {
+        if (DEBUG) {
+            Slog.d(TAG, "notifyActivityEventChangedLocked");
+        }
+        if (mActiveSession == null || !mActiveSession.mShown) {
+            if (DEBUG) {
+                Slog.d(TAG, "notifyActivityEventChangedLocked not allowed on no session or"
+                        + " hidden session");
+            }
+            return;
+        }
+        mActiveSession.notifyActivityEventChangedLocked();
+    }
+
     public void updateStateLocked(
             @NonNull Identity voiceInteractorIdentity,
             @Nullable PersistableBundle options,
diff --git a/services/voiceinteraction/java/com/android/server/voiceinteraction/VoiceInteractionSessionConnection.java b/services/voiceinteraction/java/com/android/server/voiceinteraction/VoiceInteractionSessionConnection.java
index 08e9703..90ccec8 100644
--- a/services/voiceinteraction/java/com/android/server/voiceinteraction/VoiceInteractionSessionConnection.java
+++ b/services/voiceinteraction/java/com/android/server/voiceinteraction/VoiceInteractionSessionConnection.java
@@ -56,6 +56,7 @@
 import android.provider.Settings;
 import android.service.voice.IVoiceInteractionSession;
 import android.service.voice.IVoiceInteractionSessionService;
+import android.service.voice.VisibleActivityInfo;
 import android.service.voice.VoiceInteractionService;
 import android.service.voice.VoiceInteractionSession;
 import android.util.Slog;
@@ -71,16 +72,20 @@
 import com.android.server.statusbar.StatusBarManagerInternal;
 import com.android.server.uri.UriGrantsManagerInternal;
 import com.android.server.wm.ActivityAssistInfo;
+import com.android.server.wm.ActivityTaskManagerInternal;
 
 import java.io.PrintWriter;
 import java.time.Instant;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
 
 final class VoiceInteractionSessionConnection implements ServiceConnection,
         AssistDataRequesterCallbacks {
 
     static final String TAG = "VoiceInteractionServiceManager";
+    static final boolean DEBUG = false;
     static final int POWER_BOOST_TIMEOUT_MS = Integer.parseInt(
             System.getProperty("vendor.powerhal.interaction.max", "200"));
     static final int BOOST_TIMEOUT_MS = 300;
@@ -114,6 +119,10 @@
     ArrayList<IVoiceInteractionSessionShowCallback> mPendingShowCallbacks = new ArrayList<>();
     private List<ActivityAssistInfo> mPendingHandleAssistWithoutData = new ArrayList<>();
     AssistDataRequester mAssistDataRequester;
+    private boolean mListeningVisibleActivity;
+    private final ScheduledExecutorService mScheduledExecutorService =
+            Executors.newSingleThreadScheduledExecutor();
+    private final List<VisibleActivityInfo> mVisibleActivityInfos = new ArrayList<>();
     private final PowerManagerInternal mPowerManagerInternal;
     private PowerBoostSetter mSetPowerBoostRunnable;
     private final Handler mFgHandler;
@@ -496,6 +505,8 @@
     }
 
     public void cancelLocked(boolean finishTask) {
+        mListeningVisibleActivity = false;
+        mVisibleActivityInfos.clear();
         hideLocked();
         mCanceled = true;
         if (mBound) {
@@ -569,6 +580,156 @@
         mPendingShowCallbacks.clear();
     }
 
+    void startListeningVisibleActivityChangedLocked() {
+        if (DEBUG) {
+            Slog.d(TAG, "startListeningVisibleActivityChangedLocked");
+        }
+        mListeningVisibleActivity = true;
+        mVisibleActivityInfos.clear();
+
+        mScheduledExecutorService.execute(() -> {
+            if (DEBUG) {
+                Slog.d(TAG, "call updateVisibleActivitiesLocked from enable listening");
+            }
+            synchronized (mLock) {
+                updateVisibleActivitiesLocked();
+            }
+        });
+    }
+
+    void stopListeningVisibleActivityChangedLocked() {
+        if (DEBUG) {
+            Slog.d(TAG, "stopListeningVisibleActivityChangedLocked");
+        }
+        mListeningVisibleActivity = false;
+        mVisibleActivityInfos.clear();
+    }
+
+    void notifyActivityEventChangedLocked() {
+        if (DEBUG) {
+            Slog.d(TAG, "notifyActivityEventChangedLocked");
+        }
+        if (!mListeningVisibleActivity) {
+            if (DEBUG) {
+                Slog.d(TAG, "not enable listening visible activity");
+            }
+            return;
+        }
+        mScheduledExecutorService.execute(() -> {
+            if (DEBUG) {
+                Slog.d(TAG, "call updateVisibleActivitiesLocked from activity event");
+            }
+            synchronized (mLock) {
+                updateVisibleActivitiesLocked();
+            }
+        });
+    }
+
+    private List<VisibleActivityInfo> getVisibleActivityInfosLocked() {
+        if (DEBUG) {
+            Slog.d(TAG, "getVisibleActivityInfosLocked");
+        }
+        List<ActivityAssistInfo> allVisibleActivities =
+                LocalServices.getService(ActivityTaskManagerInternal.class)
+                        .getTopVisibleActivities();
+        if (DEBUG) {
+            Slog.d(TAG,
+                    "getVisibleActivityInfosLocked: allVisibleActivities=" + allVisibleActivities);
+        }
+        if (allVisibleActivities == null || allVisibleActivities.isEmpty()) {
+            Slog.w(TAG, "no visible activity");
+            return null;
+        }
+        final int count = allVisibleActivities.size();
+        final List<VisibleActivityInfo> visibleActivityInfos = new ArrayList<>(count);
+        for (int i = 0; i < count; i++) {
+            ActivityAssistInfo info = allVisibleActivities.get(i);
+            if (DEBUG) {
+                Slog.d(TAG, " : activityToken=" + info.getActivityToken()
+                        + ", assistToken=" + info.getAssistToken()
+                        + ", taskId=" + info.getTaskId());
+            }
+            visibleActivityInfos.add(
+                    new VisibleActivityInfo(info.getTaskId(), info.getAssistToken()));
+        }
+        return visibleActivityInfos;
+    }
+
+    private void updateVisibleActivitiesLocked() {
+        if (DEBUG) {
+            Slog.d(TAG, "updateVisibleActivitiesLocked");
+        }
+        if (mSession == null) {
+            return;
+        }
+        if (!mShown || !mListeningVisibleActivity || mCanceled) {
+            return;
+        }
+        final List<VisibleActivityInfo> newVisibleActivityInfos = getVisibleActivityInfosLocked();
+
+        if (newVisibleActivityInfos == null || newVisibleActivityInfos.isEmpty()) {
+            updateVisibleActivitiesChangedLocked(mVisibleActivityInfos,
+                    VisibleActivityInfo.TYPE_ACTIVITY_REMOVED);
+            mVisibleActivityInfos.clear();
+            return;
+        }
+        if (mVisibleActivityInfos.isEmpty()) {
+            updateVisibleActivitiesChangedLocked(newVisibleActivityInfos,
+                    VisibleActivityInfo.TYPE_ACTIVITY_ADDED);
+            mVisibleActivityInfos.addAll(newVisibleActivityInfos);
+            return;
+        }
+
+        final List<VisibleActivityInfo> addedActivities = new ArrayList<>();
+        final List<VisibleActivityInfo> removedActivities = new ArrayList<>();
+
+        removedActivities.addAll(mVisibleActivityInfos);
+        for (int i = 0; i < newVisibleActivityInfos.size(); i++) {
+            final VisibleActivityInfo candidateVisibleActivityInfo = newVisibleActivityInfos.get(i);
+            if (!removedActivities.isEmpty() && removedActivities.contains(
+                    candidateVisibleActivityInfo)) {
+                removedActivities.remove(candidateVisibleActivityInfo);
+            } else {
+                addedActivities.add(candidateVisibleActivityInfo);
+            }
+        }
+
+        if (!addedActivities.isEmpty()) {
+            updateVisibleActivitiesChangedLocked(addedActivities,
+                    VisibleActivityInfo.TYPE_ACTIVITY_ADDED);
+        }
+        if (!removedActivities.isEmpty()) {
+            updateVisibleActivitiesChangedLocked(removedActivities,
+                    VisibleActivityInfo.TYPE_ACTIVITY_REMOVED);
+        }
+
+        mVisibleActivityInfos.clear();
+        mVisibleActivityInfos.addAll(newVisibleActivityInfos);
+    }
+
+    private void updateVisibleActivitiesChangedLocked(
+            List<VisibleActivityInfo> visibleActivityInfos, int type) {
+        if (visibleActivityInfos == null || visibleActivityInfos.isEmpty()) {
+            return;
+        }
+        if (mSession == null) {
+            return;
+        }
+        try {
+            for (int i = 0; i < visibleActivityInfos.size(); i++) {
+                mSession.updateVisibleActivityInfo(visibleActivityInfos.get(i), type);
+            }
+        } catch (RemoteException e) {
+            if (DEBUG) {
+                Slog.w(TAG, "updateVisibleActivitiesChangedLocked RemoteException : " + e);
+            }
+        }
+        if (DEBUG) {
+            Slog.d(TAG, "updateVisibleActivitiesChangedLocked type=" + type + ", count="
+                    + visibleActivityInfos.size());
+        }
+    }
+
     @Override
     public void onServiceConnected(ComponentName name, IBinder service) {
         synchronized (mLock) {