diff --git a/quickstep/src/com/android/quickstep/util/ActiveTrackpadList.kt b/quickstep/src/com/android/quickstep/util/ActiveTrackpadList.kt
index 63bd03d..a1ff0ce 100644
--- a/quickstep/src/com/android/quickstep/util/ActiveTrackpadList.kt
+++ b/quickstep/src/com/android/quickstep/util/ActiveTrackpadList.kt
@@ -30,7 +30,7 @@
 
     init {
         inputManager.registerInputDeviceListener(this, Executors.UI_HELPER_EXECUTOR.handler)
-        inputManager.inputDeviceIds.forEach { deviceId -> onInputDeviceAdded(deviceId) }
+        inputManager.inputDeviceIds.filter(this::isTrackpadDevice).forEach(this::add)
     }
 
     override fun onInputDeviceAdded(deviceId: Int) {
diff --git a/quickstep/tests/multivalentTests/src/com/android/quickstep/util/ActiveTrackpadListTest.kt b/quickstep/tests/multivalentTests/src/com/android/quickstep/util/ActiveTrackpadListTest.kt
new file mode 100644
index 0000000..b4c236e
--- /dev/null
+++ b/quickstep/tests/multivalentTests/src/com/android/quickstep/util/ActiveTrackpadListTest.kt
@@ -0,0 +1,136 @@
+/*
+ * Copyright (C) 2025 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.quickstep.util
+
+import android.hardware.input.InputManager
+import android.view.InputDevice
+import android.view.InputDevice.SOURCE_MOUSE
+import android.view.InputDevice.SOURCE_TOUCHPAD
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import com.android.launcher3.util.Executors.MAIN_EXECUTOR
+import com.android.launcher3.util.IntArray
+import com.android.launcher3.util.SandboxApplication
+import com.android.launcher3.util.TestUtil
+import junit.framework.Assert.assertEquals
+import junit.framework.Assert.assertFalse
+import junit.framework.Assert.assertTrue
+import org.junit.Before
+import org.junit.Rule
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.mockito.ArgumentMatchers.eq
+import org.mockito.Mockito.mock
+import org.mockito.MockitoAnnotations
+import org.mockito.kotlin.doAnswer
+import org.mockito.kotlin.doReturn
+import org.mockito.kotlin.whenever
+
+@RunWith(AndroidJUnit4::class)
+class ActiveTrackpadListTest {
+
+    @get:Rule val context = SandboxApplication()
+
+    private val inputDeviceIds = IntArray()
+    private lateinit var inputManager: InputManager
+
+    @Before
+    fun setup() {
+        MockitoAnnotations.initMocks(this)
+
+        inputManager = context.spyService(InputManager::class.java)
+        doAnswer { inputDeviceIds.toArray() }.whenever(inputManager).inputDeviceIds
+
+        doReturn(null).whenever(inputManager).getInputDevice(eq(1))
+        doReturn(mockDevice(SOURCE_MOUSE or SOURCE_TOUCHPAD))
+            .whenever(inputManager)
+            .getInputDevice(eq(2))
+        doReturn(mockDevice(SOURCE_MOUSE or SOURCE_TOUCHPAD))
+            .whenever(inputManager)
+            .getInputDevice(eq(3))
+        doReturn(mockDevice(SOURCE_MOUSE)).whenever(inputManager).getInputDevice(eq(4))
+    }
+
+    @Test
+    fun `initialize correct devices`() {
+        inputDeviceIds.addAll(IntArray.wrap(1, 2, 3, 4))
+
+        val list = ActiveTrackpadList(context) {}
+        assertEquals(2, list.size())
+        assertTrue(list.contains(2))
+        assertTrue(list.contains(3))
+    }
+
+    @Test
+    fun `update callback not called in constructor`() {
+        inputDeviceIds.addAll(IntArray.wrap(2, 3))
+
+        var updateCalled = false
+        val list = ActiveTrackpadList(context) { updateCalled = true }
+        TestUtil.runOnExecutorSync(MAIN_EXECUTOR) {}
+
+        assertEquals(2, list.size())
+        assertFalse(updateCalled)
+    }
+
+    @Test
+    fun `update called on add only once`() {
+        var updateCalled = false
+        val list = ActiveTrackpadList(context) { updateCalled = true }
+        TestUtil.runOnExecutorSync(MAIN_EXECUTOR) {}
+
+        assertFalse(updateCalled)
+        assertEquals(0, list.size())
+
+        list.onInputDeviceAdded(1)
+        TestUtil.runOnExecutorSync(MAIN_EXECUTOR) {}
+        assertFalse(updateCalled)
+        assertEquals(0, list.size())
+
+        list.onInputDeviceAdded(2)
+        TestUtil.runOnExecutorSync(MAIN_EXECUTOR) {}
+        assertTrue(updateCalled)
+        assertEquals(1, list.size())
+
+        updateCalled = false
+        list.onInputDeviceAdded(3)
+        TestUtil.runOnExecutorSync(MAIN_EXECUTOR) {}
+        assertFalse(updateCalled)
+        assertEquals(2, list.size())
+    }
+
+    @Test
+    fun `update called on remove only once`() {
+        var updateCalled = false
+        inputDeviceIds.addAll(IntArray.wrap(1, 2, 3, 4))
+        val list = ActiveTrackpadList(context) { updateCalled = true }
+        TestUtil.runOnExecutorSync(MAIN_EXECUTOR) {}
+        assertEquals(2, list.size())
+
+        list.onInputDeviceRemoved(2)
+        TestUtil.runOnExecutorSync(MAIN_EXECUTOR) {}
+        assertEquals(1, list.size())
+        assertFalse(updateCalled)
+
+        list.onInputDeviceRemoved(3)
+        TestUtil.runOnExecutorSync(MAIN_EXECUTOR) {}
+        assertEquals(0, list.size())
+        assertTrue(updateCalled)
+    }
+
+    private fun mockDevice(sources: Int) =
+        mock(InputDevice::class.java).apply { doReturn(sources).whenever(this).sources }
+}