diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
index 97ffa9d1e9..6043530cd1 100644
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -1076,7 +1076,7 @@
     <activity android:name=".MainActivity"
               android:enableOnBackInvokedCallback="true"
               android:theme="@style/Theme.Signal.DayNight.NoActionBar"
-              android:configChanges="touchscreen|keyboard|keyboardHidden|orientation|screenLayout|screenSize"
+              android:configChanges="touchscreen|keyboard|keyboardHidden|orientation|screenLayout"
               android:resizeableActivity="true"
               android:exported="false"/>
 
diff --git a/app/src/main/java/org/thoughtcrime/securesms/MainActivity.kt b/app/src/main/java/org/thoughtcrime/securesms/MainActivity.kt
index 2449cb674b..57a85a1cdb 100644
--- a/app/src/main/java/org/thoughtcrime/securesms/MainActivity.kt
+++ b/app/src/main/java/org/thoughtcrime/securesms/MainActivity.kt
@@ -29,11 +29,12 @@ import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.displayCutoutPadding
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.systemBarsPadding
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.adaptive.ExperimentalMaterial3AdaptiveApi
 import androidx.compose.material3.adaptive.currentWindowAdaptiveInfo
 import androidx.compose.material3.adaptive.layout.ThreePaneScaffoldRole
-import androidx.compose.material3.adaptive.layout.calculatePaneScaffoldDirectiveWithTwoPanesOnMediumWidth
+import androidx.compose.material3.adaptive.layout.calculatePaneScaffoldDirective
 import androidx.compose.material3.adaptive.navigation.rememberListDetailPaneScaffoldNavigator
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
@@ -93,6 +94,7 @@ import org.thoughtcrime.securesms.main.MainToolbar
 import org.thoughtcrime.securesms.main.MainToolbarCallback
 import org.thoughtcrime.securesms.main.MainToolbarMode
 import org.thoughtcrime.securesms.main.MainToolbarViewModel
+import org.thoughtcrime.securesms.main.NavigationBarSpacerCompat
 import org.thoughtcrime.securesms.main.SnackbarState
 import org.thoughtcrime.securesms.mediasend.camerax.CameraXUtil
 import org.thoughtcrime.securesms.mediasend.v2.MediaSelectionActivity
@@ -236,9 +238,10 @@ class MainActivity : PassphraseRequiredActivity(), VoiceNoteMediaControllerOwner
 
       MainContainer {
         val scaffoldNavigator = rememberListDetailPaneScaffoldNavigator<Any>(
-          scaffoldDirective = calculatePaneScaffoldDirectiveWithTwoPanesOnMediumWidth(
+          scaffoldDirective = calculatePaneScaffoldDirective(
             currentWindowAdaptiveInfo()
           ).copy(
+            maxHorizontalPartitions = if (windowSizeClass.isSplitPane()) 2 else 1,
             horizontalPartitionSpacerSize = contentLayoutData.partitionWidth,
             defaultPanePreferredWidth = contentLayoutData.rememberDefaultPanePreferredWidth(maxWidth)
           )
@@ -258,10 +261,20 @@ class MainActivity : PassphraseRequiredActivity(), VoiceNoteMediaControllerOwner
           navigator = scaffoldNavigator,
           bottomNavContent = {
             if (isNavigationVisible) {
-              MainNavigationBar(
-                state = mainNavigationState,
-                onDestinationSelected = mainNavigationCallback
-              )
+              Column(
+                modifier = Modifier
+                  .clip(contentLayoutData.navigationBarShape)
+                  .background(color = SignalTheme.colors.colorSurface2)
+              ) {
+                MainNavigationBar(
+                  state = mainNavigationState,
+                  onDestinationSelected = mainNavigationCallback
+                )
+
+                if (!windowSizeClass.isSplitPane()) {
+                  NavigationBarSpacerCompat()
+                }
+              }
             }
           },
           navRailContent = {
@@ -360,11 +373,6 @@ class MainActivity : PassphraseRequiredActivity(), VoiceNoteMediaControllerOwner
   @Composable
   private fun MainContainer(content: @Composable BoxWithConstraintsScope.() -> Unit) {
     val windowSizeClass = WindowSizeClass.rememberWindowSizeClass()
-    val modifier = if (windowSizeClass.isLandscape()) {
-      Modifier.displayCutoutPadding()
-    } else {
-      Modifier
-    }
 
     SignalTheme(isDarkMode = DynamicTheme.isDarkTheme(this)) {
       val backgroundColor = if (windowSizeClass.isCompact()) {
@@ -373,6 +381,12 @@ class MainActivity : PassphraseRequiredActivity(), VoiceNoteMediaControllerOwner
         SignalTheme.colors.colorSurface1
       }
 
+      val modifier = if (windowSizeClass.isSplitPane()) {
+        Modifier.systemBarsPadding().displayCutoutPadding()
+      } else {
+        Modifier
+      }
+
       BoxWithConstraints(
         modifier = Modifier
           .background(color = backgroundColor)
diff --git a/app/src/main/java/org/thoughtcrime/securesms/components/settings/app/internal/InternalSettingsFragment.kt b/app/src/main/java/org/thoughtcrime/securesms/components/settings/app/internal/InternalSettingsFragment.kt
index e340a3a283..0026792b58 100644
--- a/app/src/main/java/org/thoughtcrime/securesms/components/settings/app/internal/InternalSettingsFragment.kt
+++ b/app/src/main/java/org/thoughtcrime/securesms/components/settings/app/internal/InternalSettingsFragment.kt
@@ -174,6 +174,16 @@ class InternalSettingsFragment : DSLSettingsFragment(R.string.preferences__inter
         }
       )
 
+      switchPref(
+        isEnabled = state.largeScreenUi,
+        title = DSLSettingsText.from("Force split pane UI on landscape phones."),
+        summary = DSLSettingsText.from("This setting requires split pane UI to be enabled."),
+        isChecked = state.forceSplitPaneOnCompactLandscape,
+        onClick = {
+          viewModel.setForceSplitPaneOnCompactLandscape(!state.forceSplitPaneOnCompactLandscape)
+        }
+      )
+
       sectionHeaderPref(DSLSettingsText.from("Playgrounds"))
 
       clickPref(
diff --git a/app/src/main/java/org/thoughtcrime/securesms/components/settings/app/internal/InternalSettingsState.kt b/app/src/main/java/org/thoughtcrime/securesms/components/settings/app/internal/InternalSettingsState.kt
index c923829fa9..298f7e2cff 100644
--- a/app/src/main/java/org/thoughtcrime/securesms/components/settings/app/internal/InternalSettingsState.kt
+++ b/app/src/main/java/org/thoughtcrime/securesms/components/settings/app/internal/InternalSettingsState.kt
@@ -26,5 +26,6 @@ data class InternalSettingsState(
   val hasPendingOneTimeDonation: Boolean,
   val hevcEncoding: Boolean,
   val newCallingUi: Boolean,
-  val largeScreenUi: Boolean
+  val largeScreenUi: Boolean,
+  val forceSplitPaneOnCompactLandscape: Boolean
 )
diff --git a/app/src/main/java/org/thoughtcrime/securesms/components/settings/app/internal/InternalSettingsViewModel.kt b/app/src/main/java/org/thoughtcrime/securesms/components/settings/app/internal/InternalSettingsViewModel.kt
index cc45321104..e8e32be73f 100644
--- a/app/src/main/java/org/thoughtcrime/securesms/components/settings/app/internal/InternalSettingsViewModel.kt
+++ b/app/src/main/java/org/thoughtcrime/securesms/components/settings/app/internal/InternalSettingsViewModel.kt
@@ -167,7 +167,8 @@ class InternalSettingsViewModel(private val repository: InternalSettingsReposito
     hasPendingOneTimeDonation = SignalStore.inAppPayments.getPendingOneTimeDonation() != null,
     hevcEncoding = SignalStore.internal.hevcEncoding,
     newCallingUi = SignalStore.internal.newCallingUi,
-    largeScreenUi = SignalStore.internal.largeScreenUi
+    largeScreenUi = SignalStore.internal.largeScreenUi,
+    forceSplitPaneOnCompactLandscape = SignalStore.internal.forceSplitPaneOnCompactLandscape
   )
 
   fun onClearOnboardingState() {
@@ -188,6 +189,11 @@ class InternalSettingsViewModel(private val repository: InternalSettingsReposito
     refresh()
   }
 
+  fun setForceSplitPaneOnCompactLandscape(forceSplitPaneOnCompactLandscape: Boolean) {
+    SignalStore.internal.forceSplitPaneOnCompactLandscape = forceSplitPaneOnCompactLandscape
+    refresh()
+  }
+
   class Factory(private val repository: InternalSettingsRepository) : ViewModelProvider.Factory {
     override fun <T : ViewModel> create(modelClass: Class<T>): T {
       return requireNotNull(modelClass.cast(InternalSettingsViewModel(repository)))
diff --git a/app/src/main/java/org/thoughtcrime/securesms/conversation/v2/ConversationFragment.kt b/app/src/main/java/org/thoughtcrime/securesms/conversation/v2/ConversationFragment.kt
index a02d03dfb7..83b81b825b 100644
--- a/app/src/main/java/org/thoughtcrime/securesms/conversation/v2/ConversationFragment.kt
+++ b/app/src/main/java/org/thoughtcrime/securesms/conversation/v2/ConversationFragment.kt
@@ -590,7 +590,7 @@ class ConversationFragment :
   override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
     binding.toolbar.isBackInvokedCallbackEnabled = false
 
-    binding.root.setUseWindowTypes(resources.getWindowSizeClass().isCompact())
+    binding.root.setUseWindowTypes(!resources.getWindowSizeClass().isSplitPane())
 
     disposables.bindTo(viewLifecycleOwner)
 
@@ -1370,9 +1370,7 @@ class ConversationFragment :
   }
 
   private fun presentNavigationIconForNormal() {
-    val windowSizeClass = resources.getWindowSizeClass()
-
-    if (windowSizeClass.isCompact()) {
+    if (!resources.getWindowSizeClass().isSplitPane()) {
       binding.toolbar.setNavigationIcon(R.drawable.ic_arrow_left_24)
       binding.toolbar.setNavigationContentDescription(R.string.ConversationFragment__content_description_back_button)
       binding.toolbar.setNavigationOnClickListener {
diff --git a/app/src/main/java/org/thoughtcrime/securesms/keyvalue/InternalValues.kt b/app/src/main/java/org/thoughtcrime/securesms/keyvalue/InternalValues.kt
index bd1d379a39..f3821d2979 100644
--- a/app/src/main/java/org/thoughtcrime/securesms/keyvalue/InternalValues.kt
+++ b/app/src/main/java/org/thoughtcrime/securesms/keyvalue/InternalValues.kt
@@ -29,6 +29,7 @@ class InternalValues internal constructor(store: KeyValueStore) : SignalStoreVal
     const val ENCODE_HEVC: String = "internal.hevc_encoding"
     const val NEW_CALL_UI: String = "internal.new.call.ui"
     const val LARGE_SCREEN_UI: String = "internal.large.screen.ui"
+    const val FORCE_SPLIT_PANE_ON_COMPACT_LANDSCAPE: String = "internal.force.split.pane.on.compact.landscape.ui"
   }
 
   public override fun onFirstEverAppLaunch() = Unit
@@ -40,6 +41,11 @@ class InternalValues internal constructor(store: KeyValueStore) : SignalStoreVal
    */
   var largeScreenUi by booleanValue(LARGE_SCREEN_UI, false).defaultForExternalUsers()
 
+  /**
+   * Force split-pane mode on compact landscape
+   */
+  var forceSplitPaneOnCompactLandscape by booleanValue(FORCE_SPLIT_PANE_ON_COMPACT_LANDSCAPE, false).defaultForExternalUsers()
+
   /**
    * Members will not be added directly to a GV2 even if they could be.
    */
diff --git a/app/src/main/java/org/thoughtcrime/securesms/main/MainContentLayoutData.kt b/app/src/main/java/org/thoughtcrime/securesms/main/MainContentLayoutData.kt
index 60abaeaa46..82f5fe656a 100644
--- a/app/src/main/java/org/thoughtcrime/securesms/main/MainContentLayoutData.kt
+++ b/app/src/main/java/org/thoughtcrime/securesms/main/MainContentLayoutData.kt
@@ -15,10 +15,14 @@ import androidx.compose.ui.unit.Dp
 import androidx.compose.ui.unit.dp
 import org.thoughtcrime.securesms.window.WindowSizeClass
 
+private val MEDIUM_CONTENT_CORNERS = 18.dp
+private val EXTENDED_CONTENT_CORNERS = 14.dp
+
 /**
  * Describes metrics for the content layout (list and detail) of the main screen.
  *
- * @param shape The shape of each of the list and detail fragments
+ * @param shape The clipping shape of each of the list and detail fragments
+ * @param navigationBarShape The clipping shape applied to the navigation bar, if present.
  * @param partitionWidth The width of the divider between list and detail
  * @param listPaddingStart The padding between the list pane and the navigation rail
  * @param detailPaddingEnd The padding at the end of the detail pane
@@ -26,6 +30,7 @@ import org.thoughtcrime.securesms.window.WindowSizeClass
 @Immutable
 data class MainContentLayoutData(
   val shape: Shape,
+  val navigationBarShape: Shape,
   val partitionWidth: Dp,
   val listPaddingStart: Dp,
   val detailPaddingEnd: Dp
@@ -49,9 +54,9 @@ data class MainContentLayoutData(
 
     return remember(maxWidth, windowSizeClass) {
       when {
-        windowSizeClass.isCompact() -> maxWidth
-        windowSizeClass.isMedium() -> (maxWidth - extraPadding) / 2f
-        else -> 416.dp
+        !windowSizeClass.isSplitPane() -> maxWidth
+        windowSizeClass.isExtended() -> 416.dp
+        else -> (maxWidth - extraPadding) / 2f
       }
     }
   }
@@ -67,24 +72,29 @@ data class MainContentLayoutData(
       return remember(windowSizeClass) {
         MainContentLayoutData(
           shape = when {
-            windowSizeClass.isCompact() -> RectangleShape
-            windowSizeClass.isMedium() -> RoundedCornerShape(18.dp)
-            else -> RoundedCornerShape(14.dp)
+            !windowSizeClass.isSplitPane() -> RectangleShape
+            windowSizeClass.isExtended() -> RoundedCornerShape(EXTENDED_CONTENT_CORNERS)
+            else -> RoundedCornerShape(MEDIUM_CONTENT_CORNERS)
+          },
+          navigationBarShape = when {
+            !windowSizeClass.isSplitPane() -> RectangleShape
+            windowSizeClass.isExtended() -> RoundedCornerShape(0.dp, 0.dp, EXTENDED_CONTENT_CORNERS, EXTENDED_CONTENT_CORNERS)
+            else -> RoundedCornerShape(0.dp, 0.dp, MEDIUM_CONTENT_CORNERS, MEDIUM_CONTENT_CORNERS)
           },
           partitionWidth = when {
-            windowSizeClass.isCompact() -> 0.dp
-            windowSizeClass.isMedium() -> 13.dp
-            else -> 16.dp
+            !windowSizeClass.isSplitPane() -> 0.dp
+            windowSizeClass.isExtended() -> 16.dp
+            else -> 13.dp
           },
           listPaddingStart = when {
-            windowSizeClass.isCompact() -> 0.dp
-            windowSizeClass.isMedium() -> 12.dp
-            else -> 16.dp
+            !windowSizeClass.isSplitPane() -> 0.dp
+            windowSizeClass.isExtended() -> 16.dp
+            else -> 12.dp
           },
           detailPaddingEnd = when {
-            windowSizeClass.isCompact() -> 0.dp
-            windowSizeClass.isMedium() -> 12.dp
-            else -> 24.dp
+            !windowSizeClass.isSplitPane() -> 0.dp
+            windowSizeClass.isExtended() -> 24.dp
+            else -> 12.dp
           }
         )
       }
diff --git a/app/src/main/java/org/thoughtcrime/securesms/main/MainNavigation.kt b/app/src/main/java/org/thoughtcrime/securesms/main/MainNavigation.kt
index d8c4b789f1..e762fb58e4 100644
--- a/app/src/main/java/org/thoughtcrime/securesms/main/MainNavigation.kt
+++ b/app/src/main/java/org/thoughtcrime/securesms/main/MainNavigation.kt
@@ -12,7 +12,6 @@ import androidx.compose.animation.core.tween
 import androidx.compose.foundation.background
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.BoxScope
-import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.WindowInsets
 import androidx.compose.foundation.layout.defaultMinSize
 import androidx.compose.foundation.layout.height
@@ -97,50 +96,46 @@ fun MainNavigationBar(
   state: MainNavigationState,
   onDestinationSelected: (MainNavigationListLocation) -> Unit
 ) {
-  Column(modifier = Modifier.background(color = SignalTheme.colors.colorSurface2)) {
-    NavigationBar(
-      containerColor = SignalTheme.colors.colorSurface2,
-      contentColor = MaterialTheme.colorScheme.onSurface,
-      modifier = Modifier.height(if (state.compact) 48.dp else 80.dp),
-      windowInsets = WindowInsets(0, 0, 0, 0)
-    ) {
-      val entries = remember(state.isStoriesFeatureEnabled) {
-        if (state.isStoriesFeatureEnabled) {
-          MainNavigationListLocation.entries
-        } else {
-          MainNavigationListLocation.entries.filterNot { it == MainNavigationListLocation.STORIES }
-        }
-      }
-
-      entries.forEach { destination ->
-
-        val badgeCount = when (destination) {
-          MainNavigationListLocation.CHATS -> state.chatsCount
-          MainNavigationListLocation.CALLS -> state.callsCount
-          MainNavigationListLocation.STORIES -> state.storiesCount
-        }
-
-        val selected = state.selectedDestination == destination
-        NavigationBarItem(
-          selected = selected,
-          icon = {
-            NavigationDestinationIcon(
-              destination = destination,
-              selected = selected
-            )
-          },
-          label = if (state.compact) null else {
-            { NavigationDestinationLabel(destination) }
-          },
-          onClick = {
-            onDestinationSelected(destination)
-          },
-          modifier = Modifier.drawNavigationBarBadge(count = badgeCount, compact = state.compact)
-        )
+  NavigationBar(
+    containerColor = SignalTheme.colors.colorSurface2,
+    contentColor = MaterialTheme.colorScheme.onSurface,
+    modifier = Modifier.height(if (state.compact) 48.dp else 80.dp),
+    windowInsets = WindowInsets(0, 0, 0, 0)
+  ) {
+    val entries = remember(state.isStoriesFeatureEnabled) {
+      if (state.isStoriesFeatureEnabled) {
+        MainNavigationListLocation.entries
+      } else {
+        MainNavigationListLocation.entries.filterNot { it == MainNavigationListLocation.STORIES }
       }
     }
 
-    NavigationBarSpacerCompat()
+    entries.forEach { destination ->
+
+      val badgeCount = when (destination) {
+        MainNavigationListLocation.CHATS -> state.chatsCount
+        MainNavigationListLocation.CALLS -> state.callsCount
+        MainNavigationListLocation.STORIES -> state.storiesCount
+      }
+
+      val selected = state.selectedDestination == destination
+      NavigationBarItem(
+        selected = selected,
+        icon = {
+          NavigationDestinationIcon(
+            destination = destination,
+            selected = selected
+          )
+        },
+        label = if (state.compact) null else {
+          { NavigationDestinationLabel(destination) }
+        },
+        onClick = {
+          onDestinationSelected(destination)
+        },
+        modifier = Modifier.drawNavigationBarBadge(count = badgeCount, compact = state.compact)
+      )
+    }
   }
 }
 
diff --git a/app/src/main/java/org/thoughtcrime/securesms/window/AppScaffold.kt b/app/src/main/java/org/thoughtcrime/securesms/window/AppScaffold.kt
index 55f6a60bbd..23990cbaa9 100644
--- a/app/src/main/java/org/thoughtcrime/securesms/window/AppScaffold.kt
+++ b/app/src/main/java/org/thoughtcrime/securesms/window/AppScaffold.kt
@@ -11,6 +11,7 @@ import androidx.compose.foundation.background
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.displayCutoutPadding
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.material3.Text
 import androidx.compose.material3.adaptive.ExperimentalMaterial3AdaptiveApi
@@ -18,7 +19,7 @@ import androidx.compose.material3.adaptive.currentWindowAdaptiveInfo
 import androidx.compose.material3.adaptive.layout.AnimatedPane
 import androidx.compose.material3.adaptive.layout.PaneExpansionState
 import androidx.compose.material3.adaptive.layout.ThreePaneScaffoldScope
-import androidx.compose.material3.adaptive.layout.calculatePaneScaffoldDirectiveWithTwoPanesOnMediumWidth
+import androidx.compose.material3.adaptive.layout.calculatePaneScaffoldDirective
 import androidx.compose.material3.adaptive.layout.rememberPaneExpansionState
 import androidx.compose.material3.adaptive.navigation.NavigableListDetailPaneScaffold
 import androidx.compose.material3.adaptive.navigation.ThreePaneScaffoldNavigator
@@ -83,6 +84,14 @@ enum class WindowSizeClass(
 
   fun isLandscape(): Boolean = this == COMPACT_LANDSCAPE || this == MEDIUM_LANDSCAPE || this == EXTENDED_LANDSCAPE
 
+  fun isSplitPane(): Boolean {
+    return if (SignalStore.internal.largeScreenUi && SignalStore.internal.forceSplitPaneOnCompactLandscape) {
+      this != COMPACT_PORTRAIT
+    } else {
+      this.navigation != Navigation.BAR
+    }
+  }
+
   companion object {
     @OptIn(ExperimentalWindowCoreApi::class)
     fun Resources.getWindowSizeClass(): WindowSizeClass {
@@ -221,7 +230,11 @@ private fun ListAndNavigation(
   bottomNavContent: @Composable () -> Unit,
   windowSizeClass: WindowSizeClass
 ) {
-  Row {
+  Row(
+    modifier = if (windowSizeClass.isLandscape()) {
+      Modifier.displayCutoutPadding()
+    } else Modifier
+  ) {
     if (windowSizeClass.navigation == Navigation.RAIL) {
       navRailContent()
     }
@@ -250,7 +263,7 @@ private fun AppScaffoldPreview() {
   Previews.Preview {
     AppScaffold(
       navigator = rememberListDetailPaneScaffoldNavigator<Any>(
-        scaffoldDirective = calculatePaneScaffoldDirectiveWithTwoPanesOnMediumWidth(
+        scaffoldDirective = calculatePaneScaffoldDirective(
           currentWindowAdaptiveInfo()
         ).copy(
           horizontalPartitionSpacerSize = 10.dp