diff --git a/Yattee/Views/Player/ControlsSectionRenderer.swift b/Yattee/Views/Player/ControlsSectionRenderer.swift
index 0c7ba687..c9569448 100644
--- a/Yattee/Views/Player/ControlsSectionRenderer.swift
+++ b/Yattee/Views/Player/ControlsSectionRenderer.swift
@@ -460,7 +460,7 @@ struct ControlsSectionRenderer: View {
 
     /// Brightness icon image using variable value SF Symbol.
     private var brightnessImage: Image {
-        Image(systemName: "sun.max.fill", variableValue: UIScreen.main.brightness)
+        Image(systemName: "sun.max.fill", variableValue: PlayerBrightness.value(for: actions.screen))
     }
 
     /// Panel toggle button content with glass background support.
@@ -796,9 +796,9 @@ struct ControlsSectionRenderer: View {
             if effectiveBehavior == .alwaysVisible || isBrightnessExpanded {
                 Slider(
                     value: Binding(
-                        get: { UIScreen.main.brightness },
+                        get: { PlayerBrightness.value(for: actions.screen) },
                         set: { newValue in
-                            UIScreen.main.brightness = newValue
+                            PlayerBrightness.set(newValue, for: actions.screen)
                         }
                     ),
                     in: 0...1,
diff --git a/Yattee/Views/Player/PlayerBrightness.swift b/Yattee/Views/Player/PlayerBrightness.swift
new file mode 100644
index 00000000..86a5c53e
--- /dev/null
+++ b/Yattee/Views/Player/PlayerBrightness.swift
@@ -0,0 +1,36 @@
+//
+//  PlayerBrightness.swift
+//  Yattee
+//
+//  Screen brightness for the player's brightness controls. On iPhone Duo the
+//  interior and exterior are separate screens, so `UIScreen.main` can name a
+//  display other than the one the player is on: brightness must go to the
+//  screen of the window hosting the controls.
+//
+
+#if os(iOS)
+
+import UIKit
+
+@MainActor
+enum PlayerBrightness {
+    /// The screen to control: the host window's screen, else the foreground
+    /// scene's, else `UIScreen.main`.
+    static func screen(for hostScreen: UIScreen?) -> UIScreen {
+        if let hostScreen { return hostScreen }
+        let activeScene = UIApplication.shared.connectedScenes
+            .compactMap { $0 as? UIWindowScene }
+            .first { $0.activationState == .foregroundActive }
+        return activeScene?.screen ?? UIScreen.main
+    }
+
+    static func value(for hostScreen: UIScreen?) -> Double {
+        screen(for: hostScreen).brightness
+    }
+
+    static func set(_ value: Double, for hostScreen: UIScreen?) {
+        screen(for: hostScreen).brightness = value
+    }
+}
+
+#endif
diff --git a/Yattee/Views/Player/PlayerControlsActions.swift b/Yattee/Views/Player/PlayerControlsActions.swift
index 31aea796..6df44b9d 100644
--- a/Yattee/Views/Player/PlayerControlsActions.swift
+++ b/Yattee/Views/Player/PlayerControlsActions.swift
@@ -57,6 +57,10 @@ struct PlayerControlsActions {
     /// behavior (details toggle, no rotate glyph, no orientation lock).
     var canRotate: Bool = true
 
+    /// Screen of the window hosting the controls; brightness targets it
+    /// (iPhone Duo interior and exterior are separate screens).
+    var screen: UIScreen?
+
     /// iPad, or an iPhone windowing mode that can't rotate on request.
     var usesRotationFreeFullscreen: Bool { isIPad || !canRotate }
 
diff --git a/Yattee/Views/Player/PlayerControlsView.swift b/Yattee/Views/Player/PlayerControlsView.swift
index 9eb6d947..244c3698 100644
--- a/Yattee/Views/Player/PlayerControlsView.swift
+++ b/Yattee/Views/Player/PlayerControlsView.swift
@@ -137,8 +137,8 @@ struct PlayerControlsView: View {
     @State private var targetSeekProgress: Double = 0
     @State private var hideTimer: Timer?
     @State private var showControls: Bool?
-    /// Tracks brightness value for side slider (needed because UIScreen.main.brightness isn't observable)
-    @State private var currentBrightness: Double = UIScreen.main.brightness
+    /// Tracks brightness value for side slider (needed because UIScreen.brightness isn't observable)
+    @State private var currentBrightness: Double = PlayerBrightness.value(for: nil)
     /// Track safe area to force re-render when it changes
     @State private var currentSafeArea: UIEdgeInsets = .zero
     /// Window hosting these controls, captured by `HostWindowReader`. Safe
@@ -146,6 +146,7 @@ struct PlayerControlsView: View {
     /// display's window (iPhone Duo exterior with its 84pt status bar inset
     /// while the player sits on the interior in Split View).
     @State private var hostWindow: UIWindow?
+    private var hostScreen: UIScreen? { hostWindow?.windowScene?.screen }
     @Environment(\.statusBarVisibilityController) private var statusBarController
     /// Active player controls layout from preset (passed from parent to avoid flashing during view recreation)
     var activeLayout: PlayerControlsLayout = .default
@@ -272,6 +273,7 @@ struct PlayerControlsView: View {
             guard window !== hostWindow else { return }
             hostWindow = window
             currentSafeArea = windowSafeArea
+            currentBrightness = PlayerBrightness.value(for: hostScreen)
         })
         .onAppear {
             // Update safe area on appear to ensure correct layout
@@ -300,7 +302,7 @@ struct PlayerControlsView: View {
             appEnvironment?.navigationCoordinator.shouldSnapPanscan = newValue
         }
         .onReceive(NotificationCenter.default.publisher(for: UIScreen.brightnessDidChangeNotification)) { _ in
-            currentBrightness = UIScreen.main.brightness
+            currentBrightness = PlayerBrightness.value(for: hostScreen)
         }
         .sheet(isPresented: $showingCaptionsSheet) {
             captionsSheet
@@ -429,6 +431,7 @@ struct PlayerControlsView: View {
             panelSide: panelSide,
             isIPad: isIPad,
             canRotate: OrientationManager.shared.canRotateProgrammatically,
+            screen: hostWindow?.windowScene?.screen,
             showVolumeControls: showVolumeControls,
             showDebugButton: onToggleDebug != nil,
             showCloseButton: onClose != nil,
@@ -1585,7 +1588,7 @@ struct PlayerControlsView: View {
     /// Always goes to the next higher preset from current position, wrapping from 100 to 0.
     private func cycleBrightnessPreset() {
         let presets: [Double] = [0.0, 0.25, 0.5, 0.75, 1.0]
-        let current = UIScreen.main.brightness
+        let current = PlayerBrightness.value(for: hostScreen)
 
         // Find next higher preset (with small tolerance for floating point)
         let newValue: Double
@@ -1596,7 +1599,7 @@ struct PlayerControlsView: View {
             newValue = 0.0
         }
 
-        UIScreen.main.brightness = newValue
+        PlayerBrightness.set(newValue, for: hostScreen)
         currentBrightness = newValue
     }
 
@@ -1632,7 +1635,7 @@ struct PlayerControlsView: View {
                 value: Binding(
                     get: { currentBrightness },
                     set: { newValue in
-                        UIScreen.main.brightness = newValue
+                        PlayerBrightness.set(newValue, for: hostScreen)
                         currentBrightness = newValue
                     }
                 ),