diff --git a/crates/weft-compositor/src/protocols/mod.rs b/crates/weft-compositor/src/protocols/mod.rs
index 860015a..a5d9ea1 100644
--- a/crates/weft-compositor/src/protocols/mod.rs
+++ b/crates/weft-compositor/src/protocols/mod.rs
@@ -28,6 +28,7 @@ pub struct WeftShellWindowData {
     pub app_id: String,
     pub title: String,
     pub role: String,
+    pub surface: Option<wayland_server::protocol::wl_surface::WlSurface>,
     pub closed: std::sync::atomic::AtomicBool,
 }
 
@@ -55,6 +56,7 @@ mod tests {
             app_id: "com.example.test".into(),
             title: "Test Window".into(),
             role: "normal".into(),
+            surface: None,
             closed: std::sync::atomic::AtomicBool::new(false),
         };
         assert_eq!(d.app_id, "com.example.test");
@@ -69,6 +71,7 @@ mod tests {
             app_id: String::new(),
             title: String::new(),
             role: String::new(),
+            surface: None,
             closed: std::sync::atomic::AtomicBool::new(false),
         };
         assert!(!d.closed.load(Ordering::Relaxed));
diff --git a/crates/weft-compositor/src/state.rs b/crates/weft-compositor/src/state.rs
index 6aeaf75..33ab910 100644
--- a/crates/weft-compositor/src/state.rs
+++ b/crates/weft-compositor/src/state.rs
@@ -454,6 +454,7 @@ impl Dispatch<ZweftShellManagerV1, ()> for WeftCompositorState {
                 app_id,
                 title,
                 role,
+                surface,
                 x,
                 y,
                 width,
@@ -465,6 +466,7 @@ impl Dispatch<ZweftShellManagerV1, ()> for WeftCompositorState {
                         app_id,
                         title,
                         role,
+                        surface,
                         closed: std::sync::atomic::AtomicBool::new(false),
                     },
                 );
diff --git a/protocol/weft-shell-unstable-v1.xml b/protocol/weft-shell-unstable-v1.xml
index e7e6150..6281ac4 100644
--- a/protocol/weft-shell-unstable-v1.xml
+++ b/protocol/weft-shell-unstable-v1.xml
@@ -68,19 +68,21 @@
       </description>
       <arg name="id"     type="new_id" interface="zweft_shell_window_v1"
            summary="new window object"/>
-      <arg name="app_id" type="string"
+      <arg name="app_id"  type="string"
            summary="application identifier, reverse-DNS format"/>
-      <arg name="title"  type="string"
+      <arg name="title"   type="string"
            summary="initial window title"/>
-      <arg name="role"   type="string"
+      <arg name="role"    type="string"
            summary="window role hint (normal, dialog, panel, overlay)"/>
-      <arg name="x"      type="int"
+      <arg name="surface" type="object" interface="wl_surface" allow-null="true"
+           summary="wl_surface backing this window slot; null for shell-owned windows"/>
+      <arg name="x"       type="int"
            summary="requested x position in compositor logical coordinates"/>
-      <arg name="y"      type="int"
+      <arg name="y"       type="int"
            summary="requested y position in compositor logical coordinates"/>
-      <arg name="width"  type="int"
+      <arg name="width"   type="int"
            summary="requested width in compositor logical coordinates"/>
-      <arg name="height" type="int"
+      <arg name="height"  type="int"
            summary="requested height in compositor logical coordinates"/>
     </request>