portal: include mapping_id in screencasts

src/ei/ei_ifs/ei_device.rs

@@ -15,8 +15,8 @@ use {
         wire_ei::{
             ei_device::{
                 ClientFrame, ClientStartEmulating, ClientStopEmulating, Destroyed, DeviceType,
-                Done, EiDeviceRequestHandler, Interface, Paused, Region, Release, Resumed,
-                ServerFrame, ServerStartEmulating,
+                Done, EiDeviceRequestHandler, Interface, Paused, Region, RegionMappingId, Release,
+                Resumed, ServerFrame, ServerStartEmulating,
             },
             EiDeviceId,
         },
@@ -100,6 +100,13 @@ impl EiDevice {
         });
     }
 
+    pub fn send_region_mapping_id(&self, mapping_id: &str) {
+        self.client.event(RegionMappingId {
+            self_id: self.id,
+            mapping_id,
+        });
+    }
+
     #[expect(dead_code)]
     pub fn send_paused(&self, serial: u32) {
         self.client.event(Paused {

src/ei/ei_ifs/ei_seat.rs

@@ -346,6 +346,7 @@ impl EiSeat {
         apply!(EI_CAP_KEYBOARD, create_keyboard);
         apply!(EI_CAP_TOUCHSCREEN, create_touchscreen);
         for output in self.client.state.root.outputs.lock().values() {
+            device.send_region_mapping_id(&output.global.connector.name);
             device.send_region(
                 output.node_absolute_position(),
                 output.global.persistent.scale.get(),