initial macos porting work

lib/ui/src/platform.rs

@@ -32,7 +32,7 @@ pub struct PlatformProxy {
 pub struct PlatformRuntime {
     proxy: PlatformProxy,
     events: mpsc::Receiver<PlatformEvent>,
-    _worker: WorkerHandle,
+    worker: Option<WorkerHandle>,
 }
 
 pub struct PlatformEndpoint {
@@ -73,6 +73,7 @@ pub enum PlatformEvent {
         window_id: WindowId,
         text: String,
     },
+    #[cfg(target_os = "linux")]
     PrimarySelectionText {
         window_id: WindowId,
         text: String,
@@ -118,10 +119,12 @@ pub enum PlatformRequest {
     RequestClipboardText {
         window_id: WindowId,
     },
+    #[cfg(target_os = "linux")]
     SetPrimarySelectionText {
         window_id: WindowId,
         text: String,
     },
+    #[cfg(target_os = "linux")]
     RequestPrimarySelectionText {
         window_id: WindowId,
     },
@@ -203,7 +206,30 @@ impl PlatformRuntime {
         Self {
             proxy,
             events: event_rx,
-            _worker: worker,
+            worker: Some(worker),
+        }
+    }
+
+    /// Creates a platform runtime hosted by the current runtime thread.
+    ///
+    /// This is useful for backends that must run on a specific host thread
+    /// (for example, AppKit on macOS main thread).
+    pub fn custom_local(start: impl FnOnce(PlatformEndpoint)) -> Self {
+        let (command_tx, command_rx) = mpsc::unbounded_channel::<PlatformRequest>();
+        let (event_tx, event_rx) = mpsc::unbounded_channel::<PlatformEvent>();
+        let proxy = PlatformProxy {
+            command_tx,
+            next_window_id: Arc::new(AtomicU64::new(1)),
+        };
+        start(PlatformEndpoint {
+            commands: command_rx,
+            events: event_tx,
+        });
+
+        Self {
+            proxy,
+            events: event_rx,
+            worker: None,
         }
     }
 
@@ -216,6 +242,7 @@ impl PlatformRuntime {
     }
 
     pub fn take_pending_events(&mut self) -> Vec<PlatformEvent> {
+        let _ = self.worker.as_ref();
         let mut events = Vec::new();
         while let Ok(event) = self.events.try_recv() {
             events.push(event);
@@ -247,6 +274,7 @@ impl PlatformProxy {
         self.send(PlatformRequest::ReplaceScene { window_id, scene })
     }
 
+    #[cfg(target_os = "linux")]
     pub fn set_primary_selection_text(
         &self,
         window_id: WindowId,
@@ -258,6 +286,7 @@ impl PlatformProxy {
         })
     }
 
+    #[cfg(target_os = "linux")]
     pub fn request_primary_selection_text(
         &self,
         window_id: WindowId,
@@ -356,7 +385,9 @@ pub fn start_headless() -> PlatformRuntime {
                             }
                             PlatformRequest::SetClipboardText { .. } => {}
                             PlatformRequest::RequestClipboardText { .. } => {}
+                            #[cfg(target_os = "linux")]
                             PlatformRequest::SetPrimarySelectionText { .. } => {}
+                            #[cfg(target_os = "linux")]
                             PlatformRequest::RequestPrimarySelectionText { .. } => {}
                             PlatformRequest::SetCursorIcon { .. } => {}
                             PlatformRequest::EmitCloseRequested { window_id } => {