diff --git a/desktop/src-tauri/src/dictation.rs b/desktop/src-tauri/src/dictation.rs
index ef7a6af..31cf9e4 100644
--- a/desktop/src-tauri/src/dictation.rs
+++ b/desktop/src-tauri/src/dictation.rs
@@ -331,32 +331,61 @@ fn set_tray_tooltip(app: &AppHandle, text: &str) {
 }
 
 /// 让识别浮层能浮在全屏 App 之上（macOS）：给 NSWindow 追加
-/// CanJoinAllSpaces | Stationary | FullScreenAuxiliary 集合行为。
+/// CanJoinAllSpaces | Stationary | FullScreenAuxiliary 集合行为，并抬高窗口层级。
 /// 仅 alwaysOnTop 不够——全屏 App 独占 Space，普通置顶窗口不会出现在其中，
 /// FullScreenAuxiliary 才让浮层作为辅助窗叠加到全屏 Space 上。
-/// 必须在主线程调用（Tauri setup 闭包即主线程），窗口创建后调用一次即可。
+///
+/// 强制派发到主线程执行（设 NSWindow 属性必须主线程）；每次显示浮层都重设一遍，
+/// 规避「setup 时隐藏窗口的原生窗口尚未就绪 / 属性被 show 重置」。
 #[cfg(target_os = "macos")]
 pub fn configure_overlay_spaces(app: &AppHandle) {
-    use objc2::{msg_send, runtime::AnyObject};
-    // NSWindowCollectionBehavior 位标志
-    const CAN_JOIN_ALL_SPACES: usize = 1 << 0;
-    const STATIONARY: usize = 1 << 4;
-    const FULL_SCREEN_AUXILIARY: usize = 1 << 8;
-    if let Some(w) = app.get_webview_window(OVERLAY) {
-        if let Ok(ptr) = w.ns_window() {
-            let ns = ptr as *mut AnyObject;
-            unsafe {
-                let cur: usize = msg_send![ns, collectionBehavior];
-                let next = cur | CAN_JOIN_ALL_SPACES | STATIONARY | FULL_SCREEN_AUXILIARY;
-                let _: () = msg_send![ns, setCollectionBehavior: next];
+    let app2 = app.clone();
+    let _ = app.run_on_main_thread(move || {
+        use objc2::{msg_send, runtime::AnyObject};
+        const CAN_JOIN_ALL_SPACES: usize = 1 << 0;
+        const STATIONARY: usize = 1 << 4;
+        const FULL_SCREEN_AUXILIARY: usize = 1 << 8;
+        // NSStatusWindowLevel(25)：浮在普通/全屏窗口之上、菜单栏之下。
+        const STATUS_LEVEL: isize = 25;
+        let Some(w) = app2.get_webview_window(OVERLAY) else {
+            overlay_diag("configure: overlay window 不存在");
+            return;
+        };
+        match w.ns_window() {
+            Ok(ptr) => {
+                let ns = ptr as *mut AnyObject;
+                unsafe {
+                    let before: usize = msg_send![ns, collectionBehavior];
+                    let next = before | CAN_JOIN_ALL_SPACES | STATIONARY | FULL_SCREEN_AUXILIARY;
+                    let _: () = msg_send![ns, setCollectionBehavior: next];
+                    let _: () = msg_send![ns, setLevel: STATUS_LEVEL];
+                    let after: usize = msg_send![ns, collectionBehavior];
+                    overlay_diag(&format!(
+                        "configure: ns_window OK behavior {before:#x} → {after:#x} level={STATUS_LEVEL}"
+                    ));
+                }
             }
+            Err(e) => overlay_diag(&format!("configure: ns_window 失败: {e}")),
         }
-    }
+    });
 }
 
 #[cfg(not(target_os = "macos"))]
 pub fn configure_overlay_spaces(_app: &AppHandle) {}
 
+// TODO(诊断): 全屏浮层排查——写文件便于 open 启动时读取，定位后删除。
+#[cfg(target_os = "macos")]
+fn overlay_diag(msg: &str) {
+    use std::io::Write;
+    if let Ok(mut f) = std::fs::OpenOptions::new()
+        .create(true)
+        .append(true)
+        .open("/tmp/dudu-overlay-diag.log")
+    {
+        let _ = writeln!(f, "{msg}");
+    }
+}
+
 fn show_overlay(app: &AppHandle) {
     if let Some(w) = app.get_webview_window(OVERLAY) {
         // 跟随光标：浮层出现在指针下方 24px，水平居中
@@ -365,6 +394,8 @@ fn show_overlay(app: &AppHandle) {
         }
         let _ = w.show();
     }
+    // 每次显示都重设全屏叠加行为（主线程派发；见 configure_overlay_spaces）。
+    configure_overlay_spaces(app);
 }
 
 fn hide_overlay(app: &AppHandle) {
diff --git a/desktop/src-tauri/src/lib.rs b/desktop/src-tauri/src/lib.rs
index 9aabdf3..d57cde4 100644
--- a/desktop/src-tauri/src/lib.rs
+++ b/desktop/src-tauri/src/lib.rs
@@ -98,6 +98,12 @@ pub fn run() {
         })
         .setup(|app| {
             let handle = app.handle().clone();
+            // dudu 是托盘应用（无主窗口）：设为 Accessory 激活策略——菜单栏辅助 App，
+            // 不占 Dock。这也是识别浮层能浮在其他 App 全屏之上的前提：标准 NSWindow
+            // 靠 collectionBehavior 无法叠加到别的 App 全屏 Space（macOS 设计限制，
+            // 见 Apple 论坛 26677 / tauri#11488），Accessory 策略 + CanJoinAllSpaces 才生效。
+            #[cfg(target_os = "macos")]
+            let _ = app.set_activation_policy(tauri::ActivationPolicy::Accessory);
             // 设置 → 管理状态
             app.manage(settings::SettingsStore::load(&handle));
             app.manage(dictation::DictationState::default());