fix: window close exits app + save dialog diagnostics

- AppDel: use NSWindow.willCloseNotification observer with visibility check
  instead of broken applicationShouldTerminateAfterLastWindowClosed logic
  (SwiftUI WindowGroup keeps hidden windows that blocked termination)
- finishWriting callback: use DispatchQueue.main.async instead of Task @MainActor
  (more reliable from non-main-thread AVFoundation callback)
- Add extensive NSLog diagnostics: callback invoked, file existence check,
  file size, status codes, nil checks

Sources/MiniPlayerApp.swift

@@ -5,11 +5,37 @@ import SwiftBricks
 #if os(macOS)
 import AppKit
 
-// 主窗口关闭时退出应用；辅助面板（播放列表等 NSPanel）关闭不退出
+// 主窗口关闭时退出应用
 class AppDel: NSObject, NSApplicationDelegate {
+    private var closeObserver: Any?
+    
+    func applicationDidFinishLaunching(_ notification: Notification) {
+        // 监听所有窗口关闭事件
+        closeObserver = NotificationCenter.default.addObserver(
+            forName: NSWindow.willCloseNotification,
+            object: nil,
+            queue: .main
+        ) { _ in
+            // 延迟检查：等当前关闭事件完成后再判断
+            DispatchQueue.main.async {
+                let nonPanelWindows = NSApp.windows.filter { !($0 is NSPanel) && $0.isVisible }
+                NSLog("[MiniPlayer] Window closed. Visible non-panel windows: %d", nonPanelWindows.count)
+                if nonPanelWindows.isEmpty {
+                    NSLog("[MiniPlayer] No visible main windows, terminating app")
+                    NSApp.terminate(nil)
+                }
+            }
+        }
+    }
+    
     func applicationShouldTerminateAfterLastWindowClosed(_ sender: NSApplication) -> Bool {
-        // 如果剩余窗口全是 NSPanel（播放列表等），说明主窗口已关闭，应退出
-        return !sender.windows.contains { !($0 is NSPanel) }
+        return true
+    }
+    
+    deinit {
+        if let obs = closeObserver {
+            NotificationCenter.default.removeObserver(obs)
+        }
     }
 }
 #endif

Sources/PlayerRecorder.swift

@@ -312,8 +312,12 @@ final class PlayerRecorder: NSObject {
         audioInput?.markAsFinished()
         
         writer?.finishWriting { [weak self] in
-            Task { @MainActor in
-                guard let self = self, let w = self.writer else { return }
+            NSLog("[Recorder] finishWriting callback invoked")
+            DispatchQueue.main.async {
+                guard let self = self, let w = self.writer else {
+                    NSLog("[Recorder] ⚠️ self or writer is nil in finishWriting callback")
+                    return
+                }
                 let vFrames = self.captureFrameCount
                 NSLog("[Recorder] finishWriting: status=%d, error=%@, videoFrames=%d, audioFrames=%d",
                       w.status.rawValue,
@@ -321,9 +325,18 @@ final class PlayerRecorder: NSObject {
                       vFrames, totalAudioFrames)
                 
                 if w.status == .completed, let tempURL = self.tempURL {
-                    // 弹出保存对话框，用户可改名
-                    self.showSaveDialog(tempURL: tempURL)
+                    // 检查文件是否存在且有内容
+                    if FileManager.default.fileExists(atPath: tempURL.path) {
+                        let size = (try? FileManager.default.attributesOfItem(atPath: tempURL.path)[.size] as? UInt64) ?? 0
+                        NSLog("[Recorder] ✓ Temp file exists: %@, size=%llu bytes", tempURL.lastPathComponent, size)
+                        self.showSaveDialog(tempURL: tempURL)
+                    } else {
+                        NSLog("[Recorder] ⚠️ Temp file missing: %@", tempURL.path)
+                        self.onError?("Recording file missing")
+                    }
                 } else {
+                    NSLog("[Recorder] ✗ finishWriting failed: status=%d, error=%@",
+                          w.status.rawValue, w.error?.localizedDescription ?? "unknown")
                     self.onError?("Recording failed: \(w.error?.localizedDescription ?? "unknown (status=\(w.status.rawValue))")")
                     if let url = self.tempURL {
                         try? FileManager.default.removeItem(at: url)