fix: debounce resize and enlarge broadcast buffer for TUI resize stability

desktop/lib/src/terminal_screen.dart

@@ -31,6 +31,11 @@ class _TerminalScreenState extends State<TerminalScreen> {
   StreamSubscription<Uint8List>? _engineOutputSub;
   StreamSubscription<Uint8List>? _backendOutputSub;
 
+  /// resize 防抖：窗口拖动时 onPtyResize 会高频触发，合并为最后一次。
+  Timer? _resizeDebounce;
+  int _pendingCols = 0;
+  int _pendingRows = 0;
+
   final _host = TextEditingController(text: '127.0.0.1');
   final _port = TextEditingController(text: '8080');
   final _session = TextEditingController();
@@ -101,6 +106,8 @@ class _TerminalScreenState extends State<TerminalScreen> {
   void _disconnect() => _tearDownSession();
 
   void _tearDownSession() {
+    _resizeDebounce?.cancel();
+    _resizeDebounce = null;
     _engineOutputSub?.cancel();
     _engineOutputSub = null;
     _backendOutputSub?.cancel();
@@ -121,15 +128,22 @@ class _TerminalScreenState extends State<TerminalScreen> {
   }
 
   void _handlePtyResize(int cols, int rows) {
-    final b = _backend;
-    if (b == null) return;
-    b.resize(rows, cols);
-    if (mounted) {
-      setState(() {
-        _cols = cols;
-        _rows = rows;
-      });
-    }
+    if (!mounted) return;
+    setState(() {
+      _cols = cols;
+      _rows = rows;
+    });
+
+    // 合并连续 resize：只发送最后一次，避免 TUI 频繁 SIGWINCH 重绘错乱。
+    _pendingCols = cols;
+    _pendingRows = rows;
+    _resizeDebounce?.cancel();
+    _resizeDebounce = Timer(const Duration(milliseconds: 80), () {
+      final b = _backend;
+      if (b == null) return;
+      // PtyBackend.resize(rows, columns) — 注意参数顺序为行/列。
+      b.resize(_pendingRows, _pendingCols);
+    });
   }
 
   @override