From 1d09760ef7c9275555ac512d66fee5af549c5d06 Mon Sep 17 00:00:00 2001
From: fufesou <linlong1266@gmail.com>
Date: Tue, 11 Aug 2026 15:54:03 +0800
Subject: [PATCH] fix(terminal): keep selection aligned after clearing
 scrollback (#15831)

Remove scrollback lines through the index-aware buffer operation so
deleted anchors are detached and retained lines are reindexed.

Signed-off-by: fufesou <linlong1266@gmail.com>
---
 flutter/lib/models/rustdesk_terminal.dart | 14 ++++++++++++++
 flutter/lib/models/terminal_model.dart    |  3 ++-
 2 files changed, 16 insertions(+), 1 deletion(-)
 create mode 100644 flutter/lib/models/rustdesk_terminal.dart

diff --git a/flutter/lib/models/rustdesk_terminal.dart b/flutter/lib/models/rustdesk_terminal.dart
new file mode 100644
index 000000000..6e3f35dfd
--- /dev/null
+++ b/flutter/lib/models/rustdesk_terminal.dart
@@ -0,0 +1,14 @@
+import 'package:xterm/xterm.dart';
+
+class RustDeskTerminal extends Terminal {
+  RustDeskTerminal({super.maxLines});
+
+  @override
+  void eraseScrollbackOnly() {
+    final scrollBack = buffer.scrollBack;
+    if (scrollBack == 0) return;
+
+    // Selection anchors require retained buffer lines to be reindexed.
+    buffer.lines.remove(0, scrollBack);
+  }
+}
diff --git a/flutter/lib/models/terminal_model.dart b/flutter/lib/models/terminal_model.dart
index 0472cb483..63e831202 100644
--- a/flutter/lib/models/terminal_model.dart
+++ b/flutter/lib/models/terminal_model.dart
@@ -10,6 +10,7 @@ import 'package:xterm/xterm.dart';
 import 'input_modifier_utils.dart';
 import 'model.dart';
 import 'platform_model.dart';
+import 'rustdesk_terminal.dart';
 import 'terminal_mouse_handler.dart';
 
 class TerminalModel with ChangeNotifier {
@@ -129,7 +130,7 @@ class TerminalModel with ChangeNotifier {
   }
 
   TerminalModel(this.parent, [this.terminalId = 0]) : id = parent.id {
-    terminal = Terminal(maxLines: 10000);
+    terminal = RustDeskTerminal(maxLines: 10000);
     terminal.mouseHandler = const WheelButtonFixMouseHandler();
     terminalController = TerminalController();