From f0b6a71a659bd339e13aeada72a618b2507b067a Mon Sep 17 00:00:00 2001
From: Your Name <you@example.com>
Date: Wed, 29 Jul 2026 06:40:37 +0800
Subject: [PATCH] fix: Delete key in terminal deleting prompt text (root@host)

_on_delete() was missing _current_line_start check that _on_backspace
already had. Clicking into the prompt area (root@hostname:~#) and pressing
Delete would erase prompt characters. Now:
- Cursor before input line: moved to input start, no deletion
- Selection crossing prompt boundary: blocked
---
 ui/terminal_panel.py | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/ui/terminal_panel.py b/ui/terminal_panel.py
index e660410..a7bd02c 100644
--- a/ui/terminal_panel.py
+++ b/ui/terminal_panel.py
@@ -583,8 +583,16 @@ class TerminalPanel(QWidget):
         cursor = self.term.textCursor()
         if cursor.atEnd():
             return
-        if cursor.columnNumber() == 0 and not cursor.hasSelection():
+        # 不允许删除当前输入行之前的内容（提示符 root@host:~# 等）
+        if cursor.position() < self._current_line_start:
+            cursor.setPosition(self._current_line_start)
+            self.term.setTextCursor(cursor)
             return
+        # 如果有选区且选区起点在当前输入行之前，不允许
+        if cursor.hasSelection():
+            sel_start = cursor.selectionStart()
+            if sel_start < self._current_line_start:
+                return
         cursor.deleteChar()
 
     def _history_prev(self):