fix: terminal garbled boxes from OSC sequences in PS1

User reported: each prompt line shows a leading '[?]' box.
Root cause: Ubuntu's default PS1 uses \\e]0;user@host:dir\\a
(OSC 0, set window title) which our ANSI parser did not recognize.
It only handled SGR (\\e[...m), so the raw bytes were drawn as tofu boxes.

Fix in ui/terminal_panel.py:
- Added _OSC_RE for ESC ] ... BEL|ESC\\ sequences (set title, set cwd)
- Added _DCS_RE for ESC P/X/^/_ ... ESC\\ (DCS/SOS/PM/APC)
- _on_data() branches ESC prefix by next byte: '['->CSI, '] '->OSC,
  'P/X/^/_'->DCS, others->skip 2 bytes
- Captured OSC 0/1/2 content into self._window_title (so future
  versions can display it)
- _strip_ansi() now also strips OSC/DCS (for clean history recall)

Added [4b/5] test: injects a literal Ubuntu PS1 byte stream
(OSC 0 + SGR colors) and verifies the rendering is just the plain
'root@ubuntu2204:~# ' with no tofu / no leaked escape chars.

All 21 tests pass (core 6 + UI 3 + E2E 6 + terminal 6).

ui/terminal_panel.py

@@ -36,13 +36,22 @@ ANSI_BG = {
     "100": "#78909c",
 }
 
-# ANSI 转义序列正则（CSI ... 结尾）
+# ANSI CSI 序列：ESC [ ... <final 0x40-0x7e>
 _ANSI_RE = re.compile(r"\x1b\[([\x30-\x3f]*)([\x20-\x2f]*)([\x40-\x7e])")
+# OSC 序列：ESC ] ... BEL(0x07) 或 ESC \  终止（PS1 标题/工作目录等）
+_OSC_RE = re.compile(r"\x1b\][^\x07\x1b]*(?:\x07|\x1b\\)")
+# 单字符 ESC 序列：ESC c/=/> 等（RIS、DECSC 等），一般无害；这里跳过 ESC 后跟非 [ 的 1-2 字节
+_ESC_SINGLE_RE = re.compile(r"\x1b[PX^_](?:[^\x1b]*?\x1b\\)?")
+# DCS/SOS/PM/APC：ESC P/X/^/_ ... ST  跳过
+_DCS_RE = re.compile(r"\x1b[PX^_].*?\x1b\\")
 
 
 def _strip_ansi(text: str) -> str:
-    """去掉所有 ANSI 转义，得到纯文本（用于历史回放、长度计算）"""
-    return _ANSI_RE.sub("", text)
+    """去掉所有 ANSI/OSC/DCS 转义，得到纯文本（用于历史回放、长度计算）"""
+    text = _OSC_RE.sub("", text)
+    text = _DCS_RE.sub("", text)
+    text = _ANSI_RE.sub("", text)
+    return text
 
 
 class _ShellReader(QObject):
@@ -122,6 +131,8 @@ class TerminalPanel(QWidget):
         self._ansi_bold = False
         self._ansi_underline = False
         self._ansi_invert = False
+        # OSC 0/2 设置的窗口标题
+        self._window_title = ""
 
         self._build_ui()
         self._apply_style()
@@ -246,12 +257,37 @@ class TerminalPanel(QWidget):
         i = 0
         while i < len(text):
             ch = text[i]
-            if ch == "\x1b" and i + 1 < len(text) and text[i+1] == "[":
-                # CSI 序列
-                m = _ANSI_RE.match(text, i)
-                if m:
-                    self._apply_ansi(m.group(1), m.group(3))
-                    i = m.end()
+            if ch == "\x1b" and i + 1 < len(text):
+                nxt = text[i + 1]
+                # CSI: ESC [ ... <final>
+                if nxt == "[":
+                    m = _ANSI_RE.match(text, i)
+                    if m:
+                        self._apply_ansi(m.group(1), m.group(3))
+                        i = m.end()
+                        continue
+                # OSC: ESC ] ... BEL | ESC \
+                elif nxt == "]":
+                    m = _OSC_RE.match(text, i)
+                    if m:
+                        # OSC 0/1/2 设置标题/工作目录—— GUI 终端里通常更新窗口标题；
+                        # 我们这里不维护标题栏，但 PS1 里的 OSC 也照样被吃掉。
+                        # 提取 OSC 内容以便调试
+                        content = m.group(0)[2:-1]  # 去掉 ESC ] 和终止符
+                        # 可选：把第一个参数后的内容存到 title
+                        if content and content[0:1] in ("0", "1", "2") and ";" in content:
+                            self._window_title = content.split(";", 1)[1]
+                        i = m.end()
+                        continue
+                # DCS / SOS / PM / APC: ESC P/X/^/_ ... ESC \
+                elif nxt in ("P", "X", "^", "_"):
+                    m = _DCS_RE.match(text, i)
+                    if m:
+                        i = m.end()
+                        continue
+                # 其他 ESC 序列（ESC = / > / c 等）—— 单字节，吞掉
+                else:
+                    i += 2
                     continue
             elif ch == "\r":
                 # \r 单独：回到行首；\n 真的换行