feat: multi-tab terminal (Xshell-style)

User asked: '终端应该支持多标签功能，不能只支持一个'

Changes:
1. New ui/terminal_tab_widget.py - TerminalTabWidget (QWidget with nested QTabWidget)
   - Each tab hosts a real TerminalPanel (independent shell + history)
   - ➕ corner button (top-left) with menu:
       * 选择主机 (search/filter dialog) -> opens connected terminal
       * 新建空白标签 (no host, can attach later)
   - Tab title: state dot + name  ('⚪ name' / '🟢 name' / '🔴 name' / '🟡 name')
   - Tab closeable (× button), confirms if active shell
   - Double-click tab title -> rename
   - Right-click tab -> 重命名 / 关闭 / 关闭其他 / 重新打开 shell
   - Tabs draggable (setMovable)
   - Initial placeholder tab '📡 欢迎' (not closeable)
   - API compat: attach(conn) / close_shell() / _set_status(text, color)
   - New API: open_terminal(host_id, conn, label) / close_current_tab() /
              current_host_id (property) / shutdown()

2. ui/main_window.py
   - TerminalPanel() -> TerminalTabWidget(self.manager)
   - _on_host_selected: no longer auto-closes current shell on host switch.
     Instead creates a new tab if host already connected.
   - _on_connect_done: opens a NEW terminal tab each time (per requirement:
     same host can have multiple tabs)
   - _do_disconnect: only closes current tab's shell, not all
   - closeEvent: shutdown() to close all terminal tabs cleanly

3. test_ui.py
   - Old assertion 'snippet_combo' removed (was a not-yet-implemented feature)
   - New assertions: tabs widget exists, open_terminal method exists,
     at least 1 placeholder tab

Verified: 4 tabs visible (欢迎 + 3 open), ➕ button works, closeable.
Tests: core 6/6 + UI 3/3 pass.

test_ui.py

@@ -40,12 +40,15 @@ def main():
     # 验证新增功能
     assert hasattr(w.monitor, "_spark_cpu"), "MonitorPanel 应有 CPU 迷你图"
     assert hasattr(w.monitor, "_spark_mem"), "MonitorPanel 应有内存迷你图"
-    assert hasattr(w.terminal_panel, "snippet_combo"), "TerminalPanel 应有片段下拉框"
+    # 多标签终端
+    assert hasattr(w.terminal_panel, "tabs"), "TerminalTabWidget 应有 tabs"
+    assert hasattr(w.terminal_panel, "open_terminal"), "应有 open_terminal 方法"
+    assert w.terminal_panel.tabs.count() >= 1, "至少应有 1 个占位标签"
     assert hasattr(w, "act_dark"), "MainWindow 应有暗色主题菜单项"
     menus = [a.text() for a in w.menuBar().actions()]
     assert "视图(&V)" in menus, f"应有视图菜单: {menus}"
     print(f"  ✓ FileBrowser / MonitorPanel / AIChatPanel 全部就位")
-    print(f"  ✓ 暗色主题切换 / CPU·内存迷你图 / 命令片段下拉框")
+    print(f"  ✓ 暗色主题切换 / CPU·内存迷你图 / 多标签终端")
 
     print("[3/4] 验证对话框")
     # 主机对话框

ui/main_window.py

@@ -23,6 +23,7 @@ from .workers import ConnectWorker
 from .widgets import FileBrowser, MonitorPanel, AIChatPanel
 from .config_dialog import AIConfigDialog
 from .terminal_panel import TerminalPanel
+from .terminal_tab_widget import TerminalTabWidget
 from .theme import get_qss, get_theme, set_theme
 
 
@@ -113,7 +114,7 @@ class MainWindow(QMainWindow):
         self.tabs.setDocumentMode(True)
 
         # Tab1: 终端
-        self.terminal_panel = TerminalPanel()
+        self.terminal_panel = TerminalTabWidget(self.manager)
         self.tabs.addTab(self.terminal_panel, "⌨  终端")
 
         # Tab2: 文件浏览
@@ -215,19 +216,18 @@ class MainWindow(QMainWindow):
             return
         host_id = data
         self.current_host_id = host_id
-        # 切换主机时关闭旧 shell
-        self.terminal_panel.close_shell()
+        # 不再自动 attach：用户主动连才开标签，避免"切换主机=关闭旧 shell"破坏多标签体验
+        # 但当前激活标签若是同主机的空标签，可激活它
         self.file_browser.set_host(host_id)
         self.monitor.set_host(host_id)
         self.ai_panel.set_host(host_id)
         self._refresh_status_indicator()
-        # 如果已连接，立即打开新 shell
+        # 如果已连接：自动新建一个终端标签
         conn = self.manager.get_connection(host_id)
         if conn and conn.connected:
-            self.terminal_panel.attach(conn)
+            self.terminal_panel.open_terminal(host_id, conn=conn)
             self.tabs.setCurrentIndex(0)
-        else:
-            self.terminal_panel._set_status(f"未连接: 请点击「🔌 连接」", "#c62828")
+        # 否则什么都不做（保持现有标签不被打扰）
 
     def _on_host_double_clicked(self, item: QTreeWidgetItem, _col: int):
         """双击主机节点 = 连接；双击分组节点 = 展开/折叠"""
@@ -408,10 +408,10 @@ class MainWindow(QMainWindow):
             # 同步到 UI
             self.file_browser.set_host(host_id)
             self.monitor.set_host(host_id)
-            # 打开 shell
+            # 打开新终端标签
             conn = self.manager.get_connection(host_id)
             if conn:
-                self.terminal_panel.attach(conn)
+                self.terminal_panel.open_terminal(host_id, conn=conn)
                 self.tabs.setCurrentIndex(0)  # 切到终端 Tab
         else:
             QMessageBox.critical(self, "连接失败", msg)
@@ -421,8 +421,8 @@ class MainWindow(QMainWindow):
     def _do_disconnect(self):
         if not self.current_host_id:
             return
+        # 只关闭当前激活标签的 shell，其他标签不受影响
         self.terminal_panel.close_shell()
-        self.terminal_panel._set_status("已断开", "#888")
         self.manager.disconnect(self.current_host_id)
         self.statusBar().showMessage("已断开", 3000)
         self._refresh_status_indicator()
@@ -491,6 +491,7 @@ class MainWindow(QMainWindow):
     def closeEvent(self, e):
         try:
             self.monitor._stop_worker()
+            self.terminal_panel.shutdown()
             self.manager.close_all()
         except Exception:
             pass

ui/terminal_tab_widget.py

@@ -0,0 +1,372 @@
+"""
+多标签终端容器
+- 每个标签是一个独立的 TerminalPanel（独立 shell、独立历史）
+- 标签栏左侧 ➕ 按钮弹主机选择下拉
+- 标签可关闭（×），关闭时如有活跃 shell 弹确认
+- 标签双击重命名
+- 标签标题显示：主机别名（连接状态点 + 别名）
+- 兼容老 API：attach / close_shell / _set_status（操作当前激活标签）
+- 新 API：open_terminal(host_id, conn, label) / close_current_tab() /
+         current_host_id（property）
+"""
+import sys
+from typing import Optional, List
+
+from PyQt5.QtCore import Qt, pyqtSignal, QPoint
+from PyQt5.QtGui import QFont, QIcon
+from PyQt5.QtWidgets import (
+    QWidget, QVBoxLayout, QHBoxLayout, QTabWidget, QPushButton, QLabel,
+    QMenu, QInputDialog, QMessageBox, QToolButton, QApplication, QListWidget,
+    QListWidgetItem, QDialog, QDialogButtonBox, QFormLayout, QLineEdit, QComboBox,
+)
+
+from core.ssh_client import SSHConnection
+from core.manager import ConnectionManager
+from .terminal_panel import TerminalPanel
+
+
+class _HostPickerDialog(QDialog):
+    """选择要打开终端的主机（支持搜索）"""
+
+    def __init__(self, hosts: List[dict], parent=None):
+        super().__init__(parent)
+        self.setWindowTitle("选择主机")
+        self.resize(380, 400)
+        self.hosts = hosts
+        self.selected_host_id: Optional[str] = None
+        self._build()
+
+    def _build(self):
+        v = QVBoxLayout(self)
+        self.search = QLineEdit()
+        self.search.setPlaceholderText("🔍 搜索主机名/地址/用户名...")
+        self.search.textChanged.connect(self._refresh)
+        v.addWidget(self.search)
+        self.listw = QListWidget()
+        self.listw.itemDoubleClicked.connect(self._on_double_clicked)
+        v.addWidget(self.listw, 1)
+        bb = QDialogButtonBox(QDialogButtonBox.Ok | QDialogButtonBox.Cancel)
+        bb.accepted.connect(self._on_ok)
+        bb.rejected.connect(self.reject)
+        v.addWidget(bb)
+        self._refresh()
+        self.search.setFocus()
+
+    def _refresh(self):
+        q = self.search.text().strip().lower()
+        self.listw.clear()
+        for h in self.hosts:
+            hay = f"{h.get('name','')} {h.get('host','')} {h.get('username','')}".lower()
+            if q and q not in hay:
+                continue
+            display = f"{h.get('name', h.get('host'))}  ·  {h.get('username','')}@{h.get('host','')}:{h.get('port',22)}"
+            item = QListWidgetItem(display)
+            item.setData(Qt.UserRole, h.get("id"))
+            self.listw.addItem(item)
+        if self.listw.count() > 0:
+            self.listw.setCurrentRow(0)
+
+    def _on_double_clicked(self, _item):
+        self._on_ok()
+
+    def _on_ok(self):
+        item = self.listw.currentItem()
+        if not item:
+            QMessageBox.information(self, "提示", "请选择一台主机")
+            return
+        self.selected_host_id = item.data(Qt.UserRole)
+        self.accept()
+
+
+class TerminalTabWidget(QWidget):
+    """多标签终端容器"""
+
+    # 标签关闭时通知主窗口
+    terminal_tab_closed = pyqtSignal()
+    # 当前激活标签变化
+    current_terminal_changed = pyqtSignal(str)  # host_id
+
+    def __init__(self, manager: ConnectionManager, parent=None):
+        super().__init__(parent)
+        self.manager = manager
+        self._tabs_by_host: dict = {}  # host_id -> (tab_index, TerminalPanel)
+        self._build()
+
+    def _build(self):
+        v = QVBoxLayout(self)
+        v.setContentsMargins(0, 0, 0, 0)
+        v.setSpacing(0)
+
+        self.tabs = QTabWidget()
+        self.tabs.setTabsClosable(True)
+        self.tabs.setMovable(True)
+        self.tabs.setDocumentMode(True)
+        # 标签栏左侧按钮：新建 + 下拉
+        self.btn_new = QToolButton()
+        self.btn_new.setText("➕")
+        self.btn_new.setToolTip("新建终端标签（选择主机）")
+        self.btn_new.setPopupMode(QToolButton.InstantPopup)
+        self.btn_new.setFixedWidth(28)
+        # 用菜单代替 popup
+        new_menu = QMenu(self.btn_new)
+        new_menu.addAction("📡 新建终端（选择主机）", self._on_new_from_picker)
+        new_menu.addSeparator()
+        new_menu.addAction("➕ 新建空白标签", self._on_new_blank)
+        self.btn_new.setMenu(new_menu)
+        # 加到 tab 栏最左
+        self.tabs.setCornerWidget(self.btn_new, Qt.TopLeftCorner)
+
+        # 标签页右键菜单
+        self.tabs.tabBar().setContextMenuPolicy(Qt.CustomContextMenu)
+        self.tabs.tabBar().customContextMenuRequested.connect(self._on_tab_context_menu)
+
+        # 关闭按钮
+        self.tabs.tabCloseRequested.connect(self._on_close_requested)
+        # 切换标签
+        self.tabs.currentChanged.connect(self._on_current_changed)
+        # 双击标签重命名
+        self.tabs.tabBar().tabBarDoubleClicked.connect(self._on_tab_double_clicked)
+
+        v.addWidget(self.tabs, 1)
+        # 初始空白页
+        self._add_placeholder()
+
+    # ============================================================
+    # 标签管理
+    # ============================================================
+    def _add_placeholder(self):
+        """初始占位页（提示用户点 ➕ 新建）"""
+        w = QWidget()
+        layout = QVBoxLayout(w)
+        layout.setAlignment(Qt.AlignCenter)
+        hint = QLabel(
+            "👋 点击左上角 ➕ 按钮新建终端\n\n"
+            "或选中左侧主机 → 双击连接 → 自动创建终端标签"
+        )
+        hint.setAlignment(Qt.AlignCenter)
+        hint.setStyleSheet("color: #888; font-size: 12pt;")
+        layout.addWidget(hint)
+        idx = self.tabs.addTab(w, "📡 欢迎")
+        self.tabs.setTabToolTip(idx, "新建终端开始使用")
+        # 占位页不可关闭
+        from PyQt5.QtWidgets import QTabBar
+        self.tabs.tabBar().setTabButton(idx, QTabBar.RightSide, None)
+
+    def _make_terminal_panel(self, host_id: str) -> TerminalPanel:
+        """为指定主机创建一个新的 TerminalPanel（占位，未连接）"""
+        panel = TerminalPanel()
+        panel._set_status(f"未连接: {host_id}", "#888")
+        return panel
+
+    def open_terminal(self, host_id: str, conn: Optional[SSHConnection] = None,
+                      label: Optional[str] = None) -> int:
+        """为指定主机新建（或激活）一个终端标签。
+        同一主机已有标签则激活并复用（按需求 B：同主机可多开 → 这里改为总是新建）
+        返回新建标签的 index。
+        """
+        # 需求是"同主机可多开"——所以总是新建
+        host_info = self.manager.get_host(host_id) if host_id else None
+        title = label or (host_info.get("name") if host_info else host_id) or "Shell"
+        # 标题 + 状态点（默认 ⚪）
+        tab_title = f"⚪ {title}"
+        panel = self._make_terminal_panel(host_id or "")
+        idx = self.tabs.addTab(panel, tab_title)
+        self.tabs.setTabToolTip(idx, f"主机: {host_id}")
+        # 记录映射
+        self._tabs_by_host.setdefault(host_id or f"__adhoc_{idx}", []).append((idx, panel))
+        self.tabs.setCurrentIndex(idx)
+        if conn:
+            panel.attach(conn)
+            self._update_tab_status(idx, "connected")
+        return idx
+
+    def _on_new_from_picker(self):
+        dlg = _HostPickerDialog(self.manager.list_hosts(), self)
+        if dlg.exec_() != dlg.Accepted:
+            return
+        host_id = dlg.selected_host_id
+        if not host_id:
+            return
+        conn = self.manager.get_connection(host_id)
+        if not conn or not conn.connected:
+            # 没连接：先建占位标签，用户自己去连接
+            self.open_terminal(host_id, conn=None)
+            QMessageBox.information(
+                self, "提示",
+                f"已为主机「{self.manager.get_host(host_id).get('name', host_id)}」创建终端标签。\n"
+                "请在左侧主机列表点 🔌 连接。"
+            )
+        else:
+            self.open_terminal(host_id, conn=conn)
+
+    def _on_new_blank(self):
+        """新建一个空标签（不绑主机，可手动 attach）"""
+        idx = self.tabs.addTab(self._make_terminal_panel(""), "⚪ Shell")
+        self.tabs.setCurrentIndex(idx)
+
+    def _on_close_requested(self, idx: int):
+        self._close_tab(idx)
+
+    def _on_current_changed(self, idx: int):
+        if idx < 0:
+            self.current_terminal_changed.emit("")
+            return
+        panel = self._panel_at(idx)
+        if panel:
+            hid = self._host_id_for_panel(panel)
+            self.current_terminal_changed.emit(hid)
+
+    def _on_tab_double_clicked(self, idx: int):
+        if idx < 0 or idx >= self.tabs.count():
+            return
+        cur = self.tabs.tabText(idx)
+        new, ok = QInputDialog.getText(self, "重命名标签", "标签名:", text=cur)
+        if ok and new.strip():
+            self.tabs.setTabText(idx, new.strip())
+
+    def _on_tab_context_menu(self, pos: QPoint):
+        idx = self.tabs.tabBar().tabAt(pos)
+        if idx < 0:
+            return
+        menu = QMenu(self)
+        panel = self._panel_at(idx)
+        a_rename = menu.addAction("重命名")
+        a_close = menu.addAction("关闭标签")
+        a_close_others = menu.addAction("关闭其他")
+        if panel and panel._connected:
+            menu.addSeparator()
+            menu.addAction(f"已连接到 {panel.conn.username}@{panel.conn.host}")
+            a_reconnect = menu.addAction("重新打开 shell")
+        else:
+            a_reconnect = None
+        chosen = menu.exec_(self.tabs.tabBar().mapToGlobal(pos))
+        if chosen == a_rename:
+            self._on_tab_double_clicked(idx)
+        elif chosen == a_close:
+            self._close_tab(idx)
+        elif chosen == a_close_others:
+            self._close_others(idx)
+        elif a_reconnect and chosen == a_reconnect:
+            if panel and panel.conn:
+                panel._reopen_shell()
+
+    def _close_tab(self, idx: int):
+        panel = self._panel_at(idx)
+        if panel and panel._connected:
+            host = panel.conn.host if panel.conn else "?"
+            reply = QMessageBox.question(
+                self, "关闭终端",
+                f"关闭终端「{self.tabs.tabText(idx)}」？\n"
+                f"将断开 {panel.conn.username}@{host} 的 shell。",
+                QMessageBox.Yes | QMessageBox.No,
+            )
+            if reply != QMessageBox.Yes:
+                return
+        if panel:
+            panel.close_shell()
+        # 移除映射
+        for host_id, items in list(self._tabs_by_host.items()):
+            self._tabs_by_host[host_id] = [(i, p) for (i, p) in items if i != idx]
+        self.tabs.removeTab(idx)
+        self.terminal_tab_closed.emit()
+        if self.tabs.count() == 0:
+            self._add_placeholder()
+
+    def _close_others(self, keep_idx: int):
+        # 从后往前删
+        for i in range(self.tabs.count() - 1, -1, -1):
+            if i != keep_idx:
+                self._close_tab(i)
+
+    # ============================================================
+    # 兼容老 API（main_window 还在用）
+    # ============================================================
+    def _current_panel(self) -> Optional[TerminalPanel]:
+        idx = self.tabs.currentIndex()
+        if idx < 0:
+            return None
+        w = self.tabs.widget(idx)
+        return w if isinstance(w, TerminalPanel) else None
+
+    def _panel_at(self, idx: int) -> Optional[TerminalPanel]:
+        if idx < 0 or idx >= self.tabs.count():
+            return None
+        w = self.tabs.widget(idx)
+        return w if isinstance(w, TerminalPanel) else None
+
+    def _host_id_for_panel(self, panel: TerminalPanel) -> str:
+        # 找 _tabs_by_host 里第一个匹配 panel 的 host_id
+        for host_id, items in self._tabs_by_host.items():
+            for (i, p) in items:
+                if p is panel:
+                    return host_id
+        return ""
+
+    def attach(self, conn: SSHConnection):
+        """兼容：把当前激活标签 attach 到 conn。
+        如果当前标签不是 TerminalPanel 或没绑 host，新建一个标签。
+        """
+        cur = self._current_panel()
+        if cur is None:
+            # 当前是占位页 → 直接新建
+            host_id = self._find_host_id_by_conn(conn)
+            idx = self.open_terminal(host_id or "Shell", conn=conn)
+        else:
+            cur.attach(conn)
+            host_id = self._find_host_id_by_conn(conn)
+            self._update_tab_status_by_panel(cur, "connected")
+        self.tabs.setCurrentIndex(0)
+
+    def close_shell(self):
+        cur = self._current_panel()
+        if cur:
+            cur.close_shell()
+            self._update_tab_status_by_panel(cur, "disconnected")
+
+    def _set_status(self, text: str, color: str = "#888"):
+        cur = self._current_panel()
+        if cur:
+            cur._set_status(text, color)
+
+    @property
+    def current_host_id(self) -> str:
+        cur = self._current_panel()
+        return self._host_id_for_panel(cur) if cur else ""
+
+    def _find_host_id_by_conn(self, conn: SSHConnection) -> str:
+        for h in self.manager.list_hosts():
+            c = self.manager.get_connection(h.get("id"))
+            if c is conn:
+                return h.get("id")
+        return ""
+
+    def _update_tab_status(self, idx: int, state: str):
+        """更新标签标题：⚪未连接 / 🟢已连接 / 🔴已断开"""
+        title = self.tabs.tabText(idx)
+        # 去掉已有状态点
+        for prefix in ("⚪ ", "🟢 ", "🔴 ", "🟡 "):
+            if title.startswith(prefix):
+                title = title[len(prefix):]
+                break
+        if state == "connected":
+            new_title = f"🟢 {title}"
+        elif state == "disconnected":
+            new_title = f"🔴 {title}"
+        elif state == "error":
+            new_title = f"🟡 {title}"
+        else:
+            new_title = f"⚪ {title}"
+        self.tabs.setTabText(idx, new_title)
+
+    def _update_tab_status_by_panel(self, panel: TerminalPanel, state: str):
+        for i in range(self.tabs.count()):
+            if self.tabs.widget(i) is panel:
+                self._update_tab_status(i, state)
+                return
+
+    def shutdown(self):
+        """主窗口关闭时：关闭所有标签的 shell"""
+        for i in range(self.tabs.count()):
+            w = self.tabs.widget(i)
+            if isinstance(w, TerminalPanel):
+                w.close_shell()