🐛 fix(sidebar): 排除已归属连接的分组选项

- 创建分组时仅展示未归属其他分组的连接
- 编辑分组时保留当前分组已有成员
- 无可选连接时显示明确空状态并补充多语言文案
- 增加连接筛选回归测试

frontend/src/components/SidebarNestedGroupMenu.test.ts

@@ -1,7 +1,10 @@
 import { readFileSync } from 'node:fs';
 import { describe, expect, it, vi } from 'vitest';
 
-import { buildConnectionTagParentOptions } from './sidebar/SidebarEntityModals';
+import {
+  buildConnectionTagParentOptions,
+  buildConnectionTagSelectableConnections,
+} from './sidebar/SidebarEntityModals';
 import { buildSidebarLegacyNodeMenuItems } from './sidebar/sidebarLegacyNodeMenu';
 
 const locales = ['zh-CN', 'zh-TW', 'en-US', 'ja-JP', 'de-DE', 'ru-RU'] as const;
@@ -22,6 +25,42 @@ describe('Sidebar nested group menu', () => {
     expect(options).toEqual([{ value: 'other', label: 'Other' }]);
   });
 
+  it('only offers unassigned connections when creating and retains the edited group members', () => {
+    const connections = [
+      {
+        id: 'host-current',
+        name: 'Current group host',
+        config: { type: 'mysql', host: 'current.local', port: 3306, user: 'root' },
+      },
+      {
+        id: 'host-other',
+        name: 'Other group host',
+        config: { type: 'mysql', host: 'other.local', port: 3306, user: 'root' },
+      },
+      {
+        id: 'host-unassigned',
+        name: 'Ungrouped host',
+        config: { type: 'mysql', host: 'unassigned.local', port: 3306, user: 'root' },
+      },
+    ];
+    const connectionTags = [
+      { id: 'current', name: 'Current', connectionIds: ['host-current'] },
+      { id: 'other', name: 'Other', connectionIds: ['host-other'] },
+    ];
+
+    expect(
+      buildConnectionTagSelectableConnections(connections, connectionTags, '')
+        .map((connection) => connection.id),
+    ).toEqual(['host-unassigned']);
+    expect(
+      buildConnectionTagSelectableConnections(connections, connectionTags, 'current')
+        .map((connection) => connection.id),
+    ).toEqual(['host-current', 'host-unassigned']);
+    expect(
+      buildConnectionTagSelectableConnections(connections.slice(0, 2), connectionTags, ''),
+    ).toEqual([]);
+  });
+
   it('preselects the clicked legacy group when creating a child group', () => {
     const createTagForm = {
       resetFields: vi.fn(),
@@ -69,6 +108,8 @@ describe('Sidebar nested group menu', () => {
   it('keeps modal and both menu implementations aligned with nested grouping', () => {
     expect(modalSource).toContain('name="parentTagId"');
     expect(modalSource).toContain('parentTagId,');
+    expect(modalSource).toContain('Empty.PRESENTED_IMAGE_SIMPLE');
+    expect(modalSource).toContain("sidebar.modal.tag.no_available_connections");
     expect(legacyMenuSource).toContain("key: 'new-child-tag'");
     expect(legacyMenuSource).toContain("t('connection.sidebar.group.newSubgroup')");
     expect(v2MenuSource).toContain("| 'new-subgroup'");
@@ -81,6 +122,7 @@ describe('Sidebar nested group menu', () => {
       'connection.sidebar.group.newSubgroup',
       'sidebar.field.parent_group',
       'sidebar.placeholder.parent_group',
+      'sidebar.modal.tag.no_available_connections',
       'connection.sidebar.group.deleteConfirmContent',
       'sidebar.modal.confirm_delete_tag.content',
     ].forEach((key) => {

frontend/src/components/sidebar/SidebarEntityModals.tsx

@@ -1,5 +1,5 @@
 import React from 'react';
-import { Checkbox, Form, Input, Select, Space } from 'antd';
+import { Checkbox, Empty, Form, Input, Select, Space } from 'antd';
 import type { FormInstance } from 'antd/es/form';
 import { FolderOpenOutlined } from '@ant-design/icons';
 import Modal from '../common/ResizableDraggableModal';
@@ -49,6 +49,26 @@ export const buildConnectionTagParentOptions = (
     });
 };
 
+export const buildConnectionTagSelectableConnections = (
+  connections: SavedConnection[],
+  connectionTags: ConnectionTag[],
+  editingTagId: string,
+): SavedConnection[] => {
+  const currentTagId = editingTagId.trim();
+  const connectionIdsAssignedToOtherTags = new Set<string>();
+
+  connectionTags.forEach((tag) => {
+    if (tag.id === currentTagId) return;
+    tag.connectionIds.forEach((connectionId) => {
+      connectionIdsAssignedToOtherTags.add(connectionId);
+    });
+  });
+
+  return connections.filter(
+    (connection) => !connectionIdsAssignedToOtherTags.has(connection.id),
+  );
+};
+
 const resolveConnectionTagParentId = (
   value: unknown,
   connectionTags: ConnectionTag[],
@@ -168,8 +188,17 @@ export const SidebarEntityModals: React.FC<SidebarEntityModalsProps> = ({
   renameSavedQueryTarget,
   setRenameSavedQueryTarget,
   handleRenameSavedQuery,
-}) => (
-  <>
+}) => {
+  const editingTagId = renameViewTarget?.type === 'tag'
+    ? String(renameViewTarget?.dataRef?.id || '')
+    : '';
+  const selectableConnections = buildConnectionTagSelectableConnections(
+    connections,
+    connectionTags,
+    editingTagId,
+  );
+
+  return (<>
     <Modal
       title={renderSidebarModalTitle(
         <FolderOpenOutlined />,
@@ -181,9 +210,6 @@ export const SidebarEntityModals: React.FC<SidebarEntityModalsProps> = ({
       styles={{ content: modalPanelStyle, header: { background: 'transparent', borderBottom: 'none', paddingBottom: 10 }, body: { paddingTop: 8 }, footer: { background: 'transparent', borderTop: 'none', paddingTop: 12 } }}
       onOk={() => {
         createTagForm.validateFields().then(values => {
-          const editingTagId = renameViewTarget?.type === 'tag'
-            ? String(renameViewTarget?.dataRef?.id || '')
-            : '';
           const parentTagId = resolveConnectionTagParentId(
             values.parentTagId,
             connectionTags,
@@ -221,7 +247,7 @@ export const SidebarEntityModals: React.FC<SidebarEntityModalsProps> = ({
               placeholder={t('sidebar.placeholder.parent_group')}
               options={buildConnectionTagParentOptions(
                 connectionTags,
-                renameViewTarget?.type === 'tag' ? String(renameViewTarget?.dataRef?.id || '') : '',
+                editingTagId,
               )}
             />
           </Form.Item>
@@ -229,11 +255,16 @@ export const SidebarEntityModals: React.FC<SidebarEntityModalsProps> = ({
             <Checkbox.Group style={{ width: '100%' }}>
               <div style={modalScrollSectionStyle}>
                 <Space direction="vertical" style={{ width: '100%' }}>
-                  {connections.map(conn => (
+                  {selectableConnections.length > 0 ? selectableConnections.map(conn => (
                     <Checkbox key={conn.id} value={conn.id}>
                       {conn.name} {conn.config.host ? `(${conn.config.host})` : ''}
                     </Checkbox>
-                  ))}
+                  )) : (
+                    <Empty
+                      image={Empty.PRESENTED_IMAGE_SIMPLE}
+                      description={t('sidebar.modal.tag.no_available_connections')}
+                    />
+                  )}
                 </Space>
               </div>
             </Checkbox.Group>
@@ -380,5 +411,5 @@ export const SidebarEntityModals: React.FC<SidebarEntityModalsProps> = ({
         </Form.Item>
       </Form>
     </Modal>
-  </>
-);
+  </>);
+};