fix: address review feedback for models and routing

src/web/pages/token-routes/tokenBindingPresentation.test.ts

@@ -30,6 +30,29 @@ describe('tokenBindingPresentation', () => {
     expect(result.helperText).toContain('不会跟着变');
   });
 
+  it('describes fixed mode when the selected token is not the account default', () => {
+    const result = describeTokenBinding([
+      { id: 1, name: 'default', isDefault: true },
+      { id: 2, name: 'backup', isDefault: false },
+    ], 2);
+
+    expect(result.bindingModeLabel).toBe('固定令牌');
+    expect(result.effectiveTokenName).toBe('backup');
+    expect(result.helperText).toContain('不会随账号默认变化');
+  });
+
+  it('describes follow-account-default mode when no default token exists yet', () => {
+    const result = describeTokenBinding([
+      { id: 2, name: 'backup', isDefault: false },
+      { id: 3, name: 'spare', isDefault: false },
+    ], 0);
+
+    expect(result.bindingModeLabel).toBe('跟随账号默认');
+    expect(result.effectiveTokenName).toBe('未设置默认令牌');
+    expect(result.helperText).toContain('当前账号还没有默认令牌');
+    expect(result.followOptionDescription).toContain('以后账号默认变化时会自动切换');
+  });
+
   it('formats fixed token options with clearer labels and descriptions', () => {
     const token = {
       id: 3,