diff --git a/public/css/admin-components.css b/public/css/admin-components.css
index 45a7912..cbe7456 100644
--- a/public/css/admin-components.css
+++ b/public/css/admin-components.css
@@ -169,3 +169,29 @@
 .platform-orders-table .governance-hint{
     line-height:1.4;
 }
+
+/* 总台管理：左侧导航二级分组（最小可用版） */
+.sidebar .nav-group{
+    margin:10px 0;
+}
+
+.sidebar .nav-group-title{
+    cursor:pointer;
+    user-select:none;
+    color:#94a3b8;
+    font-size:12px;
+    text-transform:uppercase;
+    letter-spacing:.08em;
+    font-weight:700;
+    margin:0 0 6px;
+    list-style:none;
+}
+
+.sidebar .nav-group summary::-webkit-details-marker{
+    display:none;
+}
+
+.sidebar .nav-item--sub{
+    display:block;
+    padding-left:12px;
+}
diff --git a/resources/views/admin/layouts/app.blade.php b/resources/views/admin/layouts/app.blade.php
index cb9b0c3..bb376c9 100644
--- a/resources/views/admin/layouts/app.blade.php
+++ b/resources/views/admin/layouts/app.blade.php
@@ -17,19 +17,31 @@
         <div class="group-title">总览</div>
         <a href="/admin">总台仪表盘</a>
 
-        <div class="group-title">平台运营</div>
-        <a href="/admin/merchants">站点管理</a>
-        <a href="/admin/plans">套餐管理</a>
-        <a href="/admin/orders">订单监控</a>
-        <a href="/admin/platform-orders">平台订单</a>
-        <a href="/admin/site-subscriptions">订阅管理</a>
-        <a href="/admin/platform-leads">开通线索</a>
-        <a href="/admin/products">商品巡检</a>
-        <a href="/admin/product-categories">商品分类</a>
+        <details class="nav-group" open>
+            <summary class="nav-group-title">收费中心</summary>
+            <a href="/admin/platform-orders" class="nav-item nav-item--sub">平台订单</a>
+            <a href="/admin/site-subscriptions" class="nav-item nav-item--sub">订阅管理</a>
+            <a href="/admin/plans" class="nav-item nav-item--sub">套餐管理</a>
+        </details>
 
-        <div class="group-title">平台配置</div>
-        <a href="/admin/settings/system">系统配置</a>
-        <a href="/admin/settings/channels">渠道配置</a>
+        <details class="nav-group" open>
+            <summary class="nav-group-title">站点治理</summary>
+            <a href="/admin/merchants" class="nav-item nav-item--sub">站点管理</a>
+            <a href="/admin/orders" class="nav-item nav-item--sub">订单监控</a>
+            <a href="/admin/products" class="nav-item nav-item--sub">商品巡检</a>
+            <a href="/admin/product-categories" class="nav-item nav-item--sub">商品分类</a>
+        </details>
+
+        <details class="nav-group" open>
+            <summary class="nav-group-title">增长转化</summary>
+            <a href="/admin/platform-leads" class="nav-item nav-item--sub">开通线索</a>
+        </details>
+
+        <details class="nav-group" open>
+            <summary class="nav-group-title">系统</summary>
+            <a href="/admin/settings/system" class="nav-item nav-item--sub">系统配置</a>
+            <a href="/admin/settings/channels" class="nav-item nav-item--sub">渠道配置</a>
+        </details>
 
         <div class="group-title">外部入口</div>
         <a href="/">返回前台</a>
diff --git a/tests/Feature/AdminNavBillingGroupLinksTest.php b/tests/Feature/AdminNavBillingGroupLinksTest.php
new file mode 100644
index 0000000..8ee2ed0
--- /dev/null
+++ b/tests/Feature/AdminNavBillingGroupLinksTest.php
@@ -0,0 +1,42 @@
+<?php
+
+namespace Tests\Feature;
+
+use Illuminate\Foundation\Testing\RefreshDatabase;
+use Tests\TestCase;
+
+class AdminNavBillingGroupLinksTest extends TestCase
+{
+    use RefreshDatabase;
+
+    protected function loginAsPlatformAdmin(): void
+    {
+        $this->seed();
+
+        $this->post('/admin/login', [
+            'email' => 'platform.admin@demo.local',
+            'password' => 'Platform@123456',
+        ])->assertRedirect('/admin');
+    }
+
+    public function test_admin_layout_should_contain_billing_group_links(): void
+    {
+        $this->loginAsPlatformAdmin();
+
+        $res = $this->get('/admin');
+        $res->assertOk();
+
+        // 一级分组标题
+        $res->assertSee('收费中心');
+
+        // 二级入口（收费闭环主链）
+        $res->assertSee('href="/admin/platform-orders"', false);
+        $res->assertSee('平台订单');
+
+        $res->assertSee('href="/admin/site-subscriptions"', false);
+        $res->assertSee('订阅管理');
+
+        $res->assertSee('href="/admin/plans"', false);
+        $res->assertSee('套餐管理');
+    }
+}