diff --git a/tests/Feature/AdminPlanFormBackHiddenInputConditionalTest.php b/tests/Feature/AdminPlanFormBackHiddenInputConditionalTest.php
new file mode 100644
index 0000000..718abba
--- /dev/null
+++ b/tests/Feature/AdminPlanFormBackHiddenInputConditionalTest.php
@@ -0,0 +1,32 @@
+<?php
+
+namespace Tests\Feature;
+
+use Illuminate\Foundation\Testing\RefreshDatabase;
+use Tests\TestCase;
+
+class AdminPlanFormBackHiddenInputConditionalTest 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_create_form_should_not_render_back_hidden_input_when_back_is_empty(): void
+    {
+        $this->loginAsPlatformAdmin();
+
+        $res = $this->get('/admin/plans/create?back=' . urlencode('https://evil.example.com/?x=1'));
+        $res->assertOk();
+
+        // PlanController 会将 unsafe back 清洗为空，因此页面不应渲染 back hidden input
+        $res->assertDontSee('name="back"', false);
+    }
+}