diff --git a/tests/Feature/AdminPlatformOrderRefundReceiptIdempotentStatusTest.php b/tests/Feature/AdminPlatformOrderRefundReceiptIdempotentStatusTest.php
new file mode 100644
index 0000000..cd6ac80
--- /dev/null
+++ b/tests/Feature/AdminPlatformOrderRefundReceiptIdempotentStatusTest.php
@@ -0,0 +1,96 @@
+<?php
+
+namespace Tests\Feature;
+
+use App\Models\Merchant;
+use App\Models\Plan;
+use App\Models\PlatformOrder;
+use Illuminate\Foundation\Testing\RefreshDatabase;
+use Tests\TestCase;
+
+class AdminPlatformOrderRefundReceiptIdempotentStatusTest 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_add_refund_receipt_will_not_downgrade_payment_status_from_refunded(): void
+    {
+        $this->loginAsPlatformAdmin();
+
+        $merchant = Merchant::query()->firstOrFail();
+        $plan = Plan::query()->create([
+            'code' => 'refund_idempotent_status',
+            'name' => '退款状态幂等测试',
+            'billing_cycle' => 'monthly',
+            'price' => 30,
+            'list_price' => 30,
+            'status' => 'active',
+            'sort' => 10,
+            'published_at' => now(),
+        ]);
+
+        $order = PlatformOrder::query()->create([
+            'merchant_id' => $merchant->id,
+            'plan_id' => $plan->id,
+            'order_no' => 'PO_REFUND_IDEMP_0001',
+            'order_type' => 'new_purchase',
+            'status' => 'activated',
+            'payment_status' => 'refunded',
+            'plan_name' => $plan->name,
+            'billing_cycle' => $plan->billing_cycle,
+            'period_months' => 1,
+            'quantity' => 1,
+            'payable_amount' => 30,
+            'paid_amount' => 30,
+            'placed_at' => now(),
+            'paid_at' => now(),
+            'activated_at' => now(),
+            'refunded_at' => now()->subHour(),
+            'meta' => [
+                'refund_receipts' => [
+                    [
+                        'type' => 'refund',
+                        'channel' => 'wechat',
+                        'amount' => 30,
+                        'refunded_at' => now()->subHour()->format('Y-m-d H:i:s'),
+                        'created_at' => now()->subHour()->toDateTimeString(),
+                        'admin_id' => 1,
+                    ],
+                ],
+                'refund_summary' => [
+                    'count' => 1,
+                    'total_amount' => 30,
+                    'last_at' => now()->subHour()->toDateTimeString(),
+                    'last_amount' => 30,
+                    'last_channel' => 'wechat',
+                ],
+            ],
+        ]);
+
+        // 追加一条 0 元退款（例如：仅留痕/重复通知），不应把 refunded 降级成 partially_refunded
+        $this->post('/admin/platform-orders/' . $order->id . '/add-refund-receipt', [
+            'type' => 'refund',
+            'channel' => 'wechat',
+            'amount' => 0,
+            'refunded_at' => now()->format('Y-m-d H:i:s'),
+            'note' => '0元留痕',
+        ])->assertRedirect();
+
+        $order->refresh();
+
+        $this->assertSame('refunded', $order->payment_status);
+        $this->assertNotNull($order->refunded_at);
+
+        $refundSummaryTotal = (float) data_get($order->meta, 'refund_summary.total_amount');
+        $this->assertSame(30.0, $refundSummaryTotal);
+    }
+}