diff --git a/tests/Feature/AdminSubscriptionActivationIdempotentTest.php b/tests/Feature/AdminSubscriptionActivationIdempotentTest.php
new file mode 100644
index 0000000..ffe78fb
--- /dev/null
+++ b/tests/Feature/AdminSubscriptionActivationIdempotentTest.php
@@ -0,0 +1,84 @@
+<?php
+
+namespace Tests\Feature;
+
+use App\Models\Merchant;
+use App\Models\Plan;
+use App\Models\PlatformOrder;
+use App\Models\SiteSubscription;
+use App\Support\SubscriptionActivationService;
+use Illuminate\Foundation\Testing\RefreshDatabase;
+use Tests\TestCase;
+
+class AdminSubscriptionActivationIdempotentTest extends TestCase
+{
+    use RefreshDatabase;
+
+    public function test_activate_order_is_idempotent_when_meta_has_subscription_activation(): void
+    {
+        $this->seed();
+
+        $merchant = Merchant::query()->firstOrFail();
+
+        $plan = Plan::query()->create([
+            'code' => 'activation_idempotent_test',
+            'name' => '订阅激活幂等测试',
+            'billing_cycle' => 'monthly',
+            'price' => 10,
+            'list_price' => 10,
+            'status' => 'active',
+            'sort' => 10,
+            'published_at' => now(),
+        ]);
+
+        $sub = SiteSubscription::query()->create([
+            'merchant_id' => $merchant->id,
+            'plan_id' => $plan->id,
+            'status' => 'activated',
+            'source' => 'manual',
+            'subscription_no' => 'SUB_IDEMP_0001',
+            'plan_name' => $plan->name,
+            'billing_cycle' => $plan->billing_cycle,
+            'period_months' => 1,
+            'amount' => 10,
+            'starts_at' => now()->subDays(2),
+            'ends_at' => now()->addDays(20),
+            'activated_at' => now()->subDays(2),
+        ]);
+
+        $service = app(SubscriptionActivationService::class);
+
+        $order = PlatformOrder::query()->create([
+            'merchant_id' => $merchant->id,
+            'plan_id' => $plan->id,
+            'site_subscription_id' => $sub->id,
+            'order_no' => 'PO_IDEMP_0001',
+            'order_type' => 'renewal',
+            'status' => 'activated',
+            'payment_status' => 'paid',
+            'plan_name' => $plan->name,
+            'billing_cycle' => $plan->billing_cycle,
+            'period_months' => 1,
+            'quantity' => 1,
+            'payable_amount' => 10,
+            'paid_amount' => 10,
+            'placed_at' => now()->subMinutes(10),
+            'paid_at' => now()->subMinutes(5),
+            'activated_at' => now()->subMinutes(1),
+        ]);
+
+        // 第一次激活：会写入 subscription_activation meta，并可能续期
+        $service->activateOrder($order->id, 1);
+        $order->refresh();
+        $sub->refresh();
+
+        $firstEndsAt = $sub->ends_at->copy();
+        $this->assertNotEmpty(data_get($order->meta, 'subscription_activation.subscription_id'));
+
+        // 第二次激活：应直接返回，不再延长 ends_at
+        $service->activateOrder($order->id, 1);
+        $sub->refresh();
+
+        $this->assertSame($firstEndsAt->format('Y-m-d H:i:s'), $sub->ends_at->format('Y-m-d H:i:s'));
+    }
+}