diff --git a/backend/internal/server/api_contract_test.go b/backend/internal/server/api_contract_test.go
index e925e54121..9c2f340f05 100644
--- a/backend/internal/server/api_contract_test.go
+++ b/backend/internal/server/api_contract_test.go
@@ -802,7 +802,7 @@ func TestAPIContracts(t *testing.T) {
 					"force_email_on_third_party_signup": false,
 					"default_concurrency": 5,
 					"default_balance": 1.25,
-					"default_platform_quotas": {"anthropic":{"daily":null,"weekly":null,"monthly":null},"antigravity":{"daily":null,"weekly":null,"monthly":null},"gemini":{"daily":null,"weekly":null,"monthly":null},"openai":{"daily":null,"weekly":null,"monthly":null}},
+					"default_platform_quotas": {"anthropic":{"daily":null,"weekly":null,"monthly":null},"antigravity":{"daily":null,"weekly":null,"monthly":null},"gemini":{"daily":null,"weekly":null,"monthly":null},"grok":{"daily":null,"weekly":null,"monthly":null},"openai":{"daily":null,"weekly":null,"monthly":null}},
 					"auth_source_default_email_platform_quotas": null,
 					"auth_source_default_github_platform_quotas": null,
 					"auth_source_default_google_platform_quotas": null,
@@ -1049,7 +1049,7 @@ func TestAPIContracts(t *testing.T) {
 					"purchase_subscription_url": "",
 					"table_default_page_size": 20,
 					"table_page_size_options": [10, 20, 50],
-					"default_platform_quotas": {"anthropic":{"daily":null,"weekly":null,"monthly":null},"antigravity":{"daily":null,"weekly":null,"monthly":null},"gemini":{"daily":null,"weekly":null,"monthly":null},"openai":{"daily":null,"weekly":null,"monthly":null}},
+					"default_platform_quotas": {"anthropic":{"daily":null,"weekly":null,"monthly":null},"antigravity":{"daily":null,"weekly":null,"monthly":null},"gemini":{"daily":null,"weekly":null,"monthly":null},"grok":{"daily":null,"weekly":null,"monthly":null},"openai":{"daily":null,"weekly":null,"monthly":null}},
 					"auth_source_default_email_platform_quotas": null,
 					"auth_source_default_github_platform_quotas": null,
 					"auth_source_default_google_platform_quotas": null,
diff --git a/backend/internal/service/setting_service_platform_quota_test.go b/backend/internal/service/setting_service_platform_quota_test.go
index a58c8274e7..cde03b462c 100644
--- a/backend/internal/service/setting_service_platform_quota_test.go
+++ b/backend/internal/service/setting_service_platform_quota_test.go
@@ -152,7 +152,7 @@ func TestGetAuthSourcePlatformQuotas_AllNegativeOrEmpty_NoEntry(t *testing.T) {
 }
 
 // TestSystemPlatformQuotas_WriteReadRoundTrip 验证系统层 platform quota 经 buildSystemSettingsUpdates（写）
-// 再由 GetDefaultPlatformQuotas（读）正确往返——覆盖真实 write→read 路径，锁住 4-key 补齐契约。
+// 再由 GetDefaultPlatformQuotas（读）正确往返，覆盖真实 write→read 路径并锁住平台补齐契约。
 func TestSystemPlatformQuotas_WriteReadRoundTrip(t *testing.T) {
 	svc := newSettingServiceForPlatformQuotaTest(nil)
 	ctx := context.Background()
@@ -171,10 +171,10 @@ func TestSystemPlatformQuotas_WriteReadRoundTrip(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	// 4-key 补齐契约：无论写了几个 platform，读回必须含全部 4 个
-	for _, p := range []string{"anthropic", "openai", "gemini", "antigravity"} {
+	// 平台补齐契约：无论写了几个 platform，读回必须含全部允许平台
+	for _, p := range AllowedQuotaPlatforms {
 		if _, ok := got[p]; !ok {
-			t.Errorf("4-key contract violated: missing platform %q", p)
+			t.Errorf("allowed-platform contract violated: missing platform %q", p)
 		}
 	}
 	// 写入值正确往返