diff --git a/backend/internal/app/provider_ark_private_assets.go b/backend/internal/app/provider_ark_private_assets.go
index 2c9ec1444..e2e8fab99 100644
--- a/backend/internal/app/provider_ark_private_assets.go
+++ b/backend/internal/app/provider_ark_private_assets.go
@@ -215,9 +215,13 @@ func (s *Service) ensureArkPrivateAsset(ctx context.Context, userID string, reso
 		}
 	}
 
-	groupID, err := s.ensureArkPrivateAssetGroup(ctx, settingRecord, setting)
-	if err != nil {
-		return "", s.failArkPrivateAssetBinding(binding, err)
+	// 重试时复用已建成的素材组，避免管理员调整配置清空 DefaultGroupID 后重复建组。
+	groupID := strings.TrimSpace(binding.AssetGroupID)
+	if groupID == "" {
+		groupID, err = s.ensureArkPrivateAssetGroup(ctx, settingRecord, setting)
+		if err != nil {
+			return "", s.failArkPrivateAssetBinding(binding, err)
+		}
 	}
 	binding.AssetGroupID = groupID
 	resourceURL, err := s.directResourceURL(resource, time.Now().Add(time.Hour))
@@ -274,11 +278,19 @@ func (s *Service) ensureArkPrivateAssetGroup(ctx context.Context, settingRecord
 	return groupID, nil
 }
 
+// shouldRetryArkPrivateAssetBinding 判断失败的素材绑定能否安全重试。
+// 素材组尚未建成（两个 ID 均为空）时任何失败都可重试：网络中断、区域配错、
+// 套餐未开通都发生在建组之前，且绝无重复上传风险。素材组已建、素材未建时仅重试
+// 创建素材阶段的失败，最坏情况是组内多出一份素材。审核拒绝发生在拿到素材 ID 之后，
+// ArkAssetID 非空，天然不会进入重试路径。
 func shouldRetryArkPrivateAssetBinding(binding *model.ArkPrivateAssetBinding) bool {
-	if binding == nil || strings.ToLower(strings.TrimSpace(binding.Status)) != arkPrivateAssetStatusFail || binding.AssetGroupID != "" || binding.ArkAssetID != "" {
+	if binding == nil || strings.ToLower(strings.TrimSpace(binding.Status)) != arkPrivateAssetStatusFail || binding.ArkAssetID != "" {
 		return false
 	}
-	return strings.Contains(binding.Error, "方舟素材库没有返回素材组 ID") || strings.Contains(binding.Error, "方舟素材库没有返回素材 ID")
+	if binding.AssetGroupID == "" {
+		return true
+	}
+	return strings.Contains(binding.Error, "上传方舟可信素材失败") || strings.Contains(binding.Error, "方舟素材库没有返回素材 ID")
 }
 
 func shouldResumeArkPrivateAssetPolling(binding *model.ArkPrivateAssetBinding) bool {
@@ -384,18 +396,45 @@ func callArkPrivateAssetAPI(ctx context.Context, setting arkPrivateAssetSettingV
 	}
 	var response map[string]interface{}
 	if err := doJSON(credentials.Sign(req), &response); err != nil {
+		// doJSON 对非 2xx 响应只按状态码生成通用提示（401/403 会被说成“模型服务鉴权失败”），
+		// 方舟把真实原因（如 SubscriptionRequired）放在响应体的 ResponseMetadata.Error 里，必须还原。
+		var httpErr providerHTTPError
+		if errors.As(err, &httpErr) && strings.TrimSpace(httpErr.Body) != "" {
+			var body map[string]interface{}
+			if json.Unmarshal([]byte(httpErr.Body), &body) == nil {
+				if detail := arkPrivateAssetUpstreamDetail(body); detail != "" {
+					return nil, fmt.Errorf("方舟素材库请求失败（HTTP %d）：%s", httpErr.StatusCode, detail)
+				}
+			}
+		}
 		return nil, err
 	}
-	if metadata, ok := response["ResponseMetadata"].(map[string]interface{}); ok {
-		if upstream, ok := metadata["Error"].(map[string]interface{}); ok {
-			code := stringField(upstream, "Code")
-			message := stringField(upstream, "Message")
-			return nil, errors.New(defaultString(strings.TrimSpace(strings.Trim(strings.Join([]string{code, message}, " "), " ")), "方舟素材库请求失败"))
-		}
+	if detail := arkPrivateAssetUpstreamDetail(response); detail != "" {
+		return nil, errors.New(detail)
 	}
 	return response, nil
 }
 
+// arkPrivateAssetUpstreamDetail 提取方舟控制面响应里 ResponseMetadata.Error 的 Code/Message，
+// 用于把上游真实失败原因透传给用户；没有上游错误时返回空串。
+func arkPrivateAssetUpstreamDetail(response map[string]interface{}) string {
+	metadata, _ := response["ResponseMetadata"].(map[string]interface{})
+	if metadata == nil {
+		return ""
+	}
+	upstream, _ := metadata["Error"].(map[string]interface{})
+	if upstream == nil {
+		return ""
+	}
+	code := stringField(upstream, "Code")
+	message := stringField(upstream, "Message")
+	detail := strings.TrimSpace(strings.Trim(strings.Join([]string{code, message}, " "), " "))
+	if detail == "" {
+		return "方舟素材库请求失败"
+	}
+	return detail
+}
+
 func arkPrivateAssetControlPlaneURL(region string) (string, error) {
 	if override := strings.TrimSpace(arkPrivateAssetAPIBaseURLOverride); override != "" {
 		return override, nil
diff --git a/backend/internal/app/provider_ark_private_assets_test.go b/backend/internal/app/provider_ark_private_assets_test.go
index d1704a162..c6c890c4f 100644
--- a/backend/internal/app/provider_ark_private_assets_test.go
+++ b/backend/internal/app/provider_ark_private_assets_test.go
@@ -7,6 +7,8 @@ import (
 	"net/http/httptest"
 	"strings"
 	"testing"
+
+	"infinite-canvas/backend/internal/model"
 )
 
 func TestArkPrivateAssetUsesRegionalArkControlPlane(t *testing.T) {
@@ -157,3 +159,99 @@ func TestArkPrivateAssetResponseFieldReadsCreateGroupID(t *testing.T) {
 		t.Fatalf("group ID = %q", got)
 	}
 }
+
+func TestShouldRetryArkPrivateAssetBinding(t *testing.T) {
+	cases := []struct {
+		name    string
+		binding *model.ArkPrivateAssetBinding
+		want    bool
+	}{
+		{
+			name:    "素材组未建成时网络失败可重试",
+			binding: &model.ArkPrivateAssetBinding{Status: arkPrivateAssetStatusFail, Error: `创建方舟素材组失败：Post "https://ark.cn-shanghai.volcengineapi.com/": EOF`},
+			want:    true,
+		},
+		{
+			name:    "素材组未建成时上游业务拒绝也可重试",
+			binding: &model.ArkPrivateAssetBinding{Status: arkPrivateAssetStatusFail, Error: "创建方舟素材组失败：方舟素材库请求失败（HTTP 403）：SubscriptionRequired"},
+			want:    true,
+		},
+		{
+			name:    "素材组已建时上传素材失败可重试",
+			binding: &model.ArkPrivateAssetBinding{Status: arkPrivateAssetStatusFail, AssetGroupID: "group-1", Error: "上传方舟可信素材失败：Post \"https://ark.cn-beijing.volcengineapi.com/\": EOF"},
+			want:    true,
+		},
+		{
+			name:    "素材组已建时素材 ID 解析失败可重试",
+			binding: &model.ArkPrivateAssetBinding{Status: arkPrivateAssetStatusFail, AssetGroupID: "group-1", Error: "方舟素材库没有返回素材 ID"},
+			want:    true,
+		},
+		{
+			name:    "审核拒绝保持终态不重试",
+			binding: &model.ArkPrivateAssetBinding{Status: arkPrivateAssetStatusFail, AssetGroupID: "group-1", ArkAssetID: "asset-1", Error: "FaceMismatch: Face consistency verification failed."},
+			want:    false,
+		},
+		{
+			name:    "素材组已建时的其他失败不重试",
+			binding: &model.ArkPrivateAssetBinding{Status: arkPrivateAssetStatusFail, AssetGroupID: "group-1", Error: "生成方舟素材临时地址失败：对象存储不可用"},
+			want:    false,
+		},
+		{
+			name:    "非失败状态不重试",
+			binding: &model.ArkPrivateAssetBinding{Status: arkPrivateAssetStatusLive, ArkAssetID: "asset-1"},
+			want:    false,
+		},
+	}
+	for _, item := range cases {
+		if got := shouldRetryArkPrivateAssetBinding(item.binding); got != item.want {
+			t.Fatalf("%s: shouldRetryArkPrivateAssetBinding() = %v, want %v", item.name, got, item.want)
+		}
+	}
+	if shouldRetryArkPrivateAssetBinding(nil) {
+		t.Fatal("shouldRetryArkPrivateAssetBinding(nil) = true, want false")
+	}
+}
+
+func TestCallArkPrivateAssetAPIPassesThroughUpstreamHTTPErrors(t *testing.T) {
+	t.Setenv("CANVAS_ALLOW_PRIVATE_UPSTREAMS", "true")
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		w.WriteHeader(http.StatusForbidden)
+		_, _ = w.Write([]byte(`{"ResponseMetadata":{"Error":{"Code":"SubscriptionRequired","Message":"This API requires an active subscription."}}}`))
+	}))
+	defer server.Close()
+
+	previousBaseURL := arkPrivateAssetAPIBaseURLOverride
+	arkPrivateAssetAPIBaseURLOverride = server.URL
+	t.Cleanup(func() { arkPrivateAssetAPIBaseURLOverride = previousBaseURL })
+
+	_, err := callArkPrivateAssetAPI(context.Background(), arkPrivateAssetSettingValue{
+		Region: "test-region", AccessKeyID: "test-access-key", AccessKeySecret: "test-secret-key",
+	}, "CreateAssetGroup", map[string]interface{}{"ProjectName": "project-test"})
+	if err == nil {
+		t.Fatal("callArkPrivateAssetAPI() error = nil, want upstream passthrough error")
+	}
+	for _, want := range []string{"403", "SubscriptionRequired", "This API requires an active subscription."} {
+		if !strings.Contains(err.Error(), want) {
+			t.Fatalf("callArkPrivateAssetAPI() error = %q, want contains %q", err.Error(), want)
+		}
+	}
+}
+
+func TestArkPrivateAssetUpstreamDetail(t *testing.T) {
+	if got := arkPrivateAssetUpstreamDetail(map[string]interface{}{}); got != "" {
+		t.Fatalf("empty response detail = %q, want empty", got)
+	}
+	response := map[string]interface{}{
+		"ResponseMetadata": map[string]interface{}{
+			"Error": map[string]interface{}{"Code": "FaceMismatch", "Message": "Face consistency verification failed."},
+		},
+	}
+	if got := arkPrivateAssetUpstreamDetail(response); got != "FaceMismatch Face consistency verification failed." {
+		t.Fatalf("detail = %q", got)
+	}
+	emptyError := map[string]interface{}{"ResponseMetadata": map[string]interface{}{"Error": map[string]interface{}{}}}
+	if got := arkPrivateAssetUpstreamDetail(emptyError); got != "方舟素材库请求失败" {
+		t.Fatalf("empty upstream error detail = %q", got)
+	}
+}
diff --git a/web/src/pages/admin/settings/ark-private-assets-settings-page.tsx b/web/src/pages/admin/settings/ark-private-assets-settings-page.tsx
index e008af584..5e65d71c4 100644
--- a/web/src/pages/admin/settings/ark-private-assets-settings-page.tsx
+++ b/web/src/pages/admin/settings/ark-private-assets-settings-page.tsx
@@ -285,8 +285,8 @@ export default function ArkPrivateAssetsSettingsPage() {
                             status={<AdminStatusBadge label={prerequisitesReady ? "已配置" : "待配置"} tone={prerequisitesReady ? "success" : "neutral"} />}
                         >
                             <div className="admin-ark-form-grid">
-                                <Form.Item name="region" label="Region">
-                                    <Input autoComplete="off" placeholder="例如：cn-beijing" />
+                                <Form.Item name="region" label="Region" extra="方舟控制面当前仅 cn-beijing 区域开放，其他区域连接会被直接重置。">
+                                    <Input autoComplete="off" placeholder="cn-beijing" />
                                 </Form.Item>
                                 <Form.Item name="projectName" label="Ark ProjectName">
                                     <Input autoComplete="off" placeholder="方舟项目名称" />