fix: resolve CI failures — gofmt, unused functions, missing test helpers

- Run gofmt on user schema, config test, group handler
- Remove unused mergeGroupIDs function
- Restore shared test helpers (newJSONResponse, queuedHTTPUpstream)
  that were in deleted Sora test file

backend/internal/config/config_test.go

@@ -1554,7 +1554,6 @@ func TestValidateConfig_LogRequiredAndRotationBounds(t *testing.T) {
 	}
 }
 
-
 func TestLoad_DefaultGatewayUsageRecordConfig(t *testing.T) {
 	resetViperWithJWTSecret(t)
 	cfg, err := Load()

backend/internal/server/api_contract_test.go

@@ -204,18 +204,10 @@ func TestAPIContracts(t *testing.T) {
 						"image_price_1k": null,
 						"image_price_2k": null,
 						"image_price_4k": null,
-							"sora_image_price_360": null,
-							"sora_image_price_540": null,
-							"sora_storage_quota_bytes": 0,
-							"sora_video_price_per_request": null,
-							"sora_video_price_per_request_hd": null,
 							"claude_code_only": false,
-						"allow_messages_dispatch": false,
-						"fallback_group_id": null,
-						"fallback_group_id_on_invalid_request": null,
-						"allow_messages_dispatch": false,
-						"require_oauth_only": false,
-						"require_privacy_set": false,
+							"allow_messages_dispatch": false,
+							"fallback_group_id": null,
+							"fallback_group_id_on_invalid_request": null,
 						"created_at": "2025-01-02T03:04:05Z",
 						"updated_at": "2025-01-02T03:04:05Z"
 					}
@@ -532,7 +524,6 @@ func TestAPIContracts(t *testing.T) {
 						"fallback_model_openai": "gpt-4o",
 						"enable_identity_patch": true,
 						"identity_patch_prompt": "",
-						"sora_client_enabled": false,
 						"invitation_code_enabled": false,
 						"home_content": "",
 					"hide_ccs_import_button": false,
@@ -653,11 +644,11 @@ func newContractDeps(t *testing.T) *contractDeps {
 	settingRepo := newStubSettingRepo()
 	settingService := service.NewSettingService(settingRepo, cfg)
 
-	adminService := service.NewAdminService(userRepo, groupRepo, &accountRepo, nil, proxyRepo, apiKeyRepo, redeemRepo, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
+	adminService := service.NewAdminService(userRepo, groupRepo, &accountRepo, proxyRepo, apiKeyRepo, redeemRepo, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
 	authHandler := handler.NewAuthHandler(cfg, nil, userService, settingService, nil, redeemService, nil)
 	apiKeyHandler := handler.NewAPIKeyHandler(apiKeyService)
 	usageHandler := handler.NewUsageHandler(usageService, apiKeyService)
-	adminSettingHandler := adminhandler.NewSettingHandler(settingService, nil, nil, nil, nil)
+	adminSettingHandler := adminhandler.NewSettingHandler(settingService, nil, nil, nil)
 	adminAccountHandler := adminhandler.NewAccountHandler(adminService, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
 
 	jwtAuth := func(c *gin.Context) {

backend/internal/service/account_test_helpers_test.go

+package service
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+
+	"github.com/Wei-Shaw/sub2api/internal/pkg/tlsfingerprint"
+)
+
+// queuedHTTPUpstream is a test helper that serves pre-loaded responses in order.
+type queuedHTTPUpstream struct {
+	responses []*http.Response
+	requests  []*http.Request
+	tlsFlags  []bool
+}
+
+func (u *queuedHTTPUpstream) Do(_ *http.Request, _ string, _ int64, _ int) (*http.Response, error) {
+	return nil, fmt.Errorf("unexpected Do call")
+}
+
+func (u *queuedHTTPUpstream) DoWithTLS(req *http.Request, _ string, _ int64, _ int, profile *tlsfingerprint.Profile) (*http.Response, error) {
+	u.requests = append(u.requests, req)
+	u.tlsFlags = append(u.tlsFlags, profile != nil)
+	if len(u.responses) == 0 {
+		return nil, fmt.Errorf("no mocked response")
+	}
+	resp := u.responses[0]
+	u.responses = u.responses[1:]
+	return resp, nil
+}
+
+// newJSONResponse creates a simple HTTP response for testing.
+func newJSONResponse(status int, body string) *http.Response {
+	return &http.Response{
+		StatusCode: status,
+		Header:     make(http.Header),
+		Body:       io.NopCloser(strings.NewReader(body)),
+	}
+}
+
+// newJSONResponseWithHeader creates a JSON response with a custom header.
+func newJSONResponseWithHeader(status int, body, key, value string) *http.Response {
+	resp := newJSONResponse(status, body)
+	resp.Header.Set(key, value)
+	return resp
+}

backend/internal/service/antigravity_smart_retry_test.go

@@ -5,13 +5,12 @@ package service
 import (
 	"bytes"
 	"context"
+	"github.com/Wei-Shaw/sub2api/internal/pkg/tlsfingerprint"
+	"github.com/stretchr/testify/require"
 	"io"
 	"net/http"
 	"strings"
 	"testing"
-
-	"github.com/Wei-Shaw/sub2api/internal/pkg/tlsfingerprint"
-	"github.com/stretchr/testify/require"
 )
 
 // stubSmartRetryCache 用于 handleSmartRetry 测试的 GatewayCache mock
@@ -81,17 +80,12 @@ func (m *mockSmartRetryUpstream) Do(req *http.Request, proxyURL string, accountI
 		m.responseBodies[respIdx] = bodyBytes
 	}
 
-	// 用缓存的 body 字节重建新的 reader
-	var body io.ReadCloser
+	// 用缓存的 body 重建 reader（支持重试场景多次读取）
+	cloned := *resp
 	if m.responseBodies[respIdx] != nil {
-		body = io.NopCloser(bytes.NewReader(m.responseBodies[respIdx]))
+		cloned.Body = io.NopCloser(bytes.NewReader(m.responseBodies[respIdx]))
 	}
-
-	return &http.Response{
-		StatusCode: resp.StatusCode,
-		Header:     resp.Header.Clone(),
-		Body:       body,
-	}, respErr
+	return &cloned, respErr
 }
 
 func (m *mockSmartRetryUpstream) DoWithTLS(req *http.Request, proxyURL string, accountID int64, accountConcurrency int, profile *tlsfingerprint.Profile) (*http.Response, error) {

backend/internal/service/openai_oauth_service.go

@@ -374,20 +374,6 @@ func (s *OpenAIOAuthService) Stop() {
 	s.sessionStore.Stop()
 }
 
-func (s *OpenAIOAuthService) resolveProxyURL(ctx context.Context, proxyID *int64) (string, error) {
-	if proxyID == nil {
-		return "", nil
-	}
-	proxy, err := s.proxyRepo.GetByID(ctx, *proxyID)
-	if err != nil {
-		return "", infraerrors.Newf(http.StatusBadRequest, "OPENAI_OAUTH_PROXY_NOT_FOUND", "proxy not found: %v", err)
-	}
-	if proxy == nil {
-		return "", nil
-	}
-	return proxy.URL(), nil
-}
-
 func normalizeOpenAIOAuthPlatform(platform string) string {
 	return openai.OAuthPlatformOpenAI
 }