feat(promo-code): complete promo code feature implementation

- Add promo_code_enabled field to SystemSettings and PublicSettings DTOs
- Add promo code validation in registration flow
- Add admin settings UI for promo code configuration
- Add i18n translations for promo code feature

backend/internal/handler/admin/setting_handler.go

@@ -47,6 +47,7 @@ func (h *SettingHandler) GetSettings(c *gin.Context) {
 	response.Success(c, dto.SystemSettings{
 		RegistrationEnabled:                  settings.RegistrationEnabled,
 		EmailVerifyEnabled:                   settings.EmailVerifyEnabled,
+		PromoCodeEnabled:                     settings.PromoCodeEnabled,
 		SMTPHost:                             settings.SMTPHost,
 		SMTPPort:                             settings.SMTPPort,
 		SMTPUsername:                         settings.SMTPUsername,
@@ -90,6 +91,7 @@ type UpdateSettingsRequest struct {
 	// 注册设置
 	RegistrationEnabled bool `json:"registration_enabled"`
 	EmailVerifyEnabled  bool `json:"email_verify_enabled"`
+	PromoCodeEnabled    bool `json:"promo_code_enabled"`
 
 	// 邮件服务设置
 	SMTPHost     string `json:"smtp_host"`
@@ -240,6 +242,7 @@ func (h *SettingHandler) UpdateSettings(c *gin.Context) {
 	settings := &service.SystemSettings{
 		RegistrationEnabled:        req.RegistrationEnabled,
 		EmailVerifyEnabled:         req.EmailVerifyEnabled,
+		PromoCodeEnabled:           req.PromoCodeEnabled,
 		SMTPHost:                   req.SMTPHost,
 		SMTPPort:                   req.SMTPPort,
 		SMTPUsername:               req.SMTPUsername,
@@ -314,6 +317,7 @@ func (h *SettingHandler) UpdateSettings(c *gin.Context) {
 	response.Success(c, dto.SystemSettings{
 		RegistrationEnabled:                  updatedSettings.RegistrationEnabled,
 		EmailVerifyEnabled:                   updatedSettings.EmailVerifyEnabled,
+		PromoCodeEnabled:                     updatedSettings.PromoCodeEnabled,
 		SMTPHost:                             updatedSettings.SMTPHost,
 		SMTPPort:                             updatedSettings.SMTPPort,
 		SMTPUsername:                         updatedSettings.SMTPUsername,

backend/internal/handler/auth_handler.go

@@ -195,6 +195,15 @@ type ValidatePromoCodeResponse struct {
 // ValidatePromoCode 验证优惠码（公开接口，注册前调用）
 // POST /api/v1/auth/validate-promo-code
 func (h *AuthHandler) ValidatePromoCode(c *gin.Context) {
+	// 检查优惠码功能是否启用
+	if h.settingSvc != nil && !h.settingSvc.IsPromoCodeEnabled(c.Request.Context()) {
+		response.Success(c, ValidatePromoCodeResponse{
+			Valid:     false,
+			ErrorCode: "PROMO_CODE_DISABLED",
+		})
+		return
+	}
+
 	var req ValidatePromoCodeRequest
 	if err := c.ShouldBindJSON(&req); err != nil {
 		response.BadRequest(c, "Invalid request: "+err.Error())

backend/internal/handler/dto/settings.go

@@ -4,6 +4,7 @@ package dto
 type SystemSettings struct {
 	RegistrationEnabled bool `json:"registration_enabled"`
 	EmailVerifyEnabled  bool `json:"email_verify_enabled"`
+	PromoCodeEnabled    bool `json:"promo_code_enabled"`
 
 	SMTPHost               string `json:"smtp_host"`
 	SMTPPort               int    `json:"smtp_port"`
@@ -55,6 +56,7 @@ type SystemSettings struct {
 type PublicSettings struct {
 	RegistrationEnabled bool   `json:"registration_enabled"`
 	EmailVerifyEnabled  bool   `json:"email_verify_enabled"`
+	PromoCodeEnabled    bool   `json:"promo_code_enabled"`
 	TurnstileEnabled    bool   `json:"turnstile_enabled"`
 	TurnstileSiteKey    string `json:"turnstile_site_key"`
 	SiteName            string `json:"site_name"`

backend/internal/service/auth_service.go

@@ -153,8 +153,8 @@ func (s *AuthService) RegisterWithVerification(ctx context.Context, email, passw
 		return "", nil, ErrServiceUnavailable
 	}
 
-	// 应用优惠码（如果提供）
-	if promoCode != "" && s.promoService != nil {
+	// 应用优惠码（如果提供且功能已启用）
+	if promoCode != "" && s.promoService != nil && s.settingService != nil && s.settingService.IsPromoCodeEnabled(ctx) {
 		if err := s.promoService.ApplyPromoCode(ctx, user.ID, promoCode); err != nil {
 			// 优惠码应用失败不影响注册，只记录日志
 			log.Printf("[Auth] Failed to apply promo code for user %d: %v", user.ID, err)

backend/internal/service/domain_constants.go

@@ -71,6 +71,7 @@ const (
 	// 注册设置
 	SettingKeyRegistrationEnabled = "registration_enabled" // 是否开放注册
 	SettingKeyEmailVerifyEnabled  = "email_verify_enabled" // 是否开启邮件验证
+	SettingKeyPromoCodeEnabled    = "promo_code_enabled"   // 是否启用优惠码功能
 
 	// 邮件服务设置
 	SettingKeySMTPHost     = "smtp_host"      // SMTP服务器地址

backend/internal/service/setting_service.go

@@ -60,6 +60,7 @@ func (s *SettingService) GetPublicSettings(ctx context.Context) (*PublicSettings
 	keys := []string{
 		SettingKeyRegistrationEnabled,
 		SettingKeyEmailVerifyEnabled,
+		SettingKeyPromoCodeEnabled,
 		SettingKeyTurnstileEnabled,
 		SettingKeyTurnstileSiteKey,
 		SettingKeySiteName,
@@ -88,6 +89,7 @@ func (s *SettingService) GetPublicSettings(ctx context.Context) (*PublicSettings
 	return &PublicSettings{
 		RegistrationEnabled: settings[SettingKeyRegistrationEnabled] == "true",
 		EmailVerifyEnabled:  settings[SettingKeyEmailVerifyEnabled] == "true",
+		PromoCodeEnabled:    settings[SettingKeyPromoCodeEnabled] != "false", // 默认启用
 		TurnstileEnabled:    settings[SettingKeyTurnstileEnabled] == "true",
 		TurnstileSiteKey:    settings[SettingKeyTurnstileSiteKey],
 		SiteName:            s.getStringOrDefault(settings, SettingKeySiteName, "Sub2API"),
@@ -125,6 +127,7 @@ func (s *SettingService) GetPublicSettingsForInjection(ctx context.Context) (any
 	return &struct {
 		RegistrationEnabled bool   `json:"registration_enabled"`
 		EmailVerifyEnabled  bool   `json:"email_verify_enabled"`
+		PromoCodeEnabled    bool   `json:"promo_code_enabled"`
 		TurnstileEnabled    bool   `json:"turnstile_enabled"`
 		TurnstileSiteKey    string `json:"turnstile_site_key,omitempty"`
 		SiteName            string `json:"site_name"`
@@ -140,6 +143,7 @@ func (s *SettingService) GetPublicSettingsForInjection(ctx context.Context) (any
 	}{
 		RegistrationEnabled: settings.RegistrationEnabled,
 		EmailVerifyEnabled:  settings.EmailVerifyEnabled,
+		PromoCodeEnabled:    settings.PromoCodeEnabled,
 		TurnstileEnabled:    settings.TurnstileEnabled,
 		TurnstileSiteKey:    settings.TurnstileSiteKey,
 		SiteName:            settings.SiteName,
@@ -162,6 +166,7 @@ func (s *SettingService) UpdateSettings(ctx context.Context, settings *SystemSet
 	// 注册设置
 	updates[SettingKeyRegistrationEnabled] = strconv.FormatBool(settings.RegistrationEnabled)
 	updates[SettingKeyEmailVerifyEnabled] = strconv.FormatBool(settings.EmailVerifyEnabled)
+	updates[SettingKeyPromoCodeEnabled] = strconv.FormatBool(settings.PromoCodeEnabled)
 
 	// 邮件服务设置（只有非空才更新密码）
 	updates[SettingKeySMTPHost] = settings.SMTPHost
@@ -248,6 +253,15 @@ func (s *SettingService) IsEmailVerifyEnabled(ctx context.Context) bool {
 	return value == "true"
 }
 
+// IsPromoCodeEnabled 检查是否启用优惠码功能
+func (s *SettingService) IsPromoCodeEnabled(ctx context.Context) bool {
+	value, err := s.settingRepo.GetValue(ctx, SettingKeyPromoCodeEnabled)
+	if err != nil {
+		return true // 默认启用
+	}
+	return value != "false"
+}
+
 // GetSiteName 获取网站名称
 func (s *SettingService) GetSiteName(ctx context.Context) string {
 	value, err := s.settingRepo.GetValue(ctx, SettingKeySiteName)
@@ -297,6 +311,7 @@ func (s *SettingService) InitializeDefaultSettings(ctx context.Context) error {
 	defaults := map[string]string{
 		SettingKeyRegistrationEnabled: "true",
 		SettingKeyEmailVerifyEnabled:  "false",
+		SettingKeyPromoCodeEnabled:    "true", // 默认启用优惠码功能
 		SettingKeySiteName:            "Sub2API",
 		SettingKeySiteLogo:            "",
 		SettingKeyDefaultConcurrency:  strconv.Itoa(s.cfg.Default.UserConcurrency),
@@ -328,6 +343,7 @@ func (s *SettingService) parseSettings(settings map[string]string) *SystemSettin
 	result := &SystemSettings{
 		RegistrationEnabled:          settings[SettingKeyRegistrationEnabled] == "true",
 		EmailVerifyEnabled:           settings[SettingKeyEmailVerifyEnabled] == "true",
+		PromoCodeEnabled:             settings[SettingKeyPromoCodeEnabled] != "false", // 默认启用
 		SMTPHost:                     settings[SettingKeySMTPHost],
 		SMTPUsername:                 settings[SettingKeySMTPUsername],
 		SMTPFrom:                     settings[SettingKeySMTPFrom],

backend/internal/service/settings_view.go

@@ -3,6 +3,7 @@ package service
 type SystemSettings struct {
 	RegistrationEnabled bool
 	EmailVerifyEnabled  bool
+	PromoCodeEnabled    bool
 
 	SMTPHost               string
 	SMTPPort               int
@@ -58,6 +59,7 @@ type SystemSettings struct {
 type PublicSettings struct {
 	RegistrationEnabled bool
 	EmailVerifyEnabled  bool
+	PromoCodeEnabled    bool
 	TurnstileEnabled    bool
 	TurnstileSiteKey    string
 	SiteName            string

frontend/src/api/admin/settings.ts

@@ -12,6 +12,7 @@ export interface SystemSettings {
   // Registration settings
   registration_enabled: boolean
   email_verify_enabled: boolean
+  promo_code_enabled: boolean
   // Default settings
   default_balance: number
   default_concurrency: number
@@ -64,6 +65,7 @@ export interface SystemSettings {
 export interface UpdateSettingsRequest {
   registration_enabled?: boolean
   email_verify_enabled?: boolean
+  promo_code_enabled?: boolean
   default_balance?: number
   default_concurrency?: number
   site_name?: string

frontend/src/i18n/locales/en.ts

@@ -2726,7 +2726,9 @@ export default {
         enableRegistration: 'Enable Registration',
         enableRegistrationHint: 'Allow new users to register',
         emailVerification: 'Email Verification',
-        emailVerificationHint: 'Require email verification for new registrations'
+        emailVerificationHint: 'Require email verification for new registrations',
+        promoCode: 'Promo Code',
+        promoCodeHint: 'Allow users to use promo codes during registration'
       },
       turnstile: {
         title: 'Cloudflare Turnstile',

frontend/src/i18n/locales/zh.ts

@@ -2879,7 +2879,9 @@ export default {
         enableRegistration: '开放注册',
         enableRegistrationHint: '允许新用户注册',
         emailVerification: '邮箱验证',
-        emailVerificationHint: '新用户注册时需要验证邮箱'
+        emailVerificationHint: '新用户注册时需要验证邮箱',
+        promoCode: '优惠码',
+        promoCodeHint: '允许用户在注册时使用优惠码'
       },
       turnstile: {
         title: 'Cloudflare Turnstile',

frontend/src/stores/app.ts

@@ -312,6 +312,7 @@ export const useAppStore = defineStore('app', () => {
       return {
         registration_enabled: false,
         email_verify_enabled: false,
+        promo_code_enabled: true,
         turnstile_enabled: false,
         turnstile_site_key: '',
         site_name: siteName.value,

frontend/src/types/index.ts

@@ -70,6 +70,7 @@ export interface SendVerifyCodeResponse {
 export interface PublicSettings {
   registration_enabled: boolean
   email_verify_enabled: boolean
+  promo_code_enabled: boolean
   turnstile_enabled: boolean
   turnstile_site_key: string
   site_name: string

frontend/src/views/admin/SettingsView.vue

@@ -323,6 +323,21 @@
               </div>
               <Toggle v-model="form.email_verify_enabled" />
             </div>
+
+            <!-- Promo Code -->
+            <div
+              class="flex items-center justify-between border-t border-gray-100 pt-4 dark:border-dark-700"
+            >
+              <div>
+                <label class="font-medium text-gray-900 dark:text-white">{{
+                  t('admin.settings.registration.promoCode')
+                }}</label>
+                <p class="text-sm text-gray-500 dark:text-gray-400">
+                  {{ t('admin.settings.registration.promoCodeHint') }}
+                </p>
+              </div>
+              <Toggle v-model="form.promo_code_enabled" />
+            </div>
           </div>
         </div>
 
@@ -1013,6 +1028,7 @@ type SettingsForm = SystemSettings & {
 const form = reactive<SettingsForm>({
   registration_enabled: true,
   email_verify_enabled: false,
+  promo_code_enabled: true,
   default_balance: 0,
   default_concurrency: 1,
   site_name: 'Sub2API',
@@ -1135,6 +1151,7 @@ async function saveSettings() {
     const payload: UpdateSettingsRequest = {
       registration_enabled: form.registration_enabled,
       email_verify_enabled: form.email_verify_enabled,
+      promo_code_enabled: form.promo_code_enabled,
       default_balance: form.default_balance,
       default_concurrency: form.default_concurrency,
       site_name: form.site_name,

frontend/src/views/auth/RegisterView.vue

@@ -96,7 +96,7 @@
         </div>
 
         <!-- Promo Code Input (Optional) -->
-        <div>
+        <div v-if="promoCodeEnabled">
           <label for="promo_code" class="input-label">
             {{ t('auth.promoCodeLabel') }}
             <span class="ml-1 text-xs font-normal text-gray-400 dark:text-dark-500">({{ t('common.optional') }})</span>
@@ -260,6 +260,7 @@ const showPassword = ref<boolean>(false)
 // Public settings
 const registrationEnabled = ref<boolean>(true)
 const emailVerifyEnabled = ref<boolean>(false)
+const promoCodeEnabled = ref<boolean>(true)
 const turnstileEnabled = ref<boolean>(false)
 const turnstileSiteKey = ref<string>('')
 const siteName = ref<string>('Sub2API')
@@ -294,22 +295,25 @@ const errors = reactive({
 // ==================== Lifecycle ====================
 
 onMounted(async () => {
-  // Read promo code from URL parameter
-  const promoParam = route.query.promo as string
-  if (promoParam) {
-    formData.promo_code = promoParam
-    // Validate the promo code from URL
-    await validatePromoCodeDebounced(promoParam)
-  }
-
   try {
     const settings = await getPublicSettings()
     registrationEnabled.value = settings.registration_enabled
     emailVerifyEnabled.value = settings.email_verify_enabled
+    promoCodeEnabled.value = settings.promo_code_enabled
     turnstileEnabled.value = settings.turnstile_enabled
     turnstileSiteKey.value = settings.turnstile_site_key || ''
     siteName.value = settings.site_name || 'Sub2API'
     linuxdoOAuthEnabled.value = settings.linuxdo_oauth_enabled
+
+    // Read promo code from URL parameter only if promo code is enabled
+    if (promoCodeEnabled.value) {
+      const promoParam = route.query.promo as string
+      if (promoParam) {
+        formData.promo_code = promoParam
+        // Validate the promo code from URL
+        await validatePromoCodeDebounced(promoParam)
+      }
+    }
   } catch (error) {
     console.error('Failed to load public settings:', error)
   } finally {