fix(notify): remove percentage threshold from balance notification

Balance low notification only supports fixed USD amount threshold.
Percentage threshold is a quota concept, not applicable to balance.
Reverted threshold_type from admin settings, user profile, and all
backend/frontend layers. DB fields (balance_notify_threshold_type,
total_recharged) retained for potential future quota use.

backend/internal/handler/admin/setting_handler.go

@@ -177,7 +177,6 @@ func (h *SettingHandler) GetSettings(c *gin.Context) {
 		EnableCCHSigning:                     settings.EnableCCHSigning,
 		WebSearchEmulationEnabled:            settings.WebSearchEmulationEnabled,
 		BalanceLowNotifyEnabled:              settings.BalanceLowNotifyEnabled,
-		BalanceLowNotifyThresholdType:        settings.BalanceLowNotifyThresholdType,
 		BalanceLowNotifyThreshold:            settings.BalanceLowNotifyThreshold,
 		AccountQuotaNotifyEmails:             settings.AccountQuotaNotifyEmails,
 		PaymentEnabled:                       paymentCfg.Enabled,
@@ -310,10 +309,9 @@ type UpdateSettingsRequest struct {
 	EnableCCHSigning             *bool `json:"enable_cch_signing"`
 
 	// Balance low notification
-	BalanceLowNotifyEnabled       *bool     `json:"balance_low_notify_enabled"`
-	BalanceLowNotifyThresholdType *string   `json:"balance_low_notify_threshold_type"`
-	BalanceLowNotifyThreshold     *float64  `json:"balance_low_notify_threshold"`
-	AccountQuotaNotifyEmails      *[]string `json:"account_quota_notify_emails"`
+	BalanceLowNotifyEnabled   *bool     `json:"balance_low_notify_enabled"`
+	BalanceLowNotifyThreshold *float64  `json:"balance_low_notify_threshold"`
+	AccountQuotaNotifyEmails  *[]string `json:"account_quota_notify_emails"`
 
 	// Payment configuration (integrated into settings, full replace)
 	PaymentEnabled           *bool    `json:"payment_enabled"`
@@ -898,12 +896,6 @@ func (h *SettingHandler) UpdateSettings(c *gin.Context) {
 			}
 			return previousSettings.BalanceLowNotifyEnabled
 		}(),
-		BalanceLowNotifyThresholdType: func() string {
-			if req.BalanceLowNotifyThresholdType != nil {
-				return *req.BalanceLowNotifyThresholdType
-			}
-			return previousSettings.BalanceLowNotifyThresholdType
-		}(),
 		BalanceLowNotifyThreshold: func() float64 {
 			if req.BalanceLowNotifyThreshold != nil {
 				return *req.BalanceLowNotifyThreshold
@@ -1063,7 +1055,6 @@ func (h *SettingHandler) UpdateSettings(c *gin.Context) {
 		EnableMetadataPassthrough:            updatedSettings.EnableMetadataPassthrough,
 		EnableCCHSigning:                     updatedSettings.EnableCCHSigning,
 		BalanceLowNotifyEnabled:              updatedSettings.BalanceLowNotifyEnabled,
-		BalanceLowNotifyThresholdType:        updatedSettings.BalanceLowNotifyThresholdType,
 		BalanceLowNotifyThreshold:            updatedSettings.BalanceLowNotifyThreshold,
 		AccountQuotaNotifyEmails:             updatedSettings.AccountQuotaNotifyEmails,
 		PaymentEnabled:                       updatedPaymentCfg.Enabled,

backend/internal/handler/dto/settings.go

@@ -150,10 +150,9 @@ type SystemSettings struct {
 	PaymentCancelRateLimitMode    string `json:"payment_cancel_rate_limit_window_mode"`
 
 	// Balance low notification
-	BalanceLowNotifyEnabled       bool     `json:"balance_low_notify_enabled"`
-	BalanceLowNotifyThresholdType string   `json:"balance_low_notify_threshold_type"`
-	BalanceLowNotifyThreshold     float64  `json:"balance_low_notify_threshold"`
-	AccountQuotaNotifyEmails      []string `json:"account_quota_notify_emails"`
+	BalanceLowNotifyEnabled   bool     `json:"balance_low_notify_enabled"`
+	BalanceLowNotifyThreshold float64  `json:"balance_low_notify_threshold"`
+	AccountQuotaNotifyEmails  []string `json:"account_quota_notify_emails"`
 }
 
 type DefaultSubscriptionSetting struct {

backend/internal/handler/user_handler.go

@@ -33,10 +33,9 @@ type ChangePasswordRequest struct {
 
 // UpdateProfileRequest represents the update profile request payload
 type UpdateProfileRequest struct {
-	Username                   *string  `json:"username"`
-	BalanceNotifyEnabled       *bool    `json:"balance_notify_enabled"`
-	BalanceNotifyThresholdType *string  `json:"balance_notify_threshold_type"`
-	BalanceNotifyThreshold     *float64 `json:"balance_notify_threshold"`
+	Username               *string  `json:"username"`
+	BalanceNotifyEnabled   *bool    `json:"balance_notify_enabled"`
+	BalanceNotifyThreshold *float64 `json:"balance_notify_threshold"`
 }
 
 // GetProfile handles getting user profile
@@ -101,10 +100,9 @@ func (h *UserHandler) UpdateProfile(c *gin.Context) {
 	}
 
 	svcReq := service.UpdateProfileRequest{
-		Username:                   req.Username,
-		BalanceNotifyEnabled:       req.BalanceNotifyEnabled,
-		BalanceNotifyThresholdType: req.BalanceNotifyThresholdType,
-		BalanceNotifyThreshold:     req.BalanceNotifyThreshold,
+		Username:               req.Username,
+		BalanceNotifyEnabled:   req.BalanceNotifyEnabled,
+		BalanceNotifyThreshold: req.BalanceNotifyThreshold,
 	}
 	updatedUser, err := h.userService.UpdateProfile(c.Request.Context(), subject.UserID, svcReq)
 	if err != nil {

backend/internal/service/balance_notify_service.go

@@ -51,12 +51,16 @@ func (s *BalanceNotifyService) CheckBalanceAfterDeduction(ctx context.Context, u
 		return
 	}
 
-	globalEnabled, globalThresholdType, globalThresholdValue := s.getBalanceNotifyConfig(ctx)
+	globalEnabled, globalThreshold := s.getBalanceNotifyConfig(ctx)
 	if !globalEnabled {
 		return
 	}
 
-	threshold := s.resolveEffectiveThreshold(user, globalThresholdType, globalThresholdValue)
+	// User custom threshold overrides system default
+	threshold := globalThreshold
+	if user.BalanceNotifyThreshold != nil {
+		threshold = *user.BalanceNotifyThreshold
+	}
 	if threshold <= 0 {
 		return
 	}
@@ -76,30 +80,6 @@ func (s *BalanceNotifyService) CheckBalanceAfterDeduction(ctx context.Context, u
 	}
 }
 
-// resolveEffectiveThreshold computes the actual USD threshold based on type and user settings.
-// When user sets a custom threshold, their type is used independently (defaults to "fixed" if unset).
-func (s *BalanceNotifyService) resolveEffectiveThreshold(user *User, globalType string, globalValue float64) float64 {
-	if user.BalanceNotifyThreshold != nil {
-		thresholdType := user.BalanceNotifyThresholdType
-		if thresholdType == "" {
-			thresholdType = ThresholdTypeFixed // user custom value defaults to fixed, not inherited
-		}
-		return computeThreshold(thresholdType, *user.BalanceNotifyThreshold, user.TotalRecharged)
-	}
-	return computeThreshold(globalType, globalValue, user.TotalRecharged)
-}
-
-// computeThreshold converts a threshold value to USD based on type.
-func computeThreshold(thresholdType string, value, totalRecharged float64) float64 {
-	if thresholdType == ThresholdTypePercentage {
-		if totalRecharged <= 0 {
-			return 0 // no recharge history → skip percentage check
-		}
-		return totalRecharged * value / 100
-	}
-	return value // fixed USD amount
-}
-
 // quotaDim describes one quota dimension for notification checking.
 type quotaDim struct {
 	name      string
@@ -154,21 +134,13 @@ func (s *BalanceNotifyService) asyncSendQuotaAlert(adminEmails []string, account
 }
 
 // getBalanceNotifyConfig reads global balance notification settings.
-func (s *BalanceNotifyService) getBalanceNotifyConfig(ctx context.Context) (enabled bool, thresholdType string, threshold float64) {
-	keys := []string{
-		SettingKeyBalanceLowNotifyEnabled,
-		SettingKeyBalanceLowNotifyThresholdType,
-		SettingKeyBalanceLowNotifyThreshold,
-	}
+func (s *BalanceNotifyService) getBalanceNotifyConfig(ctx context.Context) (enabled bool, threshold float64) {
+	keys := []string{SettingKeyBalanceLowNotifyEnabled, SettingKeyBalanceLowNotifyThreshold}
 	settings, err := s.settingRepo.GetMultiple(ctx, keys)
 	if err != nil {
-		return false, ThresholdTypeFixed, 0
+		return false, 0
 	}
 	enabled = settings[SettingKeyBalanceLowNotifyEnabled] == "true"
-	thresholdType = settings[SettingKeyBalanceLowNotifyThresholdType]
-	if thresholdType == "" {
-		thresholdType = ThresholdTypeFixed
-	}
 	if v := settings[SettingKeyBalanceLowNotifyThreshold]; v != "" {
 		if f, err := strconv.ParseFloat(v, 64); err == nil {
 			threshold = f

backend/internal/service/domain_constants.go

@@ -251,13 +251,8 @@ const (
 	SettingKeyEnableCCHSigning = "enable_cch_signing"
 
 	// Balance Low Notification
-	SettingKeyBalanceLowNotifyEnabled       = "balance_low_notify_enabled"        // 全局开关
-	SettingKeyBalanceLowNotifyThresholdType = "balance_low_notify_threshold_type" // "fixed" | "percentage"
-	SettingKeyBalanceLowNotifyThreshold     = "balance_low_notify_threshold"      // 默认阈值（USD 或百分比）
-
-	// Threshold type constants
-	ThresholdTypeFixed      = "fixed"
-	ThresholdTypePercentage = "percentage"
+	SettingKeyBalanceLowNotifyEnabled   = "balance_low_notify_enabled"   // 全局开关
+	SettingKeyBalanceLowNotifyThreshold = "balance_low_notify_threshold" // 默认阈值（USD）
 
 	// Account Quota Notification
 	SettingKeyAccountQuotaNotifyEmails = "account_quota_notify_emails" // 管理员通知邮箱列表（JSON 数组）

backend/internal/service/setting_service.go

@@ -608,11 +608,6 @@ func (s *SettingService) UpdateSettings(ctx context.Context, settings *SystemSet
 
 	// Balance low notification
 	updates[SettingKeyBalanceLowNotifyEnabled] = strconv.FormatBool(settings.BalanceLowNotifyEnabled)
-	thresholdType := settings.BalanceLowNotifyThresholdType
-	if thresholdType != ThresholdTypeFixed && thresholdType != ThresholdTypePercentage {
-		thresholdType = ThresholdTypeFixed
-	}
-	updates[SettingKeyBalanceLowNotifyThresholdType] = thresholdType
 	updates[SettingKeyBalanceLowNotifyThreshold] = strconv.FormatFloat(settings.BalanceLowNotifyThreshold, 'f', 8, 64)
 	accountQuotaNotifyEmailsJSON, err := json.Marshal(settings.AccountQuotaNotifyEmails)
 	if err != nil {
@@ -1252,10 +1247,6 @@ func (s *SettingService) parseSettings(settings map[string]string) *SystemSettin
 
 	// Balance low notification
 	result.BalanceLowNotifyEnabled = settings[SettingKeyBalanceLowNotifyEnabled] == "true"
-	result.BalanceLowNotifyThresholdType = settings[SettingKeyBalanceLowNotifyThresholdType]
-	if result.BalanceLowNotifyThresholdType == "" {
-		result.BalanceLowNotifyThresholdType = ThresholdTypeFixed
-	}
 	if v, err := strconv.ParseFloat(settings[SettingKeyBalanceLowNotifyThreshold], 64); err == nil && v >= 0 {
 		result.BalanceLowNotifyThreshold = v
 	}

backend/internal/service/settings_view.go

@@ -108,9 +108,8 @@ type SystemSettings struct {
 	EnableCCHSigning             bool // 是否对 billing header cch 进行签名（默认 false）
 
 	// Balance low notification
-	BalanceLowNotifyEnabled       bool
-	BalanceLowNotifyThresholdType string // "fixed" (default) | "percentage"
-	BalanceLowNotifyThreshold     float64
+	BalanceLowNotifyEnabled   bool
+	BalanceLowNotifyThreshold float64
 
 	// Account quota notification
 	AccountQuotaNotifyEmails []string

backend/internal/service/user_service.go

@@ -62,12 +62,11 @@ type UserRepository interface {
 
 // UpdateProfileRequest 更新用户资料请求
 type UpdateProfileRequest struct {
-	Email                      *string  `json:"email"`
-	Username                   *string  `json:"username"`
-	Concurrency                *int     `json:"concurrency"`
-	BalanceNotifyEnabled       *bool    `json:"balance_notify_enabled"`
-	BalanceNotifyThresholdType *string  `json:"balance_notify_threshold_type"`
-	BalanceNotifyThreshold     *float64 `json:"balance_notify_threshold"`
+	Email                  *string  `json:"email"`
+	Username               *string  `json:"username"`
+	Concurrency            *int     `json:"concurrency"`
+	BalanceNotifyEnabled   *bool    `json:"balance_notify_enabled"`
+	BalanceNotifyThreshold *float64 `json:"balance_notify_threshold"`
 }
 
 // ChangePasswordRequest 修改密码请求
@@ -144,11 +143,6 @@ func (s *UserService) UpdateProfile(ctx context.Context, userID int64, req Updat
 	if req.BalanceNotifyEnabled != nil {
 		user.BalanceNotifyEnabled = *req.BalanceNotifyEnabled
 	}
-	if req.BalanceNotifyThresholdType != nil {
-		if *req.BalanceNotifyThresholdType == ThresholdTypeFixed || *req.BalanceNotifyThresholdType == ThresholdTypePercentage {
-			user.BalanceNotifyThresholdType = *req.BalanceNotifyThresholdType
-		}
-	}
 	if req.BalanceNotifyThreshold != nil {
 		if *req.BalanceNotifyThreshold <= 0 {
 			user.BalanceNotifyThreshold = nil // clear to system default

frontend/src/api/admin/settings.ts

@@ -137,7 +137,6 @@ export interface SystemSettings {
 
   // Balance & quota notification
   balance_low_notify_enabled: boolean
-  balance_low_notify_threshold_type: 'fixed' | 'percentage'
   balance_low_notify_threshold: number
   account_quota_notify_emails: string[]
 }
@@ -241,7 +240,6 @@ export interface UpdateSettingsRequest {
   payment_cancel_rate_limit_window_mode?: string
   // Balance & quota notification
   balance_low_notify_enabled?: boolean
-  balance_low_notify_threshold_type?: 'fixed' | 'percentage'
   balance_low_notify_threshold?: number
   account_quota_notify_emails?: string[]
 }

frontend/src/i18n/locales/en.ts

@@ -4633,12 +4633,8 @@ export default {
         title: 'Balance Low Notification',
         description: 'Send email notification when user balance falls below threshold',
         enabled: 'Enable Balance Low Notification',
-        thresholdType: 'Threshold Type',
-        typeFixed: 'Fixed Amount',
-        typePercentage: 'Percentage of Recharged',
         threshold: 'Default Threshold',
         thresholdHint: 'Used when user has not set a custom value',
-        percentageHint: 'Notify when balance falls below this percentage of total recharged amount',
         thresholdPlaceholder: 'Enter amount',
       },
       quotaNotify: {

frontend/src/i18n/locales/zh.ts

@@ -4797,12 +4797,8 @@ export default {
         title: '余额不足提醒',
         description: '当用户余额低于阈值时发送邮件提醒',
         enabled: '启用余额不足提醒',
-        thresholdType: '阈值类型',
-        typeFixed: '固定金额',
-        typePercentage: '充值百分比',
-        threshold: '提醒阈值',
+        threshold: '默认提醒阈值',
         thresholdHint: '用户未自定义时使用此值',
-        percentageHint: '当余额低于累计充值额的此百分比时提醒',
         thresholdPlaceholder: '输入金额',
       },
       quotaNotify: {

frontend/src/views/admin/SettingsView.vue

@@ -2675,43 +2675,13 @@
               <label class="mb-0 block text-sm font-medium text-gray-700 dark:text-gray-300">{{ t('admin.settings.balanceNotify.enabled') }}</label>
               <Toggle v-model="form.balance_low_notify_enabled" />
             </div>
-            <div v-if="form.balance_low_notify_enabled" class="space-y-3">
-              <!-- Threshold type selector -->
-              <div>
-                <label class="mb-2 block text-sm font-medium text-gray-700 dark:text-gray-300">{{ t('admin.settings.balanceNotify.thresholdType') }}</label>
-                <div class="flex gap-4">
-                  <label class="flex items-center gap-1.5 text-sm cursor-pointer">
-                    <input type="radio" v-model="form.balance_low_notify_threshold_type" value="fixed" class="accent-primary-500" />
-                    {{ t('admin.settings.balanceNotify.typeFixed') }}
-                  </label>
-                  <label class="flex items-center gap-1.5 text-sm cursor-pointer">
-                    <input type="radio" v-model="form.balance_low_notify_threshold_type" value="percentage" class="accent-primary-500" />
-                    {{ t('admin.settings.balanceNotify.typePercentage') }}
-                  </label>
-                </div>
-              </div>
-              <!-- Threshold value -->
-              <div>
-                <label class="mb-2 block text-sm font-medium text-gray-700 dark:text-gray-300">{{ t('admin.settings.balanceNotify.threshold') }}</label>
-                <div class="relative">
-                  <span class="absolute left-3 top-1/2 -translate-y-1/2 text-gray-400">
-                    {{ form.balance_low_notify_threshold_type === 'percentage' ? '%' : '$' }}
-                  </span>
-                  <input
-                    v-model.number="form.balance_low_notify_threshold"
-                    type="number"
-                    :min="0"
-                    :max="form.balance_low_notify_threshold_type === 'percentage' ? 100 : undefined"
-                    :step="form.balance_low_notify_threshold_type === 'percentage' ? 1 : 0.01"
-                    class="input pl-7"
-                  />
-                </div>
-                <p class="mt-1 text-xs text-gray-500 dark:text-gray-400">
-                  {{ form.balance_low_notify_threshold_type === 'percentage'
-                    ? t('admin.settings.balanceNotify.percentageHint')
-                    : t('admin.settings.balanceNotify.thresholdHint') }}
-                </p>
+            <div v-if="form.balance_low_notify_enabled">
+              <label class="mb-2 block text-sm font-medium text-gray-700 dark:text-gray-300">{{ t('admin.settings.balanceNotify.threshold') }}</label>
+              <div class="relative">
+                <span class="absolute left-3 top-1/2 -translate-y-1/2 text-gray-400">$</span>
+                <input v-model.number="form.balance_low_notify_threshold" type="number" min="0" step="0.01" class="input pl-7" />
               </div>
+              <p class="mt-1 text-xs text-gray-500 dark:text-gray-400">{{ t('admin.settings.balanceNotify.thresholdHint') }}</p>
             </div>
           </div>
         </div>
@@ -3026,7 +2996,6 @@ const form = reactive<SettingsForm>({
   enable_cch_signing: false,
   // Balance & quota notification
   balance_low_notify_enabled: false,
-  balance_low_notify_threshold_type: 'fixed' as 'fixed' | 'percentage',
   balance_low_notify_threshold: 0,
   account_quota_notify_emails: [] as string[]
 })
@@ -3591,7 +3560,6 @@ async function saveSettings() {
       payment_cancel_rate_limit_window_mode: form.payment_cancel_rate_limit_window_mode,
       // Balance & quota notification
       balance_low_notify_enabled: form.balance_low_notify_enabled,
-      balance_low_notify_threshold_type: form.balance_low_notify_threshold_type,
       balance_low_notify_threshold: Number(form.balance_low_notify_threshold) || 0,
       account_quota_notify_emails: (form.account_quota_notify_emails || []).filter((e: string) => e.trim() !== ''),
     }