feat(subscription): 支持调整订阅时长（延长/缩短）

- 将"延长订阅"功能改为"调整订阅"，支持正数延长、负数缩短
- 后端验证：调整天数范围 -36500 到 36500，缩短后剩余天数必须 > 0
- 前端同步更新界面文案和验证逻辑

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/internal/handler/admin/subscription_handler.go

@@ -53,9 +53,9 @@ type BulkAssignSubscriptionRequest struct {
 	Notes        string  `json:"notes"`
 }
 
-// ExtendSubscriptionRequest represents extend subscription request
-type ExtendSubscriptionRequest struct {
-	Days int `json:"days" binding:"required,min=1,max=36500"` // max 100 years
+// AdjustSubscriptionRequest represents adjust subscription request (extend or shorten)
+type AdjustSubscriptionRequest struct {
+	Days int `json:"days" binding:"required,min=-36500,max=36500"` // negative to shorten, positive to extend
 }
 
 // List handles listing all subscriptions with pagination and filters
@@ -180,7 +180,7 @@ func (h *SubscriptionHandler) BulkAssign(c *gin.Context) {
 	response.Success(c, dto.BulkAssignResultFromService(result))
 }
 
-// Extend handles extending a subscription
+// Extend handles adjusting a subscription (extend or shorten)
 // POST /api/v1/admin/subscriptions/:id/extend
 func (h *SubscriptionHandler) Extend(c *gin.Context) {
 	subscriptionID, err := strconv.ParseInt(c.Param("id"), 10, 64)
@@ -189,7 +189,7 @@ func (h *SubscriptionHandler) Extend(c *gin.Context) {
 		return
 	}
 
-	var req ExtendSubscriptionRequest
+	var req AdjustSubscriptionRequest
 	if err := c.ShouldBindJSON(&req); err != nil {
 		response.BadRequest(c, "Invalid request: "+err.Error())
 		return

backend/internal/service/subscription_service.go

@@ -27,6 +27,7 @@ var (
 	ErrWeeklyLimitExceeded       = infraerrors.TooManyRequests("WEEKLY_LIMIT_EXCEEDED", "weekly usage limit exceeded")
 	ErrMonthlyLimitExceeded      = infraerrors.TooManyRequests("MONTHLY_LIMIT_EXCEEDED", "monthly usage limit exceeded")
 	ErrSubscriptionNilInput      = infraerrors.BadRequest("SUBSCRIPTION_NIL_INPUT", "subscription input cannot be nil")
+	ErrAdjustWouldExpire         = infraerrors.BadRequest("ADJUST_WOULD_EXPIRE", "adjustment would result in expired subscription (remaining days must be > 0)")
 )
 
 // SubscriptionService 订阅服务
@@ -308,17 +309,20 @@ func (s *SubscriptionService) RevokeSubscription(ctx context.Context, subscripti
 	return nil
 }
 
-// ExtendSubscription 延长订阅
+// ExtendSubscription 调整订阅时长（正数延长，负数缩短）
 func (s *SubscriptionService) ExtendSubscription(ctx context.Context, subscriptionID int64, days int) (*UserSubscription, error) {
 	sub, err := s.userSubRepo.GetByID(ctx, subscriptionID)
 	if err != nil {
 		return nil, ErrSubscriptionNotFound
 	}
 
-	// 限制延长天数
+	// 限制调整天数范围
 	if days > MaxValidityDays {
 		days = MaxValidityDays
 	}
+	if days < -MaxValidityDays {
+		days = -MaxValidityDays
+	}
 
 	// 计算新的过期时间
 	newExpiresAt := sub.ExpiresAt.AddDate(0, 0, days)
@@ -326,6 +330,14 @@ func (s *SubscriptionService) ExtendSubscription(ctx context.Context, subscripti
 		newExpiresAt = MaxExpiresAt
 	}
 
+	// 如果是缩短（负数），检查新的过期时间必须大于当前时间
+	if days < 0 {
+		now := time.Now()
+		if !newExpiresAt.After(now) {
+			return nil, ErrAdjustWouldExpire
+		}
+	}
+
 	if err := s.userSubRepo.ExtendExpiry(ctx, subscriptionID, newExpiresAt); err != nil {
 		return nil, err
 	}

frontend/src/i18n/locales/en.ts

@@ -950,7 +950,7 @@ export default {
       title: 'Subscription Management',
       description: 'Manage user subscriptions and quota limits',
       assignSubscription: 'Assign Subscription',
-      extendSubscription: 'Extend Subscription',
+      adjustSubscription: 'Adjust Subscription',
       revokeSubscription: 'Revoke Subscription',
       allStatus: 'All Status',
       allGroups: 'All Groups',
@@ -965,6 +965,7 @@ export default {
       resetInHoursMinutes: 'Resets in {hours}h {minutes}m',
       resetInDaysHours: 'Resets in {days}d {hours}h',
       daysRemaining: 'days remaining',
+      remainingDays: 'Remaining days',
       noExpiration: 'No expiration',
       status: {
         active: 'Active',
@@ -983,28 +984,32 @@ export default {
         user: 'User',
         group: 'Subscription Group',
         validityDays: 'Validity (Days)',
-        extendDays: 'Extend by (Days)'
+        adjustDays: 'Adjust by (Days)'
       },
       selectUser: 'Select a user',
       selectGroup: 'Select a subscription group',
       groupHint: 'Only groups with subscription billing type are shown',
       validityHint: 'Number of days the subscription will be valid',
-      extendingFor: 'Extending subscription for',
+      adjustingFor: 'Adjusting subscription for',
       currentExpiration: 'Current expiration',
+      adjustDaysPlaceholder: 'Positive to extend, negative to shorten',
+      adjustHint: 'Enter positive number to extend, negative to shorten (remaining days must be > 0)',
       assign: 'Assign',
       assigning: 'Assigning...',
-      extend: 'Extend',
-      extending: 'Extending...',
+      adjust: 'Adjust',
+      adjusting: 'Adjusting...',
       revoke: 'Revoke',
       noSubscriptionsYet: 'No subscriptions yet',
       assignFirstSubscription: 'Assign a subscription to get started.',
       subscriptionAssigned: 'Subscription assigned successfully',
-      subscriptionExtended: 'Subscription extended successfully',
+      subscriptionAdjusted: 'Subscription adjusted successfully',
       subscriptionRevoked: 'Subscription revoked successfully',
       failedToLoad: 'Failed to load subscriptions',
       failedToAssign: 'Failed to assign subscription',
-      failedToExtend: 'Failed to extend subscription',
+      failedToAdjust: 'Failed to adjust subscription',
       failedToRevoke: 'Failed to revoke subscription',
+      adjustWouldExpire: 'Remaining days after adjustment must be greater than 0',
+      adjustOutOfRange: 'Adjustment days must be between -36500 and 36500',
       pleaseSelectUser: 'Please select a user',
       pleaseSelectGroup: 'Please select a group',
       validityDaysRequired: 'Please enter a valid number of days (at least 1)',

frontend/src/i18n/locales/zh.ts

@@ -1025,7 +1025,7 @@ export default {
       title: '订阅管理',
       description: '管理用户订阅和配额限制',
       assignSubscription: '分配订阅',
-      extendSubscription: '延长订阅',
+      adjustSubscription: '调整订阅',
       revokeSubscription: '撤销订阅',
       allStatus: '全部状态',
       allGroups: '全部分组',
@@ -1040,6 +1040,7 @@ export default {
       resetInHoursMinutes: '{hours} 小时 {minutes} 分钟后重置',
       resetInDaysHours: '{days} 天 {hours} 小时后重置',
       daysRemaining: '天剩余',
+      remainingDays: '剩余天数',
       noExpiration: '无过期时间',
       status: {
         active: '生效中',
@@ -1058,28 +1059,32 @@ export default {
         user: '用户',
         group: '订阅分组',
         validityDays: '有效期（天）',
-        extendDays: '延长天数'
+        adjustDays: '调整天数'
       },
       selectUser: '选择用户',
       selectGroup: '选择订阅分组',
       groupHint: '仅显示订阅计费类型的分组',
       validityHint: '订阅的有效天数',
-      extendingFor: '为以下用户延长订阅',
+      adjustingFor: '为以下用户调整订阅',
       currentExpiration: '当前到期时间',
+      adjustDaysPlaceholder: '正数延长，负数缩短',
+      adjustHint: '输入正数延长订阅，负数缩短订阅（缩短后剩余天数需大于0）',
       assign: '分配',
       assigning: '分配中...',
-      extend: '延长',
-      extending: '延长中...',
+      adjust: '调整',
+      adjusting: '调整中...',
       revoke: '撤销',
       noSubscriptionsYet: '暂无订阅',
       assignFirstSubscription: '分配一个订阅以开始使用。',
       subscriptionAssigned: '订阅分配成功',
-      subscriptionExtended: '订阅延长成功',
+      subscriptionAdjusted: '订阅调整成功',
       subscriptionRevoked: '订阅撤销成功',
       failedToLoad: '加载订阅列表失败',
       failedToAssign: '分配订阅失败',
-      failedToExtend: '延长订阅失败',
+      failedToAdjust: '调整订阅失败',
       failedToRevoke: '撤销订阅失败',
+      adjustWouldExpire: '调整后剩余天数必须大于0',
+      adjustOutOfRange: '调整天数必须在 -36500 到 36500 之间',
       pleaseSelectUser: '请选择用户',
       pleaseSelectGroup: '请选择分组',
       validityDaysRequired: '请输入有效的天数（至少1天）',

frontend/src/views/admin/SubscriptionsView.vue

@@ -359,10 +359,10 @@
               <button
                 v-if="row.status === 'active'"
                 @click="handleExtend(row)"
-                class="flex flex-col items-center gap-0.5 rounded-lg p-1.5 text-gray-500 transition-colors hover:bg-green-50 hover:text-green-600 dark:hover:bg-green-900/20 dark:hover:text-green-400"
+                class="flex flex-col items-center gap-0.5 rounded-lg p-1.5 text-gray-500 transition-colors hover:bg-blue-50 hover:text-blue-600 dark:hover:bg-blue-900/20 dark:hover:text-blue-400"
               >
-                <Icon name="clock" size="sm" />
-                <span class="text-xs">{{ t('admin.subscriptions.extend') }}</span>
+                <Icon name="calendar" size="sm" />
+                <span class="text-xs">{{ t('admin.subscriptions.adjust') }}</span>
               </button>
               <button
                 v-if="row.status === 'active'"
@@ -512,10 +512,10 @@
       </template>
     </BaseDialog>
 
-    <!-- Extend Subscription Modal -->
+    <!-- Adjust Subscription Modal -->
     <BaseDialog
       :show="showExtendModal"
-      :title="t('admin.subscriptions.extendSubscription')"
+      :title="t('admin.subscriptions.adjustSubscription')"
       width="narrow"
       @close="closeExtendModal"
     >
@@ -527,7 +527,7 @@
       >
         <div class="rounded-lg bg-gray-50 p-4 dark:bg-dark-700">
           <p class="text-sm text-gray-600 dark:text-gray-400">
-            {{ t('admin.subscriptions.extendingFor') }}
+            {{ t('admin.subscriptions.adjustingFor') }}
             <span class="font-medium text-gray-900 dark:text-white">{{
               extendingSubscription.user?.email
             }}</span>
@@ -542,10 +542,25 @@
               }}
             </span>
           </p>
+          <p v-if="extendingSubscription.expires_at" class="mt-1 text-sm text-gray-600 dark:text-gray-400">
+            {{ t('admin.subscriptions.remainingDays') }}:
+            <span class="font-medium text-gray-900 dark:text-white">
+              {{ getDaysRemaining(extendingSubscription.expires_at) ?? 0 }}
+            </span>
+          </p>
         </div>
         <div>
-          <label class="input-label">{{ t('admin.subscriptions.form.extendDays') }}</label>
-          <input v-model.number="extendForm.days" type="number" min="1" required class="input" />
+          <label class="input-label">{{ t('admin.subscriptions.form.adjustDays') }}</label>
+          <div class="flex items-center gap-2">
+            <input
+              v-model.number="extendForm.days"
+              type="number"
+              required
+              class="input text-center"
+              :placeholder="t('admin.subscriptions.adjustDaysPlaceholder')"
+            />
+          </div>
+          <p class="input-hint">{{ t('admin.subscriptions.adjustHint') }}</p>
         </div>
       </form>
       <template #footer>
@@ -559,7 +574,7 @@
             :disabled="submitting"
             class="btn btn-primary"
           >
-            {{ submitting ? t('admin.subscriptions.extending') : t('admin.subscriptions.extend') }}
+            {{ submitting ? t('admin.subscriptions.adjusting') : t('admin.subscriptions.adjust') }}
           </button>
         </div>
       </template>
@@ -1000,17 +1015,27 @@ const closeExtendModal = () => {
 const handleExtendSubscription = async () => {
   if (!extendingSubscription.value) return
 
+  // 前端验证：调整后剩余天数必须 > 0
+  if (extendingSubscription.value.expires_at) {
+    const currentDaysRemaining = getDaysRemaining(extendingSubscription.value.expires_at) ?? 0
+    const newDaysRemaining = currentDaysRemaining + extendForm.days
+    if (newDaysRemaining <= 0) {
+      appStore.showError(t('admin.subscriptions.adjustWouldExpire'))
+      return
+    }
+  }
+
   submitting.value = true
   try {
     await adminAPI.subscriptions.extend(extendingSubscription.value.id, {
       days: extendForm.days
     })
-    appStore.showSuccess(t('admin.subscriptions.subscriptionExtended'))
+    appStore.showSuccess(t('admin.subscriptions.subscriptionAdjusted'))
     closeExtendModal()
     loadSubscriptions()
   } catch (error: any) {
-    appStore.showError(error.response?.data?.detail || t('admin.subscriptions.failedToExtend'))
-    console.error('Error extending subscription:', error)
+    appStore.showError(error.response?.data?.detail || t('admin.subscriptions.failedToAdjust'))
+    console.error('Error adjusting subscription:', error)
   } finally {
     submitting.value = false
   }