fix: scheduler now refreshes last 3 months billing

Volcengine bill data has 1-2 day delay. Previously the scheduler
only refreshed current month, so when the month rolls over the
previous month's incomplete snapshot was frozen. Now it refreshes
the current month plus 2 prior months.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend/utils/scheduler.py

@@ -19,7 +19,19 @@ def check_spending():
 
     config = GlobalConfig.get_solo()
     webhook = config.feishu_webhook_url
-    bill_period = timezone.now().strftime("%Y-%m")
+
+    # 同时刷新最近 3 个月的账单（火山账单延迟 1-2 天，月初切换时上月账单还在补全）
+    now = timezone.now()
+    bill_periods = []
+    y, m = now.year, now.month
+    for _ in range(3):
+        bill_periods.append(f"{y:04d}-{m:02d}")
+        m -= 1
+        if m == 0:
+            m = 12
+            y -= 1
+    current_period = bill_periods[0]
+    logger.info(f"刷新账单期: {bill_periods}")
 
     for volc_account in VolcAccount.objects.filter(is_active=True):
         ak = decrypt(volc_account.access_key_enc)
@@ -31,12 +43,14 @@ def check_spending():
         billing = BillingService(ak, sk)
         iam_svc = IAMService(ak, sk)
 
-        # 一次性查询所有项目的消费（避免 N+1 API 调用）
-        try:
-            all_project_spending = billing.get_spending_all_projects(bill_period)
-        except Exception as e:
-            logger.error(f"批量查询消费失败: {e}")
-            all_project_spending = {}
+        # 批量查询最近 3 个月每个项目的消费
+        spending_by_period = {}
+        for period in bill_periods:
+            try:
+                spending_by_period[period] = billing.get_spending_all_projects(period)
+            except Exception as e:
+                logger.error(f"批量查询 {period} 消费失败: {e}")
+                spending_by_period[period] = {}
 
         users = IAMUser.objects.filter(
             volc_account=volc_account,
@@ -45,7 +59,7 @@ def check_spending():
 
         for user in users:
             try:
-                # --- 遍历所有开启监测的项目，从批量结果中获取消费 ---
+                # --- 遍历所有开启监测的项目，更新最近 3 个月的快照 ---
                 enabled_projects = IAMUserProject.objects.filter(
                     iam_user=user, monitor_enabled=True
                 )
@@ -54,26 +68,24 @@ def check_spending():
                     logger.info(f"用户 {user.username} 无开启监测的项目，跳过")
                     continue
 
-                total_spending = Decimal('0')
-
                 for project in enabled_projects:
-                    proj_spending = all_project_spending.get(
+                    # 更新当月项目级消费（用于前端显示）
+                    proj_current = spending_by_period.get(current_period, {}).get(
                         project.project_name, project.current_spending
                     )
-
-                    # 更新项目级消费
-                    project.current_spending = proj_spending
+                    project.current_spending = proj_current
                     project.save(update_fields=['current_spending'])
 
-                    # 记录项目级月度快照
-                    SpendingRecord.objects.update_or_create(
-                        iam_user=user,
-                        project_name=project.project_name,
-                        bill_period=bill_period,
-                        defaults={'amount': proj_spending},
-                    )
-
-                    total_spending += proj_spending
+                    # 更新最近 3 个月每个月的快照
+                    for period in bill_periods:
+                        period_data = spending_by_period.get(period, {})
+                        if project.project_name in period_data:
+                            SpendingRecord.objects.update_or_create(
+                                iam_user=user,
+                                project_name=project.project_name,
+                                bill_period=period,
+                                defaults={'amount': period_data[project.project_name]},
+                            )
 
                 # 更新子账号总消费
                 # 累计消费 = 所有月份的所有开启监测项目的消费之和