From 65e2f09b97a16b757eaf9abaeea19e4600765bdb Mon Sep 17 00:00:00 2001
From: "Logan.Li" <admin@attacker.club>
Date: Wed, 29 Jul 2026 05:57:07 +0800
Subject: [PATCH] =?UTF-8?q?fix:=20=E6=8C=89=E4=B8=9A=E5=8A=A1=E6=97=B6?=
 =?UTF-8?q?=E5=8C=BA=E5=90=8C=E6=AD=A5=E6=98=A8=E6=97=A5=E8=B4=A6=E5=8D=95?=
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- 固定按 Asia/Shanghai 计算账单昨日日期

- 补充 UTC 服务器时区回归测试
---
 backend/pkg/billingsync/sync.go      | 11 ++++++++++-
 backend/pkg/billingsync/sync_test.go | 14 ++++++++++++++
 2 files changed, 24 insertions(+), 1 deletion(-)
 create mode 100644 backend/pkg/billingsync/sync_test.go

diff --git a/backend/pkg/billingsync/sync.go b/backend/pkg/billingsync/sync.go
index 72bc283..12f79bb 100644
--- a/backend/pkg/billingsync/sync.go
+++ b/backend/pkg/billingsync/sync.go
@@ -23,7 +23,16 @@ type Result struct {
 
 // Yesterday 昨日日期 YYYY-MM-DD
 func Yesterday() string {
-	return time.Now().AddDate(0, 0, -1).Format("2006-01-02")
+	return billingYesterdayAt(time.Now())
+}
+
+// billingYesterdayAt 按平台业务时区计算昨日，避免服务器 UTC 时区造成日期偏差。 // Logan.Li
+func billingYesterdayAt(now time.Time) string {
+	location, err := time.LoadLocation("Asia/Shanghai")
+	if err != nil {
+		location = time.FixedZone("CST", 8*60*60)
+	}
+	return now.In(location).AddDate(0, 0, -1).Format("2006-01-02")
 }
 
 // SyncDate 同步指定日期账单（全部或单个活跃云账号）
diff --git a/backend/pkg/billingsync/sync_test.go b/backend/pkg/billingsync/sync_test.go
new file mode 100644
index 0000000..6da20ab
--- /dev/null
+++ b/backend/pkg/billingsync/sync_test.go
@@ -0,0 +1,14 @@
+package billingsync
+
+import (
+	"testing"
+	"time"
+)
+
+// TestBillingYesterdayAt 验证 UTC 服务器按中国业务时区计算昨日。 // Logan.Li
+func TestBillingYesterdayAt(t *testing.T) {
+	now := time.Date(2026, 7, 28, 21, 30, 0, 0, time.UTC)
+	if got := billingYesterdayAt(now); got != "2026-07-28" {
+		t.Fatalf("昨日日期错误: got=%s want=2026-07-28", got)
+	}
+}