fix(redenvelope): reset daily limit at local midnight

internal/apps/redenvelope/routers.go

@@ -150,7 +150,7 @@ func Create(c *gin.Context) {
 
 	// 查询今日已发送的红包数量
 	var todayCount int64
-	today := time.Now().Truncate(24 * time.Hour)
+	today := startOfDay(time.Now())
 	if err := db.DB(c.Request.Context()).Model(&model.RedEnvelope{}).
 		Where("creator_id = ? AND created_at >= ?", currentUser.ID, today).
 		Count(&todayCount).Error; err != nil {

internal/apps/redenvelope/utils.go

@@ -18,10 +18,15 @@ package redenvelope
 
 import (
 	"math/rand"
+	"time"
 
 	"github.com/shopspring/decimal"
 )
 
+func startOfDay(now time.Time) time.Time {
+	return time.Date(now.Year(), now.Month(), now.Day(), 0, 0, 0, 0, now.Location())
+}
+
 // calculateRandomAmount 二倍均值算法计算随机红包金额
 func calculateRandomAmount(remaining decimal.Decimal, count int) decimal.Decimal {
 	// 如果是最后一个红包，返回所有剩余金额（避免舍入误差）

internal/apps/redenvelope/utils_test.go

@@ -0,0 +1,32 @@
+/*
+Copyright 2025 linux.do
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package redenvelope
+
+import (
+	"testing"
+	"time"
+)
+
+func TestStartOfDayUsesLocalMidnight(t *testing.T) {
+	location := time.FixedZone("UTC+8", 8*60*60)
+	now := time.Date(2026, time.September, 4, 1, 30, 0, 0, location)
+	want := time.Date(2026, time.September, 4, 0, 0, 0, 0, location)
+
+	if got := startOfDay(now); !got.Equal(want) {
+		t.Fatalf("startOfDay(%v) = %v, want %v", now, got, want)
+	}
+}