diff --git a/internal/api/admin/dashboard_admin.go b/internal/api/admin/dashboard_admin.go
index 8c74b3e..db73610 100755
--- a/internal/api/admin/dashboard_admin.go
+++ b/internal/api/admin/dashboard_admin.go
@@ -761,11 +761,11 @@ func parseCustomDateRange(startS, endS string) (time.Time, time.Time, bool) {
 		return time.Time{}, time.Time{}, false
 	}
 
-	st, err := time.Parse("2006-01-02", startS)
+	st, err := time.ParseInLocation("2006-01-02", startS, time.Local)
 	if err != nil {
 		return time.Time{}, time.Time{}, false
 	}
-	et, err := time.Parse("2006-01-02", endS)
+	et, err := time.ParseInLocation("2006-01-02", endS, time.Local)
 	if err != nil {
 		return time.Time{}, time.Time{}, false
 	}
@@ -773,9 +773,9 @@ func parseCustomDateRange(startS, endS string) (time.Time, time.Time, bool) {
 		return time.Time{}, time.Time{}, false
 	}
 
-	et = et.Add(24 * time.Hour).Add(-time.Second)
-	if et.Sub(st) > 365*24*time.Hour {
-		et = st.Add(365 * 24 * time.Hour).Add(-time.Second)
+	et = et.Add(24 * time.Hour)
+	if et.Sub(st) > 366*24*time.Hour {
+		et = st.Add(366 * 24 * time.Hour)
 	}
 	return st, et, true
 }
@@ -907,9 +907,10 @@ func daysBetween(start, end time.Time) []time.Time {
 }
 
 type bucket struct {
-	Label string
-	Start time.Time
-	End   time.Time
+	Label        string
+	Start        time.Time
+	End          time.Time
+	EndExclusive time.Time
 }
 
 func normalizeGranularity(in string) string {
@@ -929,12 +930,17 @@ func normalizeGranularity(in string) string {
 
 func buildBuckets(start, end time.Time, gran string) []bucket {
 	if gran == "day" {
-		days := daysBetween(start, end)
+		days := daysBetween(start, end.Add(-time.Second))
 		out := make([]bucket, 0, len(days))
 		for _, d := range days {
 			ds := time.Date(d.Year(), d.Month(), d.Day(), 0, 0, 0, 0, d.Location())
-			de := ds.Add(24 * time.Hour).Add(-time.Second)
-			out = append(out, bucket{Label: ds.Format("2006-01-02"), Start: ds, End: de})
+			de := ds.Add(24 * time.Hour)
+			out = append(out, bucket{
+				Label:        ds.Format("2006-01-02"),
+				Start:        ds,
+				End:          de.Add(-time.Second),
+				EndExclusive: de,
+			})
 		}
 		return out
 	}
@@ -944,15 +950,22 @@ func buildBuckets(start, end time.Time, gran string) []bucket {
 			s = s.Add(-24 * time.Hour)
 		}
 		out := []bucket{}
-		for cur := s; cur.Before(end) || cur.Equal(end); cur = cur.Add(7 * 24 * time.Hour) {
+		for cur := s; cur.Before(end); cur = cur.Add(7 * 24 * time.Hour) {
 			ds := time.Date(cur.Year(), cur.Month(), cur.Day(), 0, 0, 0, 0, cur.Location())
-			de := ds.Add(7 * 24 * time.Hour).Add(-time.Second)
+			de := ds.Add(7 * 24 * time.Hour)
+			endInclusive := de.Add(-time.Second)
 			label := ds.Format("2006-01-02")
 			if de.After(end) {
 				de = end
+				endInclusive = end
 			}
-			out = append(out, bucket{Label: label, Start: ds, End: de})
-			if de.Equal(end) {
+			out = append(out, bucket{
+				Label:        label,
+				Start:        ds,
+				End:          endInclusive,
+				EndExclusive: de,
+			})
+			if !de.Before(end) {
 				break
 			}
 		}
@@ -960,35 +973,60 @@ func buildBuckets(start, end time.Time, gran string) []bucket {
 	}
 	if gran == "hour" {
 		out := []bucket{}
-		// 步长 1 小时
-		for cur := start; !cur.After(end); cur = cur.Add(time.Hour) {
+		for cur := start; cur.Before(end); cur = cur.Add(time.Hour) {
 			s := time.Date(cur.Year(), cur.Month(), cur.Day(), cur.Hour(), 0, 0, 0, cur.Location())
-			de := s.Add(time.Hour).Add(-time.Second)
-			out = append(out, bucket{Label: s.Format("01-02 15h"), Start: s, End: de})
+			de := s.Add(time.Hour)
+			endInclusive := de.Add(-time.Second)
+			if de.After(end) {
+				de = end
+				endInclusive = end
+			}
+			out = append(out, bucket{
+				Label:        s.Format("01-02 15h"),
+				Start:        s,
+				End:          endInclusive,
+				EndExclusive: de,
+			})
 		}
 		return out
 	}
 	if gran == "minute" {
 		out := []bucket{}
-		// 步长 1 分钟
-		for cur := start; !cur.After(end); cur = cur.Add(time.Minute) {
+		for cur := start; cur.Before(end); cur = cur.Add(time.Minute) {
 			s := time.Date(cur.Year(), cur.Month(), cur.Day(), cur.Hour(), cur.Minute(), 0, 0, cur.Location())
-			de := s.Add(time.Minute).Add(-time.Second)
-			out = append(out, bucket{Label: s.Format("01-02 15:04"), Start: s, End: de})
+			de := s.Add(time.Minute)
+			endInclusive := de.Add(-time.Second)
+			if de.After(end) {
+				de = end
+				endInclusive = end
+			}
+			out = append(out, bucket{
+				Label:        s.Format("01-02 15:04"),
+				Start:        s,
+				End:          endInclusive,
+				EndExclusive: de,
+			})
 		}
 		return out
 	}
 	s := time.Date(start.Year(), start.Month(), 1, 0, 0, 0, 0, start.Location())
 	out := []bucket{}
-	for cur := s; cur.Before(end) || cur.Equal(end); cur = cur.AddDate(0, 1, 0) {
+	for cur := s; cur.Before(end); cur = cur.AddDate(0, 1, 0) {
 		ds := time.Date(cur.Year(), cur.Month(), 1, 0, 0, 0, 0, cur.Location())
-		de := ds.AddDate(0, 1, 0).Add(-time.Second)
+		de := ds.AddDate(0, 1, 0)
+		endInclusive := de.Add(-time.Second)
 		label := ds.Format("2006-01")
 		if de.After(end) {
 			de = end
+			endInclusive = end
 		}
-		out = append(out, bucket{Label: label, Start: ds, End: de})
-		if de.Equal(end) {
+		out = append(out, bucket{
+			Label:        label,
+			Start:        ds,
+			End:          endInclusive,
+			EndExclusive: de,
+		})
+		if !de.Before(end) {
 			break
 		}
 	}
@@ -1771,7 +1809,7 @@ func (h *handler) DashboardSalesDrawTrend() core.HandlerFunc {
 				Where("source_type IN ?", []int32{2, 3, 4}).
 				Where("(ext_order_id = '' OR ext_order_id IS NULL)").
 				Where("paid_at >= ?", b.Start).
-				Where("paid_at <= ?", b.End).
+				Where("paid_at < ?", b.EndExclusive).
 				Select("COUNT(id) as orders, COALESCE(SUM(actual_amount + discount_amount), 0) as gmv, COALESCE(SUM(actual_amount), 0) as paid_amount").
 				Scan(&orderStats)
 
diff --git a/internal/api/admin/dashboard_admin_test.go b/internal/api/admin/dashboard_admin_test.go
index 08a547e..c1e4190 100755
--- a/internal/api/admin/dashboard_admin_test.go
+++ b/internal/api/admin/dashboard_admin_test.go
@@ -7,6 +7,23 @@ import (
 	"time"
 )
 
+func useShanghaiLocal(t *testing.T) *time.Location {
+	t.Helper()
+
+	loc, err := time.LoadLocation("Asia/Shanghai")
+	if err != nil {
+		t.Fatalf("load Asia/Shanghai: %v", err)
+	}
+
+	oldLocal := time.Local
+	time.Local = loc
+	t.Cleanup(func() {
+		time.Local = oldLocal
+	})
+
+	return loc
+}
+
 func TestPercentChange(t *testing.T) {
 	if s := percentChange(0, 10); s != "+0%" {
 		t.Fatalf("prev0")
@@ -38,13 +55,16 @@ func TestDaysBetween(t *testing.T) {
 }
 
 func TestParseSalesTrendRange_PrefersStartEnd(t *testing.T) {
+	loc := useShanghaiLocal(t)
 	now := time.Date(2026, 3, 3, 12, 0, 0, 0, time.UTC)
 	s, e := parseSalesTrendRange("week", "2026-01-01", "2026-01-10", now, nil)
 
-	if !s.Equal(time.Date(2026, 1, 1, 0, 0, 0, 0, time.UTC)) {
+	expectedStart := time.Date(2026, 1, 1, 0, 0, 0, 0, loc)
+	expectedEnd := time.Date(2026, 1, 11, 0, 0, 0, 0, loc)
+	if !s.Equal(expectedStart) {
 		t.Fatalf("unexpected start: %v", s)
 	}
-	if !e.Equal(time.Date(2026, 1, 10, 23, 59, 59, 0, time.UTC)) {
+	if !e.Equal(expectedEnd) {
 		t.Fatalf("unexpected end: %v", e)
 	}
 }
@@ -87,11 +107,12 @@ func TestParseSalesTrendRange_AliasAndAllFallback(t *testing.T) {
 }
 
 func TestParseSalesTrendRange_CustomSpanCap(t *testing.T) {
+	loc := useShanghaiLocal(t)
 	now := time.Date(2026, 3, 3, 12, 0, 0, 0, time.UTC)
 	s, e := parseSalesTrendRange("custom", "2025-01-01", "2026-12-31", now, nil)
 
-	expectedStart := time.Date(2025, 1, 1, 0, 0, 0, 0, time.UTC)
-	expectedEnd := expectedStart.Add(365 * 24 * time.Hour).Add(-time.Second)
+	expectedStart := time.Date(2025, 1, 1, 0, 0, 0, 0, loc)
+	expectedEnd := expectedStart.Add(366 * 24 * time.Hour)
 	if !s.Equal(expectedStart) {
 		t.Fatalf("unexpected custom start: %v", s)
 	}
@@ -100,6 +121,21 @@ func TestParseSalesTrendRange_CustomSpanCap(t *testing.T) {
 	}
 }
 
+func TestParseSalesTrendRange_CustomSingleDayLocal(t *testing.T) {
+	loc := useShanghaiLocal(t)
+	now := time.Date(2026, 3, 3, 12, 0, 0, 0, time.UTC)
+	s, e := parseSalesTrendRange("custom", "2026-03-01", "2026-03-01", now, nil)
+
+	expectedStart := time.Date(2026, 3, 1, 0, 0, 0, 0, loc)
+	expectedEnd := time.Date(2026, 3, 2, 0, 0, 0, 0, loc)
+	if !s.Equal(expectedStart) {
+		t.Fatalf("unexpected custom single-day start: %v", s)
+	}
+	if !e.Equal(expectedEnd) {
+		t.Fatalf("unexpected custom single-day end: %v", e)
+	}
+}
+
 func TestShouldUseMonthlyGranularityForAll(t *testing.T) {
 	start := time.Date(2025, 1, 1, 0, 0, 0, 0, time.UTC)
 	endLong := start.Add(181 * 24 * time.Hour)
@@ -119,6 +155,28 @@ func TestShouldUseMonthlyGranularityForAll(t *testing.T) {
 	}
 }
 
+func TestBuildBuckets_DayUsesHalfOpenInterval(t *testing.T) {
+	loc := useShanghaiLocal(t)
+	start := time.Date(2026, 3, 1, 0, 0, 0, 0, loc)
+	endExclusive := time.Date(2026, 3, 2, 0, 0, 0, 0, loc)
+
+	buckets := buildBuckets(start, endExclusive, "day")
+	if len(buckets) != 1 {
+		t.Fatalf("expected 1 bucket, got %d", len(buckets))
+	}
+
+	b := buckets[0]
+	if !b.Start.Equal(start) {
+		t.Fatalf("unexpected bucket start: %v", b.Start)
+	}
+	if !b.End.Equal(time.Date(2026, 3, 1, 23, 59, 59, 0, loc)) {
+		t.Fatalf("unexpected bucket inclusive end: %v", b.End)
+	}
+	if !b.EndExclusive.Equal(endExclusive) {
+		t.Fatalf("unexpected bucket exclusive end: %v", b.EndExclusive)
+	}
+}
+
 func TestTrendPointJSONIncludesPaidAmount(t *testing.T) {
 	point := trendPoint{
 		Date:       "2026-03-01",