fix: normalize timezone history filters

go/vehicle-gateway/internal/history/query.go

@@ -810,6 +810,9 @@ func normalizeDateTimeLiteral(value string) string {
 	if len(value) == len("2006-01-02T15:04:05") && value[10] == 'T' {
 		return value[:10] + " " + value[11:]
 	}
+	if parsed, err := time.Parse(time.RFC3339, value); err == nil {
+		return parsed.In(time.FixedZone("Asia/Shanghai", 8*3600)).Format("2006-01-02 15:04:05")
+	}
 	return value
 }
 

go/vehicle-gateway/internal/history/query_test.go

@@ -268,6 +268,17 @@ func TestParseRawFrameQueryAcceptsDatetimeLocalValues(t *testing.T) {
 	}
 }
 
+func TestNormalizeDateTimeLiteralConvertsRFC3339ToShanghaiTime(t *testing.T) {
+	for raw, want := range map[string]string{
+		"2026-07-01T00:00:00+08:00": "2026-07-01 00:00:00",
+		"2026-06-30T16:00:00Z":      "2026-07-01 00:00:00",
+	} {
+		if got := normalizeDateTimeLiteral(raw); got != want {
+			t.Fatalf("normalizeDateTimeLiteral(%q) = %q, want %q", raw, got, want)
+		}
+	}
+}
+
 func TestParseMessageIDSupportsDecimalAndHex(t *testing.T) {
 	for raw, want := range map[string]int64{
 		"512":    512,