fix(open-platform): align realtime online status across protocols

vehicle-data-platform/apps/api/internal/openplatform/mysql_test.go

@@ -185,6 +185,33 @@ func TestTotalMileageUsesProtocolPriorityAndLatestRecordAtOrBeforeTime(t *testin
 	}
 }
 
+func TestRealtimeVehiclesAnyFreshProtocolKeepsSelectedSourceOnline(t *testing.T) {
+	db, mock, err := sqlmock.New()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+	now := time.Date(2026, 8, 3, 21, 37, 30, 0, time.Local)
+	vin := "LTEST32960VIN0001"
+	mock.ExpectQuery("SELECT l.vin,l.protocol.*FROM vehicle_realtime_location").
+		WithArgs(vin, now.Add(-10*time.Minute)).
+		WillReturnRows(sqlmock.NewRows([]string{"vin", "protocol", "longitude", "latitude", "speed_kmh", "total_mileage_km", "updated_at"}).
+			AddRow(vin, "GB32960", 120.1, 30.2, 0, 1000, now.Add(-2*time.Minute)).
+			AddRow(vin, "JT808", 120.2, 30.3, 10, 0, now.Add(-20*time.Second)))
+
+	points, err := NewMySQLRepository(db).RealtimeVehicles(context.Background(), []string{vin}, now)
+	if err != nil {
+		t.Fatal(err)
+	}
+	point := points[vin]
+	if point.Protocol != "GB32960" || !point.Online || !point.ObservedAt.Equal(now.Add(-2*time.Minute)) {
+		t.Fatalf("selected source and aggregate online state mismatch: %#v", point)
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Fatal(err)
+	}
+}
+
 func TestListVehicleGrantsUsesBinaryVINJoin(t *testing.T) {
 	db, mock, err := sqlmock.New()
 	if err != nil {