   // Update full history chart (48 hours)
        heartRateChart.data.labels = interpolatedData.map((d) =>
          new Date(d.timestamp).toLocaleString("en-US", {
            month: "short",
            day: "numeric",
            hour: "2-digit",
            minute: "2-digit",
          }),
        );
        heartRateChart.data.datasets[0].data = interpolatedData.map(
          (d) => d.value,
        );
        heartRateChart.update("none");

        // Update 3-hour chart with actual timestamps
     