fix: timezone-aware timestamp parsing, favicon 404, and performance lag

main.py

@@ -217,6 +217,7 @@ async def favicon():
 
 
 
+
 # === WebSocket endpoint for live vitals ===
 @app.websocket("/ws/vitals")
 async def websocket_vitals(websocket: WebSocket):

static/dashboard.html

@@ -2559,6 +2559,23 @@
             document.body.classList.add('minimal-mode');
         }
 
+        // Helper: Calculate age in milliseconds robustly against UTC and local timezones
+        function getTimestampAgeMs(ts) {
+            if (!ts) return 999999999;
+            try {
+                let str = String(ts).trim();
+                if (!str.endsWith('Z') && !str.includes('+') && !/[-+]\d{2}:\d{2}$/.test(str)) {
+                    str = str + 'Z';
+                }
+                const time = new Date(str).getTime();
+                if (isNaN(time)) return 999999999;
+                return Math.abs(Date.now() - time);
+            } catch (e) {
+                return 999999999;
+            }
+        }
+
+
         function getTargetPatientBadge() {
             const items = [];
             if (targetMrn) items.push(`<span class="patient-mrn-badge" style="padding: 4px 10px; font-size: 12px;">📋 MRN: <strong>${targetMrn}</strong></span>`);
@@ -3127,7 +3144,7 @@
                                 const now = Date.now();
                                 for (let i = readings.length - 1; i >= 0; i--) {
                                     const r = readings[i];
-                                    const rAge = r.timestamp ? (now - new Date(r.timestamp).getTime()) : 9999999;
+                                    const rAge = getTimestampAgeMs(r.timestamp);
                                     if (rAge <= 25000) {
                                         if (r.heart_rate != null) merged.heart_rate = r.heart_rate;
                                         if (r.spo2 != null) merged.spo2 = r.spo2;
@@ -3220,7 +3237,7 @@
                             const now = Date.now();
                             for (let i = readings.length - 1; i >= 0; i--) {
                                 const r = readings[i];
-                                const rAge = r.timestamp ? (now - new Date(r.timestamp).getTime()) : 9999999;
+                                const rAge = getTimestampAgeMs(r.timestamp);
                                 if (rAge <= 25000) {
                                     if (r.heart_rate != null) merged.heart_rate = r.heart_rate;
                                     if (r.spo2 != null) merged.spo2 = r.spo2;
@@ -3652,7 +3669,7 @@
                 if (readings.length > 0) {
                     const now = Date.now();
                     readings.forEach(r => {
-                        const rAge = r.timestamp ? (now - new Date(r.timestamp).getTime()) : 9999999;
+                        const rAge = getTimestampAgeMs(r.timestamp);
                         if (rAge > 25000) {
                             r.heart_rate = null;
                             r.spo2 = null;
@@ -3743,7 +3760,7 @@
                         const devKey = r.device_id;
                         if (devKey && connectedDevices[devKey]) {
                             const dev = connectedDevices[devKey];
-                            const rAge = r.timestamp ? (now - new Date(r.timestamp).getTime()) : 9999999;
+                            const rAge = getTimestampAgeMs(r.timestamp);
                             if (rAge <= 25000) {
                                 if ((dev.heart_rate === undefined || dev.heart_rate === null) && r.heart_rate != null) dev.heart_rate = r.heart_rate;
                                 if ((dev.spo2 === undefined || dev.spo2 === null) && r.spo2 != null) dev.spo2 = r.spo2;