fix: Implement dynamic age calculation for aircraft tracking

Resolves issue #3 where aircraft age field was always showing 0 seconds.

Backend Changes:
- Fix MarshalJSON in merger.go to calculate age dynamically using time.Since(a.LastUpdate)
- Add comprehensive tests for age calculation in merger_test.go

Frontend Changes:
- Add calculateAge() utility method to both aircraft-manager.js and ui-manager.js
- Update popup content and aircraft table to use client-side age calculation
- Implement real-time age updates every second in app.js
- Add updateOpenPopupAges() function to refresh popup displays

Key Benefits:
- Aircraft age now shows actual seconds since last transmission
- Real-time updates in UI without requiring new WebSocket data
- Proper data staleness indicators for aviation tracking
- No additional server load - client-side calculation using last_update timestamp

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

assets/static/js/app.js

@@ -469,10 +469,40 @@ class SkyView {
         this.radar3d.renderer.render(this.radar3d.scene, this.radar3d.camera);
     }
 
+    updateOpenPopupAges() {
+        // Find any open aircraft popups and update their age displays
+        if (!this.aircraftManager) return;
+        
+        this.aircraftManager.aircraftMarkers.forEach((marker, icao) => {
+            if (marker.isPopupOpen()) {
+                const aircraft = this.aircraftManager.aircraftData.get(icao);
+                if (aircraft) {
+                    // Refresh the popup content with current age
+                    marker.setPopupContent(this.aircraftManager.createPopupContent(aircraft));
+                    
+                    // Re-enhance callsign display for the updated popup
+                    const popupElement = marker.getPopup().getElement();
+                    if (popupElement) {
+                        this.aircraftManager.enhanceCallsignDisplay(popupElement);
+                    }
+                }
+            }
+        });
+    }
+
     startPeriodicTasks() {
         // Update clocks every second
         setInterval(() => this.uiManager.updateClocks(), 1000);
         
+        // Update aircraft ages and refresh displays every second
+        setInterval(() => {
+            // Update aircraft table to show current ages
+            this.uiManager.updateAircraftTable();
+            
+            // Update any open aircraft popups with current ages
+            this.updateOpenPopupAges();
+        }, 1000);
+        
         // Update charts every 10 seconds
         setInterval(() => this.updateCharts(), 10000);
         

assets/static/js/modules/aircraft-manager.js

@@ -491,7 +491,7 @@ export class AircraftManager {
                         <strong>Messages:</strong> ${aircraft.TotalMessages || 0}
                     </div>
                     <div class="detail-row">
-                        <strong>Age:</strong> ${aircraft.Age ? aircraft.Age.toFixed(1) : '0'}s
+                        <strong>Age:</strong> ${this.calculateAge(aircraft).toFixed(1)}s
                     </div>
                 </div>
             </div>
@@ -513,6 +513,16 @@ export class AircraftManager {
         return minDistance === Infinity ? null : minDistance;
     }
 
+    calculateAge(aircraft) {
+        if (!aircraft.last_update) return 0;
+        
+        const lastUpdate = new Date(aircraft.last_update);
+        const now = new Date();
+        const ageMs = now.getTime() - lastUpdate.getTime();
+        
+        return Math.max(0, ageMs / 1000); // Return age in seconds, minimum 0
+    }
+
     // Enhance callsign display in popup after it's created
     async enhanceCallsignDisplay(popupElement) {
         if (!this.callsignManager) return;

assets/static/js/modules/ui-manager.js

@@ -129,7 +129,7 @@ export class UIManager {
             <td>${aircraft.Track || '-'}°</td>
             <td>${sources}</td>
             <td><span class="${this.getSignalClass(bestSignal)}">${bestSignal ? bestSignal.toFixed(1) : '-'}</span></td>
-            <td>${aircraft.Age ? aircraft.Age.toFixed(0) : '0'}s</td>
+            <td>${this.calculateAge(aircraft).toFixed(0)}s</td>
         `;
         
         row.addEventListener('click', () => {
@@ -161,6 +161,16 @@ export class UIManager {
         return 'commercial';
     }
 
+    calculateAge(aircraft) {
+        if (!aircraft.last_update) return 0;
+        
+        const lastUpdate = new Date(aircraft.last_update);
+        const now = new Date();
+        const ageMs = now.getTime() - lastUpdate.getTime();
+        
+        return Math.max(0, ageMs / 1000); // Return age in seconds, minimum 0
+    }
+
     getBestSignalFromSources(sources) {
         if (!sources) return null;
         let bestSignal = -999;

internal/merger/merger.go

@@ -202,7 +202,7 @@ func (a *AircraftState) MarshalJSON() ([]byte, error) {
 		SpeedHistory:    a.SpeedHistory,
 		Distance:        a.Distance,
 		Bearing:         a.Bearing,
-		Age:             a.Age,
+		Age:             time.Since(a.LastUpdate).Seconds(),
 		MLATSources:     a.MLATSources,
 		PositionSource:  a.PositionSource,
 		UpdateRate:      a.UpdateRate,

internal/merger/merger_test.go

@@ -0,0 +1,92 @@
+package merger
+
+import (
+	"encoding/json"
+	"testing"
+	"time"
+
+	"skyview/internal/modes"
+)
+
+func TestAircraftState_MarshalJSON_AgeCalculation(t *testing.T) {
+	// Create a test aircraft state with a known LastUpdate time
+	pastTime := time.Now().Add(-30 * time.Second) // 30 seconds ago
+
+	state := &AircraftState{
+		Aircraft: &modes.Aircraft{
+			ICAO24:   0x123456,
+			Callsign: "TEST123",
+		},
+		LastUpdate: pastTime,
+	}
+
+	// Marshal to JSON
+	jsonData, err := json.Marshal(state)
+	if err != nil {
+		t.Fatalf("Failed to marshal AircraftState: %v", err)
+	}
+
+	// Parse the JSON to check the age field
+	var result map[string]interface{}
+	if err := json.Unmarshal(jsonData, &result); err != nil {
+		t.Fatalf("Failed to unmarshal JSON: %v", err)
+	}
+
+	// Check that age is not 0 and is approximately 30 seconds
+	age, ok := result["age"].(float64)
+	if !ok {
+		t.Fatal("Age field not found or not a number")
+	}
+
+	if age < 25 || age > 35 {
+		t.Errorf("Expected age to be around 30 seconds, got %f", age)
+	}
+
+	if age == 0 {
+		t.Error("Age should not be 0 - this indicates the bug is still present")
+	}
+
+	t.Logf("Aircraft age calculated correctly: %f seconds", age)
+}
+
+func TestAircraftState_MarshalJSON_ZeroAge(t *testing.T) {
+	// Test with very recent time to ensure age is very small but not exactly 0
+	recentTime := time.Now()
+
+	state := &AircraftState{
+		Aircraft: &modes.Aircraft{
+			ICAO24:   0x123456,
+			Callsign: "TEST123",
+		},
+		LastUpdate: recentTime,
+	}
+
+	// Marshal to JSON
+	jsonData, err := json.Marshal(state)
+	if err != nil {
+		t.Fatalf("Failed to marshal AircraftState: %v", err)
+	}
+
+	// Parse the JSON to check the age field
+	var result map[string]interface{}
+	if err := json.Unmarshal(jsonData, &result); err != nil {
+		t.Fatalf("Failed to unmarshal JSON: %v", err)
+	}
+
+	// Check that age is very small but should not be exactly 0 (unless extremely fast)
+	age, ok := result["age"].(float64)
+	if !ok {
+		t.Fatal("Age field not found or not a number")
+	}
+
+	if age < 0 {
+		t.Errorf("Age should not be negative, got %f", age)
+	}
+
+	// Age should be very small (less than 1 second) but might not be exactly 0
+	if age > 1.0 {
+		t.Errorf("Age should be very small for recent update, got %f", age)
+	}
+
+	t.Logf("Recent aircraft age calculated correctly: %f seconds", age)
+}