feat: auto-remove stale devices after 60s timeout

- Add deviceLastSeen tracking for all WiFi and BT devices
- Add cleanupStaleDevices() that runs every 10 seconds
- Remove devices not seen for 60 seconds (STALE_DEVICE_TIMEOUT_MS)
- Works regardless of live tracking state
- Updates lastSeen in all scan paths: manual, WS, polling, node switch

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/rf_mapper/web/static/js/app.js

@@ -64,6 +64,11 @@ let deviceDistanceHistory = {};
 let deviceMissCount = {};
 const MAX_MISSED_SCANS = 5; // Remove device after this many consecutive misses (~20s with 4s interval)
 
+// Track last seen timestamp per device for timeout-based removal
+let deviceLastSeen = {}; // { address: timestamp_ms }
+const STALE_DEVICE_TIMEOUT_MS = 60000; // Remove devices not seen for 60 seconds
+let staleDeviceCleanupInterval = null;
+
 // Calculate mean of array
 function mean(arr) {
     if (arr.length === 0) return 0;
@@ -142,6 +147,81 @@ function filterScannerDevices(data) {
     return data;
 }
 
+// Update last seen timestamp for a device
+function updateDeviceLastSeen(address) {
+    deviceLastSeen[address] = Date.now();
+}
+
+// Clean up stale devices that haven't been seen recently
+function cleanupStaleDevices() {
+    if (!scanData) return;
+
+    const now = Date.now();
+    let removedCount = 0;
+
+    // Clean up Bluetooth devices
+    if (scanData.bluetooth_devices) {
+        const before = scanData.bluetooth_devices.length;
+        scanData.bluetooth_devices = scanData.bluetooth_devices.filter(dev => {
+            const lastSeen = deviceLastSeen[dev.address];
+            if (!lastSeen || (now - lastSeen) > STALE_DEVICE_TIMEOUT_MS) {
+                // Clean up tracking data
+                delete deviceMissCount[dev.address];
+                delete deviceDistanceHistory[dev.address];
+                delete deviceLastSeen[dev.address];
+                if (deviceTrails[dev.address]) {
+                    clearDeviceTrail(dev.address);
+                }
+                console.log(`[Stale] Removed BT ${dev.name || dev.address} (timeout)`);
+                return false;
+            }
+            return true;
+        });
+        removedCount += before - scanData.bluetooth_devices.length;
+    }
+
+    // Clean up WiFi networks
+    if (scanData.wifi_networks) {
+        const before = scanData.wifi_networks.length;
+        scanData.wifi_networks = scanData.wifi_networks.filter(net => {
+            const id = net.bssid || net.ssid;
+            const lastSeen = deviceLastSeen[id];
+            if (!lastSeen || (now - lastSeen) > STALE_DEVICE_TIMEOUT_MS) {
+                delete deviceLastSeen[id];
+                console.log(`[Stale] Removed WiFi ${net.ssid || net.bssid} (timeout)`);
+                return false;
+            }
+            return true;
+        });
+        removedCount += before - scanData.wifi_networks.length;
+    }
+
+    // Update UI if devices were removed
+    if (removedCount > 0) {
+        document.getElementById('wifi-count').textContent = scanData.wifi_networks?.length || 0;
+        document.getElementById('bt-count').textContent = scanData.bluetooth_devices?.length || 0;
+        document.getElementById('bt-list-count').textContent = scanData.bluetooth_devices?.length || 0;
+        drawRadar();
+        update3DMarkers();
+        updateMapMarkers();
+    }
+}
+
+// Start stale device cleanup interval
+function startStaleDeviceCleanup() {
+    if (staleDeviceCleanupInterval) return;
+    staleDeviceCleanupInterval = setInterval(cleanupStaleDevices, 10000); // Check every 10 seconds
+    console.log('[Cleanup] Stale device cleanup started (timeout: ' + (STALE_DEVICE_TIMEOUT_MS / 1000) + 's)');
+}
+
+// Stop stale device cleanup interval
+function stopStaleDeviceCleanup() {
+    if (staleDeviceCleanupInterval) {
+        clearInterval(staleDeviceCleanupInterval);
+        staleDeviceCleanupInterval = null;
+    }
+}
+
 // Device positions for hit detection (radar view)
 let devicePositions = [];
 
@@ -170,6 +250,7 @@ document.addEventListener('DOMContentLoaded', () => {
     loadAutoScanStatus();
     loadDevicePositions();  // Load saved manual positions
     loadTrilateratedPositions();  // Load multi-scanner trilaterated positions
+    startStaleDeviceCleanup();  // Auto-remove devices not seen for 60s
 
     // Initialize 3D map as default view
     setTimeout(() => {
@@ -336,6 +417,7 @@ async function switchNode(nodeId) {
 
             if (latestResp.ok) {
                 scanData = filterScannerDevices(await latestResp.json());
+                markAllDevicesSeen();
                 if (floorsResp.ok) {
                     const floorsData = await floorsResp.json();
                     updateDeviceFloors(floorsData);
@@ -434,6 +516,7 @@ function handleWebSocketScanUpdate(data) {
 
                 // Reset miss count - device was detected
                 deviceMissCount[newDev.address] = 0;
+                updateDeviceLastSeen(newDev.address);
 
                 if (existing) {
                     // Update RSSI and estimated distance, preserve custom values
@@ -465,6 +548,7 @@ function handleWebSocketScanUpdate(data) {
                     // Clean up tracking data for removed device
                     delete deviceMissCount[dev.address];
                     delete deviceDistanceHistory[dev.address];
+                    delete deviceLastSeen[dev.address];
                     // Clear trail if showing
                     if (deviceTrails[dev.address]) {
                         clearDeviceTrail(dev.address);
@@ -483,6 +567,7 @@ function handleWebSocketScanUpdate(data) {
                 isDeviceMoving(dev.address, dev.estimated_distance_m);
                 dev.is_moving = false;
                 deviceMissCount[dev.address] = 0;
+                updateDeviceLastSeen(dev.address);
             });
             scanData = {
                 wifi_networks: [],
@@ -609,12 +694,25 @@ function setView(view) {
     }
 }
 
+// Mark all devices in scanData as seen now
+function markAllDevicesSeen() {
+    if (!scanData) return;
+    const now = Date.now();
+    (scanData.wifi_networks || []).forEach(net => {
+        deviceLastSeen[net.bssid || net.ssid] = now;
+    });
+    (scanData.bluetooth_devices || []).forEach(dev => {
+        deviceLastSeen[dev.address] = now;
+    });
+}
+
 // Load latest scan
 async function loadLatestScan() {
     try {
         const response = await fetch('/api/latest');
         if (response.ok) {
             scanData = filterScannerDevices(await response.json());
+            markAllDevicesSeen();
             updateUI();
         } else {
             document.getElementById('wifi-list').innerHTML = '<div style="color:#888;padding:1rem;">No scans yet. Click "New Scan" to start.</div>';
@@ -651,6 +749,7 @@ async function triggerScan() {
 
         if (response.ok) {
             scanData = filterScannerDevices(await response.json());
+            markAllDevicesSeen();
             updateUI();
             status.textContent = `Scanned at ${new Date().toLocaleTimeString()}`;
         } else {
@@ -2448,6 +2547,7 @@ async function performLiveBTScan() {
 
                     // Reset miss count - device was detected
                     deviceMissCount[newDev.address] = 0;
+                    updateDeviceLastSeen(newDev.address);
 
                     if (existing) {
                         // Update RSSI and estimated distance, preserve custom values
@@ -2479,6 +2579,7 @@ async function performLiveBTScan() {
                         // Clean up tracking data for removed device
                         delete deviceMissCount[dev.address];
                         delete deviceDistanceHistory[dev.address];
+                        delete deviceLastSeen[dev.address];
                         // Clear trail if showing
                         if (deviceTrails[dev.address]) {
                             clearDeviceTrail(dev.address);
@@ -2497,6 +2598,7 @@ async function performLiveBTScan() {
                     isDeviceMoving(dev.address, dev.estimated_distance_m);
                     dev.is_moving = false;
                     deviceMissCount[dev.address] = 0;
+                    updateDeviceLastSeen(dev.address);
                 });
                 scanData = {
                     wifi_networks: [],