diff --git a/uiserver/webpack.config.js b/uiserver/webpack.config.js
index 10901c4..80f8941 100644
--- a/uiserver/webpack.config.js
+++ b/uiserver/webpack.config.js
@@ -32,8 +32,15 @@ const agentClients = new Map(); // devicePrefix -> Set<ws>
 function validateApiKey(apiKey) {
     if (!db) return null;
     try {
-        const stmt = db.prepare('SELECT * FROM api_keys WHERE key = ? AND enabled = 1');
-        return stmt.get(apiKey);
+        const stmt = db.prepare('SELECT id, name, device_prefix FROM api_keys WHERE key = ?');
+        const result = stmt.get(apiKey);
+
+        if (result) {
+            // Update last_used_at timestamp
+            db.prepare("UPDATE api_keys SET last_used_at = datetime('now') WHERE id = ?").run(result.id);
+        }
+
+        return result || null;
     } catch (err) {
         console.error('[WS] Error validating API key:', err.message);
         return null;
@@ -43,59 +50,77 @@ function validateApiKey(apiKey) {
 function insertReadingsSmart(devicePrefix, readings) {
     if (!db) throw new Error('Database not connected');
 
-    let inserted = 0;
-    let updated = 0;
+    const isoTimestamp = new Date().toISOString();
 
-    const insertStmt = db.prepare(`
-        INSERT INTO sensor_events (timestamp, channel, device, value, data, data_type)
-        VALUES (?, ?, ?, ?, ?, ?)
+    const stmtLast = db.prepare(`
+        SELECT id, value, data, data_type 
+        FROM sensor_events 
+        WHERE device = ? AND channel = ? 
+        ORDER BY timestamp DESC 
+        LIMIT 1
     `);
 
-    const updateUntilStmt = db.prepare(`
+    const stmtUpdate = db.prepare(`
         UPDATE sensor_events SET until = ? WHERE id = ?
     `);
 
-    const getLastStmt = db.prepare(`
-        SELECT id, value, data FROM sensor_events 
-        WHERE device = ? AND channel = ? 
-        ORDER BY timestamp DESC LIMIT 1
+    const stmtInsert = db.prepare(`
+        INSERT INTO sensor_events (timestamp, until, device, channel, value, data, data_type)
+        VALUES (?, NULL, ?, ?, ?, ?, ?)
     `);
 
-    const now = new Date().toISOString();
+    const transaction = db.transaction((items) => {
+        let inserted = 0;
+        let updated = 0;
 
-    for (const reading of readings) {
-        const device = `${devicePrefix}${reading.device}`;
-        const channel = reading.channel;
-        const value = reading.value ?? null;
-        const data = reading.data ? JSON.stringify(reading.data) : null;
-        const dataType = value !== null ? 'number' : 'json';
+        for (const reading of items) {
+            const fullDevice = `${devicePrefix}${reading.device}`;
+            const channel = reading.channel;
 
-        // Check last value for RLE
-        const last = getLastStmt.get(device, channel);
+            // Determine type and values
+            let dataType = 'number';
+            let value = null;
+            let data = null;
 
-        if (last) {
-            const lastValue = last.value;
-            const lastData = last.data;
-
-            // If same value, just update 'until'
-            if (value !== null && lastValue === value) {
-                updateUntilStmt.run(now, last.id);
-                updated++;
-                continue;
+            if (reading.value !== undefined && reading.value !== null) {
+                dataType = 'number';
+                value = reading.value;
+            } else if (reading.data !== undefined) {
+                dataType = 'json';
+                data = typeof reading.data === 'string' ? reading.data : JSON.stringify(reading.data);
+            } else {
+                continue; // Skip invalid
             }
-            if (data !== null && lastData === data) {
-                updateUntilStmt.run(now, last.id);
+
+            // Check last reading for RLE
+            const last = stmtLast.get(fullDevice, channel);
+            let isDuplicate = false;
+
+            if (last && last.data_type === dataType) {
+                if (dataType === 'number') {
+                    if (Math.abs(last.value - value) < Number.EPSILON) {
+                        isDuplicate = true;
+                    }
+                } else {
+                    // Compare JSON strings
+                    if (last.data === data) {
+                        isDuplicate = true;
+                    }
+                }
+            }
+
+            if (isDuplicate) {
+                stmtUpdate.run(isoTimestamp, last.id);
                 updated++;
-                continue;
+            } else {
+                stmtInsert.run(isoTimestamp, fullDevice, channel, value, data, dataType);
+                inserted++;
             }
         }
+        return { inserted, updated };
+    });
 
-        // Insert new reading
-        insertStmt.run(now, channel, device, value, data, dataType);
-        inserted++;
-    }
-
-    return { inserted, updated };
+    return transaction(readings);
 }
 
 function createAgentWebSocketServer() {
@@ -108,9 +133,17 @@ function createAgentWebSocketServer() {
         const clientState = {
             authenticated: false,
             devicePrefix: null,
-            name: null
+            name: null,
+            lastPong: Date.now()
         };
 
+        // Set up ping/pong for keepalive
+        ws.isAlive = true;
+        ws.on('pong', () => {
+            ws.isAlive = true;
+            clientState.lastPong = Date.now();
+        });
+
         ws.on('message', (data) => {
             try {
                 const message = JSON.parse(data.toString());
@@ -133,6 +166,22 @@ function createAgentWebSocketServer() {
         });
     });
 
+    // Ping interval to detect dead connections
+    const pingInterval = setInterval(() => {
+        wss.clients.forEach((ws) => {
+            if (ws.isAlive === false) {
+                console.log('[WS] Terminating unresponsive client');
+                return ws.terminate();
+            }
+            ws.isAlive = false;
+            ws.ping();
+        });
+    }, 30000);
+
+    wss.on('close', () => {
+        clearInterval(pingInterval);
+    });
+
     console.log(`[WS] WebSocket server listening on port ${WS_PORT}`);
     return wss;
 }