feat: Implement heartbeat mechanism to maintain WebSocket connection

app/src/main/java/com/rosetta/messenger/network/Protocol.kt

@@ -69,6 +69,9 @@ class Protocol(
     private var lastPublicKey: String? = null
     private var lastPrivateHash: String? = null
     
+    // Heartbeat
+    private var heartbeatJob: Job? = null
+    
     // Supported packets
     private val supportedPackets = mapOf(
         0x00 to { PacketHandshake() },
@@ -92,6 +95,30 @@ class Protocol(
                 handshakeComplete = true
                 _state.value = ProtocolState.AUTHENTICATED
                 flushPacketQueue()
+                
+                // Start heartbeat with interval from server
+                startHeartbeat(packet.heartbeatInterval)
+            }
+        }
+    }
+    
+    /**
+     * Start heartbeat to keep connection alive
+     */
+    private fun startHeartbeat(intervalSeconds: Int) {
+        heartbeatJob?.cancel()
+        
+        val intervalMs = (intervalSeconds * 1000L) / 2 // Send at half the interval
+        log("💓 Starting heartbeat with interval: ${intervalSeconds}s (sending every ${intervalMs}ms)")
+        
+        heartbeatJob = scope.launch {
+            while (isActive) {
+                delay(intervalMs)
+                if (webSocket?.send("heartbeat") == true) {
+                    log("💓 Heartbeat sent")
+                } else {
+                    log("💔 Heartbeat failed to send")
+                }
             }
         }
     }
@@ -100,13 +127,19 @@ class Protocol(
      * Initialize connection to server
      */
     fun connect() {
-        if (_state.value == ProtocolState.CONNECTING || _state.value == ProtocolState.CONNECTED) {
-            log("Already connecting or connected")
+        if (_state.value == ProtocolState.CONNECTING) {
+            log("Already connecting, skipping...")
+            return
+        }
+        
+        // Allow reconnection even if connected (for manual reconnect)
+        if (_state.value == ProtocolState.CONNECTED || _state.value == ProtocolState.AUTHENTICATED) {
+            log("Already connected/authenticated, skipping...")
             return
         }
         
         isManuallyClosed = false
-        reconnectAttempts = 0  // Reset reconnect attempts on new connection
+        // Don't reset reconnectAttempts here - it's reset on successful connection in onOpen
         _state.value = ProtocolState.CONNECTING
         _lastError.value = null
         
@@ -266,6 +299,7 @@ class Protocol(
         _state.value = ProtocolState.DISCONNECTED
         handshakeComplete = false
         handshakeJob?.cancel()
+        heartbeatJob?.cancel()
         
         if (!isManuallyClosed && reconnectAttempts < MAX_RECONNECT_ATTEMPTS) {
             reconnectAttempts++
@@ -302,6 +336,7 @@ class Protocol(
         log("Disconnecting...")
         isManuallyClosed = true
         handshakeJob?.cancel()
+        heartbeatJob?.cancel()
         webSocket?.close(1000, "User disconnected")
         webSocket = null
         _state.value = ProtocolState.DISCONNECTED
@@ -332,6 +367,7 @@ class Protocol(
      */
     fun destroy() {
         disconnect()
+        heartbeatJob?.cancel()
         scope.cancel()
     }
 }