Fix blank message row and API misuse warnings

- Fix blank row appearing when peer disconnects by ensuring display names are never empty
- Add validation to prevent system messages with empty content from being displayed
- Fix API MISUSE warnings by adding connection state checks before writing to peripherals
- Improve write queue processing with additional safety checks
- Update activity tracking when processing queued writes

These fixes address UI glitches and improve Bluetooth reliability.

bitchat/Services/BluetoothMeshService.swift

@@ -201,17 +201,26 @@ class BluetoothMeshService: NSObject {
     private func writeToPeripheral(_ data: Data, peripheral: CBPeripheral, characteristic: CBCharacteristic, peerID: String? = nil) {
         let peripheralID = peripheral.identifier.uuidString
         
-        if peripheral.state == .connected {
+        // Double check the peripheral state to avoid API misuse
-            // Direct write if connected
+        guard peripheral.state == .connected else {
-            let writeType: CBCharacteristicWriteType = data.count > 512 ? .withResponse : .withoutResponse
-            peripheral.writeValue(data, for: characteristic, type: writeType)
-            
-            // Update activity tracking
-            updatePeripheralActivity(peripheralID)
-        } else {
             // Queue write for disconnected peripheral
             queueWrite(data: data, peripheralID: peripheralID, peerID: peerID)
+            return
         }
+        
+        // Verify characteristic is valid and writable
+        guard characteristic.properties.contains(.write) || characteristic.properties.contains(.writeWithoutResponse) else {
+            SecureLogger.log("Characteristic does not support writing for peripheral \(peripheralID)", 
+                           category: SecureLogger.session, level: .warning)
+            return
+        }
+        
+        // Direct write if connected
+        let writeType: CBCharacteristicWriteType = data.count > 512 ? .withResponse : .withoutResponse
+        peripheral.writeValue(data, for: characteristic, type: writeType)
+        
+        // Update activity tracking
+        updatePeripheralActivity(peripheralID)
     }
     
     private func queueWrite(data: Data, peripheralID: String, peerID: String?) {
@@ -263,10 +272,17 @@ class BluetoothMeshService: NSObject {
         // Process queued writes with small delay between them
         for (index, queuedWrite) in queue.enumerated() {
             DispatchQueue.main.asyncAfter(deadline: .now() + Double(index) * 0.01) { [weak self] in
-                guard peripheral.state == .connected else { return }
+                guard let self = self,
+                      peripheral.state == .connected,
+                      characteristic.properties.contains(.write) || characteristic.properties.contains(.writeWithoutResponse) else { 
+                    return 
+                }
                 
                 let writeType: CBCharacteristicWriteType = queuedWrite.data.count > 512 ? .withResponse : .withoutResponse
                 peripheral.writeValue(queuedWrite.data, for: characteristic, type: writeType)
+                
+                // Update activity tracking
+                self.updatePeripheralActivity(peripheralID)
             }
         }
     }

bitchat/ViewModels/ChatViewModel.swift

@@ -1953,9 +1953,11 @@ extension ChatViewModel: BitchatDelegate {
                     }
                 }
             } else {
-                // System message - always add
+                // System message - check for empty content before adding
-                messages.append(finalMessage)
+                if !finalMessage.content.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty {
-                messages.sort { $0.timestamp < $1.timestamp }
+                    messages.append(finalMessage)
+                    messages.sort { $0.timestamp < $1.timestamp }
+                }
             }
         }
         
@@ -2067,9 +2069,12 @@ extension ChatViewModel: BitchatDelegate {
         // Resolve nickname using helper
         let displayName = resolveNickname(for: peerID)
         
+        // Ensure we have a valid display name
+        let finalDisplayName = displayName.isEmpty ? "peer" : displayName
+        
         let systemMessage = BitchatMessage(
             sender: "system",
-            content: "\(displayName) connected",
+            content: "\(finalDisplayName) connected",
             timestamp: Date(),
             isRelay: false,
             originalSender: nil
@@ -2098,9 +2103,12 @@ extension ChatViewModel: BitchatDelegate {
         // Resolve nickname using helper
         let displayName = resolveNickname(for: peerID)
         
+        // Ensure we have a valid display name
+        let finalDisplayName = displayName.isEmpty ? "peer" : displayName
+        
         let systemMessage = BitchatMessage(
             sender: "system",
-            content: "\(displayName) disconnected",
+            content: "\(finalDisplayName) disconnected",
             timestamp: Date(),
             isRelay: false,
             originalSender: nil