diff --git a/shared/lora_device.py b/shared/lora_device.py
index 1ed0f29..0b3cb09 100644
--- a/shared/lora_device.py
+++ b/shared/lora_device.py
@@ -20,6 +20,8 @@ else:
 class BaseLoraDevice:
     """Base class providing automatic ACK generation, retries, and duplicate filtering."""
 
+    MAX_PAYLOAD_SIZE = 222  # Maximum safe LoRa payload size in bytes
+
     def __init__(self):
         self.processed_msg_ids = set()
         self.received_acks = set()
@@ -225,6 +227,13 @@ if IS_MICROPYTHON:
                     payload = payload.encode('utf-8')
                     
                 paquet_physique = bytes([group]) + payload
+                
+                if len(paquet_physique) > self.MAX_PAYLOAD_SIZE:
+                    raise ValueError(
+                        f"[LoRa SPI] Payload exceeds MTU limit: {len(paquet_physique)} bytes "
+                        f"(max allowed: {self.MAX_PAYLOAD_SIZE} bytes)."
+                    )
+                
                 try:
                     self.lora.send(paquet_physique)
                 except Exception as e:
@@ -290,18 +299,19 @@ else:
             # Initial configuration
             self.configure(freq=868.1, sf=7, bw=125)
 
-        def _send_at_cmd(self, cmd, wait_time=0.3):
-            """Sends AT command, draining unread serial noise first."""
-            # Drain any lingering lines (like 'Rssi= -4' or incoming data)
-            if self.ser.in_waiting > 0:
-                self.ser.read_all()
-
+        def _send_at_cmd(self, cmd, timeout=1.5):
+            """Sends AT command and reads response until line received or timeout."""
             self.ser.write(f"{cmd}\r\n".encode('utf-8'))
-            time.sleep(wait_time)
             
+            start = time.time()
             resp = ""
-            while self.ser.in_waiting > 0:
-                resp += self.ser.readline().decode('utf-8', errors='ignore')
+            while (time.time() - start) < timeout:
+                if self.ser.in_waiting > 0:
+                    line = self.ser.readline().decode('utf-8', errors='ignore')
+                    resp += line
+                    if "OK" in line or "ERROR" in line or "AT_BUSY" in line:
+                        break
+                time.sleep(0.02)
             return resp
 
         def configure(self, freq=868.1, sf=7, bw=125):
@@ -312,14 +322,14 @@ else:
                 
                 # Parameters: Freq, SF, BW, CR(0=4/5), Preamble(8), Header(1=Explicit), CRC(1=ON), IQ(0=Standard), NetMode(0=P2P), Power(14), SyncWord(18=0x12), Format(0), Type(1)
                 at_cfg_cmd = f"AT+CFG={freq_hz},{sf},{bw_code},0,8,1,1,0,0,14,18,0,1"
-                self._send_at_cmd(at_cfg_cmd, wait_time=0.2)
+                self._send_at_cmd(at_cfg_cmd, timeout=0.2)
                 
                 # Fallback standalone commands
-                self._send_at_cmd("AT+SYNCWORD=18", wait_time=0.1)
-                self._send_at_cmd("AT+PRECV=65535", wait_time=0.1)
+                self._send_at_cmd("AT+SYNCWORD=18", timeout=0.1)
+                self._send_at_cmd("AT+PRECV=65535", timeout=0.1)
                 self.ser.reset_input_buffer()
 
-        def send(self, payload, group=None):
+        def send(self, payload, group=None, retries=0):
             """Encodes payload into a HEX string and transmits via 4-parameter AT+SEND."""
             with self.lock:
                 if group is None:
@@ -331,14 +341,20 @@ else:
                 if isinstance(payload, str):
                     payload = payload.encode('utf-8')
                     
+                if len(payload) > self.MAX_PAYLOAD_SIZE:
+                    raise ValueError(
+                        f"[LoRa Serial] Payload exceeds MTU limit: {len(payload)} bytes "
+                        f"(max allowed: {self.MAX_PAYLOAD_SIZE} bytes)."
+                    )
+                    
                 hex_payload = payload.hex()
 
                 log(f"[RPi LoRa Serial] Transmitting HEX string: {hex_payload}")
                 
                 # Format: AT+SEND=<group>,<payload_string>,<confirm>,<retries>
-                cmd = f"AT+SEND={group},{hex_payload},0,3"
+                cmd = f"AT+SEND={group},{hex_payload},0,{retries}"
                 
-                resp = self._send_at_cmd(cmd, wait_time=0.3)
+                resp = self._send_at_cmd(cmd, timeout=0.3)
                 log(f"[RPi LoRa Serial] AT+SEND response: {resp}")
 
         def receive_packet(self, timeout_ms=500):
@@ -424,4 +440,5 @@ class LoraCommands:
     PING = "ping"
     COOKING_STATE_UPDATE = "cooking_state_update"
     TOGGLE_PAUSE = "toggle_pause"
-    TOGGLE_DEFROST = "toggle_defrost"
\ No newline at end of file
+    TOGGLE_DEFROST = "toggle_defrost"
+    NEW_ALERT = "new_alert"
\ No newline at end of file