add tests and more validation to packets, remove crc setting from config as hardcoded.

config.yaml.example

@@ -133,9 +133,6 @@ radio:
   # Sync word (LoRa network ID)
   sync_word: 13380
 
-  # Enable CRC checking
-  crc_enabled: true
-
   # Use implicit header mode
   implicit_header: false
 

repeater/engine.py

@@ -513,6 +513,8 @@ class RepeaterHandler(BaseHandler):
         if self.is_duplicate(packet):
             packet.drop_reason = "Duplicate"
             return None
+        
+        self.mark_seen(packet)
 
         if packet.path is None:
             packet.path = bytearray()
@@ -522,12 +524,22 @@ class RepeaterHandler(BaseHandler):
         packet.path.append(self.local_hash)
         packet.path_len = len(packet.path)
 
-        self.mark_seen(packet)
-
         return packet
 
     def direct_forward(self, packet: Packet) -> Optional[Packet]:
 
+        # Validate packet (empty payload, oversized path, etc.)
+        valid, reason = self.validate_packet(packet)
+        if not valid:
+            packet.drop_reason = reason
+            return None
+
+        # Check if packet is marked do-not-retransmit
+        if packet.is_marked_do_not_retransmit():
+            if not packet.drop_reason:
+                packet.drop_reason = "Marked do not retransmit"
+            return None
+
         # Check if we're the next hop
         if not packet.path or len(packet.path) == 0:
             packet.drop_reason = "Direct: no path"
@@ -543,12 +555,11 @@ class RepeaterHandler(BaseHandler):
             packet.drop_reason = "Duplicate"
             return None
 
-        original_path = list(packet.path)
+        self.mark_seen(packet)
+
         packet.path = bytearray(packet.path[1:])
         packet.path_len = len(packet.path)
 
-        self.mark_seen(packet)
-
         return packet
 
     @staticmethod