只有hello包实现多跳，还没加入业务数据

具体的还要看opencode和gpt记录接着优化

sim/core/packet.py

@@ -2,11 +2,12 @@
 Packet model for LoRa route simulation.
 
 Defines packet types and structure for HELLO, DATA, and ACK packets.
+Includes path tracing for multi-hop verification.
 """
 
 from dataclasses import dataclass
 from enum import IntEnum
-from typing import Optional
+from typing import Optional, List
 
 
 class PacketType(IntEnum):
@@ -20,7 +21,7 @@ class PacketType(IntEnum):
 @dataclass
 class Packet:
     """
-    LoRa packet structure.
+    LoRa packet structure with path tracing.
 
     Attributes:
         type: Packet type (HELLO, DATA, or ACK)
@@ -28,6 +29,7 @@ class Packet:
         dst: Destination node ID (-1 for broadcast)
         seq: Sequence number
         hop: Current hop count
+        path: List of node IDs traversed (for multi-hop verification)
         payload: Optional payload data
         rssi: Received signal strength indicator (set on receive)
     """
@@ -37,15 +39,26 @@ class Packet:
     dst: int
     seq: int
     hop: int = 0
+    path: List[int] = None  # Path trace for observability
     payload: Optional[str] = None
-    rssi: Optional[float] = None  # Set by receiver
+    rssi: Optional[float] = None
+
+    def __post_init__(self):
+        """Initialize path if not provided."""
+        if self.path is None:
+            self.path = [self.src]
 
     def __repr__(self) -> str:
         return (
             f"Packet({self.type.name}, src={self.src}, dst={self.dst}, "
-            f"seq={self.seq}, hop={self.hop})"
+            f"seq={self.seq}, hop={self.hop}, path={self.path})"
         )
 
+    def add_hop(self, node_id: int):
+        """Add a node to the path and increment hop count."""
+        self.hop += 1
+        self.path.append(node_id)
+
     @property
     def is_broadcast(self) -> bool:
         """Check if packet is broadcast (dst = -1)."""
@@ -66,6 +79,11 @@ class Packet:
         """Check if packet is an ACK packet."""
         return self.type == PacketType.ACK
 
+    @property
+    def path_length(self) -> int:
+        """Get the path length (number of hops)."""
+        return len(self.path) - 1 if self.path else 0
+
     def to_dict(self) -> dict:
         """Convert packet to dictionary for serialization."""
         return {
@@ -74,6 +92,7 @@ class Packet:
             "dst": self.dst,
             "seq": self.seq,
             "hop": self.hop,
+            "path": self.path,
             "payload": self.payload,
             "rssi": self.rssi,
         }