fix(discovery): correct modern protocol status offset to 0x8A

Status code is at offset 0x8A, not 0x90. The old offset was reading
the LAN mode flag byte instead. Also corrects serial number field
size from 130 to 128 bytes to match actual packet layout.

Author: GhostTypes

flashforge/discovery/discovery.py

@@ -427,18 +427,18 @@ def parse_discovery_response(
             return None
 
     def parse_modern_protocol(self, buffer: bytes, ip_address: str) -> DiscoveredPrinter:
-        """Parse a modern 276-byte discovery response."""
+        """Parse a modern 276-byte (0x114) discovery response."""
         if len(buffer) < MODERN_PROTOCOL_SIZE:
             raise InvalidResponseError(len(buffer), ip_address)
 
         name = buffer[0:0x84].decode("utf-8", errors="ignore").split("\x00", 1)[0]
         command_port = int.from_bytes(buffer[0x84:0x86], byteorder="big")
         vendor_id = int.from_bytes(buffer[0x86:0x88], byteorder="big")
         product_id = int.from_bytes(buffer[0x88:0x8A], byteorder="big")
+        status_code = int.from_bytes(buffer[0x8A:0x8C], byteorder="big")
         product_type = int.from_bytes(buffer[0x8C:0x8E], byteorder="big")
         event_port = int.from_bytes(buffer[0x8E:0x90], byteorder="big")
-        status_code = int.from_bytes(buffer[0x90:0x92], byteorder="big")
-        serial_number = buffer[0x92 : 0x92 + 130].decode("utf-8", errors="ignore").split("\x00", 1)[0]
+        serial_number = buffer[0x92 : 0x92 + 128].decode("utf-8", errors="ignore").split("\x00", 1)[0]
         model = self.detect_modern_model(name, product_type)
 
         return DiscoveredPrinter(

tests/test_discovery.py

@@ -35,9 +35,9 @@ def _build_modern_buffer(
     buffer[0x84:0x86] = command_port.to_bytes(2, byteorder="big")
     buffer[0x86:0x88] = vendor_id.to_bytes(2, byteorder="big")
     buffer[0x88:0x8A] = product_id.to_bytes(2, byteorder="big")
+    buffer[0x8A:0x8C] = status_code.to_bytes(2, byteorder="big")
     buffer[0x8C:0x8E] = product_type.to_bytes(2, byteorder="big")
     buffer[0x8E:0x90] = event_port.to_bytes(2, byteorder="big")
-    buffer[0x90:0x92] = status_code.to_bytes(2, byteorder="big")
     buffer[0x92 : 0x92 + len(serial_number)] = serial_number.encode("utf-8")
     return bytes(buffer)