Harden per-client session state and socket writes

server/client_session.py

@@ -17,7 +17,10 @@ class ClientSession:
     packets_received: int = 0
     packets_sent: int = 0
     packets_broadcast: int = 0
+    gameplay_active: bool = False
+    protocol_version: int = 0
     _lock: Any = field(repr=False, compare=False, default_factory=threading.RLock)
+    _send_lock: Any = field(repr=False, compare=False, default_factory=threading.Lock)
 
     @property
     def label(self) -> str:
@@ -39,6 +42,18 @@ class ClientSession:
             if broadcast:
                 self.packets_broadcast += 1
 
+    def mark_gameplay_active(self, protocol_version: int) -> bool:
+        with self._lock:
+            if self.gameplay_active:
+                return False
+            self.gameplay_active = True
+            self.protocol_version = int(protocol_version)
+            return True
+
+    def send_bytes(self, payload: bytes) -> None:
+        with self._send_lock:
+            self.connection.sendall(payload)
+
     def to_snapshot(self) -> dict[str, Any]:
         with self._lock:
             return {
@@ -51,4 +66,6 @@ class ClientSession:
                 "packetsReceived": self.packets_received,
                 "packetsSent": self.packets_sent,
                 "packetsBroadcast": self.packets_broadcast,
+                "gameplayActive": self.gameplay_active,
+                "protocolVersion": self.protocol_version,
             }