fix: FASS2 状态机与 UDP 枢纽审查项

等锁超时、全路径签名、无锁窗口不下发、Fault 终态可等待、Pass+机构不再短路、Alarm 不杀单、catch-up 停在未完成站；VehicleCode=0/重复车号拒绝注册，Hub 已运行时不抢监听口；FileLogger 空目录可写。

Co-authored-by: Cursor <cursoragent@cursor.com>

StandardScene.Magnetic/Protocol/Fass2UdpHub.cs

@@ -23,16 +23,37 @@ namespace StandardScene.Magnetic.Protocol
         private static int _listenPort = 20103;
         private static readonly Dictionary<ushort, long> _lastUnknownCarLogUtcTicks = new Dictionary<ushort, long>();
 
-        public static void Register(IFass2UdpCar car)
+        internal static bool IsRunning => _running;
+
+        internal static int ListenPort => _listenPort;
+
+        public static bool Register(IFass2UdpCar car)
         {
             if (car == null)
             {
-                return;
+                return false;
+            }
+
+            if (car.VehicleCode == 0)
+            {
+                Diagnosis.Post("Fass2UdpHub 拒绝注册 VehicleCode=0，请为每台 Mag2Car 配置唯一车号", "Fass2UdpHub", true);
+                return false;
             }
 
             lock (SyncRoot)
             {
+                if (CarsByCode.TryGetValue(car.VehicleCode, out var existing) &&
+                    !ReferenceEquals(existing, car))
+                {
+                    Diagnosis.Post(
+                        $"Fass2UdpHub 拒绝覆盖 VehicleCode={car.VehicleCode}（已被另一台车占用）",
+                        "Fass2UdpHub",
+                        true);
+                    return false;
+                }
+
                 CarsByCode[car.VehicleCode] = car;
+                return true;
             }
         }
 
@@ -64,9 +85,31 @@ namespace StandardScene.Magnetic.Protocol
 
         public static void EnsureStarted(int listenPort)
         {
-            if (listenPort > 0)
+            if (listenPort <= 0)
             {
-                _listenPort = listenPort;
+                listenPort = _listenPort;
+            }
+
+            var needRestart = false;
+            lock (SyncRoot)
+            {
+                if (_running && listenPort != _listenPort)
+                {
+                    needRestart = true;
+                }
+                else if (_running)
+                {
+                    return;
+                }
+            }
+
+            if (needRestart)
+            {
+                Diagnosis.Post(
+                    $"Fass2UdpHub 监听口 {_listenPort} → {listenPort}，重启枢纽",
+                    "Fass2UdpHub",
+                    true);
+                Stop();
             }
 
             lock (SyncRoot)
@@ -76,6 +119,7 @@ namespace StandardScene.Magnetic.Protocol
                     return;
                 }
 
+                _listenPort = listenPort;
                 _listener = new UdpClient(_listenPort);
                 _running = true;
                 _receiveThread = new Thread(ReceiveLoop)
@@ -209,6 +253,7 @@ namespace StandardScene.Magnetic.Protocol
         private static void LogUnknownCar(ushort carCode)
         {
             var nowTicks = DateTime.UtcNow.Ticks;
+            string registered;
             lock (SyncRoot)
             {
                 if (_lastUnknownCarLogUtcTicks.TryGetValue(carCode, out var lastTicks)
@@ -218,12 +263,9 @@ namespace StandardScene.Magnetic.Protocol
                 }
 
                 _lastUnknownCarLogUtcTicks[carCode] = nowTicks;
-            }
-
-            var registered = string.Join(",", CarsByCode.Keys);
-            if (string.IsNullOrEmpty(registered))
-            {
-                registered = "(无)";
+                registered = CarsByCode.Count == 0
+                    ? "(无)"
+                    : string.Join(",", CarsByCode.Keys);
             }
 
             Diagnosis.Post(