Fix firelocks

Content.Server/Atmos/TileAtmosphere.cs

@@ -1158,10 +1158,16 @@ namespace Content.Server.Atmos
         }
 
         public void UpdateAdjacent(AtmosDirection direction)
-        {
-            if (!_gridAtmosphereComponent.IsAirBlocked(GridIndices.Offset(direction.ToDirection())))
         {
             _adjacentTiles[direction.ToIndex()] = _gridAtmosphereComponent.GetTile(GridIndices.Offset(direction.ToDirection()));
+
+            if (!_gridAtmosphereComponent.IsAirBlocked(GridIndices.Offset(direction.ToDirection()), direction.GetOpposite()))
+            {
+                _adjacentBits |= direction;
+            }
+            else
+            {
+                _adjacentBits &= ~direction;
             }
         }
 

Content.Shared/Atmos/AtmosDirection.cs

@@ -87,6 +87,11 @@ namespace Content.Shared.Atmos
         {
             return direction | other;
         }
+
+        public static AtmosDirection WithoutFlag(this AtmosDirection direction, AtmosDirection other)
+        {
+            return direction & ~other;
+        }
     }
 
     public sealed class AtmosDirectionFlags { }

Resources/Prototypes/Entities/Constructible/Doors/firelock.yml

@@ -15,6 +15,8 @@
         - state: closed_unlit
           shader: unshaded
           map: ["enum.DoorVisualLayers.BaseUnlit"]
+        - state: welded
+          map: ["enum.DoorVisualLayers.BaseWelded"]
         - state: bolted
           shader: unshaded
           map: ["enum.DoorVisualLayers.BaseBolted"]