added ability set unmountable entities

src/main/java/carpet/fakes/EntityInterface.java

@@ -7,4 +7,8 @@ public interface EntityInterface
     float getMainYaw(float partialTicks);
 
     EntityEventsGroup getEventContainer();
+
+    boolean isPermanentVehicle();
+
+    void setPermanentVehicle(boolean permanent);
 }

src/main/java/carpet/mixins/Entity_scarpetEventsMixin.java

@@ -14,6 +14,8 @@ public abstract class Entity_scarpetEventsMixin implements EntityInterface
 {
     @Shadow public boolean removed;
 
+    private boolean permanentVehicle;
+
     private final EntityEventsGroup events = new EntityEventsGroup();
 
     @Override
@@ -22,6 +24,18 @@ public abstract class Entity_scarpetEventsMixin implements EntityInterface
         return events;
     }
 
+    @Override
+    public boolean isPermanentVehicle()
+    {
+        return permanentVehicle;
+    }
+
+    @Override
+    public void setPermanentVehicle(boolean permanent)
+    {
+        permanentVehicle = permanent;
+    }
+
     @Inject(method = "tick", at = @At("HEAD"))
     private void onTickCall(CallbackInfo ci)
     {
@@ -34,4 +48,6 @@ public abstract class Entity_scarpetEventsMixin implements EntityInterface
     {
         if (!removed) events.onEvent(EntityEventsGroup.EntityEventType.ON_REMOVED, (Entity) (Object) this);
     }
+
+
 }

src/main/java/carpet/mixins/ServerPlayerEntity_scarpetEventMixin.java

@@ -1,5 +1,6 @@
 package carpet.mixins;
 
+import carpet.fakes.EntityInterface;
 import com.mojang.authlib.GameProfile;
 import net.minecraft.entity.player.PlayerEntity;
 import net.minecraft.item.ItemStack;
@@ -53,4 +54,14 @@ public abstract class ServerPlayerEntity_scarpetEventMixin extends PlayerEntity
     {
         STATISTICS.onPlayerStatistic((ServerPlayerEntity) (Object)this, stat, amount);
     }
+
+    @Redirect(method = "method_14218", at = @At(
+            value = "INVOKE",
+            target = "Lnet/minecraft/server/network/ServerPlayerEntity;setSneaking(Z)V"
+    ))
+    private void setSneakingConditionally(ServerPlayerEntity serverPlayerEntity, boolean sneaking)
+    {
+        if (!((EntityInterface)serverPlayerEntity.getVehicle()).isPermanentVehicle()) // won't since that method makes sure its not null
+            serverPlayerEntity.setSneaking(sneaking);
+    }
 }

src/main/java/carpet/script/value/EntityValue.java

@@ -228,6 +228,7 @@ public class EntityValue extends Value
         put("is_ridden", (e, a) -> new NumericValue(e.hasPassengers()));
         put("passengers", (e, a) -> ListValue.wrap(e.getPassengerList().stream().map(EntityValue::new).collect(Collectors.toList())));
         put("mount", (e, a) -> (e.getVehicle()!=null)?new EntityValue(e.getVehicle()):Value.NULL);
+        put("unmountable", (e, a) -> new NumericValue(((EntityInterface)e).isPermanentVehicle()));
         put("tags", (e, a) -> ListValue.wrap(e.getScoreboardTags().stream().map(StringValue::new).collect(Collectors.toList())));
         put("has_tag", (e, a) -> new NumericValue(e.getScoreboardTags().contains(a.getString())));
         put("yaw", (e, a)-> new NumericValue(e.yaw));
@@ -661,6 +662,11 @@ public class EntityValue extends Value
                 //...
             }
         });
+        put("unmountable", (e, v) ->{
+            if (v == null)
+                v = Value.TRUE;
+            ((EntityInterface)e).setPermanentVehicle(v.getBoolean());
+        });
         put("drop_passengers", (e, v) -> e.removeAllPassengers());
         put("mount_passengers", (e, v) -> {
             if (v==null)