fix players picking up items in contraption bounds when seated

src/main/java/com/simibubi/create/foundation/mixin/PlayerMixin.java

@@ -0,0 +1,35 @@
+package com.simibubi.create.foundation.mixin;
+
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+
+import com.llamalad7.mixinextras.injector.ModifyExpressionValue;
+import com.simibubi.create.content.contraptions.AbstractContraptionEntity;
+
+import net.minecraft.world.entity.EntityType;
+import net.minecraft.world.entity.LivingEntity;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.level.Level;
+
+@Mixin(Player.class)
+public abstract class PlayerMixin extends LivingEntity {
+	protected PlayerMixin(EntityType<? extends LivingEntity> entityType, Level level) {
+		super(entityType, level);
+	}
+
+	@ModifyExpressionValue(
+		method = "aiStep",
+		at = @At(
+			value = "INVOKE",
+			target = "Lnet/minecraft/world/entity/player/Player;isPassenger()Z"
+		)
+	)
+	private boolean pretendNotPassenger(boolean isPassenger) {
+		// avoid touching all items in the contraption's massive hitbox
+		if (isPassenger && this.getVehicle() instanceof AbstractContraptionEntity) {
+			return false;
+		}
+
+		return isPassenger;
+	}
+}

src/main/resources/create.mixins.json

@@ -16,6 +16,7 @@
     "LavaSwimmingMixin",
     "LootingEnchantFunctionMixin",
     "MapItemSavedDataMixin",
+    "PlayerMixin",
     "ProjectileUtilMixin",
     "ShulkerBoxBlockMixin",
     "SmithingMenuMixin",