fix item equipping

src/main/java/one/devos/nautical/succ/SimpleEquipableItem.java

@@ -0,0 +1,27 @@
+package one.devos.nautical.succ;
+
+import java.util.Objects;
+
+import org.jetbrains.annotations.NotNull;
+
+import net.minecraft.world.entity.EquipmentSlot;
+import net.minecraft.world.item.Equipable;
+import net.minecraft.world.item.Item;
+
+/**
+ * Workaround for QSL bug: <a href="https://github.com/QuiltMC/quilt-standard-libraries/issues/320">QSL#320</a>
+ */
+public class SimpleEquipableItem extends Item implements Equipable {
+	private final EquipmentSlot slot;
+
+	public SimpleEquipableItem(Properties settings, EquipmentSlot slot) {
+		super(settings);
+		this.slot = Objects.requireNonNull(slot);
+	}
+
+	@Override
+	@NotNull
+	public EquipmentSlot getEquipmentSlot() {
+		return slot;
+	}
+}

src/main/java/one/devos/nautical/succ/Succ.java

@@ -32,8 +32,8 @@ public class Succ implements ModInitializer {
 
 	public static TwisterChampionTrigger TWISTER_CHAMPION = CriteriaTriggers.register(new TwisterChampionTrigger());
 
-	public static Item SUCTION_CUP = new SuctionCupItem(new QuiltItemSettings().equipmentSlot(EquipmentSlot.HEAD).maxCount(2));
-	public static Item SUCTION_CUP_BOOTS = new Item(new QuiltItemSettings().equipmentSlot(EquipmentSlot.FEET).maxCount(1));
+	public static Item SUCTION_CUP = new SuctionCupItem(new QuiltItemSettings().maxCount(2));
+	public static Item SUCTION_CUP_BOOTS = new SimpleEquipableItem(new QuiltItemSettings().maxCount(1), EquipmentSlot.FEET);
 	@SuppressWarnings("deprecation") // entity constructor deprecated to prevent misuse, should only be used here
 	public static EntityType<ClimbingSuctionCupEntity> SUCTION_CUP_ENTITY_TYPE = FabricEntityTypeBuilder
 			.<ClimbingSuctionCupEntity>create(MobCategory.MISC, ClimbingSuctionCupEntity::new)

src/main/java/one/devos/nautical/succ/SuctionCupItem.java

@@ -1,9 +1,10 @@
 package one.devos.nautical.succ;
 
+import org.jetbrains.annotations.NotNull;
+
 import net.minecraft.core.BlockPos;
 import net.minecraft.core.Direction;
 import net.minecraft.core.Direction.Axis;
-import net.minecraft.core.Registry;
 import net.minecraft.core.registries.Registries;
 import net.minecraft.network.chat.Component;
 import net.minecraft.server.level.ServerPlayer;
@@ -14,6 +15,7 @@
 import net.minecraft.world.entity.EquipmentSlot;
 import net.minecraft.world.entity.Pose;
 import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.item.Equipable;
 import net.minecraft.world.item.Item;
 import net.minecraft.world.item.ItemStack;
 import net.minecraft.world.item.context.UseOnContext;
@@ -22,7 +24,7 @@
 import net.minecraft.world.phys.AABB;
 import net.minecraft.world.phys.Vec3;
 
-public class SuctionCupItem extends Item {
+public class SuctionCupItem extends Item implements Equipable {
 	public static final EquipmentSlot[] CUP_SLOTS = { EquipmentSlot.MAINHAND, EquipmentSlot.OFFHAND, EquipmentSlot.FEET };
 	public static final TagKey<Item> HAND_CLIMBING_CUPS = TagKey.create(Registries.ITEM, Succ.id("hand_climbing_cups"));
 	public static final TagKey<Item> FEET_CLIMBING_CUPS = TagKey.create(Registries.ITEM, Succ.id("feet_climbing_cups"));
@@ -38,6 +40,7 @@ public SuctionCupItem(Properties properties) {
 	}
 
 	@Override
+	@NotNull
 	public InteractionResult useOn(UseOnContext context) {
 		Player player = context.getPlayer();
 		if (player instanceof ServerPlayer serverPlayer) {
@@ -46,6 +49,12 @@ public InteractionResult useOn(UseOnContext context) {
 		return InteractionResult.FAIL;
 	}
 
+	@Override
+	@NotNull
+	public EquipmentSlot getEquipmentSlot() {
+		return EquipmentSlot.HEAD;
+	}
+
 	public void tryStartClimbing(ServerPlayer player, UseOnContext ctx) {
 		if (GlobalClimbingManager.isClimbing(player)) {
 			return;
@@ -56,9 +65,6 @@ public void tryStartClimbing(ServerPlayer player, UseOnContext ctx) {
 			return;
 		}
 		Level level = ctx.getLevel();
-		if (level == null) {
-			return;
-		}
 		if (missingCups(player)) {
 			fail(player, MISSING_CUPS);
 			return;
@@ -74,7 +80,7 @@ public void tryStartClimbing(ServerPlayer player, UseOnContext ctx) {
 			return;
 		}
 		// offset to the center of the block to prevent getting stuck in adjacent walls
-		clickPos = new Vec3(Math.floor(headPos.getX()) + 0.5, clickPos.y, Math.floor(headPos.getZ()) + 0.5);
+		clickPos = new Vec3(headPos.getX() + 0.5, clickPos.y, headPos.getZ() + 0.5);
 		GlobalClimbingManager.startClimbing(player, clickPos, clickedFace);
 	}
 

src/main/java/one/devos/nautical/succ/mixin/InventoryMixin.java

@@ -8,10 +8,10 @@
 import net.minecraft.world.entity.player.Inventory;
 import one.devos.nautical.succ.LocalClimbingManager;
 
-@Mixin(Inventory.class) // note: this is a client-only mixin despite entity not being client only
+@Mixin(Inventory.class) // note: this is a client-only mixin despite Inventory not being client only
 public class InventoryMixin {
 	@Inject(method = "swapPaint", at = @At("HEAD"), cancellable = true)
-	private void succ$preventItemSwapping(double scrollAmount, CallbackInfo ci) {
+	private void succ$preventItemSwappingWhileClimbing(double scrollAmount, CallbackInfo ci) {
 		if (LocalClimbingManager.INSTANCE != null) {
 			ci.cancel();
 		}