fix(D-01/A): 3 review bugs + null guards (BUG-001, BUG-002, BUG-003, RISK-003)

BUG-001: TyingInteractionHelper swap now checks V2EquipResult — on failure,
rolls back by re-equipping the old bind instead of leaving target untied

BUG-002: OwnershipComponent.onUnequipped no longer double-calls
unregisterWearer — onCollarRemoved already handles it. Suppressed-alert
path calls unregister directly since onCollarRemoved is skipped.

BUG-003: PacketSelfBondage handleV2SelfBind now clears completed tying
task from PlayerBindState to prevent blocking future tying interactions

RISK-003: StruggleCollar get/setResistanceState null-guard on player

src/main/java/com/tiedup/remake/network/selfbondage/PacketSelfBondage.java

@@ -291,6 +291,12 @@ public class PacketSelfBondage {
         if (playerState.getCurrentTyingTask() == newTask) {
             newTask.update();
         }
+
+        // Clear completed task to prevent blocking future tying interactions
+        TyingTask activeTask = playerState.getCurrentTyingTask();
+        if (activeTask != null && activeTask.isStopped()) {
+            playerState.setCurrentTyingTask(null);
+        }
     }
 
     private static void handleV2SelfAccessory(

src/main/java/com/tiedup/remake/state/struggle/StruggleCollar.java

@@ -47,6 +47,7 @@ public class StruggleCollar extends StruggleState {
     @Override
     protected int getResistanceState(PlayerBindState state) {
         Player player = state.getPlayer();
+        if (player == null) return 0;
         ItemStack collar = V2EquipmentHelper.getInRegion(player, BodyRegionV2.NECK);
 
         if (collar.isEmpty() || !CollarHelper.isCollar(collar)) return 0;
@@ -66,6 +67,7 @@ public class StruggleCollar extends StruggleState {
     @Override
     protected void setResistanceState(PlayerBindState state, int resistance) {
         Player player = state.getPlayer();
+        if (player == null) return;
         ItemStack collar = V2EquipmentHelper.getInRegion(player, BodyRegionV2.NECK);
 
         if (collar.isEmpty() || !CollarHelper.isCollar(collar)) return;

src/main/java/com/tiedup/remake/v2/bondage/TyingInteractionHelper.java

@@ -9,6 +9,7 @@ import com.tiedup.remake.tasks.V2TyingPlayerTask;
 import com.tiedup.remake.util.KidnappedHelper;
 import com.tiedup.remake.v2.BodyRegionV2;
 import com.tiedup.remake.v2.bondage.capability.V2EquipmentHelper;
+import com.tiedup.remake.v2.bondage.V2EquipResult;
 import net.minecraft.server.level.ServerPlayer;
 import net.minecraft.world.InteractionHand;
 import net.minecraft.world.InteractionResult;
@@ -50,11 +51,18 @@ public final class TyingInteractionHelper {
             if (stack.isEmpty()) return InteractionResult.PASS;
             ItemStack oldBind = V2EquipmentHelper.unequipFromRegion(target, BodyRegionV2.ARMS);
             if (!oldBind.isEmpty()) {
-                V2EquipmentHelper.equipItem(target, stack.copy());
+                V2EquipResult result = V2EquipmentHelper.equipItem(target, stack.copy());
+                if (result.isSuccess()) {
                     stack.shrink(1);
                     target.spawnAtLocation(oldBind);
                     TiedUpMod.LOGGER.debug("[TyingInteraction] Swapped bind on {}", target.getName().getString());
                     return InteractionResult.SUCCESS;
+                } else {
+                    // Equip failed — rollback: re-equip old bind
+                    V2EquipmentHelper.equipItem(target, oldBind);
+                    TiedUpMod.LOGGER.debug("[TyingInteraction] Swap failed, rolled back old bind on {}", target.getName().getString());
+                    return InteractionResult.PASS;
+                }
             }
             return InteractionResult.PASS;
         }

src/main/java/com/tiedup/remake/v2/bondage/component/OwnershipComponent.java

@@ -67,16 +67,18 @@ public class OwnershipComponent implements IItemComponent {
         if (entity.level().isClientSide()) return;
         if (!(entity.level() instanceof ServerLevel serverLevel)) return;
 
-        // Alert kidnappers if removal wasn't suppressed
+        // Alert kidnappers + unregister from CollarRegistry
+        // onCollarRemoved handles both the alert AND the unregister call internally,
+        // so we do NOT call registry.unregisterWearer() separately to avoid double unregister.
         if (!CollarHelper.isRemovalAlertSuppressed()) {
             ItemCollar.onCollarRemoved(entity, true);
-        }
-
+        } else {
+            // Suppressed alert path: still need to unregister, just skip the alert
             try {
                 CollarRegistry registry = CollarRegistry.get(serverLevel);
                 registry.unregisterWearer(entity.getUUID());
                 TiedUpMod.LOGGER.debug(
-                "[OwnershipComponent] Unregistered collar for {}",
+                    "[OwnershipComponent] Unregistered collar for {} (alert suppressed)",
                     entity.getName().getString()
                 );
             } catch (Exception e) {
@@ -86,6 +88,7 @@ public class OwnershipComponent implements IItemComponent {
                 );
             }
         }
+    }
 
     @Override
     public void appendTooltip(ItemStack stack, @Nullable Level level, List<Component> tooltip, TooltipFlag flag) {