diff --git a/CLAUDE.md b/CLAUDE.md
new file mode 100644
index 0000000..d316ddc
--- /dev/null
+++ b/CLAUDE.md
@@ -0,0 +1,67 @@
+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Project Overview
+
+Border is a BentoBox addon for Minecraft Paper servers that creates and renders per-player world borders around islands. Players cannot pass the border. It supports two rendering modes: barrier blocks with particles, and vanilla world borders.
+
+**Target:** Paper 1.21+ with BentoBox 3.10+, Java 21
+
+## Build Commands
+
+```bash
+mvn clean package          # Build the plugin JAR
+mvn test                   # Run all tests
+mvn test -Dtest=BorderTest # Run a single test class
+mvn verify                 # Full build with JaCoCo coverage
+```
+
+Output JAR: `target/Border-{version}.jar`
+
+## Architecture
+
+### Addon Lifecycle (BentoBox Pladdon pattern)
+
+`BorderPladdon` (plugin entry point) → `Border` (addon, extends `Addon`) → registers commands, listeners, and border implementations per game mode.
+
+### Border Rendering — Strategy + Proxy
+
+`BorderShower` is the core interface with methods: `showBorder`, `hideBorder`, `clearUser`, `refreshView`, `teleportEntity`.
+
+Two implementations:
+- **`ShowBarrier`** — Renders barrier blocks and colored particles around island edges. Caches barrier block positions per player. Uses async chunk loading.
+- **`ShowWorldBorder`** — Uses Paper's per-player WorldBorder API. Manipulates border animation (shrink/grow/static) to achieve color effects.
+
+**`PerPlayerBorderProxy`** delegates to the correct implementation based on per-player metadata. Falls back to addon-wide default settings.
+
+### Per-Player State via Metadata
+
+Player preferences are stored as BentoBox `MetaDataValue` entries:
+- `Border_state` — border on/off toggle
+- `Border_bordertype` — BARRIER or VANILLA (stored as byte id)
+- `Border_color` — RED, GREEN, or BLUE
+
+### Commands
+
+Registered as subcommands under each game mode's player command:
+- `IslandBorderCommand` (`/[gamemode] border`) — toggle border visibility
+- `BorderTypeCommand` (`/[gamemode] bordertype`) — switch between barrier/vanilla
+- `BorderColorCommand` (`/[gamemode] bordercolor`) — change border color
+
+### Event Handling
+
+`PlayerListener` handles all player events (join, quit, move, teleport, mount, item drop) to trigger border show/hide/refresh and enforce boundary teleportation.
+
+## Testing
+
+Uses JUnit 5 + Mockito 5 + MockBukkit. All test classes extend `CommonTestSetup` which provides comprehensive mocking of BentoBox, Bukkit server, worlds, players, and island managers.
+
+`WhiteBox` is a reflection utility for accessing private fields in tests.
+
+## Key Conventions
+
+- Configuration is managed via the `Settings` class with BentoBox's `@StoreAt`/`@ConfigComment` annotations and `Config<Settings>` loader
+- Game modes can be excluded via `Settings.getDisabledGameModes()`
+- Localization files live in `src/main/resources/locales/` (20+ languages, YAML format)
+- `BorderType` is an enum with byte-based serialization ids (`fromId`/`getId`)
diff --git a/pom.xml b/pom.xml
index 56e11ea..060ec23 100644
--- a/pom.xml
+++ b/pom.xml
@@ -51,7 +51,7 @@
         <!-- Revision variable removes warning about dynamic version -->
         <revision>${build.version}-SNAPSHOT</revision>
         <!-- This allows to change between versions and snapshots. -->
-        <build.version>4.8.0</build.version>
+        <build.version>4.8.1</build.version>
         <build.number>-LOCAL</build.number>
         <!-- Sonar Cloud -->
         <sonar.projectKey>BentoBoxWorld_Border</sonar.projectKey>
@@ -102,25 +102,41 @@
     </profiles>
 
     <repositories>
+        <!-- jitpack first so MockBukkit snapshots resolve without hitting other repos -->
         <repository>
             <id>jitpack.io</id>
             <url>https://jitpack.io</url>
+            <snapshots>
+                <enabled>true</enabled>
+            </snapshots>
         </repository>
         <repository>
-          <id>papermc</id>
-          <url>https://repo.papermc.io/repository/maven-public/</url>
+            <id>papermc</id>
+            <url>https://repo.papermc.io/repository/maven-public/</url>
+            <snapshots>
+                <enabled>false</enabled>
+            </snapshots>
         </repository>
         <repository>
             <id>bentoboxworld</id>
             <url>https://repo.codemc.org/repository/bentoboxworld/</url>
+            <snapshots>
+                <enabled>false</enabled>
+            </snapshots>
         </repository>
         <repository>
             <id>codemc</id>
             <url>https://repo.codemc.org/repository/maven-snapshots/</url>
+            <snapshots>
+                <enabled>true</enabled>
+            </snapshots>
         </repository>
         <repository>
             <id>codemc-repo</id>
             <url>https://repo.codemc.org/repository/maven-public/</url>
+            <snapshots>
+                <enabled>false</enabled>
+            </snapshots>
         </repository>
     </repositories>
 
diff --git a/src/main/java/world/bentobox/border/Border.java b/src/main/java/world/bentobox/border/Border.java
index beab5d2..0cc2b61 100644
--- a/src/main/java/world/bentobox/border/Border.java
+++ b/src/main/java/world/bentobox/border/Border.java
@@ -9,7 +9,6 @@
 import world.bentobox.bentobox.api.addons.GameModeAddon;
 import world.bentobox.bentobox.api.configuration.Config;
 import world.bentobox.bentobox.api.metadata.MetaDataValue;
-import world.bentobox.bentobox.util.Util;
 import world.bentobox.border.commands.BorderColorCommand;
 import world.bentobox.border.commands.BorderTypeCommand;
 import world.bentobox.border.commands.IslandBorderCommand;
@@ -122,7 +121,11 @@ public Settings getSettings() {
      * @return true if world is being handled by Border
      */
     public boolean inGameWorld(World world) {
-        return gameModes.stream().anyMatch(gm -> gm.inWorld(Util.getWorld(world)));
+        if (world.getEnvironment() == World.Environment.NETHER &&
+                !getPlugin().getIWM().isIslandNether(world)) { return false;}
+        if (world.getEnvironment() == World.Environment.THE_END &&
+                !getPlugin().getIWM().isIslandEnd(world)) { return false;}
+        return gameModes.stream().anyMatch(gm -> gm.inWorld(world));
     }
 
     public Set<BorderType> getAvailableBorderTypesView() {
diff --git a/src/main/java/world/bentobox/border/listeners/PlayerListener.java b/src/main/java/world/bentobox/border/listeners/PlayerListener.java
index 2eb3a24..cfb4bfa 100644
--- a/src/main/java/world/bentobox/border/listeners/PlayerListener.java
+++ b/src/main/java/world/bentobox/border/listeners/PlayerListener.java
@@ -38,6 +38,7 @@
 import org.bukkit.util.RayTraceResult;
 import org.bukkit.util.Vector;
 
+import world.bentobox.bentobox.BentoBox;
 import world.bentobox.bentobox.api.addons.Addon;
 import world.bentobox.bentobox.api.events.island.IslandProtectionRangeChangeEvent;
 import world.bentobox.bentobox.api.flags.Flag;
@@ -238,13 +239,14 @@ public void onPlayerTeleport(PlayerTeleportEvent e) {
             return;
         }
         Location to = e.getTo();
-
-        show.clearUser(User.getInstance(player));
-
+        User user = User.getInstance(player);
+        show.hideBorder(user);
+        show.clearUser(user);
         if (!addon.inGameWorld(to.getWorld())) {
             return;
         }
 
+
         TeleportCause cause = e.getCause();
         boolean isBlacklistedCause = cause == TeleportCause.ENDER_PEARL || cause == TeleportCause.CONSUMABLE_EFFECT;
 
@@ -287,6 +289,9 @@ public void onPlayerTeleport(PlayerTeleportEvent e) {
      */
     @EventHandler(priority = EventPriority.NORMAL, ignoreCancelled = true)
     public void onPlayerLeaveIsland(PlayerMoveEvent e) {
+        if (!addon.inGameWorld(e.getTo().getWorld())) {
+            return;
+        }
         Player p = e.getPlayer();
         if (!isOn(p)) {
             return;
@@ -295,13 +300,16 @@ public void onPlayerLeaveIsland(PlayerMoveEvent e) {
         if (!addon.getSettings().isReturnTeleport() || !outsideCheck(e.getPlayer(), from, e.getTo())) {
             return;
         }
+        BentoBox.getInstance().logDebug("Player " + p.getName() + " is trying to leave the island protection zone.");
         // Move the player back inside the border
         if (addon.getIslands().getProtectedIslandAt(from).isPresent()) {
+            BentoBox.getInstance().logDebug("Player " + p.getName() + " is being teleported back inside the island protection zone.");
             e.setCancelled(true);
             inTeleport.add(p.getUniqueId());
             Util.teleportAsync(p, from).thenRun(() -> inTeleport.remove(p.getUniqueId()));
             return;
         }
+        BentoBox.getInstance().logDebug("Player " + p.getName() + " is not on an island, trying to find the nearest island to teleport them back to.");
         // Backtrack - try to find island at current location, or fall back to the player's own island
         Optional<Island> optionalIsland = addon.getIslands().getIslandAt(p.getLocation());
         if (optionalIsland.isEmpty()) {
@@ -340,6 +348,7 @@ public void onPlayerLeaveIsland(PlayerMoveEvent e) {
                 }
                 Util.teleportAsync(p, targetPos).thenRun(() -> inTeleport.remove(p.getUniqueId()));
             } else {
+                BentoBox.getInstance().logDebug("Ray trace did not find a valid position for player " + p.getName() + " so teleporting them back to their island home.");
                 Util.teleportAsync(p, i.getHome("")).thenRun(() -> inTeleport.remove(p.getUniqueId()));
             }
 
diff --git a/src/main/java/world/bentobox/border/listeners/ShowWorldBorder.java b/src/main/java/world/bentobox/border/listeners/ShowWorldBorder.java
index c98051e..afebc51 100644
--- a/src/main/java/world/bentobox/border/listeners/ShowWorldBorder.java
+++ b/src/main/java/world/bentobox/border/listeners/ShowWorldBorder.java
@@ -78,6 +78,16 @@ public void hideBorder(User user) {
         user.getPlayer().setWorldBorder(null);
     }
 
+    @Override
+    public void clearUser(User user) {
+        user.getPlayer().setWorldBorder(null);
+    }
+
+    @Override
+    public void refreshView(User user, Island island) {
+        showBorder(user.getPlayer(), island);
+    }
+
     /**
      * Teleport player back within the island space they are in
      * @param entity player
diff --git a/src/test/java/world/bentobox/border/BorderTest.java b/src/test/java/world/bentobox/border/BorderTest.java
index b6e2ee2..a313258 100644
--- a/src/test/java/world/bentobox/border/BorderTest.java
+++ b/src/test/java/world/bentobox/border/BorderTest.java
@@ -14,6 +14,8 @@
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
+import org.bukkit.World.Environment;
+
 import world.bentobox.bentobox.api.addons.GameModeAddon;
 import world.bentobox.bentobox.util.Util;
 
@@ -51,6 +53,44 @@ public void testInGameWorldReturnsFalseWhenNoGameModeMatches() throws Exception
         assertFalse(border.inGameWorld(world));
     }
 
+    @Test
+    public void testInGameWorldReturnsFalseForVanillaNether() {
+        when(world.getEnvironment()).thenReturn(Environment.NETHER);
+        when(iwm.isIslandNether(world)).thenReturn(false);
+
+        assertFalse(border.inGameWorld(world));
+    }
+
+    @Test
+    public void testInGameWorldReturnsFalseForVanillaEnd() {
+        when(world.getEnvironment()).thenReturn(Environment.THE_END);
+        when(iwm.isIslandEnd(world)).thenReturn(false);
+
+        assertFalse(border.inGameWorld(world));
+    }
+
+    @Test
+    public void testInGameWorldDelegatesToGameModeForIslandNether() throws Exception {
+        when(world.getEnvironment()).thenReturn(Environment.NETHER);
+        when(iwm.isIslandNether(world)).thenReturn(true);
+        GameModeAddon matching = mock(GameModeAddon.class);
+        when(matching.inWorld(world)).thenReturn(true);
+        getGameModes().add(matching);
+
+        assertTrue(border.inGameWorld(world));
+    }
+
+    @Test
+    public void testInGameWorldDelegatesToGameModeForIslandEnd() throws Exception {
+        when(world.getEnvironment()).thenReturn(Environment.THE_END);
+        when(iwm.isIslandEnd(world)).thenReturn(true);
+        GameModeAddon matching = mock(GameModeAddon.class);
+        when(matching.inWorld(world)).thenReturn(true);
+        getGameModes().add(matching);
+
+        assertTrue(border.inGameWorld(world));
+    }
+
     @Test
     public void testGetAvailableBorderTypesViewIsUnmodifiable() {
         Set<BorderType> view = border.getAvailableBorderTypesView();
diff --git a/src/test/java/world/bentobox/border/listeners/PlayerListenerTest.java b/src/test/java/world/bentobox/border/listeners/PlayerListenerTest.java
index a6a0e70..b223d91 100644
--- a/src/test/java/world/bentobox/border/listeners/PlayerListenerTest.java
+++ b/src/test/java/world/bentobox/border/listeners/PlayerListenerTest.java
@@ -132,6 +132,7 @@ public void setUp() throws Exception {
         when(gma.getPermissionPrefix()).thenReturn("bskyblock.");
         when(iwm.getAddon(world)).thenReturn(Optional.of(gma));
         when(plugin.getIWM()).thenReturn(iwm);
+        when(iwm.isIslandNether(any())).thenReturn(true);
 
         // Util
         CompletableFuture<Boolean> future = new CompletableFuture<>();
@@ -200,18 +201,53 @@ public void testOnPlayerTeleportNotInGameWorld() {
         when(addon.inGameWorld(any())).thenReturn(false);
         PlayerTeleportEvent event = new PlayerTeleportEvent(player, from, to, TeleportCause.NETHER_PORTAL);
         pl.onPlayerTeleport(event);
+        verify(show).hideBorder(user);
         verify(show).clearUser(user);
         mockedBukkit.verify(Bukkit::getScheduler, never());
     }
-    
+
     /**
      * Test method for {@link world.bentobox.border.listeners.PlayerListener#onPlayerTeleport(org.bukkit.event.player.PlayerTeleportEvent)}.
      */
     @Test
     public void testOnPlayerTeleportInGameWorld() {
         when(addon.inGameWorld(any())).thenReturn(true);
+        when(iwm.isIslandNether(any())).thenReturn(false); // In-game world teleport (non-island nether) should still trigger scheduler
+        PlayerTeleportEvent event = new PlayerTeleportEvent(player, from, to, TeleportCause.NETHER_PORTAL);
+        pl.onPlayerTeleport(event);
+        verify(show).hideBorder(user);
+        verify(show).clearUser(user);
+        mockedBukkit.verify(Bukkit::getScheduler);
+    }
+
+    /**
+     * Test method for {@link world.bentobox.border.listeners.PlayerListener#onPlayerTeleport(org.bukkit.event.player.PlayerTeleportEvent)}.
+     * Island nether world - should proceed with border management.
+     */
+    @Test
+    public void testOnPlayerTeleportInIslandNether() {
+        when(addon.inGameWorld(any())).thenReturn(true);
+        when(iwm.isIslandNether(any())).thenReturn(true);
+        when(iwm.isIslandEnd(any())).thenReturn(false);
         PlayerTeleportEvent event = new PlayerTeleportEvent(player, from, to, TeleportCause.NETHER_PORTAL);
         pl.onPlayerTeleport(event);
+        verify(show).hideBorder(user);
+        verify(show).clearUser(user);
+        mockedBukkit.verify(Bukkit::getScheduler);
+    }
+
+    /**
+     * Test method for {@link world.bentobox.border.listeners.PlayerListener#onPlayerTeleport(org.bukkit.event.player.PlayerTeleportEvent)}.
+     * Island end world - should proceed with border management.
+     */
+    @Test
+    public void testOnPlayerTeleportInIslandEnd() {
+        when(addon.inGameWorld(any())).thenReturn(true);
+        when(iwm.isIslandNether(any())).thenReturn(false);
+        when(iwm.isIslandEnd(any())).thenReturn(true);
+        PlayerTeleportEvent event = new PlayerTeleportEvent(player, from, to, TeleportCause.END_PORTAL);
+        pl.onPlayerTeleport(event);
+        verify(show).hideBorder(user);
         verify(show).clearUser(user);
         mockedBukkit.verify(Bukkit::getScheduler);
     }
@@ -251,7 +287,67 @@ public void testOnPlayerLeaveIslandReturnTeleportOutsideCheckNotInGameWorld() {
         pl.onPlayerLeaveIsland(event);
         verify(addon, never()).getIslands();
     }
-    
+
+    /**
+     * Test method for {@link world.bentobox.border.listeners.PlayerListener#onPlayerLeaveIsland(org.bukkit.event.player.PlayerMoveEvent)}.
+     * Tests that movement in a vanilla (non-island) nether world is ignored — players should NOT
+     * be teleported back when using the vanilla nether.
+     */
+    @Test
+    public void testOnPlayerLeaveIslandVanillaNether() {
+        when(addon.inGameWorld(any())).thenReturn(false); // vanilla nether is not a game world
+        settings.setReturnTeleport(true);
+        PlayerMoveEvent event = new PlayerMoveEvent(player, from, to);
+        pl.onPlayerLeaveIsland(event);
+        verify(addon, never()).getIslands();
+    }
+
+    /**
+     * Test method for {@link world.bentobox.border.listeners.PlayerListener#onPlayerLeaveIsland(org.bukkit.event.player.PlayerMoveEvent)}.
+     * Tests that movement in a vanilla (non-island) end world is ignored.
+     */
+    @Test
+    public void testOnPlayerLeaveIslandVanillaEnd() {
+        when(addon.inGameWorld(any())).thenReturn(false); // vanilla end is not a game world
+        settings.setReturnTeleport(true);
+        PlayerMoveEvent event = new PlayerMoveEvent(player, from, to);
+        pl.onPlayerLeaveIsland(event);
+        verify(addon, never()).getIslands();
+    }
+
+    /**
+     * Test method for {@link world.bentobox.border.listeners.PlayerListener#onPlayerLeaveIsland(org.bukkit.event.player.PlayerMoveEvent)}.
+     * Tests that a player trying to leave the protection zone in an island nether world is
+     * teleported back.
+     */
+    @Test
+    public void testOnPlayerLeaveIslandIslandNetherReturnsTeleport() {
+        when(iwm.isIslandNether(any())).thenReturn(true);
+        when(iwm.isIslandEnd(any())).thenReturn(false);
+        when(island.onIsland(any())).thenReturn(false);
+        settings.setReturnTeleport(true);
+        PlayerMoveEvent event = new PlayerMoveEvent(player, from, to);
+        pl.onPlayerLeaveIsland(event);
+        assertTrue(event.isCancelled());
+    }
+
+    /**
+     * Test method for {@link world.bentobox.border.listeners.PlayerListener#onPlayerLeaveIsland(org.bukkit.event.player.PlayerMoveEvent)}.
+     * Tests that a player trying to leave the protection zone in an island end world is
+     * teleported back.
+     */
+    @Test
+    public void testOnPlayerLeaveIslandIslandEndReturnsTeleport() {
+        when(iwm.isIslandNether(any())).thenReturn(false);
+        when(iwm.isIslandEnd(any())).thenReturn(true);
+        when(island.onIsland(any())).thenReturn(false);
+        settings.setReturnTeleport(true);
+        PlayerMoveEvent event = new PlayerMoveEvent(player, from, to);
+        pl.onPlayerLeaveIsland(event);
+        assertTrue(event.isCancelled());
+    }
+
+
     /**
      * Test method for {@link world.bentobox.border.listeners.PlayerListener#onPlayerLeaveIsland(org.bukkit.event.player.PlayerMoveEvent)}.
      */
diff --git a/src/test/java/world/bentobox/border/listeners/ShowWorldBorderTest.java b/src/test/java/world/bentobox/border/listeners/ShowWorldBorderTest.java
index 44a266e..f5c1487 100644
--- a/src/test/java/world/bentobox/border/listeners/ShowWorldBorderTest.java
+++ b/src/test/java/world/bentobox/border/listeners/ShowWorldBorderTest.java
@@ -121,6 +121,25 @@ public void testHideBorder() {
         svwb.hideBorder(user);
         verify(mockPlayer).setWorldBorder(null);
     }
+
+    /**
+     * Test method for {@link world.bentobox.border.listeners.ShowWorldBorder#clearUser(world.bentobox.bentobox.api.user.User)}.
+     */
+    @Test
+    public void testClearUser() {
+        svwb.clearUser(user);
+        verify(mockPlayer).setWorldBorder(null);
+    }
+
+    /**
+     * Test method for {@link world.bentobox.border.listeners.ShowWorldBorder#refreshView(world.bentobox.bentobox.api.user.User, world.bentobox.bentobox.database.objects.Island)}.
+     */
+    @Test
+    public void testRefreshView() {
+        svwb.refreshView(user, island);
+        verify(mockPlayer).setWorldBorder(wb);
+        verify(wb).setSize(200.0D);
+    }
     
     /**
      * Test method for {@link world.bentobox.border.listeners.ShowWorldBorder#showBorder(org.bukkit.entity.Player, world.bentobox.bentobox.database.objects.Island)}.