fix(hologram): recover display after chunk unload and stale entity reference

core/src/main/java/github/nighter/smartspawner/commands/clear/ClearHologramsSubCommand.java

@@ -37,7 +37,9 @@ public int execute(CommandContext<CommandSourceStack> context) {
         try {
             // Execute the Minecraft command to kill all text_display entities
             Bukkit.dispatchCommand(Bukkit.getConsoleSender(), "minecraft:kill @e[type=text_display]");
-
+
+            plugin.getSpawnerManager().reloadAllHolograms();
+
             // Send success message to player
             plugin.getMessageService().sendMessage(sender, "hologram.cleared");
 

core/src/main/java/github/nighter/smartspawner/commands/hologram/HologramClearSubCommand.java

@@ -37,7 +37,9 @@ public int execute(CommandContext<CommandSourceStack> context) {
         try {
             // Execute the Minecraft command to kill all text_display entities
             Bukkit.dispatchCommand(Bukkit.getConsoleSender(), "minecraft:kill @e[type=text_display]");
-
+
+            plugin.getSpawnerManager().reloadAllHolograms();
+
             // Send success message to player
             plugin.getMessageService().sendMessage(sender, "hologram.cleared");
 

core/src/main/java/github/nighter/smartspawner/commands/hologram/SpawnerHologram.java

@@ -164,9 +164,20 @@ private static String formatOneDecimal(double value) {
     // Public update API
     // -------------------------------------------------------------------------
 
+    public boolean isAlive() {
+        TextDisplay display = textDisplay.get();
+        return display != null && display.isValid();
+    }
+
     public void updateText() {
         TextDisplay display = textDisplay.get();
-        if (display == null || entityType == null) return;
+        if (entityType == null) return;
+        if (display == null) return;
+        if (!display.isValid()) {
+            textDisplay.set(null);
+            createHologram();
+            return;
+        }
 
         // Compute the text on the calling (region) thread – avoids doing string work
         // inside the entity-thread lambda and keeps the lambda allocation tiny.
@@ -182,8 +193,14 @@ public void updateText() {
     public void updateData(int stackSize, EntityType entityType, long currentExp, long maxExp, int currentItems, int maxSlots) {
         TextDisplay display = textDisplay.get();
 
-        // Skip entirely when nothing has changed and the hologram already exists.
+        if (display != null && !display.isValid()) {
+            textDisplay.set(null);
+            display = null;
+        }
+
+        // Skip entirely when nothing has changed and the hologram display is still alive.
         if (display != null
+                && display.isValid()
                 && this.stackSize == stackSize
                 && this.entityType == entityType
                 && this.currentExp == currentExp
@@ -205,13 +222,14 @@ public void updateData(int stackSize, EntityType entityType, long currentExp, lo
         } else {
             // Pre-compute text here (region thread) so the entity-thread lambda
             // only needs to call display.setText() – no extra task dispatch.
+            final TextDisplay activeDisplay = display;
             final String finalText = computeText();
-            Scheduler.runEntityTask(display, () -> {
-                if (!display.isValid()) {
+            Scheduler.runEntityTask(activeDisplay, () -> {
+                if (!activeDisplay.isValid()) {
                     textDisplay.set(null);
                     createHologram();
                 } else {
-                    display.setText(finalText);
+                    activeDisplay.setText(finalText);
                 }
             });
         }

core/src/main/java/github/nighter/smartspawner/spawner/data/WorldEventHandler.java

@@ -4,10 +4,14 @@
 import github.nighter.smartspawner.spawner.properties.SpawnerData;
 import github.nighter.smartspawner.Scheduler;
 import org.bukkit.Bukkit;
+import org.bukkit.Chunk;
+import org.bukkit.Material;
 import org.bukkit.World;
+import org.bukkit.block.BlockState;
 import org.bukkit.event.EventHandler;
 import org.bukkit.event.EventPriority;
 import org.bukkit.event.Listener;
+import org.bukkit.event.world.ChunkLoadEvent;
 import org.bukkit.event.world.WorldInitEvent;
 import org.bukkit.event.world.WorldLoadEvent;
 import org.bukkit.event.world.WorldSaveEvent;
@@ -65,6 +69,8 @@ public void onWorldLoad(WorldLoadEvent event) {
         // Try to load any pending spawners for this world
         loadPendingSpawnersForWorld(worldName);
 
+        ensureHologramsInLoadedChunks(world);
+
         // If this is during server startup, also attempt initial load
         if (!initialLoadAttempted) {
             // Delay slightly to ensure world is fully ready
@@ -105,6 +111,47 @@ public void onWorldUnload(WorldUnloadEvent event) {
         unloadSpawnersFromWorld(worldName);
     }
 
+    @EventHandler(priority = EventPriority.MONITOR, ignoreCancelled = true)
+    public void onChunkLoad(ChunkLoadEvent event) {
+        ensureHologramsInChunk(event.getChunk());
+    }
+
+    private void ensureHologramsInChunk(Chunk chunk) {
+        if (!plugin.getConfig().getBoolean("hologram.enabled", false)) {
+            return;
+        }
+
+        World world = chunk.getWorld();
+        int chunkX = chunk.getX();
+        int chunkZ = chunk.getZ();
+
+        Scheduler.runChunkTask(world, chunkX, chunkZ, () -> {
+            if (!world.isChunkLoaded(chunkX, chunkZ)) {
+                return;
+            }
+
+            Chunk loadedChunk = world.getChunkAt(chunkX, chunkZ);
+            for (BlockState state : loadedChunk.getTileEntities(
+                    block -> block.getType() == Material.SPAWNER, false)) {
+                SpawnerData spawner = plugin.getSpawnerManager()
+                        .getSpawnerByLocation(state.getBlock().getLocation());
+                if (spawner != null) {
+                    spawner.ensureHologram();
+                }
+            }
+        });
+    }
+
+    private void ensureHologramsInLoadedChunks(World world) {
+        if (!plugin.getConfig().getBoolean("hologram.enabled", false)) {
+            return;
+        }
+
+        for (Chunk loadedChunk : world.getLoadedChunks()) {
+            ensureHologramsInChunk(loadedChunk);
+        }
+    }
+
     /**
      * Attempt to perform initial spawner loading, checking for available worlds
      */

core/src/main/java/github/nighter/smartspawner/spawner/properties/SpawnerData.java

@@ -9,6 +9,7 @@
 import lombok.Setter;
 import org.bukkit.Location;
 import org.bukkit.Material;
+import org.bukkit.World;
 import org.bukkit.entity.EntityType;
 import org.bukkit.inventory.ItemStack;
 import org.bukkit.inventory.meta.ItemMeta;
@@ -392,22 +393,58 @@ public void updateHologramData() {
     }
 
     public void reloadHologramData() {
+        if (!plugin.getConfig().getBoolean("hologram.enabled", false)) {
+            removeHologram();
+            return;
+        }
         if (hologram != null) {
             hologram.remove();
-            createHologram();
         }
+        if (!isSpawnerChunkLoaded()) {
+            return;
+        }
+        createHologram();
     }
 
     public void refreshHologram() {
         if (plugin.getConfig().getBoolean("hologram.enabled", false)) {
-            if (hologram == null) {
-                createHologram();
-            }
-        } else if (hologram != null) {
+            ensureHologram();
+        } else {
             removeHologram();
         }
     }
 
+    /**
+     * Recreate hologram display if missing or dead. No-op when display is alive.
+     * Must be invoked on or scheduled to the spawner's region thread.
+     */
+    public void ensureHologram() {
+        if (!plugin.getConfig().getBoolean("hologram.enabled", false)) {
+            removeHologram();
+            return;
+        }
+        if (!isSpawnerChunkLoaded()) {
+            return;
+        }
+        if (hologram != null && hologram.isAlive()) {
+            return;
+        }
+        if (hologram != null) {
+            hologram.remove();
+        }
+        createHologram();
+    }
+
+    private boolean isSpawnerChunkLoaded() {
+        if (spawnerLocation == null || spawnerLocation.getWorld() == null) {
+            return false;
+        }
+        World world = spawnerLocation.getWorld();
+        int chunkX = spawnerLocation.getBlockX() >> 4;
+        int chunkZ = spawnerLocation.getBlockZ() >> 4;
+        return world.isChunkLoaded(chunkX, chunkZ);
+    }
+
     public void removeHologram() {
         if (hologram != null) {
             hologram.remove();