fix: thread safety, resource leaks, dead code, shutdown hangs

- TicketModule: ticketCounter → AtomicInteger (prevents duplicate ticket numbers)
- StatusModule: .complete() → .queue() on shutdown (prevents server hang)
- DiscordReactionListener: null check on onReactionRemove (prevents NPE)
- ConfigManager: try-with-resources for InputStream in migrateIfNeeded/reload
- ZDiscordCommand: HashSet → ConcurrentHashMap.newKeySet() for dismissedUpdates
- AdvancementListener: remove dead RARITY_THRESHOLD constant
- SlashCommandManager: remove dead CONFESSION_COOLDOWN_MS constant
- ReactionRoleModule: HashMap → ConcurrentHashMap for thread safety
- plugin.yml: add panel/update to usage string

Author: ZDiscord Maintainer

src/main/java/dev/demonz/zdiscord/config/ConfigManager.java

@@ -110,13 +110,12 @@ private void migrateIfNeeded() {
         logger.info("Configuration is at v" + current
                 + "; current schema is v" + CURRENT_VERSION + ". Merging in any new keys.");
 
-        InputStream defStream = defaultResource == null ? null : defaultResource.get();
-        if (defStream == null) {
-            logger.warning("Default config.yml not found in JAR; skipping migration.");
-            return;
-        }
+        try (InputStream defStream = defaultResource == null ? null : defaultResource.get()) {
+            if (defStream == null) {
+                logger.warning("Default config.yml not found in JAR; skipping migration.");
+                return;
+            }
 
-        try {
             FileConfiguration defaults = YamlConfiguration.loadConfiguration(new InputStreamReader(defStream));
             for (String key : defaults.getKeys(true)) {
                 if (!config.contains(key)) {
@@ -135,6 +134,8 @@ private void migrateIfNeeded() {
                         StandardCopyOption.REPLACE_EXISTING);
             } catch (IOException ignored) {
             }
+        } catch (Exception e) {
+            logger.warning("Failed to read default config for migration: " + e.getMessage());
         }
     }
 
@@ -143,11 +144,14 @@ public void reload() {
 
         // Also merge in defaults from the JAR so that newly added keys are
         // visible via getX(path, defaultValue) even if the on-disk file is older.
-        InputStream defStream = defaultResource == null ? null : defaultResource.get();
-        if (defStream != null) {
-            YamlConfiguration defaults = YamlConfiguration.loadConfiguration(new InputStreamReader(defStream));
-            config.setDefaults(defaults);
-            config.options().copyDefaults(true);
+        try (InputStream defStream = defaultResource == null ? null : defaultResource.get()) {
+            if (defStream != null) {
+                YamlConfiguration defaults = YamlConfiguration.loadConfiguration(new InputStreamReader(defStream));
+                config.setDefaults(defaults);
+                config.options().copyDefaults(true);
+            }
+        } catch (Exception e) {
+            logger.warning("Failed to load default config: " + e.getMessage());
         }
     }
 

src/main/java/dev/demonz/zdiscord/discord/SlashCommandManager.java

@@ -46,8 +46,6 @@
  */
 public class SlashCommandManager extends ListenerAdapter {
 
-    private static final long CONFESSION_COOLDOWN_MS = 5 * 60 * 1000L;
-
     private final ZDiscord plugin;
 
     /** discord user id → last confession epoch ms (rate-limit). */

src/main/java/dev/demonz/zdiscord/discord/listeners/DiscordReactionListener.java

@@ -44,6 +44,9 @@ public void onMessageReactionAdd(MessageReactionAddEvent event) {
 
     @Override
     public void onMessageReactionRemove(MessageReactionRemoveEvent event) {
+        if (event.getUser() == null || event.getUser().isBot()) {
+            return;
+        }
         if (plugin.getReactionRoleModule() != null) {
             plugin.getReactionRoleModule().onReactionRemove(event);
         }

src/main/java/dev/demonz/zdiscord/minecraft/commands/ZDiscordCommand.java

@@ -24,9 +24,9 @@
 import org.bukkit.command.TabCompleter;
 import org.bukkit.entity.Player;
 
-import java.util.HashSet;
 import java.util.Set;
 import java.util.UUID;
+import java.util.concurrent.ConcurrentHashMap;
 
 import java.io.File;
 import java.io.FileWriter;
@@ -47,7 +47,7 @@
 public class ZDiscordCommand implements CommandExecutor, TabCompleter {
 
     private final ZDiscord plugin;
-    private final Set<UUID> dismissedUpdates = new HashSet<>();
+    private final Set<UUID> dismissedUpdates = ConcurrentHashMap.newKeySet();
 
     public ZDiscordCommand(ZDiscord plugin) {
         this.plugin = plugin;

src/main/java/dev/demonz/zdiscord/minecraft/listeners/AdvancementListener.java

@@ -39,12 +39,6 @@
  */
 public class AdvancementListener implements Listener {
 
-    /**
-     * Unlockers below this fraction of the active player base
-     * are considered "rare" and the embed shows the trophy
-     * badge. 0.25 = bottom 25%.
-     */
-    private static final double RARITY_THRESHOLD = 0.25;
 
     private final ZDiscord plugin;
 

src/main/java/dev/demonz/zdiscord/modules/ReactionRoleModule.java

@@ -30,6 +30,7 @@
 import java.io.IOException;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.UUID;
 
 /**
@@ -41,7 +42,7 @@ public class ReactionRoleModule {
     private final ZDiscord plugin;
     private final File dataFile;
     private FileConfiguration data;
-    private final Map<String, Map<String, RoleMapping>> mappings = new HashMap<>();
+    private final Map<String, Map<String, RoleMapping>> mappings = new ConcurrentHashMap<>();
 
     public ReactionRoleModule(ZDiscord plugin) {
         this.plugin = plugin;

src/main/java/dev/demonz/zdiscord/modules/StatusModule.java

@@ -157,7 +157,9 @@ public void shutdown() {
         ctx.maxCount = BukkitMaxPlayers();
 
         try {
-            channel.editMessageEmbedsById(statusMessageId, StatusEmbedBuilder.build(ctx)).complete();
+            channel.editMessageEmbedsById(statusMessageId, StatusEmbedBuilder.build(ctx)).queue(
+                    null,
+                    e -> plugin.debug("Failed to send offline status: " + e.getMessage()));
         } catch (Exception e) {
             plugin.debug("Failed to send offline status: " + e.getMessage());
         }

src/main/java/dev/demonz/zdiscord/modules/TicketModule.java

@@ -40,6 +40,7 @@
 import java.util.Map;
 import java.util.UUID;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.atomic.AtomicInteger;
 
 /**
  * Support ticket system. Each ticket is a private Discord channel
@@ -54,14 +55,14 @@ public class TicketModule {
 
     private final ZDiscord plugin;
     private final Map<String, Integer> openTicketsByUser = new ConcurrentHashMap<>();
-    private int ticketCounter = 0;
+    private final AtomicInteger ticketCounter = new AtomicInteger(0);
 
     public TicketModule(ZDiscord plugin) {
         this.plugin = plugin;
     }
 
     public void init() {
-        ticketCounter = plugin.getStorageManager().getDataInt("ticket-counter", 0);
+        ticketCounter.set(plugin.getStorageManager().getDataInt("ticket-counter", 0));
         String openData = plugin.getStorageManager().getData("open-tickets", "");
         openTicketsByUser.clear();
         if (!openData.isEmpty()) {
@@ -78,7 +79,7 @@ public void init() {
                 }
             }
         }
-        plugin.debug("Ticket module initialised (counter: " + ticketCounter
+        plugin.debug("Ticket module initialised (counter: " + ticketCounter.get()
                 + ", categories: " + getCategories().size()
                 + ", tracked users: " + openTicketsByUser.size() + ")");
     }
@@ -277,12 +278,12 @@ private TextChannel createTicketChannel(String username, String subject,
             category = guild.getCategoryById(categoryChannelId);
         }
 
-        ticketCounter++;
-        plugin.getStorageManager().setData("ticket-counter", ticketCounter);
+        int currentTicket = ticketCounter.incrementAndGet();
+        plugin.getStorageManager().setData("ticket-counter", currentTicket);
 
         TicketCategory cat = getCategory(categoryId);
 
-        String channelName = "ticket-" + String.format("%04d", ticketCounter)
+        String channelName = "ticket-" + String.format("%04d", currentTicket)
                 + "-" + username.toLowerCase().replaceAll("[^a-z0-9-]", "");
 
         try {
@@ -341,7 +342,7 @@ private void sendTicketWelcome(TextChannel channel, String username,
                 .addField("Category", categoryLabel, true)
                 .addField("Opened by", "`" + username + "`", true)
                 .setColor(ColorUtil.parseHex(color))
-                .setFooter("Ticket #" + ticketCounter + " \u2022 Use the buttons below to manage")
+                .setFooter("Ticket #" + currentTicket + " \u2022 Use the buttons below to manage")
                 .setTimestamp(Instant.now());
 
         channel.sendMessageEmbeds(embed.build())
@@ -475,7 +476,7 @@ private void saveOpenTickets() {
     }
 
     public void shutdown() {
-        plugin.getStorageManager().setData("ticket-counter", ticketCounter);
+        plugin.getStorageManager().setData("ticket-counter", ticketCounter.get());
         saveOpenTickets();
     }
 

src/main/resources/plugin.yml

@@ -17,7 +17,7 @@ softdepend:
 commands:
   zdiscord:
     description: ZDiscord admin command
-    usage: /<command> [reload|status|link|embed|ticket|lockdown|dump]
+    usage: /<command> [reload|status|link|embed|ticket|panel|lockdown|update|dump]
     permission: zdiscord.admin
     aliases: [zd]
   discord: