feat(stealth): conceal identity for prepared sessions

src/main/java/games/dmg/spigotstealth/BukkitIdentityPresentation.java

@@ -0,0 +1,75 @@
+package games.dmg.spigotstealth;
+
+import java.util.Collection;
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.Objects;
+import java.util.UUID;
+import java.util.function.Supplier;
+import org.bukkit.entity.Player;
+import org.bukkit.scoreboard.Scoreboard;
+import org.bukkit.scoreboard.Team;
+
+/** Uses scoreboard metadata and tab-only packets while leaving player entities visible. */
+public final class BukkitIdentityPresentation implements IdentityPresentation {
+    private final Supplier<? extends Collection<? extends Player>> onlinePlayers;
+    private final Scoreboard scoreboard;
+    private final TabListController tabLists;
+    private final Map<UUID, Player> concealedPlayers = new LinkedHashMap<>();
+
+    public BukkitIdentityPresentation(
+            Supplier<? extends Collection<? extends Player>> onlinePlayers,
+            Scoreboard scoreboard,
+            TabListController tabLists) {
+        this.onlinePlayers = Objects.requireNonNull(onlinePlayers, "onlinePlayers");
+        this.scoreboard = Objects.requireNonNull(scoreboard, "scoreboard");
+        this.tabLists = Objects.requireNonNull(tabLists, "tabLists");
+    }
+
+    @Override
+    public void conceal(Player player) {
+        concealedPlayers.put(player.getUniqueId(), player);
+        Team team = scoreboard.getTeam(teamName(player.getUniqueId()));
+        if (team == null) {
+            team = scoreboard.registerNewTeam(teamName(player.getUniqueId()));
+        }
+        team.setOption(Team.Option.NAME_TAG_VISIBILITY, Team.OptionStatus.NEVER);
+        team.addEntry(player.getName());
+        for (Player observer : onlinePlayers.get()) {
+            if (!observer.getUniqueId().equals(player.getUniqueId())) {
+                tabLists.remove(observer, player.getUniqueId());
+            }
+        }
+    }
+
+    @Override
+    public void reveal(Player player) {
+        boolean wasConcealed = concealedPlayers.remove(player.getUniqueId()) != null;
+        Team team = scoreboard.getTeam(teamName(player.getUniqueId()));
+        if (team != null) {
+            wasConcealed = true;
+            team.removeEntry(player.getName());
+            team.unregister();
+        }
+        if (wasConcealed) {
+            for (Player observer : onlinePlayers.get()) {
+                if (!observer.getUniqueId().equals(player.getUniqueId())) {
+                    tabLists.add(observer, player);
+                }
+            }
+        }
+    }
+
+    @Override
+    public void refreshForObserver(Player observer) {
+        for (UUID concealedPlayerId : concealedPlayers.keySet()) {
+            if (!observer.getUniqueId().equals(concealedPlayerId)) {
+                tabLists.remove(observer, concealedPlayerId);
+            }
+        }
+    }
+
+    public static String teamName(UUID playerId) {
+        return "stlth" + playerId.toString().replace("-", "").substring(0, 11);
+    }
+}

src/main/java/games/dmg/spigotstealth/IdentityPresentation.java

@@ -0,0 +1,12 @@
+package games.dmg.spigotstealth;
+
+import org.bukkit.entity.Player;
+
+/** Presentation boundary that changes identity metadata without hiding the physical player entity. */
+public interface IdentityPresentation {
+    void conceal(Player player);
+
+    void reveal(Player player);
+
+    void refreshForObserver(Player observer);
+}

src/main/java/games/dmg/spigotstealth/InvisibilityEffectListener.java

@@ -8,7 +8,6 @@ import org.bukkit.event.EventHandler;
 import org.bukkit.event.EventPriority;
 import org.bukkit.event.Listener;
 import org.bukkit.event.entity.EntityPotionEffectEvent;
-import org.bukkit.event.player.PlayerQuitEvent;
 import org.bukkit.potion.PotionEffectType;
 
 /** Attributes invisibility changes to directly consumed potions and closes intervals safely. */
@@ -50,8 +49,4 @@ public final class InvisibilityEffectListener implements Listener {
         }
     }
 
-    @EventHandler(priority = EventPriority.MONITOR)
-    public void onQuit(PlayerQuitEvent event) {
-        progression.stop(event.getPlayer().getUniqueId());
-    }
 }

src/main/java/games/dmg/spigotstealth/ProtocolLibTabListController.java

@@ -0,0 +1,52 @@
+package games.dmg.spigotstealth;
+
+import com.comphenix.protocol.PacketType;
+import com.comphenix.protocol.ProtocolManager;
+import com.comphenix.protocol.events.PacketContainer;
+import com.comphenix.protocol.wrappers.EnumWrappers;
+import com.comphenix.protocol.wrappers.PlayerInfoData;
+import com.comphenix.protocol.wrappers.WrappedChatComponent;
+import com.comphenix.protocol.wrappers.WrappedGameProfile;
+import com.comphenix.protocol.wrappers.WrappedRemoteChatSessionData;
+import java.util.EnumSet;
+import java.util.List;
+import java.util.Objects;
+import java.util.UUID;
+import org.bukkit.entity.Player;
+
+/** ProtocolLib adapter for tab-list-only removal and restoration packets. */
+public final class ProtocolLibTabListController implements TabListController {
+    private final ProtocolManager protocolManager;
+
+    public ProtocolLibTabListController(ProtocolManager protocolManager) {
+        this.protocolManager = Objects.requireNonNull(protocolManager, "protocolManager");
+    }
+
+    @Override
+    public void remove(Player observer, UUID targetPlayerId) {
+        PacketContainer packet = protocolManager.createPacket(PacketType.Play.Server.PLAYER_INFO_REMOVE);
+        packet.getUUIDLists().write(0, List.of(targetPlayerId));
+        protocolManager.sendServerPacket(observer, packet);
+    }
+
+    @Override
+    public void add(Player observer, Player target) {
+        PacketContainer packet = protocolManager.createPacket(PacketType.Play.Server.PLAYER_INFO);
+        packet.getPlayerInfoActions().write(0, EnumSet.of(
+                EnumWrappers.PlayerInfoAction.ADD_PLAYER,
+                EnumWrappers.PlayerInfoAction.UPDATE_GAME_MODE,
+                EnumWrappers.PlayerInfoAction.UPDATE_LISTED,
+                EnumWrappers.PlayerInfoAction.UPDATE_LATENCY,
+                EnumWrappers.PlayerInfoAction.UPDATE_DISPLAY_NAME));
+        PlayerInfoData data = new PlayerInfoData(
+                target.getUniqueId(),
+                target.getPing(),
+                true,
+                EnumWrappers.NativeGameMode.fromBukkit(target.getGameMode()),
+                WrappedGameProfile.fromPlayer(target),
+                WrappedChatComponent.fromText(target.getPlayerListName()),
+                (WrappedRemoteChatSessionData) null);
+        packet.getPlayerInfoDataLists().write(1, List.of(data));
+        protocolManager.sendServerPacket(observer, packet);
+    }
+}

src/main/java/games/dmg/spigotstealth/SpigotStealthPlugin.java

@@ -1,5 +1,6 @@
 package games.dmg.spigotstealth;
 
+import com.comphenix.protocol.ProtocolLibrary;
 import java.nio.file.Path;
 import java.time.Clock;
 import java.util.Objects;
@@ -12,6 +13,8 @@ public final class SpigotStealthPlugin extends JavaPlugin {
     private CompletableFuture<StealthStateManager> stateManagerFuture;
     private StealthSettings settings;
     private QualifyingInvisibilityService progression;
+    private StealthSessionService sessions;
+    private IdentityPresentation identityPresentation;
 
     @Override
     public void onEnable() {
@@ -38,6 +41,14 @@ public final class SpigotStealthPlugin extends JavaPlugin {
 
     @Override
     public void onDisable() {
+        if (identityPresentation != null && sessions != null) {
+            for (org.bukkit.entity.Player player : getServer().getOnlinePlayers()) {
+                if (sessions.isConcealed(player.getUniqueId())) {
+                    identityPresentation.reveal(player);
+                    sessions.endConcealment(player.getUniqueId());
+                }
+            }
+        }
         if (progression != null) {
             progression.stopAll().join();
         }
@@ -57,8 +68,15 @@ public final class SpigotStealthPlugin extends JavaPlugin {
                 settings.unlockedMessage());
         progression = new QualifyingInvisibilityService(
                 manager, settings.unlockThreshold(), System::nanoTime, notifier);
+        sessions = new StealthSessionService(manager, progression);
+        identityPresentation = new BukkitIdentityPresentation(
+                getServer()::getOnlinePlayers,
+                Objects.requireNonNull(getServer().getScoreboardManager(), "scoreboard manager").getMainScoreboard(),
+                new ProtocolLibTabListController(ProtocolLibrary.getProtocolManager()));
         getServer().getPluginManager().registerEvents(
                 new InvisibilityEffectListener(progression, Clock.systemUTC()), this);
+        getServer().getPluginManager().registerEvents(
+                new StealthSessionListener(sessions, identityPresentation, settings.concealedMessage()), this);
         Objects.requireNonNull(getCommand("stealth"), "stealth command")
                 .setExecutor(new StealthCommand(manager, progression, settings));
         getServer().getScheduler().runTaskTimer(this, ignored -> {
@@ -66,6 +84,11 @@ public final class SpigotStealthPlugin extends JavaPlugin {
                 logSaveFailure(progression.checkpoint(playerId));
             }
         }, 20L, 20L);
+        getServer().getScheduler().runTaskTimer(this, ignored -> {
+            for (org.bukkit.entity.Player observer : getServer().getOnlinePlayers()) {
+                identityPresentation.refreshForObserver(observer);
+            }
+        }, 20L, 20L);
         getServer().getScheduler().runTaskTimer(this, ignored -> logSaveFailure(manager.save()), 6000L, 6000L);
         getLogger().info("Spigot Stealth enabled");
     }

src/main/java/games/dmg/spigotstealth/StealthSessionListener.java

@@ -0,0 +1,53 @@
+package games.dmg.spigotstealth;
+
+import java.util.Objects;
+import org.bukkit.entity.Player;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.EventPriority;
+import org.bukkit.event.Listener;
+import org.bukkit.event.player.PlayerJoinEvent;
+import org.bukkit.event.player.PlayerQuitEvent;
+import org.bukkit.event.player.PlayerRespawnEvent;
+
+/** Applies session transitions and identity presentation on Bukkit lifecycle events. */
+public final class StealthSessionListener implements Listener {
+    private final StealthSessionService sessions;
+    private final IdentityPresentation presentation;
+    private final String concealedMessage;
+
+    public StealthSessionListener(
+            StealthSessionService sessions,
+            IdentityPresentation presentation,
+            String concealedMessage) {
+        this.sessions = Objects.requireNonNull(sessions, "sessions");
+        this.presentation = Objects.requireNonNull(presentation, "presentation");
+        this.concealedMessage = Objects.requireNonNull(concealedMessage, "concealedMessage");
+    }
+
+    @EventHandler(priority = EventPriority.HIGHEST)
+    public void onJoin(PlayerJoinEvent event) {
+        Player player = event.getPlayer();
+        StealthSessionService.LoginTransition transition = sessions.login(player.getUniqueId(), player.getName());
+        if (transition.concealed()) {
+            event.setJoinMessage(null);
+            presentation.conceal(player);
+            player.sendMessage(concealedMessage);
+        } else {
+            presentation.reveal(player);
+        }
+        presentation.refreshForObserver(player);
+    }
+
+    @EventHandler(priority = EventPriority.MONITOR)
+    public void onQuit(PlayerQuitEvent event) {
+        presentation.reveal(event.getPlayer());
+        sessions.disconnect(event.getPlayer().getUniqueId());
+    }
+
+    @EventHandler(priority = EventPriority.MONITOR)
+    public void onRespawn(PlayerRespawnEvent event) {
+        if (sessions.isConcealed(event.getPlayer().getUniqueId())) {
+            presentation.conceal(event.getPlayer());
+        }
+    }
+}

src/main/java/games/dmg/spigotstealth/StealthSessionService.java

@@ -0,0 +1,52 @@
+package games.dmg.spigotstealth;
+
+import java.util.Objects;
+import java.util.UUID;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+/** Owns prepared-login and current concealed-session state transitions. */
+public final class StealthSessionService {
+    private final StealthStateManager stateManager;
+    private final QualifyingInvisibilityService progression;
+
+    public StealthSessionService(
+            StealthStateManager stateManager,
+            QualifyingInvisibilityService progression) {
+        this.stateManager = Objects.requireNonNull(stateManager, "stateManager");
+        this.progression = Objects.requireNonNull(progression, "progression");
+    }
+
+    public CompletableFuture<Void> disconnect(UUID playerId) {
+        boolean qualifyingAtDisconnect = progression.isQualifying(playerId);
+        return progression.stop(playerId).thenCompose(ignored -> stateManager.update(state -> {
+            PlayerStealthState player = state.player(playerId);
+            boolean prepareNextLogin = qualifyingAtDisconnect && player.unlocked();
+            return state.withPlayer(player.withSession(prepareNextLogin, false));
+        }));
+    }
+
+    public LoginTransition login(UUID playerId, String playerName) {
+        AtomicBoolean concealed = new AtomicBoolean();
+        CompletableFuture<Void> saved = stateManager.update(state -> {
+            PlayerStealthState player = state.player(playerId).withLastKnownName(playerName);
+            boolean conceal = player.unlocked() && player.preparedLogin();
+            concealed.set(conceal);
+            return state.withPlayer(player.withSession(false, conceal).withQualifyingSince(null));
+        });
+        return new LoginTransition(concealed.get(), saved);
+    }
+
+    public CompletableFuture<Void> endConcealment(UUID playerId) {
+        return stateManager.update(state -> {
+            PlayerStealthState player = state.player(playerId);
+            return state.withPlayer(player.withSession(player.preparedLogin(), false));
+        });
+    }
+
+    public boolean isConcealed(UUID playerId) {
+        return stateManager.snapshot().player(playerId).concealed();
+    }
+
+    public record LoginTransition(boolean concealed, CompletableFuture<Void> saved) { }
+}

src/main/java/games/dmg/spigotstealth/TabListController.java

@@ -0,0 +1,11 @@
+package games.dmg.spigotstealth;
+
+import java.util.UUID;
+import org.bukkit.entity.Player;
+
+/** Packet-level tab-list operations that do not hide the physical player entity. */
+public interface TabListController {
+    void remove(Player observer, UUID targetPlayerId);
+
+    void add(Player observer, Player target);
+}

src/main/resources/plugin.yml

@@ -4,6 +4,7 @@ main: games.dmg.spigotstealth.SpigotStealthPlugin
 api-version: "1.20"
 description: Rewards invisibility potion use with identity-concealed sessions.
 author: dmg.games
+depend: [ProtocolLib]
 commands:
   stealth:
     description: View and use Spigot Stealth features.