feat(stealth): reveal nearby players to eligible Eye wearers

Use private client teams and current recipient-specific metadata authorization without changing server teams, potion effects or other identity channels. Preserve effective team visibility and platform hiding. Add immediate lifecycle invalidation, fail-closed capture and cleanup-before-recreation recovery, verified with native codecs, delivery, ProtocolLib and plugin lifecycle tests. No deployment is included.

README.md

@@ -16,7 +16,9 @@ Earn a separate, personal unlock through eight cumulative online hours of Night
 
 After the unlock is saved, craft an **Eye of True Seeing** with eight Netherite Blocks around an Eye of Ender. Right-click an authenticated Eye in either hand to move it into an empty helmet slot. Existing helmets are not replaced. Traded Eyes still require the holder's own saved unlock; renamed ordinary Eyes do not qualify. Automated crafters cannot bypass progression. Vanilla handles crafting ingredient consumption.
 
-**Local name/body revelation is separate US-008 work and is not implemented by this acquisition story.** Eligibility is checked even for an Eye manually placed in the helmet slot.
+While worn by an eligible player, the Eye reveals active Stealth targets' real overhead names within **16 blocks in three dimensions and line of sight**. It also reveals their bodies if they have gameplay invisibility, only to that observer. Ordinary invisible players without a concealed Stealth session are not revealed. Platform hiding, spectator mode, vanished metadata and effective team name-visibility restrictions take precedence. Eligibility is checked even for an Eye manually placed in the helmet slot.
+
+Revelation uses private client-only teams and recipient-specific metadata; it does not change server teams, remove potion effects or end Stealth sessions. Tab-list, chat, suggestions and server-list concealment remain unchanged, including for the wearer. Unequipping, leaving range/sight, lifecycle changes and disable withdraw the projection and restore current raw state. Failed deliveries revoke authorization and queue cleanup before recreation. Live-client appearance/timing and compatibility remain separate validation follow-ups.
 
 Eye records are independently UUID-keyed in `plugins/SpigotStealth/state.yml` (schema 2). Legacy Stealth records and extension fields are preserved. Crafting/use wait for successful save acknowledgement. Shutdown queues a final snapshot without blocking the tick thread, and initialization callbacks cannot revive a disabled or superseded lifecycle. Unacknowledged progress at abrupt process/power loss is not guaranteed.
 
@@ -28,6 +30,6 @@ The repository and checkout are now `purpur-stealth` (previously remote `spigot-
 
 Replace the old plugin JAR when installing the new distribution; never load both JARs together. Old tags and `spigot-stealth-*` release assets are preserved. Repository rename redirects have been checked against the previously deployed v1.5.0 download. Publishing a release does not authorize deployment.
 
-The v2.0.0 migration itself left the Eye, combat reveal and concealed-chat stories pending. Subsequent Eye acquisition work is described above; Eye revelation, combat reveal and system-chat routing remain separate unfinished stories. Runtime plugin metadata is unchanged.
+The v2.0.0 migration itself left the Eye, combat reveal and concealed-chat stories pending. Subsequent Eye acquisition and local revelation work is described above; combat-session breaking and system-chat routing remain separate unfinished stories. Runtime plugin metadata is unchanged.
 
 See the [canonical project](https://git.garvis.dev/dmg/somc-okf/src/branch/main/projects/purpur-stealth/index.md), [stories](https://git.garvis.dev/dmg/somc-okf/src/branch/main/user-stories/purpur-stealth/index.md), and [development cycle](https://git.garvis.dev/dmg/somc-okf/src/branch/main/runbooks/development-cycle.md).

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

@@ -0,0 +1,66 @@
+package games.dmg.spigotstealth;
+
+import com.comphenix.protocol.PacketType;
+import com.comphenix.protocol.events.ListenerPriority;
+import com.comphenix.protocol.events.PacketAdapter;
+import com.comphenix.protocol.events.PacketContainer;
+import com.comphenix.protocol.events.PacketEvent;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.UUID;
+import java.util.function.Consumer;
+import java.util.function.Supplier;
+import org.bukkit.plugin.Plugin;
+
+/** Outgoing packet projection reads immutable authorization and never queries world or inventory state. */
+public final class EyePacketListener extends PacketAdapter {
+    private final Supplier<Map<UUID, Map<Integer, EyeRevealController.Projection>>> views;
+    private final Consumer<UUID> refresh;
+    private final Consumer<String> warning;
+    private final Set<PacketType> warned = ConcurrentHashMap.newKeySet();
+
+    public EyePacketListener(Plugin plugin, Supplier<Map<UUID, Map<Integer, EyeRevealController.Projection>>> views,
+            Consumer<UUID> refresh, Consumer<String> warning) {
+        super(plugin, ListenerPriority.HIGHEST, PacketType.Play.Server.ENTITY_METADATA, PacketType.Play.Server.SCOREBOARD_TEAM);
+        this.views = Objects.requireNonNull(views);
+        this.refresh = Objects.requireNonNull(refresh);
+        this.warning = Objects.requireNonNull(warning);
+    }
+
+    @Override public void onPacketSending(PacketEvent event) {
+        if (event.isCancelled() || event.getPlayer() == null || event.isPlayerTemporary()) { return; }
+        try {
+            // UUID is immutable connection identity; no inventory, world, visibility or effect queries occur here.
+            UUID viewer = event.getPlayer().getUniqueId();
+            if (viewer == null) { return; }
+            var current = views.get().getOrDefault(viewer, Map.of());
+            if (current.isEmpty()) { return; }
+            Object original = event.getPacket().getHandle();
+            if (event.getPacketType().equals(PacketType.Play.Server.ENTITY_METADATA)) {
+                int id = (Integer) original.getClass().getMethod("id").invoke(original);
+                var projection = current.get(id);
+                if (projection != null && projection.revealBody()) {
+                    event.setPacket(new PacketContainer(event.getPacketType(), EyePacketProjection.metadataPacket(original)));
+                }
+            } else if (event.getPacketType().equals(PacketType.Play.Server.SCOREBOARD_TEAM)) {
+                String name = (String) original.getClass().getMethod("getName").invoke(original);
+                var privateTeams = current.values().stream().map(EyeRevealController.Projection::privateTeam)
+                        .collect(java.util.stream.Collectors.toUnmodifiableSet());
+                var names = current.values().stream().map(EyeRevealController.Projection::playerName)
+                        .collect(java.util.stream.Collectors.toUnmodifiableSet());
+                if (!privateTeams.contains(name) && current.values().stream().anyMatch(p -> p.sourceTeam().filter(name::equals).isPresent())) {
+                    refresh.accept(viewer); // Only marks work; the callback must not query Bukkit here.
+                }
+                Object projected = EyePacketProjection.teamPacket(original, privateTeams, names);
+                if (projected != original) { event.setPacket(new PacketContainer(event.getPacketType(), projected)); }
+            }
+        } catch (ReflectiveOperationException | RuntimeException exception) {
+            if (warned.add(event.getPacketType())) {
+                warning.accept("Eye projection unavailable for " + event.getPacketType()
+                        + "; original packet retained. Failure: " + exception.getClass().getSimpleName());
+            }
+        }
+    }
+}

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

@@ -0,0 +1,115 @@
+package games.dmg.spigotstealth;
+
+import java.lang.reflect.RecordComponent;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Objects;
+
+/** Pure copies of declared-runtime packet data; no Bukkit lookups or global entity/team mutations. */
+public final class EyePacketProjection {
+    private static final String TEAM_PARAMETERS = "net.minecraft.network.protocol.game.ClientboundSetPlayerTeamPacket$Parameters";
+    private EyePacketProjection() { }
+
+    public static Object teamPacket(Object original, java.util.Set<String> privateTeams, java.util.Set<String> projectedPlayers) {
+        Objects.requireNonNull(original, "original");
+        Class<?> type = original.getClass();
+        if (!type.getName().equals("net.minecraft.network.protocol.game.ClientboundSetPlayerTeamPacket")) {
+            throw new IllegalArgumentException("Unsupported native team packet");
+        }
+        try {
+            String name = (String) type.getMethod("getName").invoke(original);
+            var players = (java.util.Collection<?>) type.getMethod("getPlayers").invoke(original);
+            var parameters = (java.util.Optional<?>) type.getMethod("getParameters").invoke(original);
+            boolean privateTeam = privateTeams.contains(name);
+            var projectedParameters = privateTeam ? parameters.map(EyePacketProjection::teamParameters) : parameters;
+            var projectedMembers = privateTeam ? players : players.stream().filter(player -> !projectedPlayers.contains(player)).toList();
+            if (projectedParameters == parameters && projectedMembers.size() == players.size()) { return original; }
+            var method = type.getDeclaredField("method");
+            method.setAccessible(true);
+            var constructor = type.getDeclaredConstructor(String.class, int.class, java.util.Optional.class, java.util.Collection.class);
+            constructor.setAccessible(true);
+            return constructor.newInstance(name, method.getInt(original), projectedParameters, projectedMembers);
+        } catch (ReflectiveOperationException exception) {
+            throw new IllegalStateException("Could not project native team membership", exception);
+        }
+    }
+
+    public static Object metadataPacket(Object original) {
+        Objects.requireNonNull(original, "original");
+        Class<?> type = original.getClass();
+        if (!type.getName().equals("net.minecraft.network.protocol.game.ClientboundSetEntityDataPacket")) {
+            throw new IllegalArgumentException("Unsupported native metadata packet");
+        }
+        try {
+            var values = (List<?>) type.getMethod("packedItems").invoke(original);
+            var projected = new ArrayList<Object>(values.size());
+            for (Object value : values) {
+                Class<?> valueType = value.getClass();
+                if (!valueType.getName().equals("net.minecraft.network.syncher.SynchedEntityData$DataValue")) {
+                    throw new IllegalArgumentException("Unsupported native metadata value");
+                }
+                int index = (Integer) valueType.getMethod("id").invoke(value);
+                if (index != 0) { projected.add(value); continue; }
+                Object raw = valueType.getMethod("value").invoke(value);
+                if (!(raw instanceof Byte flags)) { throw new IllegalArgumentException("Shared entity flags must be a byte"); }
+                Object serializer = valueType.getMethod("serializer").invoke(value);
+                projected.add(valueType.getConstructor(int.class,
+                        Class.forName("net.minecraft.network.syncher.EntityDataSerializer"), Object.class)
+                        .newInstance(index, serializer, (byte) (flags & ~0x20)));
+            }
+            return type.getConstructor(int.class, List.class)
+                    .newInstance(type.getMethod("id").invoke(original), List.copyOf(projected));
+        } catch (ReflectiveOperationException exception) {
+            throw new IllegalStateException("Could not project native entity metadata", exception);
+        }
+    }
+
+    public static Object teamParameters(Object original) {
+        try {
+            Object empty = Class.forName("net.minecraft.network.chat.Component").getMethod("empty").invoke(null);
+            return copyParameters(original, java.util.Map.of("playerPrefix", empty));
+        } catch (ReflectiveOperationException exception) {
+            throw new IllegalStateException("Could not project the native team prefix", exception);
+        }
+    }
+
+    public static Object teamVisibility(Object original, boolean visible) {
+        try {
+            Object visibility = Class.forName("net.minecraft.world.scores.Team$Visibility").getField(visible ? "ALWAYS" : "NEVER").get(null);
+            return copyParameters(original, java.util.Map.of("nameTagVisibility", visibility));
+        } catch (ReflectiveOperationException exception) {
+            throw new IllegalStateException("Could not preserve effective team visibility", exception);
+        }
+    }
+
+    private static Object copyParameters(Object original, java.util.Map<String, Object> replacements) {
+        Objects.requireNonNull(original, "original");
+        Class<?> type = original.getClass();
+        if (!TEAM_PARAMETERS.equals(type.getName()) || !type.isRecord()) {
+            throw new IllegalArgumentException("Unsupported native team parameter layout");
+        }
+        try {
+            RecordComponent[] components = type.getRecordComponents();
+            Class<?>[] types = new Class<?>[components.length];
+            Object[] values = new Object[components.length];
+            int replaced = 0;
+            for (int index = 0; index < components.length; index++) {
+                var component = components[index];
+                types[index] = component.getType();
+                if (replacements.containsKey(component.getName())) {
+                    values[index] = replacements.get(component.getName());
+                    replaced++;
+                } else {
+                    // Accessors may consult global collision configuration. Copy the stored record data verbatim.
+                    var field = type.getDeclaredField(component.getName());
+                    field.setAccessible(true);
+                    values[index] = field.get(original);
+                }
+            }
+            if (replaced != replacements.size()) { throw new IllegalArgumentException("Required native team fields are unavailable"); }
+            return type.getDeclaredConstructor(types).newInstance(values);
+        } catch (ReflectiveOperationException exception) {
+            throw new IllegalStateException("Could not project the native team prefix", exception);
+        }
+    }
+}

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

@@ -0,0 +1,233 @@
+package games.dmg.spigotstealth;
+
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Optional;
+import java.util.Set;
+import java.util.UUID;
+import java.util.function.Predicate;
+import java.util.function.Supplier;
+import org.bukkit.GameMode;
+import org.bukkit.Location;
+import org.bukkit.World;
+import org.bukkit.entity.Player;
+import org.bukkit.metadata.MetadataValue;
+import org.bukkit.potion.PotionEffectType;
+
+/** Server-thread visibility capture and delivery; published projections contain no mutable Bukkit objects. */
+public final class EyeRevealController implements Runnable, AutoCloseable {
+    public record Projection(UUID targetId, int entityId, String playerName, String privateTeam,
+            Optional<String> sourceTeam, boolean revealBody) { }
+    public interface Delivery {
+        void show(Player viewer, Player target, Projection projection, boolean create);
+        void restore(Player viewer, Optional<Player> target, Projection projection);
+    }
+
+    private final Supplier<? extends Collection<? extends Player>> onlinePlayers;
+    private final EyeEquipment equipment;
+    private final Predicate<UUID> concealed;
+    private final Delivery delivery;
+    private final Supplier<String> teamNames;
+    private final java.util.function.Consumer<Throwable> failure;
+    private record RestoreKey(UUID viewer, String team) { }
+    private record TargetKey(UUID viewer, UUID target) { }
+    private final Map<RestoreKey, Projection> restoring = new java.util.LinkedHashMap<>();
+    private final Set<UUID> warned = new HashSet<>();
+    private volatile Map<UUID, Map<Integer, Projection>> views = Map.of();
+    private volatile boolean closed;
+    private final Set<UUID> dirty = java.util.concurrent.ConcurrentHashMap.newKeySet();
+
+    public EyeRevealController(Supplier<? extends Collection<? extends Player>> onlinePlayers, EyeEquipment equipment,
+            Predicate<UUID> concealed, Delivery delivery, Supplier<String> teamNames) {
+        this(onlinePlayers, equipment, concealed, delivery, teamNames,
+                error -> java.util.logging.Logger.getLogger(EyeRevealController.class.getName())
+                        .warning("Eye delivery failed; cleanup queued: " + error.getClass().getSimpleName()));
+    }
+
+    public EyeRevealController(Supplier<? extends Collection<? extends Player>> onlinePlayers, EyeEquipment equipment,
+            Predicate<UUID> concealed, Delivery delivery, Supplier<String> teamNames, java.util.function.Consumer<Throwable> failure) {
+        this.onlinePlayers = Objects.requireNonNull(onlinePlayers);
+        this.equipment = Objects.requireNonNull(equipment);
+        this.concealed = Objects.requireNonNull(concealed);
+        this.delivery = Objects.requireNonNull(delivery);
+        this.teamNames = Objects.requireNonNull(teamNames);
+        this.failure = Objects.requireNonNull(failure);
+    }
+
+    public Map<UUID, Map<Integer, Projection>> snapshot() { return views; }
+
+    /** Packet-thread safe: defer all Bukkit access and actual delivery to the next server-thread frame. */
+    public void requestRefresh(UUID viewer) {
+        if (!closed) { dirty.add(Objects.requireNonNull(viewer)); }
+    }
+
+    @Override public void run() {
+        if (closed) { return; }
+        var requested = Set.copyOf(dirty);
+        requested.forEach(dirty::remove);
+        List<? extends Player> online = List.copyOf(onlinePlayers.get());
+        var players = new HashMap<UUID, Player>();
+        online.forEach(player -> players.put(player.getUniqueId(), player));
+        var attemptedRestores = new HashSet<RestoreKey>();
+        retryRestores(players, attemptedRestores);
+        var blocked = restoring.entrySet().stream().map(entry -> new TargetKey(entry.getKey().viewer(), entry.getValue().targetId()))
+                .collect(java.util.stream.Collectors.toUnmodifiableSet());
+        Map<UUID, Map<Integer, Projection>> previous = views;
+        var usedNames = new HashSet<String>();
+        previous.values().forEach(view -> view.values().forEach(projection -> usedNames.add(projection.privateTeam())));
+        restoring.values().forEach(projection -> usedNames.add(projection.privateTeam()));
+        var next = new HashMap<UUID, Map<Integer, Projection>>();
+        for (Player viewer : online) {
+            try {
+                if (!viewer.isOnline() || viewer.isDead() || !equipment.isEligibleWearer(viewer)) { continue; }
+                Location origin = viewer.getLocation();
+                var observer = new EyeVisibility.Viewer(viewer.getUniqueId(), position(origin), true);
+                var targets = new HashMap<Integer, Projection>();
+                for (Player target : online) {
+                    if (!target.isOnline() || target.isDead() || blocked.contains(new TargetKey(viewer.getUniqueId(), target.getUniqueId()))) { continue; }
+                    Location destination = target.getLocation();
+                    var subject = new EyeVisibility.Target(target.getUniqueId(), position(destination),
+                            concealed.test(target.getUniqueId()), target.getGameMode() == GameMode.SPECTATOR,
+                            target.getMetadata("vanished").stream().anyMatch(MetadataValue::asBoolean));
+                    boolean visible = viewer.canSee(target) && target.getTrackedBy().contains(viewer);
+                    if (!EyeVisibility.canReveal(observer, subject, visible, true)) { continue; }
+                    var sourceTeam = viewer.getScoreboard().getEntryTeam(target.getName());
+                    if (!EyeTeamVisibility.visible(viewer, sourceTeam)
+                            || !chunksLoaded(origin.getWorld(), origin, destination) || !viewer.hasLineOfSight(target)) { continue; }
+                    Projection old = previous.getOrDefault(viewer.getUniqueId(), Map.of()).get(target.getEntityId());
+                    String team = old != null && old.targetId().equals(target.getUniqueId()) && old.playerName().equals(target.getName())
+                            ? old.privateTeam() : allocateTeam(viewer, usedNames);
+                    var baseline = Optional.ofNullable(sourceTeam).map(org.bukkit.scoreboard.Team::getName);
+                    targets.put(target.getEntityId(), new Projection(target.getUniqueId(), target.getEntityId(), target.getName(),
+                            team, baseline, target.hasPotionEffect(PotionEffectType.INVISIBILITY)));
+                }
+                if (!targets.isEmpty()) { next.put(viewer.getUniqueId(), Map.copyOf(targets)); }
+            } catch (RuntimeException error) {
+                // Never retain a stale authorization when an authoritative visibility query fails.
+                report(viewer.getUniqueId(), error);
+            }
+        }
+        views = Map.copyOf(next); // Publish authorization before any outgoing projection/restoration packet.
+        previous.forEach((viewerId, targets) -> {
+            Player viewer = players.get(viewerId);
+            if (viewer == null || !viewer.isOnline()) { return; }
+            targets.values().forEach(old -> {
+                Projection current = views.getOrDefault(viewerId, Map.of()).get(old.entityId());
+                if (current == null || !current.privateTeam().equals(old.privateTeam())) {
+                    restoring.putIfAbsent(new RestoreKey(viewerId, old.privateTeam()), old);
+                }
+            });
+        });
+        retryRestores(players, attemptedRestores);
+        views.forEach((viewerId, targets) -> targets.values().forEach(current -> {
+            Projection old = previous.getOrDefault(viewerId, Map.of()).get(current.entityId());
+            if (!current.equals(old) || requested.contains(viewerId)) {
+                try {
+                    delivery.show(players.get(viewerId), players.get(current.targetId()), current,
+                            old == null || !current.privateTeam().equals(old.privateTeam()));
+                    warned.remove(viewerId);
+                } catch (RuntimeException error) {
+                    deny(viewerId, current.targetId());
+                    restoring.putIfAbsent(new RestoreKey(viewerId, current.privateTeam()), current);
+                    report(viewerId, error);
+                }
+            }
+        }));
+    }
+
+    public void hide(UUID viewer, UUID target) {
+        withdraw((observer, projection) -> observer.equals(viewer) && projection.targetId().equals(target));
+    }
+    public void withdrawViewer(UUID viewer) { withdraw((observer, projection) -> observer.equals(viewer)); }
+    public void withdrawTarget(UUID target) { withdraw((observer, projection) -> projection.targetId().equals(target)); }
+
+    /** Lifecycle callbacks call this on the server thread before the next scheduled visibility capture. */
+    private void withdraw(java.util.function.BiPredicate<UUID, Projection> remove) {
+        var previous = views;
+        var next = new HashMap<UUID, Map<Integer, Projection>>();
+        previous.forEach((viewer, targets) -> {
+            var retained = new HashMap<Integer, Projection>();
+            targets.forEach((id, projection) -> { if (!remove.test(viewer, projection)) { retained.put(id, projection); } });
+            if (!retained.isEmpty()) { next.put(viewer, Map.copyOf(retained)); }
+        });
+        views = Map.copyOf(next);
+        var players = new HashMap<UUID, Player>();
+        onlinePlayers.get().forEach(player -> players.put(player.getUniqueId(), player));
+        previous.forEach((viewerId, targets) -> {
+            Player viewer = players.get(viewerId);
+            if (viewer != null && viewer.isOnline()) {
+                targets.values().stream().filter(projection -> remove.test(viewerId, projection))
+                        .forEach(projection -> restoring.putIfAbsent(new RestoreKey(viewerId, projection.privateTeam()), projection));
+            }
+        });
+        retryRestores(players, new HashSet<>());
+    }
+
+    @Override public void close() {
+        if (closed && restoring.isEmpty()) { return; }
+        closed = true;
+        dirty.clear();
+        withdraw((viewer, projection) -> true);
+    }
+
+    private void retryRestores(Map<UUID, Player> players, Set<RestoreKey> attempted) {
+        for (var entry : List.copyOf(restoring.entrySet())) {
+            var key = entry.getKey();
+            if (!attempted.add(key)) { continue; }
+            var projection = entry.getValue();
+            Player viewer = players.get(key.viewer());
+            if (viewer == null || !viewer.isOnline()) { restoring.remove(key); continue; }
+            try {
+                delivery.restore(viewer, Optional.ofNullable(players.get(projection.targetId())), projection);
+                restoring.remove(key);
+            } catch (RuntimeException error) {
+                deny(key.viewer(), projection.targetId());
+                report(key.viewer(), error);
+            }
+        }
+    }
+
+    private void deny(UUID viewer, UUID target) {
+        var next = new HashMap<>(views);
+        var retained = new HashMap<>(next.getOrDefault(viewer, Map.of()));
+        retained.values().removeIf(projection -> projection.targetId().equals(target));
+        if (retained.isEmpty()) { next.remove(viewer); }
+        else { next.put(viewer, Map.copyOf(retained)); }
+        views = Map.copyOf(next);
+    }
+
+    private void report(UUID viewer, RuntimeException error) {
+        if (warned.add(viewer)) { failure.accept(error); }
+    }
+
+    private String allocateTeam(Player viewer, Set<String> used) {
+        for (int attempt = 0; attempt < 32; attempt++) {
+            String name = teamNames.get();
+            if (name != null && name.matches("[a-zA-Z0-9_-]{1,16}") && !used.contains(name)
+                    && viewer.getScoreboard().getTeam(name) == null) {
+                used.add(name);
+                return name;
+            }
+        }
+        throw new IllegalStateException("Could not allocate an isolated Eye team name");
+    }
+
+    private static EyeVisibility.Position position(Location location) {
+        return new EyeVisibility.Position(location.getWorld().getUID(), location.getX(), location.getY(), location.getZ());
+    }
+
+    private static boolean chunksLoaded(World world, Location from, Location to) {
+        int minX = (int) Math.floor(Math.min(from.getX(), to.getX())) >> 4;
+        int maxX = (int) Math.floor(Math.max(from.getX(), to.getX())) >> 4;
+        int minZ = (int) Math.floor(Math.min(from.getZ(), to.getZ())) >> 4;
+        int maxZ = (int) Math.floor(Math.max(from.getZ(), to.getZ())) >> 4;
+        for (int x = minX; x <= maxX; x++) {
+            for (int z = minZ; z <= maxZ; z++) { if (!world.isChunkLoaded(x, z)) { return false; } }
+        }
+        return true;
+    }
+}

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

@@ -0,0 +1,57 @@
+package games.dmg.spigotstealth;
+
+import com.destroystokyo.paper.event.player.PlayerArmorChangeEvent;
+import io.papermc.paper.event.player.PlayerUntrackEntityEvent;
+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.entity.PlayerDeathEvent;
+import org.bukkit.event.player.PlayerChangedWorldEvent;
+import org.bukkit.event.player.PlayerGameModeChangeEvent;
+import org.bukkit.event.player.PlayerHideEntityEvent;
+import org.bukkit.event.player.PlayerQuitEvent;
+import org.bukkit.event.player.PlayerRespawnEvent;
+import org.bukkit.event.player.PlayerTeleportEvent;
+
+/** Immediate server-thread invalidation; ordinary motion and line-of-sight changes are polled each tick. */
+public final class EyeRevealEvents implements Listener {
+    private final EyeRevealController controller;
+    public EyeRevealEvents(EyeRevealController controller) { this.controller = java.util.Objects.requireNonNull(controller); }
+
+    @EventHandler(priority = EventPriority.MONITOR) public void onHide(PlayerHideEntityEvent event) {
+        if (event.getEntity() instanceof org.bukkit.entity.Player player) { controller.hide(event.getPlayer().getUniqueId(), player.getUniqueId()); }
+    }
+    @EventHandler(priority = EventPriority.MONITOR) public void onUntrack(PlayerUntrackEntityEvent event) {
+        if (event.getEntity() instanceof org.bukkit.entity.Player player) { controller.hide(event.getPlayer().getUniqueId(), player.getUniqueId()); }
+    }
+    @EventHandler(priority = EventPriority.MONITOR) public void onArmor(PlayerArmorChangeEvent event) {
+        if (event.getSlot() == org.bukkit.inventory.EquipmentSlot.HEAD) { controller.withdrawViewer(event.getPlayer().getUniqueId()); }
+    }
+    @EventHandler(priority = EventPriority.MONITOR, ignoreCancelled = true) public void onGameMode(PlayerGameModeChangeEvent event) {
+        if (!event.isCancelled() && event.getNewGameMode() == org.bukkit.GameMode.SPECTATOR) { both(event.getPlayer().getUniqueId()); }
+    }
+    @EventHandler(priority = EventPriority.MONITOR, ignoreCancelled = true) public void onEffect(EntityPotionEffectEvent event) {
+        if (!event.isCancelled() && event.getEntity() instanceof org.bukkit.entity.Player player
+                && org.bukkit.potion.PotionEffectType.INVISIBILITY.equals(event.getModifiedType())) {
+            controller.withdrawTarget(player.getUniqueId());
+        }
+    }
+    @EventHandler(priority = EventPriority.MONITOR) public void onQuit(PlayerQuitEvent event) { both(event.getPlayer().getUniqueId()); }
+    @EventHandler(priority = EventPriority.MONITOR, ignoreCancelled = true) public void onTeleport(PlayerTeleportEvent event) {
+        if (!event.isCancelled()) { both(event.getPlayer().getUniqueId()); }
+    }
+    @EventHandler(priority = EventPriority.MONITOR) public void onRespawn(PlayerRespawnEvent event) { both(event.getPlayer().getUniqueId()); }
+    @EventHandler(priority = EventPriority.MONITOR, ignoreCancelled = true) public void onDeath(PlayerDeathEvent event) {
+        if (!cancelled(event)) { both(event.getEntity().getUniqueId()); }
+    }
+    @EventHandler(priority = EventPriority.MONITOR) public void onWorld(PlayerChangedWorldEvent event) { both(event.getPlayer().getUniqueId()); }
+
+    private void both(java.util.UUID player) {
+        controller.withdrawViewer(player);
+        controller.withdrawTarget(player);
+    }
+    private static boolean cancelled(org.bukkit.event.Event event) {
+        return event instanceof org.bukkit.event.Cancellable cancellable && cancellable.isCancelled();
+    }
+}

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

@@ -0,0 +1,58 @@
+package games.dmg.spigotstealth;
+
+import com.comphenix.protocol.ProtocolManager;
+import java.util.Objects;
+import java.util.UUID;
+import java.util.function.Predicate;
+import org.bukkit.event.HandlerList;
+import org.bukkit.plugin.java.JavaPlugin;
+import org.bukkit.scheduler.BukkitTask;
+
+/** Owns only the Eye's viewer-specific runtime and its lifecycle resources. */
+final class EyeRevealRuntime implements AutoCloseable {
+    private final JavaPlugin plugin;
+    private final ProtocolManager protocol;
+    private final EyeRevealController controller;
+    private final EyePacketListener packets;
+    private final EyeRevealEvents events;
+    private BukkitTask task;
+    private boolean started;
+    private boolean closed;
+
+    EyeRevealRuntime(JavaPlugin plugin, EyeEquipment equipment, Predicate<UUID> concealed, ProtocolManager protocol) {
+        this.plugin = Objects.requireNonNull(plugin);
+        this.protocol = Objects.requireNonNull(protocol);
+        controller = new EyeRevealController(plugin.getServer()::getOnlinePlayers, equipment, concealed, new NativeEyeDelivery(),
+                () -> UUID.randomUUID().toString().replace("-", "").substring(0, 16),
+                failure -> plugin.getLogger().warning("Eye rendering failed; unsafe views withheld: " + failure.getClass().getSimpleName()));
+        packets = new EyePacketListener(plugin, controller::snapshot, controller::requestRefresh, plugin.getLogger()::warning);
+        events = new EyeRevealEvents(controller);
+    }
+
+    public void start() {
+        if (closed) { throw new IllegalStateException("Eye runtime is closed"); }
+        if (started) { return; }
+        if (!plugin.isEnabled()) { throw new IllegalStateException("Cannot start Eye rendering for a disabled plugin"); }
+        started = true;
+        try {
+            protocol.addPacketListener(packets);
+            plugin.getServer().getPluginManager().registerEvents(events, plugin);
+            task = plugin.getServer().getScheduler().runTaskTimer(plugin, controller, 1L, 1L);
+        } catch (RuntimeException exception) {
+            close();
+            throw exception;
+        }
+    }
+
+    @Override public void close() {
+        if (closed) { return; }
+        closed = true;
+        if (task != null) { task.cancel(); }
+        try {
+            controller.close(); // Withdraw authorization and restore raw state before unregistering the outgoing gate.
+        } finally {
+            protocol.removePacketListener(packets);
+            HandlerList.unregisterAll(events);
+        }
+    }
+}

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

@@ -0,0 +1,20 @@
+package games.dmg.spigotstealth;
+
+import org.bukkit.entity.Player;
+import org.bukkit.scoreboard.Team;
+
+/** Preserve effective name visibility when a viewer-only team changes client membership relationships. */
+final class EyeTeamVisibility {
+    private EyeTeamVisibility() { }
+    static boolean visible(Player viewer, Team source) {
+        if (source == null) { return true; }
+        boolean sameTeam = source.equals(viewer.getScoreboard().getEntryTeam(viewer.getName()));
+        return switch (source.getOption(Team.Option.NAME_TAG_VISIBILITY)) {
+            case ALWAYS -> true;
+            case NEVER -> false;
+            // CraftTeam maps these to native HIDE_FOR_* values by ordinal, not to SHOW_FOR_*.
+            case FOR_OWN_TEAM -> !sameTeam;
+            case FOR_OTHER_TEAMS -> sameTeam;
+        };
+    }
+}

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

@@ -0,0 +1,21 @@
+package games.dmg.spigotstealth;
+
+import java.util.UUID;
+
+/** Immutable, platform-independent inputs to the local Eye reveal decision. */
+public final class EyeVisibility {
+    private EyeVisibility() { }
+    public record Position(UUID world, double x, double y, double z) { }
+    public record Viewer(UUID id, Position position, boolean eligible) { }
+    public record Target(UUID id, Position position, boolean concealed, boolean spectator, boolean vanished) { }
+
+    public static boolean canReveal(Viewer viewer, Target target, boolean visibleToViewer, boolean lineOfSight) {
+        if (!viewer.eligible() || !target.concealed() || target.spectator() || target.vanished()
+                || !visibleToViewer || !lineOfSight || viewer.id().equals(target.id())
+                || !viewer.position().world().equals(target.position().world())) { return false; }
+        double dx = viewer.position().x() - target.position().x();
+        double dy = viewer.position().y() - target.position().y();
+        double dz = viewer.position().z() - target.position().z();
+        return dx * dx + dy * dy + dz * dz <= 16.0 * 16.0;
+    }
+}

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

@@ -0,0 +1,108 @@
+package games.dmg.spigotstealth;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import java.util.Optional;
+import org.bukkit.entity.Player;
+
+/** Main-thread native packet preparation/delivery. Outgoing authorization performs the final projection. */
+final class NativeEyeDelivery implements EyeRevealController.Delivery {
+    private final Constructor<?> teamPacket;
+    private final Constructor<?> parameters;
+    private final Constructor<?> scoreboard;
+    private final Constructor<?> playerTeam;
+    private final Constructor<?> metadata;
+    private final Constructor<?> dataValue;
+    private final Field nativeTeam;
+    private final Method playerHandle;
+    private final Method entityData;
+    private final Method dataGet;
+    private final Object sharedFlags;
+    private final Object byteSerializer;
+    private final Field connection;
+    private final Method sendPacket;
+
+    NativeEyeDelivery() {
+        try {
+            Class<?> team = Class.forName("net.minecraft.world.scores.PlayerTeam");
+            Class<?> board = Class.forName("net.minecraft.world.scores.Scoreboard");
+            teamPacket = Class.forName("net.minecraft.network.protocol.game.ClientboundSetPlayerTeamPacket")
+                    .getDeclaredConstructor(String.class, int.class, Optional.class, Collection.class);
+            teamPacket.setAccessible(true);
+            parameters = Class.forName("net.minecraft.network.protocol.game.ClientboundSetPlayerTeamPacket$Parameters")
+                    .getConstructor(team);
+            scoreboard = board.getConstructor();
+            playerTeam = team.getConstructor(board, String.class);
+            nativeTeam = Class.forName("org.bukkit.craftbukkit.scoreboard.CraftTeam").getDeclaredField("team");
+            nativeTeam.setAccessible(true);
+            playerHandle = Class.forName("org.bukkit.craftbukkit.entity.CraftPlayer").getMethod("getHandle");
+            Class<?> entity = Class.forName("net.minecraft.world.entity.Entity");
+            entityData = entity.getMethod("getEntityData");
+            var flags = entity.getDeclaredField("DATA_SHARED_FLAGS_ID");
+            flags.setAccessible(true);
+            sharedFlags = flags.get(null);
+            Class<?> accessor = Class.forName("net.minecraft.network.syncher.EntityDataAccessor");
+            dataGet = Class.forName("net.minecraft.network.syncher.SynchedEntityData").getMethod("get", accessor);
+            byteSerializer = Class.forName("net.minecraft.network.syncher.EntityDataSerializers").getField("BYTE").get(null);
+            dataValue = Class.forName("net.minecraft.network.syncher.SynchedEntityData$DataValue").getConstructor(
+                    int.class, Class.forName("net.minecraft.network.syncher.EntityDataSerializer"), Object.class);
+            metadata = Class.forName("net.minecraft.network.protocol.game.ClientboundSetEntityDataPacket").getConstructor(int.class, List.class);
+            connection = Class.forName("net.minecraft.server.level.ServerPlayer").getField("connection");
+            sendPacket = Class.forName("net.minecraft.server.network.ServerCommonPacketListenerImpl")
+                    .getMethod("send", Class.forName("net.minecraft.network.protocol.Packet"));
+        } catch (ReflectiveOperationException exception) {
+            throw new IllegalStateException("Native Eye delivery is unsupported on this server version", exception);
+        }
+    }
+
+    @Override public void show(Player viewer, Player target, EyeRevealController.Projection projection, boolean create) {
+        try {
+            var source = viewer.getScoreboard().getEntryTeam(projection.playerName());
+            Object basis = source == null ? playerTeam.newInstance(scoreboard.newInstance(), projection.privateTeam()) : nativeTeam.get(source);
+            // Send unprojected data. The packet listener checks the latest per-viewer authorization at dispatch.
+            Object privateParameters = EyePacketProjection.teamVisibility(parameters.newInstance(basis), EyeTeamVisibility.visible(viewer, source));
+            Object team = teamPacket.newInstance(projection.privateTeam(), create ? 0 : 2,
+                    Optional.of(privateParameters), create ? List.of(projection.playerName()) : List.of());
+            var packets = List.of(team, rawMetadata(target));
+            for (Object packet : packets) { send(viewer, packet); }
+        } catch (ReflectiveOperationException exception) {
+            throw new IllegalStateException("Could not deliver a private Eye view", exception);
+        }
+    }
+
+    @Override public void restore(Player viewer, Optional<Player> target, EyeRevealController.Projection projection) {
+        try {
+            var packets = new ArrayList<Object>();
+            var source = viewer.getScoreboard().getEntryTeam(projection.playerName());
+            Object basis = source == null ? playerTeam.newInstance(scoreboard.newInstance(), projection.privateTeam()) : nativeTeam.get(source);
+            Object baseline = parameters.newInstance(basis);
+            // Restore presentation before changing membership, avoiding a temporary unteamed/plain-name gap.
+            packets.add(teamPacket.newInstance(projection.privateTeam(), 2,
+                    Optional.of(EyePacketProjection.teamVisibility(baseline, EyeTeamVisibility.visible(viewer, source))), List.of()));
+            if (target.isPresent() && target.orElseThrow().isOnline()) { packets.add(rawMetadata(target.orElseThrow())); }
+            if (source != null) {
+                packets.add(teamPacket.newInstance(source.getName(), 2, Optional.of(baseline), List.of()));
+                packets.add(teamPacket.newInstance(source.getName(), 3, Optional.empty(), List.of(projection.playerName())));
+            }
+            packets.add(teamPacket.newInstance(projection.privateTeam(), 1, Optional.empty(), List.of()));
+            // Prepare everything before sending, avoiding half-created views on reflection/layout failures.
+            for (Object packet : packets) { send(viewer, packet); }
+        } catch (ReflectiveOperationException exception) {
+            throw new IllegalStateException("Could not restore an Eye observer's baseline", exception);
+        }
+    }
+
+    private Object rawMetadata(Player player) throws ReflectiveOperationException {
+        Object value = dataGet.invoke(entityData.invoke(playerHandle.invoke(player)), sharedFlags);
+        if (!(value instanceof Byte)) { throw new IllegalStateException("Native player flags are unavailable"); }
+        return metadata.newInstance(player.getEntityId(), List.of(dataValue.newInstance(0, byteSerializer, value)));
+    }
+
+    private void send(Player viewer, Object packet) throws ReflectiveOperationException {
+        sendPacket.invoke(connection.get(playerHandle.invoke(viewer)), packet);
+    }
+}

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

@@ -22,6 +22,7 @@ public final class SpigotStealthPlugin extends JavaPlugin {
     private EyeProgressionService eyeProgression;
     private EyePotionListener eyePotions;
     private boolean eyeRecipeRegistered;
+    private EyeRevealRuntime eyeReveal;
 
     @Override
     public void onEnable() {
@@ -68,6 +69,7 @@ public final class SpigotStealthPlugin extends JavaPlugin {
                 logSaveFailure(eyeProgression.stopAll());
             }
             if (progression != null) { logSaveFailure(progression.stopAll()); }
+            if (eyeReveal != null) { eyeReveal.close(); }
             if (protocolManager != null) { protocolManager.removePacketListeners(this); }
             if (identityPresentation != null && sessions != null) {
                 for (org.bukkit.entity.Player player : getServer().getOnlinePlayers()) {
@@ -166,7 +168,16 @@ public final class SpigotStealthPlugin extends JavaPlugin {
         eyeRecipeRegistered = true;
         getServer().getPluginManager().registerEvents(eyePotions, this);
         getServer().getPluginManager().registerEvents(eyeCrafting, this);
-        getServer().getPluginManager().registerEvents(new EyeEquipment(eyeProgression, eyeItems), this);
+        var eyeEquipment = new EyeEquipment(eyeProgression, eyeItems);
+        getServer().getPluginManager().registerEvents(eyeEquipment, this);
+        try {
+            eyeReveal = new EyeRevealRuntime(this, eyeEquipment, sessions::isConcealed, protocolManager);
+            eyeReveal.start();
+        } catch (RuntimeException exception) {
+            getLogger().severe("Unable to initialize Eye rendering: " + rootMessage(exception));
+            getServer().getPluginManager().disablePlugin(this);
+            return;
+        }
         getServer().getScheduler().runTaskTimer(this, ignored -> {
             eyePotions.checkpoint(getServer()::getPlayer);
             for (var player : getServer().getOnlinePlayers()) {

src/nativeTest/java/games/dmg/spigotstealth/EyeMetadataProjectionTest.java

@@ -0,0 +1,58 @@
+package games.dmg.spigotstealth;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import io.netty.buffer.Unpooled;
+import java.util.List;
+import net.minecraft.network.RegistryFriendlyByteBuf;
+import net.minecraft.network.protocol.game.ClientboundSetEntityDataPacket;
+import net.minecraft.network.syncher.EntityDataAccessor;
+import net.minecraft.network.syncher.EntityDataSerializers;
+import net.minecraft.network.syncher.SynchedEntityData;
+import org.bukkit.craftbukkit.CraftRegistry;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+class EyeMetadataProjectionTest {
+    @BeforeAll static void bootstrap() throws Exception { NativeRuntime.bootstrap(); }
+
+    @Test
+    void nativeMetadataProjectionClearsOnlyInvisibilityAndKeepsTheSharedPacketUnchanged() throws Exception {
+        var config = new io.papermc.paper.configuration.GlobalConfiguration();
+        config.anticheat = config.new Anticheat();
+        config.anticheat.obfuscation = config.anticheat.new Obfuscation();
+        config.anticheat.obfuscation.items = config.anticheat.obfuscation.new Items();
+        var server = org.mockito.Mockito.mock(net.minecraft.server.MinecraftServer.class);
+        org.mockito.Mockito.when(server.registryAccess()).thenReturn(CraftRegistry.getMinecraftRegistry().freeze());
+        try (var runtime = org.mockito.Mockito.mockStatic(net.minecraft.server.MinecraftServer.class);
+                var platform = org.mockito.Mockito.mockStatic(io.papermc.paper.configuration.GlobalConfiguration.class)) {
+            runtime.when(net.minecraft.server.MinecraftServer::getServer).thenReturn(server);
+            platform.when(io.papermc.paper.configuration.GlobalConfiguration::get).thenReturn(config);
+            config.anticheat.obfuscation.items.bindDataSanitizer();
+            assertProjection();
+        }
+    }
+
+    private static void assertProjection() throws Exception {
+        var accessorField = net.minecraft.world.entity.Entity.class.getDeclaredField("DATA_SHARED_FLAGS_ID");
+        accessorField.setAccessible(true);
+        var accessor = assertInstanceOf(EntityDataAccessor.class, accessorField.get(null));
+        assertEquals(0, accessor.id());
+        assertSame(EntityDataSerializers.BYTE, accessor.serializer());
+        for (int flags = 0; flags <= 255; flags++) {
+            var sharedFlags = new SynchedEntityData.DataValue<>(0, EntityDataSerializers.BYTE, (byte) flags);
+            var air = new SynchedEntityData.DataValue<>(1, EntityDataSerializers.INT, 300);
+            var original = new ClientboundSetEntityDataPacket(42, List.of(sharedFlags, air));
+            var projected = assertInstanceOf(ClientboundSetEntityDataPacket.class, EyePacketProjection.metadataPacket(original));
+            assertEquals(42, projected.id());
+            assertEquals((byte) (flags & ~0x20), projected.packedItems().getFirst().value(), "flag byte " + flags);
+            assertSame(air, projected.packedItems().get(1));
+            assertEquals((byte) flags, original.packedItems().getFirst().value());
+            var buffer = new RegistryFriendlyByteBuf(Unpooled.buffer(), CraftRegistry.getMinecraftRegistry());
+            try {
+                ClientboundSetEntityDataPacket.STREAM_CODEC.encode(buffer, projected);
+                assertEquals(projected, ClientboundSetEntityDataPacket.STREAM_CODEC.decode(buffer));
+            } finally { buffer.release(); }
+        }
+    }
+}

src/nativeTest/java/games/dmg/spigotstealth/EyePacketListenerTest.java

@@ -0,0 +1,122 @@
+package games.dmg.spigotstealth;
+
+import static org.junit.jupiter.api.Assertions.*;
+import static org.mockito.Mockito.*;
+
+import com.comphenix.protocol.PacketType;
+import com.comphenix.protocol.events.PacketContainer;
+import com.comphenix.protocol.events.PacketEvent;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+import java.util.UUID;
+import java.util.concurrent.atomic.AtomicReference;
+import net.minecraft.network.protocol.game.ClientboundSetEntityDataPacket;
+import net.minecraft.network.syncher.EntityDataSerializers;
+import net.minecraft.network.syncher.SynchedEntityData;
+import org.bukkit.entity.Player;
+import org.bukkit.plugin.Plugin;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+class EyePacketListenerTest {
+    @BeforeAll static void bootstrap() throws Exception { NativeRuntime.bootstrap(); }
+
+    @Test
+    @SuppressWarnings("try")
+    void metadataIsProjectedOnlyForTheCurrentlyAuthorizedRecipientWithoutMutatingSharedPackets() {
+        var server = mock(org.bukkit.craftbukkit.CraftServer.class);
+        try (var platform = mockStatic(org.bukkit.Bukkit.class, call -> switch (call.getMethod().getName()) {
+            case "getServer" -> server;
+            case "isPrimaryThread" -> true;
+            case "getVersion" -> "Purpur 2618 (MC: 26.2)";
+            case "getMinecraftVersion" -> "26.2";
+            case "getBukkitVersion" -> "26.2-R0.1-SNAPSHOT";
+            default -> call.callRealMethod();
+        })) {
+            UUID viewerId = UUID.randomUUID();
+            var viewer = mock(Player.class);
+            when(viewer.getUniqueId()).thenReturn(viewerId);
+            var other = mock(Player.class);
+            when(other.getUniqueId()).thenReturn(UUID.randomUUID());
+            var projection = new EyeRevealController.Projection(UUID.randomUUID(), 42, "Concealed", "eye-private", Optional.of("source"), true);
+            var snapshot = new AtomicReference<>(Map.of(viewerId, Map.of(42, projection)));
+            var warnings = new ArrayList<String>();
+            var dirty = new ArrayList<UUID>();
+            var listener = new EyePacketListener(mock(Plugin.class), snapshot::get, dirty::add, warnings::add);
+            assertEquals(Set.of(PacketType.Play.Server.ENTITY_METADATA, PacketType.Play.Server.SCOREBOARD_TEAM),
+                    listener.getSendingWhitelist().getTypes());
+            var raw = new ClientboundSetEntityDataPacket(42, List.of(new SynchedEntityData.DataValue<>(0, EntityDataSerializers.BYTE, (byte) 0x63)));
+            var shared = new PacketContainer(PacketType.Play.Server.ENTITY_METADATA, raw);
+            var first = PacketEvent.fromServer(this, shared, viewer);
+            listener.onPacketSending(first);
+            var shown = assertInstanceOf(ClientboundSetEntityDataPacket.class, first.getPacket().getHandle());
+            assertEquals((byte) 0x43, shown.packedItems().getFirst().value());
+            assertEquals((byte) 0x63, raw.packedItems().getFirst().value());
+            var second = PacketEvent.fromServer(this, shared, other);
+            listener.onPacketSending(second);
+            assertSame(shared, second.getPacket());
+            snapshot.set(Map.of());
+            var late = PacketEvent.fromServer(this, shared, viewer);
+            listener.onPacketSending(late);
+            assertSame(shared, late.getPacket(), "queued packets must use current, not captured authorization");
+            snapshot.set(Map.of(viewerId, Map.of(42, projection)));
+            var cancelled = PacketEvent.fromServer(this, shared, viewer);
+            cancelled.setCancelled(true);
+            listener.onPacketSending(cancelled);
+            assertTrue(cancelled.isCancelled());
+            assertSame(shared, cancelled.getPacket());
+            var noBody = new EyeRevealController.Projection(projection.targetId(), 42, projection.playerName(),
+                    projection.privateTeam(), projection.sourceTeam(), false);
+            snapshot.set(Map.of(viewerId, Map.of(42, noBody)));
+            var notGameplayInvisible = PacketEvent.fromServer(this, shared, viewer);
+            listener.onPacketSending(notGameplayInvisible);
+            assertSame(shared, notGameplayInvisible.getPacket());
+            snapshot.set(Map.of(viewerId, Map.of(42, projection)));
+            var board = new net.minecraft.world.scores.Scoreboard();
+            var privateTeam = board.addPlayerTeam("eye-private");
+            privateTeam.setPlayerPrefix(net.minecraft.network.chat.Component.empty().withStyle(net.minecraft.ChatFormatting.OBFUSCATED));
+            board.addPlayerToTeam("Concealed", privateTeam);
+            var privateRaw = net.minecraft.network.protocol.game.ClientboundSetPlayerTeamPacket.createAddOrModifyPacket(privateTeam, true);
+            var privateWrapped = new PacketContainer(PacketType.Play.Server.SCOREBOARD_TEAM, privateRaw);
+            var privateEvent = PacketEvent.fromServer(this, privateWrapped, viewer);
+            listener.onPacketSending(privateEvent);
+            var shownTeam = assertInstanceOf(net.minecraft.network.protocol.game.ClientboundSetPlayerTeamPacket.class, privateEvent.getPacket().getHandle());
+            assertFalse(shownTeam.getParameters().orElseThrow().playerPrefix().getStyle().isObfuscated());
+            assertTrue(privateRaw.getParameters().orElseThrow().playerPrefix().getStyle().isObfuscated());
+            assertTrue(dirty.isEmpty(), "our own private updates must not create a refresh loop");
+            var source = board.addPlayerTeam("source");
+            source.setPlayerPrefix(net.minecraft.network.chat.Component.empty().withStyle(net.minecraft.ChatFormatting.OBFUSCATED));
+            board.addPlayerToTeam("Concealed", source);
+            board.addPlayerToTeam("Other", source);
+            var sourceRaw = net.minecraft.network.protocol.game.ClientboundSetPlayerTeamPacket.createAddOrModifyPacket(source, true);
+            var sourceWrapped = new PacketContainer(PacketType.Play.Server.SCOREBOARD_TEAM, sourceRaw);
+            var sourceEvent = PacketEvent.fromServer(this, sourceWrapped, viewer);
+            listener.onPacketSending(sourceEvent);
+            var filtered = assertInstanceOf(net.minecraft.network.protocol.game.ClientboundSetPlayerTeamPacket.class, sourceEvent.getPacket().getHandle());
+            assertEquals(Set.of("Other"), Set.copyOf(filtered.getPlayers()));
+            assertTrue(filtered.getParameters().orElseThrow().playerPrefix().getStyle().isObfuscated());
+            assertEquals(List.of(viewerId), dirty, "source style updates request a main-thread refresh");
+            var otherEvent = PacketEvent.fromServer(this, sourceWrapped, other);
+            listener.onPacketSending(otherEvent);
+            assertSame(sourceWrapped, otherEvent.getPacket());
+            var system = new PacketContainer(PacketType.Play.Server.SYSTEM_CHAT,
+                    new net.minecraft.network.protocol.game.ClientboundSystemChatPacket(net.minecraft.network.chat.Component.literal("Unchanged"), false));
+            var systemEvent = PacketEvent.fromServer(this, system, viewer);
+            listener.onPacketSending(systemEvent);
+            assertSame(system, systemEvent.getPacket());
+            var tabRemoval = new PacketContainer(PacketType.Play.Server.PLAYER_INFO_REMOVE);
+            tabRemoval.getUUIDLists().write(0, List.of(projection.targetId()));
+            var tabEvent = PacketEvent.fromServer(this, tabRemoval, viewer);
+            listener.onPacketSending(tabEvent);
+            assertSame(tabRemoval, tabEvent.getPacket());
+            assertEquals(List.of(projection.targetId()), tabEvent.getPacket().getUUIDLists().read(0));
+            assertTrue(warnings.isEmpty());
+            verify(viewer, never()).getInventory();
+            verify(viewer, never()).getWorld();
+            verify(viewer, never()).hasLineOfSight(any(org.bukkit.entity.Entity.class));
+        }
+    }
+}

src/nativeTest/java/games/dmg/spigotstealth/EyePluginLifecycleTest.java

@@ -100,6 +100,9 @@ class EyePluginLifecycleTest {
             default -> call.callRealMethod();
         }); var protocol = mockStatic(ProtocolLibrary.class)) {
             var protocolManager = mock(ProtocolManager.class);
+            var registeredPackets = new ArrayList<com.comphenix.protocol.events.PacketListener>();
+            doAnswer(call -> { registeredPackets.add(call.getArgument(0)); return null; }).when(protocolManager).addPacketListener(any());
+            doAnswer(call -> { registeredPackets.remove(call.getArgument(0)); return null; }).when(protocolManager).removePacketListener(any());
             protocol.when(ProtocolLibrary::getProtocolManager).thenReturn(protocolManager);
             try {
                 plugin.onEnable();
@@ -133,6 +136,8 @@ class EyePluginLifecycleTest {
                 assertTrue(new EyeItems().isEye(recipe.get().getResult()));
                 assertTrue(listeners.stream().anyMatch(EyePotionListener.class::isInstance));
                 assertTrue(listeners.stream().anyMatch(EyeEquipment.class::isInstance));
+                assertTrue(listeners.stream().anyMatch(EyeRevealEvents.class::isInstance), "plugin startup must register reveal invalidation hooks");
+                assertTrue(registeredPackets.stream().anyMatch(EyePacketListener.class::isInstance), "plugin startup must register the per-observer packet gate");
                 var inventory = mock(CraftingInventory.class);
                 when(inventory.getRecipe()).thenAnswer(ignored -> recipe.get());
                 var result = new AtomicReference<>(recipe.get().getResult());

src/nativeTest/java/games/dmg/spigotstealth/EyeRevealControllerTest.java

@@ -0,0 +1,335 @@
+package games.dmg.spigotstealth;
+
+import static org.junit.jupiter.api.Assertions.*;
+import static org.mockito.Mockito.*;
+
+import java.nio.file.Path;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+import java.util.UUID;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicReference;
+import org.bukkit.GameMode;
+import org.bukkit.Location;
+import org.bukkit.Material;
+import org.bukkit.World;
+import org.bukkit.entity.Player;
+import org.bukkit.inventory.ItemStack;
+import org.bukkit.inventory.PlayerInventory;
+import org.bukkit.potion.PotionEffectType;
+import org.bukkit.scoreboard.Scoreboard;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+class EyeRevealControllerTest {
+    @TempDir Path directory;
+    @BeforeAll static void bootstrap() throws Exception { NativeRuntime.bootstrap(); }
+
+    @Test
+    void onlyTheEligibleObserverGetsAnImmutableProjectionAndUnequippingRestoresTheBaseline() throws Exception {
+        var world = mock(World.class);
+        when(world.getUID()).thenReturn(UUID.randomUUID());
+        when(world.isChunkLoaded(anyInt(), anyInt())).thenReturn(true);
+        var viewer = player(world, "Viewer", 1, 0);
+        var unearned = player(world, "Unearned", 2, 0);
+        var target = player(world, "Concealed", 42, 8);
+        when(target.getTrackedBy()).thenReturn(Set.of(viewer, unearned));
+        when(viewer.canSee(target)).thenReturn(true);
+        when(viewer.hasLineOfSight(target)).thenReturn(true);
+        when(target.hasPotionEffect(PotionEffectType.INVISIBILITY)).thenReturn(true);
+        var items = new EyeItems();
+        var helmet = new AtomicReference<>(items.create());
+        when(viewer.getInventory().getHelmet()).thenAnswer(ignored -> helmet.get());
+        when(unearned.getInventory().getHelmet()).thenReturn(items.create());
+        var repository = new YamlStealthStateRepository(directory.resolve("state.yml"));
+        var initial = new PersistentStealthState(Map.of(), Map.of())
+                .withEyeProgress(viewer.getUniqueId(), new EyeProgress(28_800_000, true));
+        var actions = new ArrayList<String>();
+        var controllerRef = new AtomicReference<EyeRevealController>();
+        var delivery = new EyeRevealController.Delivery() {
+            @Override public void show(Player observer, Player subject, EyeRevealController.Projection projection, boolean create) {
+                actions.add((create ? "create:" : "refresh:") + observer.getName() + ":" + subject.getName());
+                assertTrue(projection.revealBody());
+                assertEquals(projection, controllerRef.get().snapshot().get(observer.getUniqueId()).get(projection.entityId()));
+            }
+            @Override public void restore(Player observer, Optional<Player> subject, EyeRevealController.Projection projection) {
+                assertFalse(controllerRef.get().snapshot().getOrDefault(observer.getUniqueId(), Map.of()).containsKey(projection.entityId()),
+                        "authorization must be withdrawn before sending restoration packets");
+                actions.add("restore:" + observer.getName() + ":" + projection.playerName());
+            }
+        };
+        try (var states = new StealthStateManager(repository, initial)) {
+            var equipment = new EyeEquipment(new EyeProgressionService(states, () -> 0L, ignored -> { }), items);
+            var ids = new AtomicInteger();
+            var controller = new EyeRevealController(() -> List.of(viewer, unearned, target), equipment,
+                    id -> id.equals(target.getUniqueId()), delivery, () -> "eye" + ids.incrementAndGet());
+            controllerRef.set(controller);
+            controller.run();
+            var snapshot = controller.snapshot();
+            assertNotNull(snapshot.get(viewer.getUniqueId()), "an eligible observer needs a projection");
+            assertEquals(Set.of(42), snapshot.get(viewer.getUniqueId()).keySet());
+            assertFalse(snapshot.containsKey(unearned.getUniqueId()));
+            assertEquals(List.of("create:Viewer:Concealed"), actions);
+            assertThrows(UnsupportedOperationException.class, () -> snapshot.clear());
+            assertThrows(UnsupportedOperationException.class, () -> snapshot.get(viewer.getUniqueId()).clear());
+            controller.run();
+            assertEquals(1, actions.size(), "unchanged frames must not resend packets");
+            UUID observerId = viewer.getUniqueId();
+            java.util.concurrent.CompletableFuture.runAsync(() -> {
+                controller.requestRefresh(observerId);
+                controller.requestRefresh(observerId);
+            }).get(3, java.util.concurrent.TimeUnit.SECONDS);
+            assertEquals(1, actions.size(), "packet-thread invalidation must not perform delivery");
+            controller.run();
+            assertEquals(List.of("create:Viewer:Concealed", "refresh:Viewer:Concealed"), actions,
+                    "source updates must coalesce into a main-thread refresh");
+            helmet.set(new ItemStack(Material.IRON_HELMET));
+            controller.run();
+            assertTrue(controller.snapshot().isEmpty());
+            assertEquals(List.of("create:Viewer:Concealed", "refresh:Viewer:Concealed", "restore:Viewer:Concealed"), actions);
+            assertEquals(1, snapshot.get(viewer.getUniqueId()).size(), "published snapshots cannot be mutated by later frames");
+            helmet.set(items.create());
+            controller.run();
+            controller.close();
+            assertTrue(controller.snapshot().isEmpty(), "disable must withdraw all projections");
+            assertEquals(5, actions.size());
+            assertEquals("restore:Viewer:Concealed", actions.getLast());
+            controller.close();
+            controller.run();
+            assertEquals(5, actions.size(), "closed controllers cannot resend or revive projections");
+            verify(target, never()).removePotionEffect(any());
+            verify(target, never()).setInvisible(anyBoolean());
+            verify(viewer, never()).hasLineOfSight(unearned);
+            verify(unearned, never()).hasLineOfSight(any(org.bukkit.entity.Entity.class));
+        }
+    }
+
+    @org.junit.jupiter.params.ParameterizedTest
+    @org.junit.jupiter.params.provider.ValueSource(strings = {"range", "sight", "hidden", "spectator", "vanished", "untracked", "unloaded", "world", "death", "session", "capture-failure", "team-hidden"})
+    void platformChangesWithdrawTheProjectionWithoutLoadingChunksOrForcingVisibility(String change) throws Exception {
+        var world = mock(World.class);
+        when(world.getUID()).thenReturn(UUID.randomUUID());
+        when(world.isChunkLoaded(anyInt(), anyInt())).thenReturn(true);
+        var viewer = player(world, "Viewer", 1, 0);
+        var target = player(world, "Concealed", 42, 8);
+        when(target.getTrackedBy()).thenReturn(Set.of(viewer));
+        when(viewer.canSee(target)).thenReturn(true);
+        when(viewer.hasLineOfSight(target)).thenReturn(true);
+        var items = new EyeItems();
+        when(viewer.getInventory().getHelmet()).thenReturn(items.create());
+        var initial = new PersistentStealthState(Map.of(), Map.of())
+                .withEyeProgress(viewer.getUniqueId(), new EyeProgress(28_800_000, true));
+        var repository = new YamlStealthStateRepository(directory.resolve("state.yml"));
+        var session = new java.util.concurrent.atomic.AtomicBoolean(true);
+        var restored = new AtomicInteger();
+        var delivery = new EyeRevealController.Delivery() {
+            @Override public void show(Player observer, Player subject, EyeRevealController.Projection projection, boolean create) {
+                assertFalse(projection.revealBody(), "identity concealment alone does not authorize changing body flags");
+            }
+            @Override public void restore(Player observer, Optional<Player> subject, EyeRevealController.Projection projection) {
+                assertSame(viewer, observer);
+                assertEquals(target.getUniqueId(), projection.targetId());
+                restored.incrementAndGet();
+            }
+        };
+        try (var states = new StealthStateManager(repository, initial)) {
+            var controller = new EyeRevealController(() -> List.of(viewer, target),
+                    new EyeEquipment(new EyeProgressionService(states, () -> 0L, ignored -> { }), items),
+                    id -> id.equals(target.getUniqueId()) && session.get(), delivery, () -> "eye1");
+            controller.run();
+            assertEquals(1, controller.snapshot().get(viewer.getUniqueId()).size());
+            switch (change) {
+                case "range" -> when(target.getLocation()).thenReturn(new Location(world, 16.001, 64, 0));
+                case "sight" -> when(viewer.hasLineOfSight(target)).thenReturn(false);
+                case "hidden" -> when(viewer.canSee(target)).thenReturn(false);
+                case "spectator" -> when(target.getGameMode()).thenReturn(GameMode.SPECTATOR);
+                case "vanished" -> {
+                    var flag = mock(org.bukkit.metadata.MetadataValue.class);
+                    when(flag.asBoolean()).thenReturn(true);
+                    when(target.getMetadata("vanished")).thenReturn(List.of(flag));
+                }
+                case "untracked" -> when(target.getTrackedBy()).thenReturn(Set.of());
+                case "unloaded" -> when(world.isChunkLoaded(anyInt(), anyInt())).thenReturn(false);
+                case "world" -> {
+                    var otherWorld = mock(World.class);
+                    when(otherWorld.getUID()).thenReturn(UUID.randomUUID());
+                    when(target.getLocation()).thenReturn(new Location(otherWorld, 8, 64, 0));
+                }
+                case "death" -> when(target.isDead()).thenReturn(true);
+                case "session" -> session.set(false);
+                case "capture-failure" -> when(target.getMetadata("vanished")).thenThrow(new IllegalStateException("Visibility state unavailable"));
+                case "team-hidden" -> {
+                    var hidden = mock(org.bukkit.scoreboard.Team.class);
+                    when(hidden.getOption(org.bukkit.scoreboard.Team.Option.NAME_TAG_VISIBILITY)).thenReturn(org.bukkit.scoreboard.Team.OptionStatus.NEVER);
+                    when(viewer.getScoreboard().getEntryTeam(target.getName())).thenReturn(hidden);
+                }
+                default -> throw new AssertionError(change);
+            }
+            org.mockito.Mockito.<Object>clearInvocations(world, viewer, target);
+            controller.run();
+            assertTrue(controller.snapshot().isEmpty(), change);
+            assertEquals(1, restored.get());
+            if (!change.equals("sight")) { verify(viewer, never()).hasLineOfSight(target); }
+            verify(world, never()).getChunkAt(anyInt(), anyInt());
+            verify(world, never()).loadChunk(anyInt(), anyInt());
+            verify(viewer, never()).showPlayer(any(), any());
+            verify(target, never()).removePotionEffect(any());
+            verify(target, never()).setInvisible(anyBoolean());
+        }
+    }
+
+    @org.junit.jupiter.params.ParameterizedTest
+    @org.junit.jupiter.params.provider.ValueSource(strings = {"pair", "viewer", "target", "hide-event", "untrack-event", "helmet-event", "spectator-event", "potion-event", "quit-event", "teleport-event", "respawn-event", "death-event", "world-event", "cancelled-teleport", "cancelled-mode", "cancelled-potion", "other-armor", "other-effect"})
+    void lifecycleInvalidationWithdrawsAuthorizationImmediatelyAndOnlyForAffectedViews(String change) throws Exception {
+        var world = mock(World.class);
+        when(world.getUID()).thenReturn(UUID.randomUUID());
+        when(world.isChunkLoaded(anyInt(), anyInt())).thenReturn(true);
+        var first = player(world, "First", 1, 0);
+        var second = player(world, "Second", 2, 0);
+        var target = player(world, "Concealed", 42, 8);
+        when(target.getTrackedBy()).thenReturn(Set.of(first, second));
+        var items = new EyeItems();
+        for (var viewer : List.of(first, second)) {
+            when(viewer.canSee(target)).thenReturn(true);
+            when(viewer.hasLineOfSight(target)).thenReturn(true);
+            when(viewer.getInventory().getHelmet()).thenReturn(items.create());
+        }
+        var initial = new PersistentStealthState(Map.of(), Map.of())
+                .withEyeProgress(first.getUniqueId(), new EyeProgress(28_800_000, true))
+                .withEyeProgress(second.getUniqueId(), new EyeProgress(28_800_000, true));
+        var restored = new ArrayList<UUID>();
+        var delivery = new EyeRevealController.Delivery() {
+            @Override public void show(Player observer, Player subject, EyeRevealController.Projection projection, boolean create) { }
+            @Override public void restore(Player observer, Optional<Player> subject, EyeRevealController.Projection projection) {
+                restored.add(observer.getUniqueId());
+            }
+        };
+        var repository = new YamlStealthStateRepository(directory.resolve("state.yml"));
+        try (var states = new StealthStateManager(repository, initial)) {
+            var ids = new AtomicInteger();
+            var controller = new EyeRevealController(() -> List.of(first, second, target),
+                    new EyeEquipment(new EyeProgressionService(states, () -> 0L, ignored -> { }), items),
+                    id -> id.equals(target.getUniqueId()), delivery, () -> "eye" + ids.incrementAndGet());
+            controller.run();
+            assertEquals(2, controller.snapshot().size());
+            var events = new EyeRevealEvents(controller);
+            switch (change) {
+                case "cancelled-teleport" -> {
+                    var event = new org.bukkit.event.player.PlayerTeleportEvent(first, first.getLocation(), target.getLocation());
+                    event.setCancelled(true);
+                    events.onTeleport(event);
+                }
+                case "cancelled-mode" -> {
+                    var event = new org.bukkit.event.player.PlayerGameModeChangeEvent(target, GameMode.SPECTATOR);
+                    event.setCancelled(true);
+                    events.onGameMode(event);
+                }
+                case "cancelled-potion" -> {
+                    var event = new org.bukkit.event.entity.EntityPotionEffectEvent(target,
+                            new org.bukkit.potion.PotionEffect(PotionEffectType.INVISIBILITY, 100, 0), null, null,
+                            org.bukkit.event.entity.EntityPotionEffectEvent.Cause.MILK, org.bukkit.event.entity.EntityPotionEffectEvent.Action.REMOVED, false);
+                    event.setCancelled(true);
+                    events.onEffect(event);
+                }
+                case "other-armor" -> events.onArmor(new com.destroystokyo.paper.event.player.PlayerArmorChangeEvent(first,
+                        com.destroystokyo.paper.event.player.PlayerArmorChangeEvent.SlotType.CHEST, new ItemStack(Material.AIR), new ItemStack(Material.IRON_CHESTPLATE)));
+                case "other-effect" -> events.onEffect(new org.bukkit.event.entity.EntityPotionEffectEvent(target, null,
+                        new org.bukkit.potion.PotionEffect(PotionEffectType.NIGHT_VISION, 100, 0), null,
+                        org.bukkit.event.entity.EntityPotionEffectEvent.Cause.COMMAND, org.bukkit.event.entity.EntityPotionEffectEvent.Action.ADDED, false));
+                case "hide-event" -> events.onHide(new org.bukkit.event.player.PlayerHideEntityEvent(first, target));
+                case "untrack-event" -> events.onUntrack(new io.papermc.paper.event.player.PlayerUntrackEntityEvent(first, target));
+                case "helmet-event" -> events.onArmor(new com.destroystokyo.paper.event.player.PlayerArmorChangeEvent(first,
+                        com.destroystokyo.paper.event.player.PlayerArmorChangeEvent.SlotType.HEAD, items.create(), new ItemStack(Material.AIR)));
+                case "spectator-event" -> events.onGameMode(new org.bukkit.event.player.PlayerGameModeChangeEvent(target, GameMode.SPECTATOR));
+                case "potion-event" -> events.onEffect(new org.bukkit.event.entity.EntityPotionEffectEvent(target,
+                        new org.bukkit.potion.PotionEffect(PotionEffectType.INVISIBILITY, 100, 0), null, null,
+                        org.bukkit.event.entity.EntityPotionEffectEvent.Cause.MILK, org.bukkit.event.entity.EntityPotionEffectEvent.Action.REMOVED, false));
+                case "quit-event" -> events.onQuit(new org.bukkit.event.player.PlayerQuitEvent(first, net.kyori.adventure.text.Component.empty()));
+                case "teleport-event" -> events.onTeleport(new org.bukkit.event.player.PlayerTeleportEvent(first, first.getLocation(), target.getLocation()));
+                case "respawn-event" -> events.onRespawn(new org.bukkit.event.player.PlayerRespawnEvent(first, first.getLocation(), false));
+                case "death-event" -> events.onDeath(new org.bukkit.event.entity.PlayerDeathEvent(target, mock(org.bukkit.damage.DamageSource.class),
+                        new ArrayList<>(), 0, net.kyori.adventure.text.Component.empty(), false));
+                case "world-event" -> events.onWorld(new org.bukkit.event.player.PlayerChangedWorldEvent(first, world));
+                case "pair" -> controller.hide(first.getUniqueId(), target.getUniqueId());
+                case "viewer" -> controller.withdrawViewer(first.getUniqueId());
+                case "target" -> controller.withdrawTarget(target.getUniqueId());
+                default -> throw new AssertionError(change);
+            }
+            if (change.startsWith("cancelled-") || change.startsWith("other-")) {
+                assertEquals(2, controller.snapshot().size());
+                assertTrue(restored.isEmpty(), "cancelled or unrelated events must not disturb valid projections");
+                return;
+            }
+            assertFalse(controller.snapshot().containsKey(first.getUniqueId()), "invalidation cannot wait for the next frame");
+            boolean allObservers = Set.of("target", "spectator-event", "potion-event", "death-event").contains(change);
+            assertEquals(allObservers ? 0 : 1, controller.snapshot().size());
+            assertEquals(allObservers ? Set.of(first.getUniqueId(), second.getUniqueId()) : Set.of(first.getUniqueId()), Set.copyOf(restored));
+        }
+    }
+
+    @Test
+    void failedDeliveryRevokesAuthorizationAndCleanupMustSucceedBeforeRetryingTheView() throws Exception {
+        var world = mock(World.class);
+        when(world.getUID()).thenReturn(UUID.randomUUID());
+        when(world.isChunkLoaded(anyInt(), anyInt())).thenReturn(true);
+        var viewer = player(world, "Viewer", 1, 0);
+        var target = player(world, "Concealed", 42, 8);
+        when(target.getTrackedBy()).thenReturn(Set.of(viewer));
+        when(viewer.canSee(target)).thenReturn(true);
+        when(viewer.hasLineOfSight(target)).thenReturn(true);
+        var items = new EyeItems();
+        when(viewer.getInventory().getHelmet()).thenReturn(items.create());
+        var initial = new PersistentStealthState(Map.of(), Map.of())
+                .withEyeProgress(viewer.getUniqueId(), new EyeProgress(28_800_000, true));
+        var shows = new AtomicInteger();
+        var restores = new AtomicInteger();
+        var failures = new ArrayList<Throwable>();
+        var delivery = new EyeRevealController.Delivery() {
+            @Override public void show(Player observer, Player subject, EyeRevealController.Projection projection, boolean create) {
+                assertTrue(create);
+                if (shows.incrementAndGet() == 1) { throw new IllegalStateException("Injected partial delivery failure"); }
+            }
+            @Override public void restore(Player observer, Optional<Player> subject, EyeRevealController.Projection projection) {
+                if (restores.incrementAndGet() == 1) { throw new IllegalStateException("Injected restoration failure"); }
+            }
+        };
+        var repository = new YamlStealthStateRepository(directory.resolve("state.yml"));
+        try (var states = new StealthStateManager(repository, initial)) {
+            var ids = new AtomicInteger();
+            var controller = new EyeRevealController(() -> List.of(viewer, target),
+                    new EyeEquipment(new EyeProgressionService(states, () -> 0L, ignored -> { }), items),
+                    id -> id.equals(target.getUniqueId()), delivery, () -> "eye" + ids.incrementAndGet(), failures::add);
+            assertDoesNotThrow(controller::run);
+            assertTrue(controller.snapshot().isEmpty(), "failed delivery cannot retain outgoing reveal authorization");
+            assertDoesNotThrow(controller::run);
+            assertEquals(1, shows.get(), "failed cleanup must block recreation of the view");
+            assertTrue(controller.snapshot().isEmpty());
+            controller.run();
+            assertEquals(2, shows.get());
+            assertEquals(2, restores.get());
+            assertEquals(1, controller.snapshot().get(viewer.getUniqueId()).size());
+            assertFalse(failures.isEmpty());
+            controller.withdrawViewer(viewer.getUniqueId());
+            assertEquals(3, restores.get());
+            assertTrue(controller.snapshot().isEmpty());
+            controller.close();
+        }
+    }
+
+    private static Player player(World world, String name, int entityId, double x) {
+        var player = mock(Player.class);
+        when(player.getUniqueId()).thenReturn(UUID.randomUUID());
+        when(player.getName()).thenReturn(name);
+        when(player.getEntityId()).thenReturn(entityId);
+        when(player.getLocation()).thenReturn(new Location(world, x, 64, 0));
+        when(player.isOnline()).thenReturn(true);
+        when(player.getGameMode()).thenReturn(GameMode.SURVIVAL);
+        when(player.getInventory()).thenReturn(mock(PlayerInventory.class));
+        when(player.getScoreboard()).thenReturn(mock(Scoreboard.class));
+        return player;
+    }
+}

src/nativeTest/java/games/dmg/spigotstealth/EyeRevealRuntimeTest.java

@@ -0,0 +1,169 @@
+package games.dmg.spigotstealth;
+
+import static org.junit.jupiter.api.Assertions.*;
+import static org.mockito.Mockito.*;
+
+import com.comphenix.protocol.PacketType;
+import com.comphenix.protocol.ProtocolManager;
+import com.comphenix.protocol.events.PacketContainer;
+import com.comphenix.protocol.events.PacketEvent;
+import com.comphenix.protocol.events.PacketListener;
+import java.nio.file.Path;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.UUID;
+import net.minecraft.ChatFormatting;
+import net.minecraft.network.chat.Component;
+import net.minecraft.network.protocol.Packet;
+import net.minecraft.network.protocol.game.ClientboundSetEntityDataPacket;
+import net.minecraft.network.protocol.game.ClientboundSetPlayerTeamPacket;
+import net.minecraft.network.syncher.EntityDataAccessor;
+import net.minecraft.network.syncher.SynchedEntityData;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.server.network.ServerGamePacketListenerImpl;
+import net.minecraft.world.scores.Scoreboard;
+import org.bukkit.Location;
+import org.bukkit.World;
+import org.bukkit.craftbukkit.CraftServer;
+import org.bukkit.craftbukkit.entity.CraftPlayer;
+import org.bukkit.craftbukkit.inventory.CraftInventoryPlayer;
+import org.bukkit.craftbukkit.scheduler.CraftScheduler;
+import org.bukkit.craftbukkit.scoreboard.CraftScoreboard;
+import org.bukkit.event.Listener;
+import org.bukkit.plugin.PluginManager;
+import org.bukkit.plugin.java.JavaPlugin;
+import org.bukkit.potion.PotionEffectType;
+import org.bukkit.scheduler.BukkitTask;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+class EyeRevealRuntimeTest {
+    @TempDir Path directory;
+    @BeforeAll static void bootstrap() throws Exception { NativeRuntime.bootstrap(); }
+
+    @Test
+    @SuppressWarnings({"try", "unchecked"})
+    void registeredRuntimeProjectsAndRestoresRealPacketsWithoutChangingTheServerOrIdentityChannels() throws Exception {
+        var server = mock(CraftServer.class);
+        try (var platform = mockStatic(org.bukkit.Bukkit.class, call -> switch (call.getMethod().getName()) {
+            case "getServer" -> server;
+            case "isPrimaryThread" -> true;
+            case "getVersion" -> "Purpur 2618 (MC: 26.2)";
+            case "getMinecraftVersion" -> "26.2";
+            case "getBukkitVersion" -> "26.2-R0.1-SNAPSHOT";
+            default -> call.callRealMethod();
+        })) {
+            var world = mock(World.class);
+            when(world.getUID()).thenReturn(UUID.randomUUID());
+            when(world.isChunkLoaded(anyInt(), anyInt())).thenReturn(true);
+            var viewer = mock(CraftPlayer.class);
+            var target = mock(CraftPlayer.class);
+            UUID viewerId = UUID.randomUUID(), targetId = UUID.randomUUID();
+            when(viewer.getUniqueId()).thenReturn(viewerId);
+            when(target.getUniqueId()).thenReturn(targetId);
+            when(viewer.getName()).thenReturn("Viewer");
+            when(target.getName()).thenReturn("Concealed");
+            when(viewer.isOnline()).thenReturn(true);
+            when(target.isOnline()).thenReturn(true);
+            when(viewer.getEntityId()).thenReturn(1);
+            when(target.getEntityId()).thenReturn(42);
+            when(viewer.getLocation()).thenReturn(new Location(world, 0, 64, 0));
+            when(target.getLocation()).thenReturn(new Location(world, 8, 64, 0));
+            when(viewer.canSee(target)).thenReturn(true);
+            when(viewer.hasLineOfSight(target)).thenReturn(true);
+            when(target.getTrackedBy()).thenReturn(Set.of(viewer));
+            when(target.hasPotionEffect(PotionEffectType.INVISIBILITY)).thenReturn(true);
+            var inventory = mock(CraftInventoryPlayer.class);
+            when(viewer.getInventory()).thenReturn(inventory);
+            var items = new EyeItems();
+            when(inventory.getHelmet()).thenReturn(items.create());
+            var board = new Scoreboard();
+            var baseline = board.addPlayerTeam("source");
+            baseline.setPlayerPrefix(Component.empty().withStyle(ChatFormatting.OBFUSCATED));
+            board.addPlayerToTeam("Concealed", baseline);
+            var constructor = CraftScoreboard.class.getDeclaredConstructor(Scoreboard.class);
+            constructor.setAccessible(true);
+            when(viewer.getScoreboard()).thenReturn(constructor.newInstance(board));
+            var viewerHandle = mock(ServerPlayer.class);
+            viewerHandle.connection = mock(ServerGamePacketListenerImpl.class);
+            when(viewer.getHandle()).thenReturn(viewerHandle);
+            var targetHandle = mock(ServerPlayer.class);
+            when(target.getHandle()).thenReturn(targetHandle);
+            var data = mock(SynchedEntityData.class);
+            when(targetHandle.getEntityData()).thenReturn(data);
+            var field = net.minecraft.world.entity.Entity.class.getDeclaredField("DATA_SHARED_FLAGS_ID");
+            field.setAccessible(true);
+            var flags = (EntityDataAccessor<Byte>) field.get(null);
+            when(data.get(flags)).thenReturn((byte) 0x60);
+            var protocol = mock(ProtocolManager.class);
+            var packetListeners = new ArrayList<PacketListener>();
+            doAnswer(call -> { packetListeners.add(call.getArgument(0)); return null; }).when(protocol).addPacketListener(any());
+            doAnswer(call -> { packetListeners.remove(call.getArgument(0)); return null; }).when(protocol).removePacketListener(any());
+            var sent = new ArrayList<Packet<?>>();
+            doAnswer(call -> {
+                Packet<?> raw = call.getArgument(0);
+                PacketType type = raw instanceof ClientboundSetPlayerTeamPacket ? PacketType.Play.Server.SCOREBOARD_TEAM : PacketType.Play.Server.ENTITY_METADATA;
+                var event = PacketEvent.fromServer(this, new PacketContainer(type, raw), viewer);
+                for (var listener : List.copyOf(packetListeners)) {
+                    if (listener.getSendingWhitelist().getTypes().contains(type)) { listener.onPacketSending(event); }
+                }
+                if (!event.isCancelled()) { sent.add((Packet<?>) event.getPacket().getHandle()); }
+                return null;
+            }).when(viewerHandle.connection).send(org.mockito.ArgumentMatchers.<Packet<?>>any());
+            var plugin = mock(JavaPlugin.class);
+            when(plugin.getServer()).thenReturn(server);
+            when(plugin.isEnabled()).thenReturn(true);
+            when(plugin.getLogger()).thenReturn(java.util.logging.Logger.getAnonymousLogger());
+            var manager = mock(PluginManager.class);
+            when(server.getPluginManager()).thenReturn(manager);
+            var listeners = new ArrayList<Listener>();
+            doAnswer(call -> { listeners.add(call.getArgument(0)); return null; }).when(manager).registerEvents(any(), eq(plugin));
+            doReturn(List.of(viewer, target)).when(server).getOnlinePlayers();
+            var scheduler = mock(CraftScheduler.class);
+            when(server.getScheduler()).thenReturn(scheduler);
+            var ticks = new ArrayList<Runnable>();
+            var task = mock(BukkitTask.class);
+            when(scheduler.runTaskTimer(eq(plugin), any(Runnable.class), eq(1L), eq(1L))).thenAnswer(call -> {
+                ticks.add(call.getArgument(1)); return task;
+            });
+            var initial = new PersistentStealthState(Map.of(), Map.of()).withEyeProgress(viewerId, new EyeProgress(28_800_000, true));
+            var repository = new YamlStealthStateRepository(directory.resolve("state.yml"));
+            try (var states = new StealthStateManager(repository, initial)) {
+                var equipment = new EyeEquipment(new EyeProgressionService(states, () -> 0L, ignored -> { }), items);
+                var runtime = new EyeRevealRuntime(plugin, equipment, targetId::equals, protocol);
+                runtime.start();
+                assertEquals(1, ticks.size(), "the runtime must register a one-tick visibility loop");
+                ticks.getFirst().run();
+                var create = assertInstanceOf(ClientboundSetPlayerTeamPacket.class, sent.getFirst());
+                assertFalse(create.getParameters().orElseThrow().playerPrefix().getStyle().isObfuscated());
+                assertEquals((byte) 0x40, assertInstanceOf(ClientboundSetEntityDataPacket.class, sent.get(1)).packedItems().getFirst().value());
+                assertSame(baseline, board.getPlayersTeam("Concealed"));
+                assertNull(board.getPlayerTeam(create.getName()));
+                var events = assertInstanceOf(EyeRevealEvents.class, listeners.getFirst());
+                when(viewer.canSee(target)).thenReturn(false);
+                events.onHide(new org.bukkit.event.player.PlayerHideEntityEvent(viewer, target));
+                assertTrue(assertInstanceOf(ClientboundSetPlayerTeamPacket.class, sent.get(2)).getParameters().orElseThrow().playerPrefix().getStyle().isObfuscated());
+                assertEquals((byte) 0x60, assertInstanceOf(ClientboundSetEntityDataPacket.class, sent.get(3)).packedItems().getFirst().value());
+                ticks.getFirst().run();
+                assertEquals(7, sent.size(), "platform-hidden targets must remain hidden");
+                when(viewer.canSee(target)).thenReturn(true);
+                ticks.getFirst().run();
+                assertFalse(assertInstanceOf(ClientboundSetPlayerTeamPacket.class, sent.get(7)).getParameters().orElseThrow().playerPrefix().getStyle().isObfuscated());
+                runtime.close();
+                int count = sent.size();
+                ticks.getFirst().run();
+                assertEquals(count, sent.size());
+                assertTrue(packetListeners.isEmpty());
+                verify(task).cancel();
+                assertSame(baseline, board.getPlayersTeam("Concealed"));
+                assertEquals((byte) 0x60, data.get(flags));
+                verify(target, never()).removePotionEffect(any());
+                verify(target, never()).setInvisible(anyBoolean());
+                assertEquals(initial, states.snapshot());
+            }
+        }
+    }
+}

src/nativeTest/java/games/dmg/spigotstealth/EyeTeamProjectionTest.java

@@ -0,0 +1,82 @@
+package games.dmg.spigotstealth;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import io.netty.buffer.Unpooled;
+import java.util.Optional;
+import net.minecraft.ChatFormatting;
+import net.minecraft.network.RegistryFriendlyByteBuf;
+import net.minecraft.network.chat.Component;
+import net.minecraft.network.protocol.game.ClientboundSetPlayerTeamPacket.Parameters;
+import net.minecraft.world.scores.Team;
+import net.minecraft.world.scores.TeamColor;
+import org.bukkit.craftbukkit.CraftRegistry;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+class EyeTeamProjectionTest {
+    @BeforeAll static void bootstrap() throws Exception { NativeRuntime.bootstrap(); }
+
+    @Test
+    void nativeTeamProjectionRemovesOnlyTheScramblingPrefixAndRoundTripsEveryOtherField() {
+        var config = new io.papermc.paper.configuration.GlobalConfiguration();
+        config.collisions = config.new Collisions();
+        config.collisions.enablePlayerCollisions = true;
+        try (var platform = org.mockito.Mockito.mockStatic(io.papermc.paper.configuration.GlobalConfiguration.class)) {
+            platform.when(io.papermc.paper.configuration.GlobalConfiguration::get).thenReturn(config);
+            assertProjection();
+        }
+    }
+
+    @Test
+    void privateTeamsRevealOnlyTheirTargetWhileSharedServerMembershipUpdatesStayMasked() {
+        var board = new net.minecraft.world.scores.Scoreboard();
+        var shared = board.addPlayerTeam("shared");
+        shared.setPlayerPrefix(Component.empty().withStyle(ChatFormatting.OBFUSCATED));
+        board.addPlayerToTeam("Alice", shared);
+        board.addPlayerToTeam("Bob", shared);
+        var packet = net.minecraft.network.protocol.game.ClientboundSetPlayerTeamPacket.createAddOrModifyPacket(shared, true);
+        var filtered = assertInstanceOf(net.minecraft.network.protocol.game.ClientboundSetPlayerTeamPacket.class,
+                EyePacketProjection.teamPacket(packet, java.util.Set.of("eye-private"), java.util.Set.of("Alice")));
+        assertEquals(java.util.Set.of("Bob"), java.util.Set.copyOf(filtered.getPlayers()),
+                "server membership updates must not pull an active Eye target out of its private team");
+        assertSame(packet.getParameters().orElseThrow(), filtered.getParameters().orElseThrow());
+        assertTrue(filtered.getParameters().orElseThrow().playerPrefix().getStyle().isObfuscated());
+        assertEquals(java.util.Set.of("Alice", "Bob"), java.util.Set.copyOf(packet.getPlayers()));
+        var isolated = board.addPlayerTeam("eye-private");
+        isolated.setPlayerPrefix(Component.empty().withStyle(ChatFormatting.OBFUSCATED));
+        board.addPlayerToTeam("Alice", isolated);
+        var privatePacket = net.minecraft.network.protocol.game.ClientboundSetPlayerTeamPacket.createAddOrModifyPacket(isolated, true);
+        var revealed = assertInstanceOf(net.minecraft.network.protocol.game.ClientboundSetPlayerTeamPacket.class,
+                EyePacketProjection.teamPacket(privatePacket, java.util.Set.of("eye-private"), java.util.Set.of("Alice")));
+        assertEquals(java.util.Set.of("Alice"), java.util.Set.copyOf(revealed.getPlayers()));
+        assertFalse(revealed.getParameters().orElseThrow().playerPrefix().getStyle().isObfuscated());
+        assertTrue(privatePacket.getParameters().orElseThrow().playerPrefix().getStyle().isObfuscated());
+        assertSame(privatePacket, EyePacketProjection.teamPacket(privatePacket, java.util.Set.of(), java.util.Set.of()),
+                "without current authorization even queued private packets must retain their original mask");
+        for (var action : net.minecraft.network.protocol.game.ClientboundSetPlayerTeamPacket.Action.values()) {
+            var membership = net.minecraft.network.protocol.game.ClientboundSetPlayerTeamPacket.createPlayerPacket(shared, "Alice", action);
+            var projected = assertInstanceOf(net.minecraft.network.protocol.game.ClientboundSetPlayerTeamPacket.class,
+                    EyePacketProjection.teamPacket(membership, java.util.Set.of("eye-private"), java.util.Set.of("Alice")));
+            assertTrue(projected.getPlayers().isEmpty());
+            assertEquals(membership.getPlayerAction(), projected.getPlayerAction());
+        }
+    }
+
+    private static void assertProjection() {
+        var original = new Parameters(Component.literal("Keep team display"),
+                Component.empty().withStyle(ChatFormatting.OBFUSCATED), Component.literal("Keep suffix"),
+                Team.Visibility.ALWAYS, Team.CollisionRule.PUSH_OWN_TEAM, Optional.of(TeamColor.AQUA), (byte) 0x53);
+        var projected = assertInstanceOf(Parameters.class, EyePacketProjection.teamParameters(original));
+        var expected = new Parameters(original.displayName(), Component.empty(), original.playerSuffix(),
+                original.nameTagVisibility(), original.collisionRule(), original.color(), original.options());
+        assertEquals(expected, projected);
+        assertNotSame(original, projected);
+        assertTrue(original.playerPrefix().getStyle().isObfuscated(), "the shared server/team packet must remain unchanged");
+        var buffer = new RegistryFriendlyByteBuf(Unpooled.buffer(), CraftRegistry.getMinecraftRegistry());
+        try {
+            Parameters.STREAM_CODEC.encode(buffer, projected);
+            assertEquals(projected, Parameters.STREAM_CODEC.decode(buffer));
+        } finally { buffer.release(); }
+    }
+}

src/nativeTest/java/games/dmg/spigotstealth/NativeEyeDeliveryTest.java

@@ -0,0 +1,125 @@
+package games.dmg.spigotstealth;
+
+import static org.junit.jupiter.api.Assertions.*;
+import static org.mockito.Mockito.*;
+
+import java.util.ArrayList;
+import java.util.Optional;
+import java.util.Set;
+import java.util.UUID;
+import java.util.concurrent.atomic.AtomicReference;
+import net.minecraft.ChatFormatting;
+import net.minecraft.network.chat.Component;
+import net.minecraft.network.protocol.Packet;
+import net.minecraft.network.protocol.game.ClientboundSetEntityDataPacket;
+import net.minecraft.network.protocol.game.ClientboundSetPlayerTeamPacket;
+import net.minecraft.network.syncher.EntityDataAccessor;
+import net.minecraft.network.syncher.SynchedEntityData;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.server.network.ServerGamePacketListenerImpl;
+import net.minecraft.world.scores.Scoreboard;
+import net.minecraft.world.scores.TeamColor;
+import org.bukkit.craftbukkit.entity.CraftPlayer;
+import org.bukkit.craftbukkit.scoreboard.CraftScoreboard;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+class NativeEyeDeliveryTest {
+    @BeforeAll static void bootstrap() throws Exception { NativeRuntime.bootstrap(); }
+
+    @org.junit.jupiter.params.ParameterizedTest
+    @org.junit.jupiter.params.provider.CsvSource({"ALWAYS,false,true", "NEVER,false,false", "HIDE_FOR_OWN_TEAM,true,false",
+            "HIDE_FOR_OWN_TEAM,false,true", "HIDE_FOR_OTHER_TEAMS,true,true", "HIDE_FOR_OTHER_TEAMS,false,false"})
+    @SuppressWarnings("unchecked") // The declared runtime accessor's BYTE serializer is verified in the metadata codec tests.
+    void deliveryUsesOnlyTheViewerConnectionAndRestoresCurrentStateWithoutChangingServerTeamsOrFlags(
+            net.minecraft.world.scores.Team.Visibility visibility, boolean teammate, boolean visible) throws Exception {
+        var board = new Scoreboard();
+        var baseline = board.addPlayerTeam("source");
+        baseline.setPlayerPrefix(Component.empty().withStyle(ChatFormatting.OBFUSCATED));
+        baseline.setColor(Optional.of(TeamColor.AQUA));
+        baseline.setNameTagVisibility(visibility);
+        if (teammate) { board.addPlayerToTeam("Viewer", baseline); }
+        board.addPlayerToTeam("Concealed", baseline);
+        board.addPlayerToTeam("OtherConcealed", baseline);
+        var boardConstructor = CraftScoreboard.class.getDeclaredConstructor(Scoreboard.class);
+        boardConstructor.setAccessible(true);
+        var bukkitBoard = boardConstructor.newInstance(board);
+        var viewer = mock(CraftPlayer.class);
+        var viewerHandle = mock(ServerPlayer.class);
+        var connection = mock(ServerGamePacketListenerImpl.class);
+        viewerHandle.connection = connection;
+        when(viewer.getHandle()).thenReturn(viewerHandle);
+        when(viewer.getName()).thenReturn("Viewer");
+        when(viewer.getScoreboard()).thenReturn(bukkitBoard);
+        var sent = new ArrayList<Packet<?>>();
+        doAnswer(call -> { sent.add(call.getArgument(0)); return null; })
+                .when(connection).send(org.mockito.ArgumentMatchers.<Packet<?>>any());
+        var target = mock(CraftPlayer.class);
+        var targetHandle = mock(ServerPlayer.class);
+        when(target.getHandle()).thenReturn(targetHandle);
+        when(target.getEntityId()).thenReturn(42);
+        when(target.isOnline()).thenReturn(true);
+        var data = mock(SynchedEntityData.class);
+        when(targetHandle.getEntityData()).thenReturn(data);
+        var accessorField = net.minecraft.world.entity.Entity.class.getDeclaredField("DATA_SHARED_FLAGS_ID");
+        accessorField.setAccessible(true);
+        var flagsAccessor = (EntityDataAccessor<Byte>) accessorField.get(null);
+        var flags = new AtomicReference<>((byte) 0xa0);
+        when(data.get(flagsAccessor)).thenAnswer(ignored -> flags.get());
+        var projection = new EyeRevealController.Projection(UUID.randomUUID(), 42, "Concealed", "eye-private",
+                Optional.of("source"), true);
+        var delivery = new NativeEyeDelivery();
+        delivery.show(viewer, target, projection, true);
+        assertEquals(2, sent.size(), "a private team and raw metadata refresh are required");
+        var team = assertInstanceOf(ClientboundSetPlayerTeamPacket.class, sent.get(0));
+        assertEquals("eye-private", team.getName());
+        assertEquals(ClientboundSetPlayerTeamPacket.Action.ADD, team.getTeamAction());
+        assertEquals(java.util.List.of("Concealed"), java.util.List.copyOf(team.getPlayers()));
+        assertEquals(visible ? net.minecraft.world.scores.Team.Visibility.ALWAYS : net.minecraft.world.scores.Team.Visibility.NEVER,
+                team.getParameters().orElseThrow().nameTagVisibility(), "private teams must preserve effective visibility, not change team relationships");
+        assertTrue(team.getParameters().orElseThrow().playerPrefix().getStyle().isObfuscated(),
+                "raw state must reach the outgoing authorization gate before any prefix is revealed");
+        var metadata = assertInstanceOf(ClientboundSetEntityDataPacket.class, sent.get(1));
+        assertEquals(42, metadata.id());
+        assertEquals((byte) 0xa0, metadata.packedItems().getFirst().value());
+        assertNull(board.getPlayerTeam("eye-private"));
+        assertEquals(teammate ? Set.of("Viewer", "Concealed", "OtherConcealed") : Set.of("Concealed", "OtherConcealed"), Set.copyOf(baseline.getPlayers()));
+        assertEquals((byte) 0xa0, flags.get());
+        // Another plugin can move the actor to a different real team while the private view is active.
+        var replacement = board.addPlayerTeam("replacement");
+        replacement.setPlayerPrefix(Component.empty().withStyle(ChatFormatting.OBFUSCATED));
+        replacement.setColor(Optional.of(TeamColor.GOLD));
+        replacement.setNameTagVisibility(visibility);
+        board.addPlayerToTeam("Concealed", replacement);
+        flags.set((byte) 9);
+        sent.clear();
+        delivery.restore(viewer, Optional.of(target), projection);
+        assertEquals(5, sent.size(), "restore the mask and flags before moving or removing client team membership");
+        var privateMask = assertInstanceOf(ClientboundSetPlayerTeamPacket.class, sent.get(0));
+        assertEquals("eye-private", privateMask.getName());
+        assertTrue(privateMask.getParameters().orElseThrow().playerPrefix().getStyle().isObfuscated());
+        boolean nowVisible = visibility == net.minecraft.world.scores.Team.Visibility.ALWAYS
+                || visibility == net.minecraft.world.scores.Team.Visibility.HIDE_FOR_OWN_TEAM;
+        assertEquals(nowVisible ? net.minecraft.world.scores.Team.Visibility.ALWAYS : net.minecraft.world.scores.Team.Visibility.NEVER,
+                privateMask.getParameters().orElseThrow().nameTagVisibility());
+        var restoredFlags = assertInstanceOf(ClientboundSetEntityDataPacket.class, sent.get(1));
+        assertEquals((byte) 9, restoredFlags.packedItems().getFirst().value());
+        var restoredTeam = assertInstanceOf(ClientboundSetPlayerTeamPacket.class, sent.get(2));
+        assertEquals("replacement", restoredTeam.getName());
+        assertEquals(Optional.of(TeamColor.GOLD), restoredTeam.getParameters().orElseThrow().color());
+        assertEquals(visibility, restoredTeam.getParameters().orElseThrow().nameTagVisibility());
+        var membership = assertInstanceOf(ClientboundSetPlayerTeamPacket.class, sent.get(3));
+        assertEquals("replacement", membership.getName());
+        assertEquals(ClientboundSetPlayerTeamPacket.Action.ADD, membership.getPlayerAction());
+        assertEquals(java.util.List.of("Concealed"), java.util.List.copyOf(membership.getPlayers()));
+        var removal = assertInstanceOf(ClientboundSetPlayerTeamPacket.class, sent.get(4));
+        assertEquals("eye-private", removal.getName());
+        assertEquals(ClientboundSetPlayerTeamPacket.Action.REMOVE, removal.getTeamAction());
+        assertSame(replacement, board.getPlayersTeam("Concealed"));
+        assertEquals(teammate ? Set.of("Viewer", "OtherConcealed") : Set.of("OtherConcealed"), Set.copyOf(baseline.getPlayers()));
+        assertNull(board.getPlayerTeam("eye-private"));
+        verify(data, never()).set(any(), any());
+        verify(connection, times(7)).send(org.mockito.ArgumentMatchers.<Packet<?>>any());
+        verifyNoMoreInteractions(connection);
+    }
+}

src/test/java/games/dmg/spigotstealth/EyeVisibilityTest.java

@@ -0,0 +1,47 @@
+package games.dmg.spigotstealth;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import java.util.UUID;
+import org.junit.jupiter.api.Test;
+
+class EyeVisibilityTest {
+    private final UUID world = UUID.randomUUID();
+    private final UUID viewerId = UUID.randomUUID();
+    private final UUID targetId = UUID.randomUUID();
+
+    @Test
+    void personalEligibilityConcealmentVisibilityAndSightMustAllPermitTheReveal() {
+        var position = new EyeVisibility.Position(world, 0, 64, 0);
+        var viewer = new EyeVisibility.Viewer(viewerId, position, true);
+        var target = new EyeVisibility.Target(targetId, position, true, false, false);
+        assertFalse(EyeVisibility.canReveal(new EyeVisibility.Viewer(viewerId, position, false), target, true, true),
+                "an unearned or unequipped observer cannot reveal a target");
+        assertFalse(EyeVisibility.canReveal(viewer, new EyeVisibility.Target(targetId, position, false, false, false), true, true));
+        assertFalse(EyeVisibility.canReveal(viewer, new EyeVisibility.Target(targetId, position, true, true, false), true, true),
+                "the Eye must not bypass spectator hiding");
+        assertFalse(EyeVisibility.canReveal(viewer, new EyeVisibility.Target(targetId, position, true, false, true), true, true),
+                "the Eye must not bypass administrative vanish");
+        assertFalse(EyeVisibility.canReveal(viewer, target, false, true), "platform visibility denial takes precedence");
+        assertFalse(EyeVisibility.canReveal(viewer, target, true, false), "walls must block revelation");
+        assertFalse(EyeVisibility.canReveal(viewer, new EyeVisibility.Target(viewerId, position, true, false, false), true, true));
+        assertFalse(EyeVisibility.canReveal(viewer, new EyeVisibility.Target(targetId,
+                new EyeVisibility.Position(UUID.randomUUID(), 0, 64, 0), true, false, false), true, true));
+        assertFalse(EyeVisibility.canReveal(viewer, new EyeVisibility.Target(targetId,
+                new EyeVisibility.Position(world, Double.NaN, 64, 0), true, false, false), true, true));
+        assertTrue(EyeVisibility.canReveal(viewer, target, true, true));
+    }
+
+    @Test
+    void anEligibleWearerCanRevealAtTheInclusiveThreeDimensionalSixteenBlockBoundary() {
+        var viewer = new EyeVisibility.Viewer(viewerId, new EyeVisibility.Position(world, 0, 64, 0), true);
+        var horizontal = new EyeVisibility.Target(targetId, new EyeVisibility.Position(world, 16, 64, 0), true, false, false);
+        var vertical = new EyeVisibility.Target(targetId, new EyeVisibility.Position(world, 0, 80, 0), true, false, false);
+        assertTrue(EyeVisibility.canReveal(viewer, horizontal, true, true));
+        assertTrue(EyeVisibility.canReveal(viewer, vertical, true, true));
+        var diagonal = new EyeVisibility.Target(targetId, new EyeVisibility.Position(world, 12, 76, 0), true, false, false);
+        var beyond = new EyeVisibility.Target(targetId, new EyeVisibility.Position(world, 16.001, 64, 0), true, false, false);
+        assertFalse(EyeVisibility.canReveal(viewer, diagonal, true, true));
+        assertFalse(EyeVisibility.canReveal(viewer, beyond, true, true));
+    }
+}