feat(stealth): earn and equip the Eye of True Seeing

Add independent eight-hour Night Vision progression, save-gated crafting and holder eligibility, authenticated helmet items and guarded inventory movement. Verify source attribution, native item/recipe/event adapters and actual plugin lifecycle. Drain final state asynchronously and reject stale lifecycle callbacks. Per-viewer revelation remains the next story; no deployment is included.

README.md

@@ -10,12 +10,24 @@ Progression-gated identity concealment for Purpur 26.2 build 2618, built and tes
 
 Artifacts are written to `build/libs/purpur-stealth-<version>.jar`. Gitea CI verifies pushes/pull requests; approved main-branch conventional commits drive versioned releases. The distribution tests inspect the built JAR, embedded version/runtime identity, Java 25 bytecode, and workflow naming.
 
+## Eye of True Seeing
+
+Earn a separate, personal unlock through eight cumulative online hours of Night Vision from directly drunk potions. Splash/lingering potions, commands, plugins and other sources do not count. Rejected and cosmetic-only replacements do not change attribution. Unattributed restored effects cannot inherit the drink timer; a new effective drink can start a new interval. Offline time is excluded.
+
+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.
+
+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queues a final snapshot without blocking the tick thread, and initialization callbacks cannot revive a disabled or superseded lifecycle.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.
+
+`check` includes `nativeStealthTest`, which downloads SHA-256-pinned Purpur 2618, patches it without starting a listening server, and exercises real potion events, items, recipes, event dispatch and plugin lifecycle with external platform doubles. Live-client appearance and gameplay checks remain separate follow-ups.
+
 ## Migration compatibility
 
 The repository and checkout are now `purpur-stealth` (previously remote `spigot-stealth`, local `spigot-invisibilty`). Runtime identity remains **SpigotStealth**, including `plugins/SpigotStealth/`, the existing Java entrypoint/packages, command names, `spigotstealth` permission/namespace identifiers, and persisted progression/session data. Java 17 is no longer supported for new builds or artifacts.
 
 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.
 
-This migration does not implement the pending Eye, combat reveal, or concealed-chat stories. Existing gameplay and plugin metadata are unchanged.
+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.
 
 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).

build.gradle.kts

@@ -1,3 +1,6 @@
+import java.net.URI
+import java.security.MessageDigest
+
 plugins {
     java
 }
@@ -43,6 +46,60 @@ tasks.test {
     systemProperty("distribution.version", project.version.toString())
 }
 
+// Exercise real potion events, item components and recipes without starting a listening server.
+val stealthRuntime = layout.buildDirectory.dir("stealth-runtime")
+val downloadStealthRuntime = tasks.register("downloadStealthRuntime") {
+    val launcher = stealthRuntime.map { it.file("purpur-26.2-2618.jar") }
+    outputs.file(launcher)
+    doLast {
+        val file = launcher.get().asFile
+        file.parentFile.mkdirs()
+        val connection = URI("https://api.purpurmc.org/v2/purpur/26.2/2618/download").toURL().openConnection()
+        connection.connectTimeout = 30_000
+        connection.readTimeout = 120_000
+        val bytes = connection.getInputStream().use { it.readBytes() }
+        val digest = MessageDigest.getInstance("SHA-256").digest(bytes).joinToString("") { "%02x".format(it) }
+        check(digest == "4a32d046a118804d89ca74ba89b798c98f6d8d1f310c18077ac573597049de31") {
+            "Purpur 2618 checksum mismatch"
+        }
+        file.writeBytes(bytes)
+    }
+}
+val prepareStealthRuntime = tasks.register<JavaExec>("prepareStealthRuntime") {
+    dependsOn(downloadStealthRuntime)
+    javaLauncher = javaToolchains.launcherFor { languageVersion = JavaLanguageVersion.of(25) }
+    classpath = files(stealthRuntime.map { it.file("purpur-26.2-2618.jar") })
+    mainClass = "io.papermc.paperclip.Main"
+    jvmArgs("-Dpaperclip.patchonly=true")
+    workingDir(stealthRuntime)
+    outputs.dir(stealthRuntime.map { it.dir("versions") })
+    outputs.dir(stealthRuntime.map { it.dir("libraries") })
+}
+val nativeTest = sourceSets.create("nativeTest")
+dependencies {
+    add(nativeTest.implementationConfigurationName, platform("org.junit:junit-bom:5.13.4"))
+    add(nativeTest.implementationConfigurationName, "org.junit.jupiter:junit-jupiter")
+    add(nativeTest.implementationConfigurationName, "org.mockito:mockito-core:5.18.0")
+    add(nativeTest.implementationConfigurationName, "net.dmulloy2:ProtocolLib:5.4.0")
+    add(nativeTest.compileOnlyConfigurationName, "org.jetbrains:annotations:26.0.2")
+    add(nativeTest.compileOnlyConfigurationName, "org.checkerframework:checker-qual:3.49.2")
+    add(nativeTest.runtimeOnlyConfigurationName, "org.junit.platform:junit-platform-launcher")
+}
+val nativeRuntimeJars = files(fileTree(stealthRuntime) {
+    include("versions/**/*.jar", "libraries/**/*.jar")
+}).builtBy(prepareStealthRuntime)
+nativeTest.compileClasspath += sourceSets.main.get().output + nativeRuntimeJars
+nativeTest.runtimeClasspath += sourceSets.main.get().output + nativeRuntimeJars
+val nativeStealthTest = tasks.register<Test>("nativeStealthTest") {
+    description = "Runs native Purpur adapter regressions without starting a server"
+    testClassesDirs = nativeTest.output.classesDirs
+    classpath = nativeTest.runtimeClasspath
+    useJUnitPlatform()
+    maxHeapSize = "1G"
+    workingDir(stealthRuntime)
+}
+tasks.check { dependsOn(nativeStealthTest) }
+
 val pluginVersion = version
 
 tasks.processResources {

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

@@ -0,0 +1,66 @@
+package games.dmg.spigotstealth;
+
+import java.util.Objects;
+import org.bukkit.Keyed;
+import org.bukkit.Material;
+import org.bukkit.NamespacedKey;
+import org.bukkit.entity.Player;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.EventPriority;
+import org.bukkit.event.Listener;
+import org.bukkit.event.inventory.PrepareItemCraftEvent;
+import org.bukkit.inventory.ShapedRecipe;
+
+/** Personal crafting unlock for the transferable Eye. Vanilla owns ingredient consumption. */
+public final class EyeCrafting implements Listener {
+    public static final NamespacedKey RECIPE_KEY = new NamespacedKey("spigotstealth", "eye_of_true_seeing");
+    private final EyeItems items;
+    private final EyeProgressionService progression;
+
+    public EyeCrafting(EyeProgressionService progression, EyeItems items) {
+        this.progression = Objects.requireNonNull(progression, "progression");
+        this.items = Objects.requireNonNull(items, "items");
+    }
+
+    public ShapedRecipe recipe() {
+        return new ShapedRecipe(RECIPE_KEY, items.create()).shape("NNN", "NEN", "NNN")
+                .setIngredient('N', Material.NETHERITE_BLOCK).setIngredient('E', Material.ENDER_EYE);
+    }
+
+    @EventHandler(priority = EventPriority.HIGHEST, ignoreCancelled = true)
+    public void onCraft(org.bukkit.event.inventory.CraftItemEvent event) {
+        if (event.isCancelled() || !matches(event.getRecipe())) { return; }
+        if (!(event.getWhoClicked() instanceof Player player) || !progression.isUnlocked(player.getUniqueId())
+                || !accepts(event.getInventory().getMatrix()) || !items.isEye(event.getInventory().getResult())
+                || event.getInventory().getResult().getAmount() != 1) {
+            event.setCancelled(true);
+            event.getInventory().setResult(null);
+        }
+    }
+
+    @EventHandler(priority = EventPriority.HIGHEST, ignoreCancelled = true)
+    public void onCrafter(org.bukkit.event.block.CrafterCraftEvent event) {
+        if (matches(event.getRecipe())) { event.setCancelled(true); }
+    }
+
+    private static boolean matches(org.bukkit.inventory.Recipe recipe) {
+        return recipe instanceof Keyed keyed && RECIPE_KEY.equals(keyed.getKey());
+    }
+
+    private static boolean accepts(org.bukkit.inventory.ItemStack[] matrix) {
+        if (matrix.length != 9) { return false; }
+        for (int index = 0; index < matrix.length; index++) {
+            if (matrix[index] == null || matrix[index].getAmount() <= 0
+                    || matrix[index].getType() != (index == 4 ? Material.ENDER_EYE : Material.NETHERITE_BLOCK)) { return false; }
+        }
+        return true;
+    }
+
+    @EventHandler(priority = EventPriority.HIGHEST)
+    public void onPrepare(PrepareItemCraftEvent event) {
+        if (!(event.getInventory().getRecipe() instanceof Keyed keyed) || !RECIPE_KEY.equals(keyed.getKey())) { return; }
+        if (!(event.getView().getPlayer() instanceof Player player) || !progression.isUnlocked(player.getUniqueId())) {
+            event.getInventory().setResult(null);
+        }
+    }
+}

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

@@ -0,0 +1,47 @@
+package games.dmg.spigotstealth;
+
+import java.util.Objects;
+import org.bukkit.entity.Player;
+import org.bukkit.event.Event;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.EventPriority;
+import org.bukkit.event.Listener;
+import org.bukkit.event.player.PlayerInteractEvent;
+import org.bukkit.inventory.EquipmentSlot;
+
+/** Player-specific eligibility and inventory movement; never invokes native Ender Eye use. */
+public final class EyeEquipment implements Listener {
+    private final EyeProgressionService progression;
+    private final EyeItems items;
+
+    public EyeEquipment(EyeProgressionService progression, EyeItems items) {
+        this.progression = Objects.requireNonNull(progression, "progression");
+        this.items = Objects.requireNonNull(items, "items");
+    }
+
+    public boolean isEligibleWearer(Player player) {
+        return progression.isUnlocked(player.getUniqueId()) && items.isEye(player.getInventory().getHelmet());
+    }
+
+    // Interact-in-air may start with block use denied; respect item-use denial rather than isCancelled().
+    @EventHandler(priority = EventPriority.HIGHEST)
+    public void onUse(PlayerInteractEvent event) {
+        if (!event.getAction().isRightClick() || event.useItemInHand() == Event.Result.DENY || !items.isEye(event.getItem())) { return; }
+        event.setUseItemInHand(Event.Result.DENY);
+        event.setUseInteractedBlock(Event.Result.DENY);
+        Player player = event.getPlayer();
+        if (player.isDead() || !progression.isUnlocked(player.getUniqueId())
+                || (event.getHand() != EquipmentSlot.HAND && event.getHand() != EquipmentSlot.OFF_HAND)) { return; }
+        var inventory = player.getInventory();
+        var helmet = inventory.getHelmet();
+        if (helmet != null && helmet.getAmount() > 0 && !helmet.getType().isAir()) { return; }
+        var held = inventory.getItem(event.getHand());
+        if (!items.isEye(held)) { return; }
+        var equipped = held.clone();
+        equipped.setAmount(1);
+        var remaining = held.clone();
+        remaining.setAmount(held.getAmount() - 1);
+        inventory.setItem(event.getHand(), remaining.getAmount() == 0 ? null : remaining);
+        inventory.setHelmet(equipped);
+    }
+}

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

@@ -0,0 +1,34 @@
+package games.dmg.spigotstealth;
+
+import net.kyori.adventure.text.Component;
+import org.bukkit.Material;
+import org.bukkit.NamespacedKey;
+import org.bukkit.inventory.EquipmentSlot;
+import org.bukkit.inventory.ItemStack;
+import org.bukkit.persistence.PersistentDataType;
+
+/** Creates and identifies the transferable Eye; eligibility belongs to the holder's durable progression. */
+public final class EyeItems {
+    private static final NamespacedKey IDENTITY = new NamespacedKey("spigotstealth", "eye_of_true_seeing");
+
+    public ItemStack create() {
+        var eye = new ItemStack(Material.ENDER_EYE);
+        var meta = eye.getItemMeta();
+        meta.displayName(Component.text("Eye of True Seeing"));
+        meta.getPersistentDataContainer().set(IDENTITY, PersistentDataType.BYTE, (byte) 1);
+        meta.setMaxStackSize(1);
+        var equippable = meta.getEquippable();
+        equippable.setSlot(EquipmentSlot.HEAD);
+        equippable.setDispensable(false);
+        equippable.setEquipOnInteract(false);
+        equippable.setDamageOnHurt(false);
+        meta.setEquippable(equippable);
+        eye.setItemMeta(meta);
+        return eye;
+    }
+
+    public boolean isEye(ItemStack item) {
+        return item != null && item.getAmount() > 0 && item.getType() == Material.ENDER_EYE && item.hasItemMeta()
+                && Byte.valueOf((byte) 1).equals(item.getItemMeta().getPersistentDataContainer().get(IDENTITY, PersistentDataType.BYTE));
+    }
+}

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

@@ -0,0 +1,101 @@
+package games.dmg.spigotstealth;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Objects;
+import java.util.UUID;
+import java.util.concurrent.CompletableFuture;
+import java.util.function.Consumer;
+import java.util.function.Function;
+import org.bukkit.entity.Player;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.EventPriority;
+import org.bukkit.event.Listener;
+import org.bukkit.event.entity.EntityPotionEffectEvent;
+import org.bukkit.event.player.PlayerQuitEvent;
+import org.bukkit.potion.PotionEffect;
+import org.bukkit.potion.PotionEffectType;
+
+/** Night Vision potion-event adapter; progression and persistence are owned by the service. */
+public final class EyePotionListener implements Listener {
+    private final EyeProgressionService progression;
+    private final Consumer<Throwable> saveFailure;
+    private final Map<UUID, PotionEffect> expectedEffects = new HashMap<>();
+
+    public EyePotionListener(EyeProgressionService progression, Consumer<Throwable> saveFailure) {
+        this.progression = Objects.requireNonNull(progression, "progression");
+        this.saveFailure = Objects.requireNonNull(saveFailure, "saveFailure");
+    }
+
+    @EventHandler(priority = EventPriority.MONITOR, ignoreCancelled = true)
+    public void onPotionEffect(EntityPotionEffectEvent event) {
+        if (event.isCancelled() || !(event.getEntity() instanceof Player player)
+                || !PotionEffectType.NIGHT_VISION.equals(event.getModifiedType())) {
+            return;
+        }
+        if (event.getAction() == EntityPotionEffectEvent.Action.CHANGED && !replacesActiveEffect(event)) {
+            return;
+        }
+        boolean addedOrChanged = event.getAction() == EntityPotionEffectEvent.Action.ADDED
+                || event.getAction() == EntityPotionEffectEvent.Action.CHANGED;
+        if (addedOrChanged && event.getCause() == EntityPotionEffectEvent.Cause.POTION_DRINK) {
+            if (!continuesEffect(expectedEffects.get(player.getUniqueId()), event.getOldEffect())) {
+                progression.abandon(player.getUniqueId());
+            }
+            expectedEffects.put(player.getUniqueId(), event.getNewEffect());
+            observe(progression.begin(player.getUniqueId()));
+        } else {
+            finish(player.getUniqueId(), event.getOldEffect());
+        }
+    }
+
+    @EventHandler(priority = EventPriority.MONITOR)
+    public void onQuit(PlayerQuitEvent event) {
+        finish(event.getPlayer().getUniqueId(), event.getPlayer().getPotionEffect(PotionEffectType.NIGHT_VISION));
+    }
+
+    /** Server-thread observation; a missing/unattributed effect cannot inherit an old drink interval. */
+    public void checkpoint(Function<UUID, Player> onlinePlayer) {
+        for (var id : progression.activePlayerIds()) {
+            Player player = onlinePlayer.apply(id);
+            var actual = player == null || !player.isOnline() || player.isDead()
+                    ? null : player.getPotionEffect(PotionEffectType.NIGHT_VISION);
+            var expected = expectedEffects.get(id);
+            if (!continuesEffect(expected, actual) || (!actual.isInfinite() && actual.getDuration() <= 0)) {
+                expectedEffects.remove(id);
+                progression.abandon(id); // Discard the unobserved tail, never attribute it to the old source.
+            } else {
+                expectedEffects.put(id, actual);
+                observe(progression.checkpoint(id));
+            }
+        }
+    }
+
+    private void finish(UUID id, PotionEffect finalEffect) {
+        var expected = expectedEffects.remove(id);
+        if (continuesEffect(expected, finalEffect)) { observe(progression.stop(id)); }
+        else { progression.abandon(id); }
+    }
+
+    private static boolean continuesEffect(PotionEffect expected, PotionEffect actual) {
+        return actual != null && expected != null && actual.getAmplifier() == expected.getAmplifier()
+                && (expected.isInfinite() ? actual.isInfinite()
+                    : !actual.isInfinite() && actual.getDuration() <= expected.getDuration());
+    }
+
+    private void observe(CompletableFuture<Void> saved) {
+        saved.whenComplete((ignored, failure) -> {
+            if (failure != null) { saveFailure.accept(failure); }
+        });
+    }
+
+    private static boolean replacesActiveEffect(EntityPotionEffectEvent event) {
+        if (!event.isOverride() || event.getOldEffect() == null || event.getNewEffect() == null) { return false; }
+        var previous = event.getOldEffect();
+        var next = event.getNewEffect();
+        // Native update can return true for particles/icons alone. Hidden weaker effects are not active yet.
+        return next.getAmplifier() > previous.getAmplifier()
+                || (next.getAmplifier() == previous.getAmplifier() && !previous.isInfinite()
+                    && (next.isInfinite() || next.getDuration() > previous.getDuration()));
+    }
+}

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

@@ -0,0 +1,13 @@
+package games.dmg.spigotstealth;
+
+import java.util.Map;
+
+/** Independent durable Eye of True Seeing progress. Active potion intervals are never resumed from disk. */
+public record EyeProgress(long accumulatedMillis, boolean unlocked, Map<String, Object> unknownFields) {
+    public EyeProgress {
+        if (accumulatedMillis < 0) { throw new IllegalArgumentException("Eye progress cannot be negative"); }
+        unknownFields = Map.copyOf(unknownFields);
+    }
+    public EyeProgress(long accumulatedMillis, boolean unlocked) { this(accumulatedMillis, unlocked, Map.of()); }
+    public static EyeProgress empty() { return new EyeProgress(0, false); }
+}

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

@@ -0,0 +1,73 @@
+package games.dmg.spigotstealth;
+
+import java.time.Duration;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Set;
+import java.util.UUID;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.function.Consumer;
+import java.util.function.LongSupplier;
+
+/** Server-thread qualifying intervals; durable rewards are acknowledged by the existing I/O executor. */
+public final class EyeProgressionService {
+    public static final Duration UNLOCK_THRESHOLD = Duration.ofHours(8);
+    private record Interval(long startedNanos, long creditedMillis) { }
+    private final StealthStateManager states;
+    private final LongSupplier nanoTime;
+    private final Consumer<UUID> unlocked;
+    private final Map<UUID, Interval> active = new HashMap<>();
+    private final Set<UUID> announced = ConcurrentHashMap.newKeySet();
+
+    /** The notification callback must marshal Bukkit work onto the server thread. */
+    public EyeProgressionService(StealthStateManager states, LongSupplier nanoTime, Consumer<UUID> unlocked) {
+        this.states = Objects.requireNonNull(states, "states");
+        this.nanoTime = Objects.requireNonNull(nanoTime, "nanoTime");
+        this.unlocked = Objects.requireNonNull(unlocked, "unlocked");
+        states.durableSnapshot().eyes().forEach((id, progress) -> {
+            if (progress.unlocked()) { announced.add(id); }
+        });
+    }
+
+    public CompletableFuture<Void> begin(UUID id) {
+        Objects.requireNonNull(id, "id");
+        if (active.containsKey(id)) { return checkpoint(id); }
+        active.put(id, new Interval(nanoTime.getAsLong(), 0));
+        return CompletableFuture.completedFuture(null);
+    }
+
+    public CompletableFuture<Void> checkpoint(UUID id) {
+        Interval interval = active.get(id);
+        if (interval == null) { return CompletableFuture.completedFuture(null); }
+        // Keep the original start: repeated checkpoints must not discard fractional milliseconds.
+        long total = Math.max(interval.creditedMillis(), Math.max(0, nanoTime.getAsLong() - interval.startedNanos()) / 1_000_000);
+        long elapsed = total - interval.creditedMillis();
+        if (elapsed == 0) { return CompletableFuture.completedFuture(null); }
+        active.put(id, new Interval(interval.startedNanos(), total));
+        return states.update(state -> {
+            EyeProgress previous = state.eyeProgress(id);
+            long accumulated = Math.addExact(previous.accumulatedMillis(), elapsed);
+            return state.withEyeProgress(id, new EyeProgress(accumulated,
+                previous.unlocked() || accumulated >= UNLOCK_THRESHOLD.toMillis(), previous.unknownFields()));
+        }).thenRun(() -> {
+            if (isUnlocked(id) && announced.add(id)) { unlocked.accept(id); }
+        });
+    }
+
+    public CompletableFuture<Void> stop(UUID id) {
+        CompletableFuture<Void> saved = checkpoint(id);
+        active.remove(id);
+        return saved;
+    }
+
+    public CompletableFuture<Void> stopAll() {
+        return CompletableFuture.allOf(activePlayerIds().stream().map(this::stop).toArray(CompletableFuture[]::new));
+    }
+
+    /** Defensive offline sweep: do not invent credit for the unobserved interval after the last checkpoint. */
+    public void abandon(UUID id) { active.remove(id); }
+    public boolean isUnlocked(UUID id) { return states.durableSnapshot().eyeProgress(id).unlocked(); }
+    public Set<UUID> activePlayerIds() { return Set.copyOf(active.keySet()); }
+}

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

@@ -9,11 +9,18 @@ import java.util.UUID;
 public record PersistentStealthState(
         Map<UUID, PlayerStealthState> players,
         SleepCountPolicy sleepCountPolicy,
-        Map<String, Object> unknownFields) {
+        Map<String, Object> unknownFields,
+        Map<UUID, EyeProgress> eyes) {
     public PersistentStealthState {
         players = Map.copyOf(new LinkedHashMap<>(Objects.requireNonNull(players, "players")));
         Objects.requireNonNull(sleepCountPolicy, "sleepCountPolicy");
         unknownFields = Map.copyOf(new LinkedHashMap<>(Objects.requireNonNull(unknownFields, "unknownFields")));
+        eyes = Map.copyOf(Objects.requireNonNull(eyes, "eyes"));
+    }
+
+    public PersistentStealthState(Map<UUID, PlayerStealthState> players, SleepCountPolicy sleepCountPolicy,
+            Map<String, Object> unknownFields) {
+        this(players, sleepCountPolicy, unknownFields, Map.of());
     }
 
     public PersistentStealthState(
@@ -22,6 +29,14 @@ public record PersistentStealthState(
         this(players, SleepCountPolicy.EXCLUDE, unknownFields);
     }
 
+    public EyeProgress eyeProgress(UUID playerId) { return eyes.getOrDefault(playerId, EyeProgress.empty()); }
+
+    public PersistentStealthState withEyeProgress(UUID playerId, EyeProgress progress) {
+        Map<UUID, EyeProgress> updated = new LinkedHashMap<>(eyes);
+        updated.put(playerId, progress);
+        return new PersistentStealthState(players, sleepCountPolicy, unknownFields, updated);
+    }
+
     public PlayerStealthState player(UUID playerId) {
         return players.getOrDefault(playerId, PlayerStealthState.empty(playerId));
     }
@@ -29,10 +44,10 @@ public record PersistentStealthState(
     public PersistentStealthState withPlayer(PlayerStealthState player) {
         Map<UUID, PlayerStealthState> updated = new LinkedHashMap<>(players);
         updated.put(player.playerId(), player);
-        return new PersistentStealthState(updated, sleepCountPolicy, unknownFields);
+        return new PersistentStealthState(updated, sleepCountPolicy, unknownFields, eyes);
     }
 
     public PersistentStealthState withSleepCountPolicy(SleepCountPolicy policy) {
-        return new PersistentStealthState(players, policy, unknownFields);
+        return new PersistentStealthState(players, policy, unknownFields, eyes);
     }
 }

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

@@ -12,14 +12,20 @@ import org.bukkit.plugin.java.JavaPlugin;
 /** Bukkit entry point for Spigot Stealth. */
 public final class SpigotStealthPlugin extends JavaPlugin {
     private CompletableFuture<StealthStateManager> stateManagerFuture;
+    private CompletableFuture<Void> shutdown;
+    private volatile long lifecycleEpoch;
     private StealthSettings settings;
     private QualifyingInvisibilityService progression;
     private StealthSessionService sessions;
     private IdentityPresentation identityPresentation;
     private ProtocolManager protocolManager;
+    private EyeProgressionService eyeProgression;
+    private EyePotionListener eyePotions;
+    private boolean eyeRecipeRegistered;
 
     @Override
     public void onEnable() {
+        long epoch = ++lifecycleEpoch;
         saveDefaultConfig();
         try {
             settings = StealthSettings.from(getConfig().getValues(true));
@@ -30,45 +36,73 @@ public final class SpigotStealthPlugin extends JavaPlugin {
         }
 
         Path stateFile = getDataFolder().toPath().resolve("state.yml");
-        stateManagerFuture = StealthStateManager.load(new YamlStealthStateRepository(stateFile));
+        stateManagerFuture = shutdownCompletion().thenCompose(ignored ->
+                StealthStateManager.load(new YamlStealthStateRepository(stateFile)));
         stateManagerFuture.whenComplete((manager, failure) -> {
             if (failure != null) {
                 getLogger().severe("Unable to load Spigot Stealth state: " + rootMessage(failure));
-                getServer().getScheduler().runTask(this, () -> getServer().getPluginManager().disablePlugin(this));
+                onServer(epoch, () -> getServer().getPluginManager().disablePlugin(this));
                 return;
             }
-            getServer().getScheduler().runTask(this, () -> finishInitialization(manager));
+            if (!isEnabled() || epoch != lifecycleEpoch) {
+                logSaveFailure(manager.closeAsync());
+                return;
+            }
+            try {
+                getServer().getScheduler().runTask(this, () -> {
+                    if (!isEnabled() || epoch != lifecycleEpoch) { logSaveFailure(manager.closeAsync()); }
+                    else { finishInitialization(manager, epoch); }
+                });
+            } catch (org.bukkit.plugin.IllegalPluginAccessException ignored) {
+                logSaveFailure(manager.closeAsync());
+            }
         });
     }
 
     @Override
     public void onDisable() {
-        if (protocolManager != null) {
-            protocolManager.removePacketListeners(this);
-        }
-        if (identityPresentation != null && sessions != null) {
-            for (org.bukkit.entity.Player player : getServer().getOnlinePlayers()) {
-                if (sessions.isConcealed(player.getUniqueId())) {
-                    identityPresentation.reveal(player);
-                    sessions.endConcealment(player.getUniqueId());
+        ++lifecycleEpoch;
+        try {
+            if (eyePotions != null) {
+                eyePotions.checkpoint(getServer()::getPlayer);
+                logSaveFailure(eyeProgression.stopAll());
+            }
+            if (progression != null) { logSaveFailure(progression.stopAll()); }
+            if (protocolManager != null) { protocolManager.removePacketListeners(this); }
+            if (identityPresentation != null && sessions != null) {
+                for (org.bukkit.entity.Player player : getServer().getOnlinePlayers()) {
+                    if (sessions.isConcealed(player.getUniqueId())) {
+                        try { identityPresentation.reveal(player); }
+                        finally { logSaveFailure(sessions.endConcealment(player.getUniqueId())); }
+                    }
+                }
+            }
+        } finally {
+            try {
+                if (eyeRecipeRegistered) {
+                    getServer().removeRecipe(EyeCrafting.RECIPE_KEY);
+                    eyeRecipeRegistered = false;
+                }
+            } finally {
+                if (stateManagerFuture != null) {
+                    shutdown = stateManagerFuture.thenCompose(StealthStateManager::closeAsync);
+                    logSaveFailure(shutdown);
                 }
             }
         }
-        if (progression != null) {
-            progression.stopAll().join();
-        }
-        if (stateManagerFuture != null && stateManagerFuture.isDone() && !stateManagerFuture.isCompletedExceptionally()) {
-            stateManagerFuture.join().close();
-        }
+    }
+
+    /** Durable shutdown acknowledgement; never wait for it on the server thread. */
+    CompletableFuture<Void> shutdownCompletion() {
+        return shutdown == null ? CompletableFuture.completedFuture(null) : shutdown;
     }
 
     public StealthSettings settings() {
         return settings;
     }
 
-    private void finishInitialization(StealthStateManager manager) {
-        java.util.function.Consumer<Runnable> mainThread =
-                runnable -> getServer().getScheduler().runTask(this, runnable);
+    private void finishInitialization(StealthStateManager manager, long epoch) {
+        java.util.function.Consumer<Runnable> mainThread = runnable -> onServer(epoch, runnable);
         BukkitUnlockNotifier notifier = new BukkitUnlockNotifier(
                 getServer()::getPlayer,
                 mainThread,
@@ -113,6 +147,36 @@ public final class SpigotStealthPlugin extends JavaPlugin {
                 settings.unlockThreshold());
         stealthAdminPluginCommand.setExecutor(stealthAdminCommand);
         stealthAdminPluginCommand.setTabCompleter(stealthAdminCommand);
+        eyeProgression = new EyeProgressionService(manager, this::monotonicNanos, id -> mainThread.accept(() -> {
+            var player = getServer().getPlayer(id);
+            if (player != null) {
+                player.discoverRecipe(EyeCrafting.RECIPE_KEY);
+                player.sendMessage("You unlocked the Eye of True Seeing! Craft it with eight Netherite Blocks around an Eye of Ender.");
+            }
+        }));
+        eyePotions = new EyePotionListener(eyeProgression,
+                failure -> getLogger().severe("Unable to save Eye progression: " + rootMessage(failure)));
+        var eyeItems = new EyeItems();
+        var eyeCrafting = new EyeCrafting(eyeProgression, eyeItems);
+        if (!getServer().addRecipe(eyeCrafting.recipe())) {
+            getLogger().severe("Unable to register the Eye recipe; disabling Stealth rather than replacing another recipe.");
+            getServer().getPluginManager().disablePlugin(this);
+            return;
+        }
+        eyeRecipeRegistered = true;
+        getServer().getPluginManager().registerEvents(eyePotions, this);
+        getServer().getPluginManager().registerEvents(eyeCrafting, this);
+        getServer().getPluginManager().registerEvents(new EyeEquipment(eyeProgression, eyeItems), this);
+        getServer().getScheduler().runTaskTimer(this, ignored -> {
+            eyePotions.checkpoint(getServer()::getPlayer);
+            for (var player : getServer().getOnlinePlayers()) {
+                if (eyeProgression.isUnlocked(player.getUniqueId())) {
+                    if (!player.hasDiscoveredRecipe(EyeCrafting.RECIPE_KEY)) { player.discoverRecipe(EyeCrafting.RECIPE_KEY); }
+                } else if (player.hasDiscoveredRecipe(EyeCrafting.RECIPE_KEY)) {
+                    player.undiscoverRecipe(EyeCrafting.RECIPE_KEY);
+                }
+            }
+        }, 20L, 20L);
         getServer().getScheduler().runTaskTimer(this, ignored -> {
             for (java.util.UUID playerId : progression.activePlayerIds()) {
                 logSaveFailure(progression.checkpoint(playerId));
@@ -127,6 +191,20 @@ public final class SpigotStealthPlugin extends JavaPlugin {
         getLogger().info("Spigot Stealth enabled");
     }
 
+    /** Clock boundary for deterministic gameplay lifecycle verification. */
+    long monotonicNanos() { return System.nanoTime(); }
+
+    private void onServer(long epoch, Runnable action) {
+        if (!isEnabled() || epoch != lifecycleEpoch) { return; }
+        try {
+            getServer().getScheduler().runTask(this, () -> {
+                if (isEnabled() && epoch == lifecycleEpoch) { action.run(); }
+            });
+        } catch (org.bukkit.plugin.IllegalPluginAccessException ignored) {
+            // A durable unlock remains saved even if disable races its notification.
+        }
+    }
+
     private void logSaveFailure(CompletableFuture<Void> save) {
         save.exceptionally(failure -> {
             getLogger().severe("Unable to save Spigot Stealth state: " + rootMessage(failure));

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

@@ -14,7 +14,9 @@ import java.util.function.UnaryOperator;
 public final class StealthStateManager implements AutoCloseable {
     private final StealthStateRepository repository;
     private final AtomicReference<PersistentStealthState> state;
+    private final AtomicReference<PersistentStealthState> durableState;
     private final ExecutorService ioExecutor;
+    private CompletableFuture<Void> closing;
 
     public StealthStateManager(StealthStateRepository repository, PersistentStealthState initialState) {
         this(repository, initialState, newIoExecutor());
@@ -26,6 +28,7 @@ public final class StealthStateManager implements AutoCloseable {
             ExecutorService ioExecutor) {
         this.repository = Objects.requireNonNull(repository, "repository");
         this.state = new AtomicReference<>(Objects.requireNonNull(initialState, "initialState"));
+        this.durableState = new AtomicReference<>(initialState);
         this.ioExecutor = ioExecutor;
     }
 
@@ -35,7 +38,7 @@ public final class StealthStateManager implements AutoCloseable {
         return CompletableFuture.supplyAsync(() -> {
             try {
                 return new StealthStateManager(repository, repository.load(), executor);
-            } catch (IOException exception) {
+            } catch (IOException | RuntimeException exception) {
                 executor.shutdown();
                 throw new CompletionException(exception);
             }
@@ -46,36 +49,51 @@ public final class StealthStateManager implements AutoCloseable {
         return state.get();
     }
 
-    public CompletableFuture<Void> update(UnaryOperator<PersistentStealthState> operation) {
+    /** Last successfully written snapshot, for rewards that must not precede persistence acknowledgement. */
+    public PersistentStealthState durableSnapshot() { return durableState.get(); }
+
+    public synchronized CompletableFuture<Void> update(UnaryOperator<PersistentStealthState> operation) {
+        if (closing != null) { return CompletableFuture.failedFuture(new IllegalStateException("Stealth state is closing")); }
         PersistentStealthState updated = state.updateAndGet(operation);
         return persist(updated);
     }
 
-    public CompletableFuture<Void> save() {
-        return persist(state.get());
+    public synchronized CompletableFuture<Void> save() {
+        return closing == null ? persist(state.get()) : closing;
     }
 
     private CompletableFuture<Void> persist(PersistentStealthState snapshot) {
         return CompletableFuture.runAsync(() -> {
             try {
                 repository.save(snapshot);
+                durableState.set(snapshot);
             } catch (IOException exception) {
                 throw new CompletionException(exception);
             }
         }, ioExecutor);
     }
 
+    /** Queue the final snapshot and stop accepting mutations, without waiting on the caller's thread. */
+    public synchronized CompletableFuture<Void> closeAsync() {
+        if (closing == null) {
+            closing = persist(state.get());
+            ioExecutor.shutdown();
+        }
+        return closing;
+    }
+
+    /** Blocking convenience for non-server callers such as tests; server lifecycle callers should use closeAsync. */
     @Override
     public void close() {
-        save().join();
-        ioExecutor.shutdown();
         try {
-            if (!ioExecutor.awaitTermination(10L, TimeUnit.SECONDS)) {
+            closeAsync().join();
+        } finally {
+            try {
+                if (!ioExecutor.awaitTermination(10L, TimeUnit.SECONDS)) { ioExecutor.shutdownNow(); }
+            } catch (InterruptedException exception) {
                 ioExecutor.shutdownNow();
+                Thread.currentThread().interrupt();
             }
-        } catch (InterruptedException exception) {
-            ioExecutor.shutdownNow();
-            Thread.currentThread().interrupt();
         }
     }
 

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

@@ -17,7 +17,8 @@ import org.bukkit.configuration.file.YamlConfiguration;
 
 /** Defensive YAML repository using atomic file replacement where available. */
 public final class YamlStealthStateRepository implements StealthStateRepository {
-    private static final Set<String> ROOT_FIELDS = Set.of("schema-version", "sleep-count-policy", "players");
+    private static final Set<String> ROOT_FIELDS = Set.of("schema-version", "sleep-count-policy", "players", "eye-progress");
+    private static final Set<String> EYE_FIELDS = Set.of("accumulated-millis", "unlocked");
     private static final Set<String> PLAYER_FIELDS = Set.of(
             "last-known-name", "accumulated-millis", "unlocked", "prepared-login", "concealed", "qualifying-since");
     private final Path stateFile;
@@ -56,14 +57,15 @@ public final class YamlStealthStateRepository implements StealthStateRepository
         return new PersistentStealthState(
                 players,
                 SleepCountPolicy.fromPersisted(yaml.get("sleep-count-policy")),
-                unknownRoot);
+                unknownRoot,
+                parseEyes(yaml.getConfigurationSection("eye-progress")));
     }
 
     @Override
     public void save(PersistentStealthState state) throws IOException {
         YamlConfiguration yaml = new YamlConfiguration();
         state.unknownFields().forEach(yaml::set);
-        yaml.set("schema-version", 1);
+        yaml.set("schema-version", 2);
         yaml.set("sleep-count-policy", state.sleepCountPolicy().persistedValue());
         for (PlayerStealthState player : state.players().values()) {
             String base = "players." + player.playerId() + ".";
@@ -75,6 +77,12 @@ public final class YamlStealthStateRepository implements StealthStateRepository
             yaml.set(base + "concealed", player.concealed());
             yaml.set(base + "qualifying-since", player.qualifyingSince() == null ? null : player.qualifyingSince().toString());
         }
+        state.eyes().forEach((id, progress) -> {
+            String base = "eye-progress." + id + ".";
+            progress.unknownFields().forEach((key, value) -> yaml.set(base + key, value));
+            yaml.set(base + "accumulated-millis", progress.accumulatedMillis());
+            yaml.set(base + "unlocked", progress.unlocked());
+        });
         Path parent = stateFile.toAbsolutePath().getParent();
         if (parent != null) {
             Files.createDirectories(parent);
@@ -88,6 +96,27 @@ public final class YamlStealthStateRepository implements StealthStateRepository
         }
     }
 
+    private static Map<UUID, EyeProgress> parseEyes(ConfigurationSection section) {
+        Map<UUID, EyeProgress> eyes = new LinkedHashMap<>();
+        if (section == null) { return eyes; }
+        for (String key : section.getKeys(false)) {
+            try {
+                UUID id = UUID.fromString(key);
+                ConfigurationSection entry = section.getConfigurationSection(key);
+                if (entry == null) { continue; }
+                Object raw = entry.get("accumulated-millis");
+                if (!(raw instanceof Long || raw instanceof Integer || raw instanceof Short || raw instanceof Byte)) {
+                    continue;
+                }
+                eyes.put(id, new EyeProgress(requireNonNegativeLong(entry, "accumulated-millis"),
+                    requireBoolean(entry, "unlocked"), unknownValues(entry, EYE_FIELDS)));
+            } catch (IllegalArgumentException ignored) {
+                // A malformed Eye record cannot grant an unlock or erase independent Stealth records.
+            }
+        }
+        return eyes;
+    }
+
     private static PlayerStealthState parsePlayer(UUID playerId, ConfigurationSection section) {
         long accumulated = requireNonNegativeLong(section, "accumulated-millis");
         boolean unlocked = requireBoolean(section, "unlocked");

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

@@ -0,0 +1,215 @@
+package games.dmg.spigotstealth;
+
+import static org.junit.jupiter.api.Assertions.*;
+import static org.mockito.Mockito.*;
+
+import java.nio.file.Path;
+import java.util.UUID;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicReference;
+import org.bukkit.Material;
+import org.bukkit.entity.Player;
+import org.bukkit.event.inventory.PrepareItemCraftEvent;
+import org.bukkit.inventory.CraftingInventory;
+import org.bukkit.inventory.InventoryView;
+import org.bukkit.inventory.ItemStack;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+class EyeCraftingTest {
+    @TempDir Path directory;
+    @BeforeAll static void bootstrap() throws Exception { NativeRuntime.bootstrap(); }
+
+    @Test
+    void eightNetheriteBlocksAroundAnEnderEyeCanOnlyBeCraftedAfterThePersonalUnlock() throws Exception {
+        var repository = new YamlStealthStateRepository(directory.resolve("state.yml"));
+        UUID id = UUID.randomUUID();
+        try (var states = new StealthStateManager(repository, repository.load())) {
+            var progression = new EyeProgressionService(states, () -> 0L, ignored -> { });
+            var items = new EyeItems();
+            var crafting = new EyeCrafting(progression, items);
+            var recipe = crafting.recipe();
+            assertArrayEquals(new String[] {"NNN", "NEN", "NNN"}, recipe.getShape());
+            assertEquals(Material.NETHERITE_BLOCK, recipe.getIngredientMap().get('N').getType());
+            assertEquals(Material.ENDER_EYE, recipe.getIngredientMap().get('E').getType());
+            assertTrue(items.isEye(recipe.getResult()));
+            var player = mock(Player.class);
+            when(player.getUniqueId()).thenReturn(id);
+            var inventory = mock(CraftingInventory.class);
+            when(inventory.getRecipe()).thenReturn(recipe);
+            when(inventory.getMatrix()).thenReturn(matrix());
+            var result = new AtomicReference<>(recipe.getResult());
+            when(inventory.getResult()).thenAnswer(ignored -> result.get());
+            doAnswer(call -> { result.set(call.getArgument(0)); return null; }).when(inventory).setResult(any());
+            var view = mock(InventoryView.class);
+            when(view.getPlayer()).thenReturn(player);
+            when(view.getTopInventory()).thenReturn(inventory);
+            var event = new PrepareItemCraftEvent(inventory, view, false);
+            crafting.onPrepare(event);
+            assertNull(result.get(), "a locked player cannot obtain the recipe result");
+            states.update(state -> state.withEyeProgress(id, new EyeProgress(28_800_000, true))).get(3, TimeUnit.SECONDS);
+            result.set(recipe.getResult()); // A fresh native recipe preparation after earning the unlock.
+            crafting.onPrepare(event);
+            assertTrue(items.isEye(result.get()));
+            assertEquals(1, result.get().getAmount());
+            verify(inventory, never()).setMatrix(any()); // Vanilla owns all ingredient consumption.
+        }
+    }
+
+    @Test
+    void resultClicksRecheckEligibilityIngredientsAndIdentityWithoutBypassingCancellation() throws Exception {
+        var repository = new YamlStealthStateRepository(directory.resolve("state.yml"));
+        UUID id = UUID.randomUUID();
+        try (var states = new StealthStateManager(repository, repository.load())) {
+            var progression = new EyeProgressionService(states, () -> 0L, ignored -> { });
+            var items = new EyeItems();
+            var crafting = new EyeCrafting(progression, items);
+            var recipe = crafting.recipe();
+            var player = mock(Player.class);
+            when(player.getUniqueId()).thenReturn(id);
+            var inventory = mock(CraftingInventory.class);
+            when(inventory.getRecipe()).thenReturn(recipe);
+            ItemStack[] ingredients = matrix();
+            when(inventory.getMatrix()).thenReturn(ingredients);
+            var result = new AtomicReference<>(recipe.getResult());
+            when(inventory.getResult()).thenAnswer(ignored -> result.get());
+            doAnswer(call -> { result.set(call.getArgument(0)); return null; }).when(inventory).setResult(any());
+            var view = mock(InventoryView.class);
+            when(view.getPlayer()).thenReturn(player);
+            when(view.getTopInventory()).thenReturn(inventory);
+            var locked = click(recipe, view);
+            crafting.onCraft(locked);
+            assertTrue(locked.isCancelled(), "a stale preview must not bypass the personal unlock on shift-click");
+            assertNull(result.get());
+            states.update(state -> state.withEyeProgress(id, new EyeProgress(28_800_000, true))).get(3, TimeUnit.SECONDS);
+            result.set(recipe.getResult());
+            var allowed = click(recipe, view);
+            crafting.onCraft(allowed);
+            assertFalse(allowed.isCancelled());
+            assertTrue(items.isEye(result.get()));
+            ingredients[0] = new ItemStack(Material.DIRT);
+            var invalidIngredients = click(recipe, view);
+            crafting.onCraft(invalidIngredients);
+            assertTrue(invalidIngredients.isCancelled());
+            assertNull(result.get());
+            ingredients[0] = new ItemStack(Material.NETHERITE_BLOCK);
+            result.set(new ItemStack(Material.ENDER_EYE));
+            var invalidResult = click(recipe, view);
+            crafting.onCraft(invalidResult);
+            assertTrue(invalidResult.isCancelled());
+            result.set(recipe.getResult());
+            result.get().setAmount(2);
+            var inflatedResult = click(recipe, view);
+            crafting.onCraft(inflatedResult);
+            assertTrue(inflatedResult.isCancelled());
+            result.set(recipe.getResult());
+            var cancelled = click(recipe, view);
+            cancelled.setCancelled(true);
+            crafting.onCraft(cancelled);
+            assertTrue(cancelled.isCancelled());
+            var otherRecipe = new org.bukkit.inventory.ShapedRecipe(new org.bukkit.NamespacedKey("other", "eye"),
+                    new ItemStack(Material.ENDER_EYE)).shape("E").setIngredient('E', Material.ENDER_EYE);
+            var unrelated = click(otherRecipe, view);
+            crafting.onCraft(unrelated);
+            assertFalse(unrelated.isCancelled());
+            verify(inventory, never()).setMatrix(any());
+        }
+    }
+
+    @Test
+    void pendingOrFailedUnlockWritesCannotExposeACraftableResult() throws Exception {
+        var disk = new YamlStealthStateRepository(directory.resolve("state.yml"));
+        var started = new java.util.concurrent.CountDownLatch(1);
+        var release = new java.util.concurrent.CountDownLatch(1);
+        var firstWrite = new java.util.concurrent.atomic.AtomicBoolean(true);
+        StealthStateRepository repository = new StealthStateRepository() {
+            @Override public PersistentStealthState load() throws java.io.IOException { return disk.load(); }
+            @Override public void save(PersistentStealthState state) throws java.io.IOException {
+                if (firstWrite.getAndSet(false)) {
+                    started.countDown();
+                    try {
+                        if (!release.await(3, TimeUnit.SECONDS)) { throw new java.io.IOException("Test write gate timed out"); }
+                    } catch (InterruptedException exception) {
+                        Thread.currentThread().interrupt();
+                        throw new java.io.IOException(exception);
+                    }
+                    throw new java.io.IOException("Injected write failure");
+                }
+                disk.save(state);
+            }
+        };
+        UUID id = UUID.randomUUID();
+        try (var states = new StealthStateManager(repository, repository.load())) {
+            try {
+                var items = new EyeItems();
+                var crafting = new EyeCrafting(new EyeProgressionService(states, () -> 0L, ignored -> { }), items);
+                var recipe = crafting.recipe();
+                var player = mock(Player.class);
+                when(player.getUniqueId()).thenReturn(id);
+                var inventory = mock(CraftingInventory.class);
+                when(inventory.getRecipe()).thenReturn(recipe);
+                when(inventory.getMatrix()).thenReturn(matrix());
+                var result = new AtomicReference<>(recipe.getResult());
+                when(inventory.getResult()).thenAnswer(ignored -> result.get());
+                doAnswer(call -> { result.set(call.getArgument(0)); return null; }).when(inventory).setResult(any());
+                var view = mock(InventoryView.class);
+                when(view.getPlayer()).thenReturn(player);
+                when(view.getTopInventory()).thenReturn(inventory);
+                var event = new PrepareItemCraftEvent(inventory, view, false);
+                var pending = states.update(state -> state.withEyeProgress(id, new EyeProgress(28_800_000, true)));
+                assertTrue(started.await(3, TimeUnit.SECONDS));
+                assertTrue(states.snapshot().eyeProgress(id).unlocked());
+                crafting.onPrepare(event);
+                assertNull(result.get(), "in-memory progress is not a durable crafting unlock");
+                release.countDown();
+                assertThrows(java.util.concurrent.ExecutionException.class, () -> pending.get(3, TimeUnit.SECONDS));
+                result.set(recipe.getResult());
+                crafting.onPrepare(event);
+                assertNull(result.get(), "failed writes must not grant the recipe");
+                var denied = click(recipe, view);
+                crafting.onCraft(denied);
+                assertTrue(denied.isCancelled());
+                states.save().get(3, TimeUnit.SECONDS);
+                result.set(recipe.getResult());
+                crafting.onPrepare(event);
+                assertTrue(items.isEye(result.get()));
+                var allowed = click(recipe, view);
+                crafting.onCraft(allowed);
+                assertFalse(allowed.isCancelled());
+            } finally { release.countDown(); }
+        }
+    }
+
+    @Test
+    void automatedCraftersCannotBypassPersonalProgression() throws Exception {
+        var repository = new YamlStealthStateRepository(directory.resolve("state.yml"));
+        try (var states = new StealthStateManager(repository, repository.load())) {
+            var items = new EyeItems();
+            var crafting = new EyeCrafting(new EyeProgressionService(states, () -> 0L, ignored -> { }), items);
+            var block = mock(org.bukkit.block.Block.class);
+            var event = new org.bukkit.event.block.CrafterCraftEvent(block, crafting.recipe(), items.create());
+            crafting.onCrafter(event);
+            assertTrue(event.isCancelled(), "a block has no personal Eye unlock");
+            var other = new org.bukkit.inventory.ShapedRecipe(new org.bukkit.NamespacedKey("other", "eye"),
+                    new ItemStack(Material.ENDER_EYE)).shape("E").setIngredient('E', Material.ENDER_EYE);
+            var unrelated = new org.bukkit.event.block.CrafterCraftEvent(block, other, other.getResult());
+            crafting.onCrafter(unrelated);
+            assertFalse(unrelated.isCancelled());
+        }
+    }
+
+    private static org.bukkit.event.inventory.CraftItemEvent click(org.bukkit.inventory.Recipe recipe, InventoryView view) {
+        return new org.bukkit.event.inventory.CraftItemEvent(recipe, view,
+                org.bukkit.event.inventory.InventoryType.SlotType.RESULT, 0,
+                org.bukkit.event.inventory.ClickType.SHIFT_LEFT, org.bukkit.event.inventory.InventoryAction.MOVE_TO_OTHER_INVENTORY);
+    }
+
+    private static ItemStack[] matrix() {
+        var result = new ItemStack[9];
+        for (int index = 0; index < result.length; index++) {
+            result[index] = new ItemStack(index == 4 ? Material.ENDER_EYE : Material.NETHERITE_BLOCK);
+        }
+        return result;
+    }
+}

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

@@ -0,0 +1,92 @@
+package games.dmg.spigotstealth;
+
+import static org.junit.jupiter.api.Assertions.*;
+import static org.mockito.Mockito.*;
+
+import java.nio.file.Path;
+import java.util.EnumMap;
+import java.util.UUID;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicReference;
+import org.bukkit.Material;
+import org.bukkit.block.BlockFace;
+import org.bukkit.entity.Player;
+import org.bukkit.event.Event;
+import org.bukkit.event.block.Action;
+import org.bukkit.event.player.PlayerInteractEvent;
+import org.bukkit.inventory.EquipmentSlot;
+import org.bukkit.inventory.ItemStack;
+import org.bukkit.inventory.PlayerInventory;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+class EyeEquipmentTest {
+    @TempDir Path directory;
+    @BeforeAll static void bootstrap() throws Exception { NativeRuntime.bootstrap(); }
+
+    @Test
+    void tradedEyesRequireTheHoldersOwnUnlockAndEquipWithoutThrowingOrReplacingAHelmet() throws Exception {
+        UUID earner = UUID.randomUUID(), holder = UUID.randomUUID();
+        var repository = new YamlStealthStateRepository(directory.resolve("state.yml"));
+        try (var states = new StealthStateManager(repository, repository.load())) {
+            states.update(state -> state.withEyeProgress(earner, new EyeProgress(28_800_000, true))).get(3, TimeUnit.SECONDS);
+            var items = new EyeItems();
+            var equipment = new EyeEquipment(new EyeProgressionService(states, () -> 0L, ignored -> { }), items);
+            var player = mock(Player.class);
+            when(player.getUniqueId()).thenReturn(holder);
+            var inventory = mock(PlayerInventory.class);
+            when(player.getInventory()).thenReturn(inventory);
+            var helmet = new AtomicReference<ItemStack>();
+            when(inventory.getHelmet()).thenAnswer(ignored -> helmet.get());
+            doAnswer(call -> { helmet.set(call.getArgument(0)); return null; }).when(inventory).setHelmet(any());
+            var hands = new EnumMap<EquipmentSlot, ItemStack>(EquipmentSlot.class);
+            when(inventory.getItem(any(EquipmentSlot.class))).thenAnswer(call -> hands.get(call.getArgument(0)));
+            doAnswer(call -> { hands.put(call.getArgument(0), call.getArgument(1)); return null; })
+                    .when(inventory).setItem(any(EquipmentSlot.class), nullable(ItemStack.class));
+            ItemStack traded = items.create();
+            hands.put(EquipmentSlot.HAND, traded);
+            helmet.set(traded.clone());
+            assertFalse(equipment.isEligibleWearer(player), "equipping somebody else's Eye must not bypass the personal unlock");
+            helmet.set(null);
+            var denied = use(player, traded, EquipmentSlot.HAND);
+            equipment.onUse(denied);
+            assertEquals(Event.Result.DENY, denied.useItemInHand(), "custom Eyes must never fall through to vanilla Ender Eye use");
+            assertNull(helmet.get());
+            assertSame(traded, hands.get(EquipmentSlot.HAND));
+            states.update(state -> state.withEyeProgress(holder, new EyeProgress(28_800_000, true))).get(3, TimeUnit.SECONDS);
+            var allowed = use(player, traded, EquipmentSlot.HAND);
+            equipment.onUse(allowed);
+            assertEquals(Event.Result.DENY, allowed.useItemInHand());
+            assertNull(hands.get(EquipmentSlot.HAND));
+            assertTrue(items.isEye(helmet.get()));
+            assertEquals(1, helmet.get().getAmount());
+            assertTrue(equipment.isEligibleWearer(player));
+            var ordinaryHelmet = new ItemStack(Material.IRON_HELMET);
+            helmet.set(ordinaryHelmet);
+            hands.put(EquipmentSlot.OFF_HAND, items.create());
+            equipment.onUse(use(player, hands.get(EquipmentSlot.OFF_HAND), EquipmentSlot.OFF_HAND));
+            assertSame(ordinaryHelmet, helmet.get());
+            assertTrue(items.isEye(hands.get(EquipmentSlot.OFF_HAND)));
+            assertFalse(equipment.isEligibleWearer(player), "holding an Eye is not wearing it");
+            helmet.set(null);
+            equipment.onUse(use(player, hands.get(EquipmentSlot.OFF_HAND), EquipmentSlot.OFF_HAND));
+            assertNull(hands.get(EquipmentSlot.OFF_HAND));
+            assertTrue(equipment.isEligibleWearer(player));
+            helmet.set(null);
+            hands.put(EquipmentSlot.HAND, items.create());
+            var cancelled = use(player, hands.get(EquipmentSlot.HAND), EquipmentSlot.HAND);
+            cancelled.setUseItemInHand(Event.Result.DENY);
+            equipment.onUse(cancelled);
+            assertNull(helmet.get());
+            assertTrue(items.isEye(hands.get(EquipmentSlot.HAND)));
+            var ordinary = use(player, new ItemStack(Material.ENDER_EYE), EquipmentSlot.HAND);
+            equipment.onUse(ordinary);
+            assertEquals(Event.Result.DEFAULT, ordinary.useItemInHand());
+        }
+    }
+
+    private static PlayerInteractEvent use(Player player, ItemStack item, EquipmentSlot hand) {
+        return new PlayerInteractEvent(player, Action.RIGHT_CLICK_AIR, item, null, BlockFace.SELF, hand);
+    }
+}

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

@@ -0,0 +1,39 @@
+package games.dmg.spigotstealth;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import net.kyori.adventure.text.Component;
+import org.bukkit.Material;
+import org.bukkit.inventory.EquipmentSlot;
+import org.bukkit.inventory.ItemStack;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+class EyeItemsTest {
+    @BeforeAll static void bootstrap() throws Exception { NativeRuntime.bootstrap(); }
+
+    @Test
+    void createdEyeIsAnAuthenticatedHelmetItemButPlainAndRenamedEyesAreNot() {
+        var items = new EyeItems();
+        ItemStack eye = items.create();
+        assertEquals(Material.ENDER_EYE, eye.getType());
+        assertEquals(Component.text("Eye of True Seeing"), eye.getItemMeta().displayName());
+        assertTrue(items.isEye(eye));
+        assertTrue(items.isEye(eye.clone()), "ordinary inventory transfer must retain item identity");
+        assertEquals(EquipmentSlot.HEAD, eye.getItemMeta().getEquippable().getSlot());
+        assertEquals(1, eye.getMaxStackSize());
+        assertFalse(eye.getItemMeta().getEquippable().isDispensable());
+        assertFalse(eye.getItemMeta().getEquippable().isEquipOnInteract(),
+                "the eligibility-checked interaction handler, not native item use, equips the Eye");
+        var ordinary = new ItemStack(Material.ENDER_EYE);
+        assertFalse(items.isEye(ordinary));
+        var renamed = ordinary.getItemMeta();
+        renamed.displayName(eye.getItemMeta().displayName());
+        ordinary.setItemMeta(renamed);
+        assertFalse(items.isEye(ordinary), "anvil/display names cannot authenticate an Eye");
+        var wrongMaterial = eye.clone();
+        wrongMaterial.setType(Material.STONE);
+        assertFalse(items.isEye(wrongMaterial));
+        assertFalse(items.isEye(null));
+    }
+}

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

@@ -0,0 +1,216 @@
+package games.dmg.spigotstealth;
+
+import static org.junit.jupiter.api.Assertions.*;
+import static org.mockito.Mockito.*;
+
+import com.comphenix.protocol.ProtocolLibrary;
+import com.comphenix.protocol.ProtocolManager;
+import java.nio.file.Path;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.UUID;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.function.Consumer;
+import java.util.logging.Logger;
+import org.bukkit.Server;
+import org.bukkit.command.PluginCommand;
+import org.bukkit.configuration.file.YamlConfiguration;
+import org.bukkit.entity.Player;
+import org.bukkit.event.Event;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.Listener;
+import org.bukkit.event.inventory.PrepareItemCraftEvent;
+import org.bukkit.inventory.CraftingInventory;
+import org.bukkit.inventory.InventoryView;
+import org.bukkit.inventory.ItemStack;
+import org.bukkit.inventory.Recipe;
+import org.bukkit.plugin.EventExecutor;
+import org.bukkit.plugin.PluginDescriptionFile;
+import org.bukkit.plugin.PluginManager;
+import org.bukkit.plugin.RegisteredListener;
+import org.bukkit.scheduler.BukkitScheduler;
+import org.bukkit.scheduler.BukkitTask;
+import org.bukkit.scoreboard.Scoreboard;
+import org.bukkit.scoreboard.ScoreboardManager;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+class EyePluginLifecycleTest {
+    @TempDir Path directory;
+    @BeforeAll static void bootstrap() throws Exception { NativeRuntime.bootstrap(); }
+
+    @org.junit.jupiter.params.ParameterizedTest
+    @org.junit.jupiter.params.provider.ValueSource(strings = {"normal", "disabled", "reenabled", "presentation-failure"})
+    @SuppressWarnings("try") // The scoped Bukkit boundary delegates non-server-metadata operations to native code.
+    void startupAndLateCallbacksRespectSavedUnlocksAndDisable(String mode) throws Exception {
+        UUID id = UUID.randomUUID(), learner = UUID.randomUUID();
+        var disk = new YamlStealthStateRepository(directory.resolve("state.yml"));
+        disk.save(new PersistentStealthState(Map.of(), Map.of()).withEyeProgress(id, new EyeProgress(28_800_000, true)));
+        var plugin = mock(SpigotStealthPlugin.class, CALLS_REAL_METHODS);
+        var clock = new java.util.concurrent.atomic.AtomicLong();
+        doAnswer(ignored -> clock.get()).when(plugin).monotonicNanos();
+        Server server = mock(org.bukkit.craftbukkit.CraftServer.class);
+        var plugins = mock(PluginManager.class);
+        BukkitScheduler scheduler = mock(org.bukkit.craftbukkit.scheduler.CraftScheduler.class);
+        var player = mock(Player.class);
+        when(player.getUniqueId()).thenReturn(id);
+        doReturn(List.of(player)).when(server).getOnlinePlayers();
+        when(server.getPlayer(id)).thenReturn(player);
+        doReturn(server).when(plugin).getServer();
+        doReturn(true).when(plugin).isEnabled();
+        doReturn(directory.toFile()).when(plugin).getDataFolder();
+        doReturn(new YamlConfiguration()).when(plugin).getConfig();
+        doReturn(Logger.getAnonymousLogger()).when(plugin).getLogger();
+        doReturn(new PluginDescriptionFile("SpigotStealth", "test", SpigotStealthPlugin.class.getName()))
+                .when(plugin).getDescription();
+        doNothing().when(plugin).saveDefaultConfig();
+        doReturn(mock(PluginCommand.class)).when(plugin).getCommand("stealth");
+        doReturn(mock(PluginCommand.class)).when(plugin).getCommand("stealthadmin");
+        when(server.getPluginManager()).thenReturn(plugins);
+        when(server.getScheduler()).thenReturn(scheduler);
+        ScoreboardManager boards = mock(org.bukkit.craftbukkit.scoreboard.CraftScoreboardManager.class);
+        when(server.getScoreboardManager()).thenReturn(boards);
+        when(boards.getMainScoreboard()).thenReturn(mock(org.bukkit.craftbukkit.scoreboard.CraftScoreboard.class));
+        var main = new LinkedBlockingQueue<Runnable>();
+        when(scheduler.runTask(eq(plugin), any(Runnable.class))).thenAnswer(call -> {
+            main.add(call.getArgument(1)); return mock(BukkitTask.class);
+        });
+        var timers = new ArrayList<Runnable>();
+        doAnswer(call -> {
+            Consumer<BukkitTask> action = call.getArgument(1);
+            timers.add(() -> action.accept(mock(BukkitTask.class)));
+            return null;
+        }).when(scheduler).runTaskTimer(eq(plugin), org.mockito.ArgumentMatchers.<Consumer<BukkitTask>>any(), anyLong(), anyLong());
+        when(scheduler.runTaskTimer(eq(plugin), any(Runnable.class), anyLong(), anyLong())).thenAnswer(call -> {
+            timers.add(call.getArgument(1)); return mock(BukkitTask.class);
+        });
+        var recipe = new AtomicReference<Recipe>();
+        when(server.addRecipe(any(Recipe.class))).thenAnswer(call -> { recipe.set(call.getArgument(0)); return true; });
+        var listeners = new ArrayList<Listener>();
+        doAnswer(call -> { listeners.add(call.getArgument(0)); return null; }).when(plugins).registerEvents(any(), eq(plugin));
+        try (var platform = mockStatic(org.bukkit.Bukkit.class, call -> switch (call.getMethod().getName()) {
+            case "getServer" -> server;
+            case "getVersion" -> "Purpur 2618 (MC: 26.2)";
+            case "getMinecraftVersion" -> "26.2";
+            case "getBukkitVersion" -> "26.2-R0.1-SNAPSHOT";
+            default -> call.callRealMethod();
+        }); var protocol = mockStatic(ProtocolLibrary.class)) {
+            var protocolManager = mock(ProtocolManager.class);
+            protocol.when(ProtocolLibrary::getProtocolManager).thenReturn(protocolManager);
+            try {
+                plugin.onEnable();
+                assertNull(recipe.get(), "Bukkit registration must wait for durable state initialization and main-thread dispatch");
+                Runnable initialization = main.poll(3, TimeUnit.SECONDS);
+                assertNotNull(initialization);
+                if (mode.equals("disabled") || mode.equals("reenabled")) {
+                    doReturn(false).when(plugin).isEnabled();
+                    plugin.onDisable();
+                    if (mode.equals("reenabled")) {
+                        doReturn(true).when(plugin).isEnabled();
+                        plugin.onEnable();
+                        Runnable currentInitialization = main.poll(3, TimeUnit.SECONDS);
+                        assertNotNull(currentInitialization);
+                        currentInitialization.run();
+                        int registeredCount = listeners.size();
+                        assertNotNull(recipe.get());
+                        initialization.run();
+                        assertEquals(registeredCount, listeners.size(), "an old lifecycle callback must not touch a re-enabled plugin");
+                        verify(server, times(1)).addRecipe(any(Recipe.class));
+                        return;
+                    }
+                    initialization.run();
+                    assertTrue(listeners.isEmpty(), "a queued initialization must not register listeners after disable");
+                    assertNull(recipe.get());
+                    verify(server, never()).removeRecipe(any());
+                    return;
+                }
+                initialization.run();
+                assertNotNull(recipe.get(), "plugin startup must register the Eye recipe");
+                assertTrue(new EyeItems().isEye(recipe.get().getResult()));
+                assertTrue(listeners.stream().anyMatch(EyePotionListener.class::isInstance));
+                assertTrue(listeners.stream().anyMatch(EyeEquipment.class::isInstance));
+                var inventory = mock(CraftingInventory.class);
+                when(inventory.getRecipe()).thenAnswer(ignored -> recipe.get());
+                var result = new AtomicReference<>(recipe.get().getResult());
+                when(inventory.getResult()).thenAnswer(ignored -> result.get());
+                doAnswer(call -> { result.set(call.getArgument(0)); return null; }).when(inventory).setResult(any());
+                var view = mock(InventoryView.class);
+                when(view.getPlayer()).thenReturn(player);
+                when(view.getTopInventory()).thenReturn(inventory);
+                var prepare = new PrepareItemCraftEvent(inventory, view, false);
+                dispatch(plugin, listeners, prepare);
+                assertTrue(new EyeItems().isEye(result.get()), "the restored personal unlock must permit crafting");
+                when(player.getUniqueId()).thenReturn(learner);
+                when(server.getPlayer(learner)).thenReturn(player);
+                dispatch(plugin, listeners, prepare);
+                assertNull(result.get(), "registered handlers must deny an unearned player's result");
+                var effect = new org.bukkit.potion.PotionEffect(org.bukkit.potion.PotionEffectType.NIGHT_VISION, 9600, 0);
+                dispatch(plugin, listeners, new org.bukkit.event.entity.EntityPotionEffectEvent(player, null, effect, player,
+                        org.bukkit.event.entity.EntityPotionEffectEvent.Cause.POTION_DRINK,
+                        org.bukkit.event.entity.EntityPotionEffectEvent.Action.ADDED, false));
+                clock.set(java.time.Duration.ofHours(8).toNanos());
+                dispatch(plugin, listeners, new org.bukkit.event.entity.EntityPotionEffectEvent(player, effect, null, null,
+                        org.bukkit.event.entity.EntityPotionEffectEvent.Cause.EXPIRATION,
+                        org.bukkit.event.entity.EntityPotionEffectEvent.Action.REMOVED, false));
+                Runnable unlocked = main.poll(3, TimeUnit.SECONDS);
+                assertNotNull(unlocked, "the registered potion listener must persist the unlock and schedule its notification");
+                assertTrue(disk.load().eyeProgress(learner).unlocked());
+                unlocked.run();
+                result.set(recipe.get().getResult());
+                dispatch(plugin, listeners, prepare);
+                assertTrue(new EyeItems().isEye(result.get()), "the registered crafting listener must see the newly saved unlock");
+                clearInvocations(player);
+                when(player.getUniqueId()).thenReturn(id);
+                timers.forEach(Runnable::run);
+                verify(player).discoverRecipe(EyeCrafting.RECIPE_KEY);
+                // Disable must checkpoint and drain an in-flight qualifying interval, not just remove the recipe.
+                when(player.getUniqueId()).thenReturn(learner);
+                when(player.isOnline()).thenReturn(true);
+                when(player.getPotionEffect(org.bukkit.potion.PotionEffectType.NIGHT_VISION)).thenReturn(effect);
+                dispatch(plugin, listeners, new org.bukkit.event.entity.EntityPotionEffectEvent(player, null, effect, player,
+                        org.bukkit.event.entity.EntityPotionEffectEvent.Cause.POTION_DRINK,
+                        org.bukkit.event.entity.EntityPotionEffectEvent.Action.ADDED, false));
+                clock.addAndGet(1_234_000_000L);
+            } finally {
+                if (mode.equals("presentation-failure")) {
+                    doThrow(new IllegalStateException("Injected presentation cleanup failure"))
+                            .when(protocolManager).removePacketListeners(plugin);
+                    try {
+                        assertThrows(IllegalStateException.class, plugin::onDisable);
+                        plugin.shutdownCompletion().get(3, TimeUnit.SECONDS);
+                        assertEquals(28_801_234, disk.load().eyeProgress(learner).accumulatedMillis(),
+                                "presentation cleanup failure must not prevent Eye progress from draining");
+                    } finally {
+                        doNothing().when(protocolManager).removePacketListeners(plugin);
+                        plugin.onDisable();
+                        plugin.shutdownCompletion().get(3, TimeUnit.SECONDS);
+                    }
+                } else {
+                    plugin.onDisable();
+                    plugin.shutdownCompletion().get(3, TimeUnit.SECONDS);
+                }
+            }
+        }
+        verify(server).removeRecipe(EyeCrafting.RECIPE_KEY);
+        assertEquals(28_801_234, disk.load().eyeProgress(learner).accumulatedMillis());
+    }
+
+    private static void dispatch(SpigotStealthPlugin plugin, List<Listener> listeners, Event event) throws Exception {
+        var registered = new ArrayList<RegisteredListener>();
+        for (var listener : listeners) {
+            for (var method : listener.getClass().getMethods()) {
+                var handler = method.getAnnotation(EventHandler.class);
+                if (handler == null || method.getParameterCount() != 1 || !method.getParameterTypes()[0].isInstance(event)) { continue; }
+                registered.add(new RegisteredListener(listener,
+                        EventExecutor.create(method, method.getParameterTypes()[0].asSubclass(Event.class)),
+                        handler.priority(), plugin, handler.ignoreCancelled()));
+            }
+        }
+        registered.sort(java.util.Comparator.comparing(RegisteredListener::getPriority));
+        for (var handler : registered) { handler.callEvent(event); }
+    }
+}

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

@@ -0,0 +1,302 @@
+package games.dmg.spigotstealth;
+
+import static org.junit.jupiter.api.Assertions.*;
+import static org.mockito.Mockito.*;
+
+import java.nio.file.Path;
+import java.time.Duration;
+import java.util.UUID;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicLong;
+import org.bukkit.entity.Player;
+import org.bukkit.event.entity.EntityPotionEffectEvent;
+import org.bukkit.potion.PotionEffect;
+import org.bukkit.potion.PotionEffectType;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+/** Real Purpur effect/event objects, real progression/persistence, only player and clock are external doubles. */
+class EyePotionProgressionTest {
+    @TempDir Path directory;
+    @BeforeAll static void bootstrap() throws Exception { NativeRuntime.bootstrap(); }
+
+    @Test
+    void aTransitionBeforeTheNextObservationCannotCreditAnUnattributedRestoredEffect() throws Exception {
+        for (String transition : java.util.List.of("quit", "remove", "refresh")) {
+            UUID id = UUID.randomUUID();
+            var player = mock(Player.class);
+            when(player.getUniqueId()).thenReturn(id);
+            when(player.isOnline()).thenReturn(true);
+            var clock = new AtomicLong();
+            var repository = new YamlStealthStateRepository(directory.resolve(transition + ".yml"));
+            try (var states = new StealthStateManager(repository, repository.load())) {
+                var progression = new EyeProgressionService(states, clock::get, ignored -> { });
+                var listener = new EyePotionListener(progression, failure -> fail(failure));
+                var strong = new PotionEffect(PotionEffectType.NIGHT_VISION, 100, 1);
+                var restored = new PotionEffect(PotionEffectType.NIGHT_VISION, 400, 0);
+                listener.onPotionEffect(new EntityPotionEffectEvent(player, null, strong, player,
+                        EntityPotionEffectEvent.Cause.POTION_DRINK, EntityPotionEffectEvent.Action.ADDED, false));
+                when(player.getPotionEffect(PotionEffectType.NIGHT_VISION)).thenReturn(strong);
+                clock.set(Duration.ofSeconds(1).toNanos());
+                listener.checkpoint(ignored -> player);
+                clock.set(Duration.ofSeconds(3).toNanos());
+                when(player.getPotionEffect(PotionEffectType.NIGHT_VISION)).thenReturn(restored);
+                switch (transition) {
+                    case "quit" -> listener.onQuit(new org.bukkit.event.player.PlayerQuitEvent(
+                            player, net.kyori.adventure.text.Component.empty()));
+                    case "remove" -> listener.onPotionEffect(new EntityPotionEffectEvent(player, restored, null, null,
+                            EntityPotionEffectEvent.Cause.EXPIRATION, EntityPotionEffectEvent.Action.REMOVED, false));
+                    case "refresh" -> listener.onPotionEffect(new EntityPotionEffectEvent(player, restored,
+                            new PotionEffect(PotionEffectType.NIGHT_VISION, 800, 0), player,
+                            EntityPotionEffectEvent.Cause.POTION_DRINK, EntityPotionEffectEvent.Action.CHANGED, true));
+                    default -> throw new AssertionError(transition);
+                }
+                states.save().get(3, TimeUnit.SECONDS);
+                assertEquals(1000, repository.load().eyeProgress(id).accumulatedMillis(), transition);
+            }
+        }
+    }
+
+    @Test
+    void periodicObservationStopsAtUnattributedHiddenEffectRestorationOrMissingPlayer() throws Exception {
+        UUID id = UUID.randomUUID();
+        var player = mock(Player.class);
+        when(player.getUniqueId()).thenReturn(id);
+        when(player.isOnline()).thenReturn(true);
+        var clock = new AtomicLong();
+        var repository = new YamlStealthStateRepository(directory.resolve("state.yml"));
+        try (var states = new StealthStateManager(repository, repository.load())) {
+            var progression = new EyeProgressionService(states, clock::get, ignored -> { });
+            var listener = new EyePotionListener(progression, failure -> fail(failure));
+            var strong = new PotionEffect(PotionEffectType.NIGHT_VISION, 100, 1);
+            listener.onPotionEffect(new EntityPotionEffectEvent(player, null, strong, player,
+                    EntityPotionEffectEvent.Cause.POTION_DRINK, EntityPotionEffectEvent.Action.ADDED, false));
+            when(player.getPotionEffect(PotionEffectType.NIGHT_VISION)).thenReturn(
+                    new PotionEffect(PotionEffectType.NIGHT_VISION, 80, 1));
+            clock.set(Duration.ofSeconds(1).toNanos());
+            listener.checkpoint(ignored -> player);
+            states.save().get(3, TimeUnit.SECONDS);
+            assertEquals(1000, repository.load().eyeProgress(id).accumulatedMillis());
+            // Native hidden-effect promotion need not emit a new potion-source event.
+            when(player.getPotionEffect(PotionEffectType.NIGHT_VISION)).thenReturn(
+                    new PotionEffect(PotionEffectType.NIGHT_VISION, 400, 0));
+            clock.set(Duration.ofSeconds(2).toNanos());
+            listener.checkpoint(ignored -> player);
+            clock.set(Duration.ofHours(12).toNanos());
+            listener.checkpoint(ignored -> player);
+            states.save().get(3, TimeUnit.SECONDS);
+            assertEquals(1000, repository.load().eyeProgress(id).accumulatedMillis(),
+                    "unattributed restored effects must not inherit the drink timer");
+            assertTrue(progression.activePlayerIds().isEmpty());
+            listener.onPotionEffect(new EntityPotionEffectEvent(player, null, strong, player,
+                    EntityPotionEffectEvent.Cause.POTION_DRINK, EntityPotionEffectEvent.Action.ADDED, false));
+            clock.addAndGet(Duration.ofDays(1).toNanos());
+            listener.checkpoint(ignored -> null);
+            states.save().get(3, TimeUnit.SECONDS);
+            assertEquals(1000, repository.load().eyeProgress(id).accumulatedMillis());
+            assertTrue(progression.activePlayerIds().isEmpty());
+        }
+    }
+
+    @Test
+    void disconnectClosesTheIntervalAndRestartDoesNotCountTheOfflineGap() throws Exception {
+        UUID id = UUID.randomUUID();
+        var player = mock(Player.class);
+        when(player.getUniqueId()).thenReturn(id);
+        var clock = new AtomicLong();
+        var repository = new YamlStealthStateRepository(directory.resolve("state.yml"));
+        try (var states = new StealthStateManager(repository, repository.load())) {
+            var progression = new EyeProgressionService(states, clock::get, ignored -> { });
+            var listener = new EyePotionListener(progression, failure -> fail(failure));
+            var effect = new PotionEffect(PotionEffectType.NIGHT_VISION, 200, 0);
+            listener.onPotionEffect(new EntityPotionEffectEvent(player, null, effect, player,
+                    EntityPotionEffectEvent.Cause.POTION_DRINK, EntityPotionEffectEvent.Action.ADDED, false));
+            clock.set(Duration.ofSeconds(1).toNanos());
+            when(player.getPotionEffect(PotionEffectType.NIGHT_VISION)).thenReturn(effect);
+            listener.onQuit(new org.bukkit.event.player.PlayerQuitEvent(player, net.kyori.adventure.text.Component.empty()));
+            clock.addAndGet(Duration.ofDays(7).toNanos());
+            progression.checkpoint(id).get(3, TimeUnit.SECONDS);
+            states.save().get(3, TimeUnit.SECONDS);
+            assertEquals(1000, repository.load().eyeProgress(id).accumulatedMillis(),
+                    "disconnect must close the qualifying interval before offline time passes");
+            assertFalse(progression.isUnlocked(id));
+        }
+        try (var restarted = new StealthStateManager(repository, repository.load())) {
+            var progression = new EyeProgressionService(restarted, clock::get, ignored -> { });
+            assertEquals(1000, restarted.snapshot().eyeProgress(id).accumulatedMillis());
+            assertTrue(progression.activePlayerIds().isEmpty());
+            assertFalse(progression.isUnlocked(id));
+        }
+    }
+
+    @Test
+    void everyNonDrinkSourceIsExcludedAndAnEffectiveExternalReplacementStopsCredit() throws Exception {
+        UUID id = UUID.randomUUID();
+        var player = mock(Player.class);
+        when(player.getUniqueId()).thenReturn(id);
+        var clock = new AtomicLong();
+        var repository = new YamlStealthStateRepository(directory.resolve("state.yml"));
+        try (var states = new StealthStateManager(repository, repository.load())) {
+            var progression = new EyeProgressionService(states, clock::get, ignored -> { });
+            var listener = new EyePotionListener(progression, failure -> fail(failure));
+            var effect = new PotionEffect(PotionEffectType.NIGHT_VISION, 200, 0);
+            for (var cause : EntityPotionEffectEvent.Cause.values()) {
+                if (cause == EntityPotionEffectEvent.Cause.POTION_DRINK) { continue; }
+                listener.onPotionEffect(new EntityPotionEffectEvent(player, null, effect, null,
+                        cause, EntityPotionEffectEvent.Action.ADDED, false));
+                clock.addAndGet(Duration.ofSeconds(1).toNanos());
+                progression.checkpoint(id).get(3, TimeUnit.SECONDS);
+                assertEquals(0, states.snapshot().eyeProgress(id).accumulatedMillis(), cause.toString());
+                listener.onPotionEffect(new EntityPotionEffectEvent(player, effect, null, null,
+                        EntityPotionEffectEvent.Cause.EXPIRATION, EntityPotionEffectEvent.Action.REMOVED, false));
+            }
+            listener.onPotionEffect(new EntityPotionEffectEvent(player, null, effect, player,
+                    EntityPotionEffectEvent.Cause.POTION_DRINK, EntityPotionEffectEvent.Action.ADDED, false));
+            clock.addAndGet(Duration.ofSeconds(1).toNanos());
+            listener.onPotionEffect(new EntityPotionEffectEvent(player, effect,
+                    new PotionEffect(PotionEffectType.NIGHT_VISION, 400, 0), null,
+                    EntityPotionEffectEvent.Cause.PLUGIN, EntityPotionEffectEvent.Action.CHANGED, true));
+            clock.addAndGet(Duration.ofHours(12).toNanos());
+            progression.checkpoint(id).get(3, TimeUnit.SECONDS);
+            states.save().get(3, TimeUnit.SECONDS);
+            assertEquals(1000, repository.load().eyeProgress(id).accumulatedMillis());
+            assertFalse(progression.isUnlocked(id));
+        }
+    }
+
+    @Test
+    void cancelledAndUnrelatedEffectEventsCannotStartOrInterruptCredit() throws Exception {
+        UUID id = UUID.randomUUID();
+        var player = mock(Player.class);
+        when(player.getUniqueId()).thenReturn(id);
+        var clock = new AtomicLong();
+        var repository = new YamlStealthStateRepository(directory.resolve("state.yml"));
+        try (var states = new StealthStateManager(repository, repository.load())) {
+            var progression = new EyeProgressionService(states, clock::get, ignored -> { });
+            var listener = new EyePotionListener(progression, failure -> fail(failure));
+            var effect = new PotionEffect(PotionEffectType.NIGHT_VISION, 200, 0);
+            var cancelled = new EntityPotionEffectEvent(player, null, effect, player,
+                    EntityPotionEffectEvent.Cause.POTION_DRINK, EntityPotionEffectEvent.Action.ADDED, false);
+            cancelled.setCancelled(true);
+            listener.onPotionEffect(cancelled);
+            clock.set(Duration.ofSeconds(1).toNanos());
+            progression.checkpoint(id).get(3, TimeUnit.SECONDS);
+            assertEquals(0, states.snapshot().eyeProgress(id).accumulatedMillis());
+            cancelled.setCancelled(false);
+            listener.onPotionEffect(cancelled);
+            clock.set(Duration.ofSeconds(2).toNanos());
+            var cancelledRemoval = new EntityPotionEffectEvent(player, effect, null, null,
+                    EntityPotionEffectEvent.Cause.MILK, EntityPotionEffectEvent.Action.CLEARED, false);
+            cancelledRemoval.setCancelled(true);
+            listener.onPotionEffect(cancelledRemoval);
+            listener.onPotionEffect(new EntityPotionEffectEvent(player, null,
+                    new PotionEffect(PotionEffectType.INVISIBILITY, 200, 0), null,
+                    EntityPotionEffectEvent.Cause.PLUGIN, EntityPotionEffectEvent.Action.ADDED, false));
+            clock.set(Duration.ofSeconds(3).toNanos());
+            progression.stop(id).get(3, TimeUnit.SECONDS);
+            assertEquals(2000, repository.load().eyeProgress(id).accumulatedMillis());
+        }
+    }
+
+    @Test
+    void cosmeticOnlyOverridesDoNotReassignTheActiveEffectsSource() throws Exception {
+        // Purpur reports override=true even when only particle/icon flags change.
+        var nativeActive = new net.minecraft.world.effect.MobEffectInstance(
+                net.minecraft.world.effect.MobEffects.NIGHT_VISION, 200, 1);
+        assertTrue(nativeActive.update(new net.minecraft.world.effect.MobEffectInstance(
+                net.minecraft.world.effect.MobEffects.NIGHT_VISION, 100, 0, false, false, false)));
+        assertEquals(1, nativeActive.getAmplifier());
+        assertEquals(200, nativeActive.getDuration());
+        UUID id = UUID.randomUUID();
+        var player = mock(Player.class);
+        when(player.getUniqueId()).thenReturn(id);
+        var clock = new AtomicLong();
+        var repository = new YamlStealthStateRepository(directory.resolve("state.yml"));
+        try (var states = new StealthStateManager(repository, repository.load())) {
+            var progression = new EyeProgressionService(states, clock::get, ignored -> { });
+            var listener = new EyePotionListener(progression, failure -> fail(failure));
+            var weak = new PotionEffect(PotionEffectType.NIGHT_VISION, 100, 0, false, false, false);
+            var strong = new PotionEffect(PotionEffectType.NIGHT_VISION, 200, 1);
+            listener.onPotionEffect(new EntityPotionEffectEvent(player, strong, weak, player,
+                    EntityPotionEffectEvent.Cause.POTION_DRINK, EntityPotionEffectEvent.Action.CHANGED, true));
+            clock.set(Duration.ofSeconds(1).toNanos());
+            progression.checkpoint(id).get(3, TimeUnit.SECONDS);
+            assertEquals(0, states.snapshot().eyeProgress(id).accumulatedMillis(),
+                    "a cosmetic drink change must not claim the stronger existing effect");
+            listener.onPotionEffect(new EntityPotionEffectEvent(player, null, strong, player,
+                    EntityPotionEffectEvent.Cause.POTION_DRINK, EntityPotionEffectEvent.Action.ADDED, false));
+            clock.set(Duration.ofSeconds(2).toNanos());
+            listener.onPotionEffect(new EntityPotionEffectEvent(player, strong, weak, null,
+                    EntityPotionEffectEvent.Cause.PLUGIN, EntityPotionEffectEvent.Action.CHANGED, true));
+            clock.set(Duration.ofSeconds(3).toNanos());
+            listener.onPotionEffect(new EntityPotionEffectEvent(player, strong, null, null,
+                    EntityPotionEffectEvent.Cause.EXPIRATION, EntityPotionEffectEvent.Action.REMOVED, false));
+            states.save().get(3, TimeUnit.SECONDS);
+            assertEquals(2000, states.snapshot().eyeProgress(id).accumulatedMillis());
+        }
+    }
+
+    @Test
+    void rejectedReplacementsNeitherStartNorStopQualifyingTime() throws Exception {
+        UUID id = UUID.randomUUID();
+        var player = mock(Player.class);
+        when(player.getUniqueId()).thenReturn(id);
+        var clock = new AtomicLong();
+        var repository = new YamlStealthStateRepository(directory.resolve("state.yml"));
+        try (var states = new StealthStateManager(repository, repository.load())) {
+            var progression = new EyeProgressionService(states, clock::get, ignored -> { });
+            var listener = new EyePotionListener(progression, failure -> fail(failure));
+            var weak = new PotionEffect(PotionEffectType.NIGHT_VISION, 100, 0);
+            var strong = new PotionEffect(PotionEffectType.NIGHT_VISION, 200, 1);
+            listener.onPotionEffect(new EntityPotionEffectEvent(player, strong, weak, player,
+                    EntityPotionEffectEvent.Cause.POTION_DRINK, EntityPotionEffectEvent.Action.CHANGED, false));
+            clock.set(Duration.ofSeconds(1).toNanos());
+            progression.checkpoint(id).get(3, TimeUnit.SECONDS);
+            assertEquals(0, states.snapshot().eyeProgress(id).accumulatedMillis(),
+                    "a rejected drink must not claim an existing non-drink effect");
+            listener.onPotionEffect(new EntityPotionEffectEvent(player, null, strong, player,
+                    EntityPotionEffectEvent.Cause.POTION_DRINK, EntityPotionEffectEvent.Action.ADDED, false));
+            clock.set(Duration.ofSeconds(2).toNanos());
+            listener.onPotionEffect(new EntityPotionEffectEvent(player, strong, weak, null,
+                    EntityPotionEffectEvent.Cause.PLUGIN, EntityPotionEffectEvent.Action.CHANGED, false));
+            clock.set(Duration.ofSeconds(3).toNanos());
+            listener.onPotionEffect(new EntityPotionEffectEvent(player, strong, null, null,
+                    EntityPotionEffectEvent.Cause.EXPIRATION, EntityPotionEffectEvent.Action.REMOVED, false));
+            states.save().get(3, TimeUnit.SECONDS);
+            assertEquals(2000, states.snapshot().eyeProgress(id).accumulatedMillis(),
+                    "a rejected plugin replacement must not interrupt the effective drunk potion");
+        }
+    }
+
+    @Test
+    void effectiveDirectDrinkAccumulatesAcrossRefreshAndDurablyUnlocksAtEightHours() throws Exception {
+        UUID id = UUID.randomUUID();
+        var player = mock(Player.class);
+        when(player.getUniqueId()).thenReturn(id);
+        var clock = new AtomicLong();
+        var repository = new YamlStealthStateRepository(directory.resolve("state.yml"));
+        try (var states = new StealthStateManager(repository, repository.load())) {
+            var progression = new EyeProgressionService(states, clock::get, ignored -> { });
+            var listener = new EyePotionListener(progression, failure -> fail(failure));
+            var nightVision = new PotionEffect(PotionEffectType.NIGHT_VISION, 9600, 0);
+            listener.onPotionEffect(new EntityPotionEffectEvent(player, null, nightVision, player,
+                    EntityPotionEffectEvent.Cause.POTION_DRINK, EntityPotionEffectEvent.Action.ADDED, true));
+            for (int refresh = 1; refresh < 60; refresh++) {
+                clock.set(Duration.ofSeconds(refresh * 480L).toNanos());
+                listener.onPotionEffect(new EntityPotionEffectEvent(player, new PotionEffect(PotionEffectType.NIGHT_VISION, 1, 0), nightVision, player,
+                        EntityPotionEffectEvent.Cause.POTION_DRINK, EntityPotionEffectEvent.Action.CHANGED, true));
+            }
+            clock.set(Duration.ofHours(8).toNanos() - 1_000_000);
+            progression.checkpoint(id).get(3, TimeUnit.SECONDS);
+            assertFalse(progression.isUnlocked(id));
+            clock.addAndGet(1_000_000);
+            listener.onPotionEffect(new EntityPotionEffectEvent(player, nightVision, null, null,
+                    EntityPotionEffectEvent.Cause.EXPIRATION, EntityPotionEffectEvent.Action.REMOVED, false));
+            states.save().get(3, TimeUnit.SECONDS);
+            assertTrue(progression.isUnlocked(id), "eight hours of effective drink events must unlock the Eye");
+            assertEquals(28_800_000, repository.load().eyeProgress(id).accumulatedMillis());
+            assertTrue(progression.activePlayerIds().isEmpty());
+        }
+    }
+}

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

@@ -0,0 +1,61 @@
+package games.dmg.spigotstealth;
+
+import java.util.List;
+import java.util.stream.Stream;
+import net.minecraft.SharedConstants;
+import net.minecraft.commands.Commands;
+import net.minecraft.core.HolderLookup;
+import net.minecraft.core.LayeredRegistryAccess;
+import net.minecraft.core.Registry;
+import net.minecraft.core.RegistryAccess;
+import net.minecraft.resources.Identifier;
+import net.minecraft.resources.RegistryDataLoader;
+import net.minecraft.server.Bootstrap;
+import net.minecraft.server.MinecraftServer;
+import net.minecraft.server.RegistryLayer;
+import net.minecraft.server.ReloadableServerResources;
+import net.minecraft.server.packs.PackType;
+import net.minecraft.server.packs.repository.ServerPacksSource;
+import net.minecraft.server.packs.resources.MultiPackResourceManager;
+import net.minecraft.server.permissions.LevelBasedPermissionSet;
+import net.minecraft.tags.TagLoader;
+import net.minecraft.util.Util;
+import net.minecraft.world.flag.FeatureFlags;
+import net.minecraft.world.level.DataPackConfig;
+import net.minecraft.world.level.WorldDataConfiguration;
+import org.bukkit.craftbukkit.CraftRegistry;
+
+/** Loads vanilla registries/tags/components using the same path as the server's own tests. */
+final class NativeRuntime {
+    private NativeRuntime() {}
+    private static boolean ready;
+
+    static synchronized void bootstrap() throws Exception {
+        if (ready) { return; }
+        SharedConstants.tryDetectVersion();
+        Bootstrap.bootStrap();
+        var flags = FeatureFlags.VANILLA_SET;
+        var packs = ServerPacksSource.createVanillaTrustedRepository();
+        MinecraftServer.configurePackRepository(packs, new WorldDataConfiguration(new DataPackConfig(
+                FeatureFlags.REGISTRY.toNames(flags).stream().map(Identifier::getPath).toList(), List.of()), flags), true, false);
+        try (var resources = new MultiPackResourceManager(PackType.SERVER_DATA, packs.openAllSelected())) {
+            LayeredRegistryAccess<RegistryLayer> layers = RegistryLayer.createRegistryAccess();
+            List<Registry.PendingTags<?>> tags = TagLoader.loadTagsForExistingRegistries(resources, layers.getLayer(RegistryLayer.STATIC));
+            List<HolderLookup.RegistryLookup<?>> lookups = TagLoader.buildUpdatedLookups(layers.getAccessForLoading(RegistryLayer.WORLDGEN), tags);
+            RegistryAccess.Frozen worldgen = RegistryDataLoader.load(resources, lookups,
+                    RegistryDataLoader.WORLDGEN_REGISTRIES, Util.backgroundExecutor()).join();
+            layers = layers.replaceFrom(RegistryLayer.WORLDGEN, worldgen);
+            RegistryAccess.Frozen dimensions = RegistryDataLoader.load(resources,
+                    Stream.concat(lookups.stream(), worldgen.listRegistries()).toList(),
+                    RegistryDataLoader.DIMENSION_REGISTRIES, Util.backgroundExecutor()).join();
+            layers = layers.replaceFrom(RegistryLayer.DIMENSIONS, dimensions);
+            Class.forName(org.bukkit.Registry.class.getName());
+            var datapack = ReloadableServerResources.loadResources(resources, layers, tags, flags,
+                    Commands.CommandSelection.DEDICATED, LevelBasedPermissionSet.ALL_PERMISSIONS,
+                    Util.backgroundExecutor(), Runnable::run).join();
+            datapack.updateComponentsAndStaticRegistryTags();
+            CraftRegistry.setMinecraftRegistry(layers.compositeAccess().freeze());
+        }
+        ready = true;
+    }
+}

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

@@ -0,0 +1,37 @@
+package games.dmg.spigotstealth;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.UUID;
+import org.junit.jupiter.api.Test;
+
+class EyeProgressStateTest {
+    @Test
+    void eyeProgressRemainsIndependentAcrossExistingStealthAndSleepUpdates() {
+        UUID id = UUID.randomUUID();
+        var original = new PersistentStealthState(Map.of(), Map.of("future-root", "preserved"));
+        var eye = new EyeProgress(28_800_123, true, Map.of("future-eye", "preserved"));
+        var withEye = original.withEyeProgress(id, eye);
+        assertEquals(eye, withEye.eyeProgress(id));
+        assertEquals(EyeProgress.empty(), original.eyeProgress(id), "Updates must leave old snapshots immutable");
+        var changed = withEye.withPlayer(PlayerStealthState.empty(id).withProgress(123, true))
+            .withSleepCountPolicy(SleepCountPolicy.INCLUDE);
+        assertEquals(eye, changed.eyeProgress(id));
+        assertEquals(123, changed.player(id).accumulatedMillis());
+        assertEquals("preserved", changed.unknownFields().get("future-root"));
+        assertEquals(EyeProgress.empty(), changed.eyeProgress(UUID.randomUUID()));
+    }
+
+    @Test
+    void progressRejectsNegativeTimeAndCopiesUnknownFields() {
+        assertThrows(IllegalArgumentException.class, () -> new EyeProgress(-1, false));
+        var extras = new HashMap<String, Object>();
+        extras.put("extension", "old");
+        var progress = new EyeProgress(1, false, extras);
+        extras.put("extension", "new");
+        assertEquals("old", progress.unknownFields().get("extension"));
+        assertThrows(UnsupportedOperationException.class, () -> progress.unknownFields().put("other", 1));
+    }
+}

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

@@ -0,0 +1,90 @@
+package games.dmg.spigotstealth;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import java.nio.file.Path;
+import java.time.Duration;
+import java.util.List;
+import java.util.Map;
+import java.util.UUID;
+import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.concurrent.atomic.AtomicLong;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+class EyeProgressionServiceTest {
+    @TempDir Path directory;
+    private final UUID id = UUID.randomUUID();
+    private final AtomicLong clock = new AtomicLong();
+    private final List<UUID> notifications = new CopyOnWriteArrayList<>();
+
+    @Test
+    void exactEightHoursUnlocksOnceWithoutOverlapOrLostSubmillisecondCredit() throws Exception {
+        var repository = new YamlStealthStateRepository(directory.resolve("state.yml"));
+        try (var states = new StealthStateManager(repository, repository.load())) {
+            var progression = new EyeProgressionService(states, clock::get, notifications::add);
+            progression.begin(id).join();
+            clock.set(600_000);
+            progression.checkpoint(id).join();
+            clock.set(1_200_000);
+            progression.begin(id).join(); // A refresh, not an overlapping timer.
+            assertEquals(1, states.snapshot().eyeProgress(id).accumulatedMillis());
+            clock.set(Duration.ofHours(8).toNanos() - 1);
+            progression.checkpoint(id).join();
+            assertFalse(progression.isUnlocked(id));
+            clock.incrementAndGet();
+            progression.checkpoint(id).join();
+            assertTrue(progression.isUnlocked(id));
+            assertEquals(List.of(id), notifications);
+            clock.addAndGet(Duration.ofSeconds(3).toNanos());
+            progression.stop(id).join();
+            assertEquals(28_803_000, states.snapshot().eyeProgress(id).accumulatedMillis());
+            assertEquals(List.of(id), notifications);
+            assertTrue(progression.activePlayerIds().isEmpty());
+        }
+    }
+
+    @Test
+    void intervalsAndRestartPreserveProgressWithoutOfflineOrUnobservedCredit() throws Exception {
+        var repository = new YamlStealthStateRepository(directory.resolve("state.yml"));
+        try (var states = new StealthStateManager(repository, repository.load())) {
+            var progression = new EyeProgressionService(states, clock::get, notifications::add);
+            progression.begin(id).join();
+            clock.addAndGet(Duration.ofHours(2).toNanos());
+            progression.stop(id).join();
+            clock.addAndGet(Duration.ofDays(30).toNanos());
+            progression.checkpoint(id).join();
+            assertEquals(Duration.ofHours(2).toMillis(), states.snapshot().eyeProgress(id).accumulatedMillis());
+        }
+        try (var states = new StealthStateManager(repository, repository.load())) {
+            var restarted = new EyeProgressionService(states, clock::get, notifications::add);
+            assertTrue(restarted.activePlayerIds().isEmpty());
+            restarted.begin(id).join();
+            clock.addAndGet(Duration.ofHours(6).toNanos());
+            restarted.stopAll().join();
+            assertTrue(restarted.isUnlocked(id));
+            assertEquals(28_800_000, repository.load().eyeProgress(id).accumulatedMillis());
+            assertTrue(restarted.activePlayerIds().isEmpty());
+        }
+    }
+
+    @Test
+    void missingDisconnectObservationDiscardsUnobservedTailAndExistingUnlocksDoNotRenotify() throws Exception {
+        var repository = new YamlStealthStateRepository(directory.resolve("state.yml"));
+        var existing = new PersistentStealthState(Map.of(), Map.of())
+            .withEyeProgress(id, new EyeProgress(28_800_000, true));
+        try (var states = new StealthStateManager(repository, existing)) {
+            var progression = new EyeProgressionService(states, clock::get, notifications::add);
+            assertTrue(progression.isUnlocked(id));
+            progression.begin(id).join();
+            clock.addAndGet(Duration.ofSeconds(1).toNanos());
+            progression.checkpoint(id).join();
+            clock.addAndGet(Duration.ofHours(1).toNanos());
+            progression.abandon(id);
+            progression.checkpoint(id).join();
+            assertEquals(28_801_000, states.snapshot().eyeProgress(id).accumulatedMillis());
+            assertTrue(progression.activePlayerIds().isEmpty());
+            assertTrue(notifications.isEmpty());
+        }
+    }
+}

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

@@ -0,0 +1,103 @@
+package games.dmg.spigotstealth;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Map;
+import java.util.UUID;
+import java.util.concurrent.CompletionException;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+class EyeStatePersistenceTest {
+    @TempDir Path directory;
+
+    @Test
+    void yamlRoundTripPreservesEyeAndStealthProgressAndUnknownFields() throws Exception {
+        UUID id = UUID.randomUUID();
+        var repository = new YamlStealthStateRepository(directory.resolve("state.yml"));
+        var eye = new EyeProgress(28_800_123, true, Map.of("future-eye", "keep"));
+        var state = new PersistentStealthState(Map.of(id, PlayerStealthState.empty(id).withProgress(456, true)),
+            Map.of("future-root", "keep")).withEyeProgress(id, eye);
+        repository.save(state);
+        var loaded = repository.load();
+        assertEquals(eye, loaded.eyeProgress(id));
+        assertEquals(state.player(id), loaded.player(id));
+        assertEquals(state.unknownFields(), loaded.unknownFields());
+    }
+
+    @Test
+    void legacyFilesStartAtZeroAndMalformedEyeRecordsCannotGrantUnlocksOrEraseStealth() throws Exception {
+        UUID id = UUID.randomUUID();
+        Path file = directory.resolve("state.yml");
+        var repository = new YamlStealthStateRepository(file);
+        var legacy = new PersistentStealthState(Map.of(id, PlayerStealthState.empty(id).withProgress(456, true)), Map.of());
+        repository.save(legacy);
+        assertEquals(EyeProgress.empty(), repository.load().eyeProgress(id));
+        // Deliberately malformed independent section, not a malformed existing player record.
+        Files.writeString(file, Files.readString(file) + "\neye-progress:\n  " + id
+            + ":\n    accumulated-millis: -1\n    unlocked: true\n");
+        var loaded = repository.load();
+        assertEquals(EyeProgress.empty(), loaded.eyeProgress(id));
+        assertEquals(legacy.player(id), loaded.player(id));
+    }
+
+    @Test
+    void pendingWriteDoesNotExposeDurableUnlockAndSavesOffTheCallingThread() throws Exception {
+        UUID id = UUID.randomUUID();
+        var initial = new PersistentStealthState(Map.of(), Map.of());
+        var entered = new CountDownLatch(1);
+        var release = new CountDownLatch(1);
+        Thread caller = Thread.currentThread();
+        var repository = new StealthStateRepository() {
+            @Override public PersistentStealthState load() { return initial; }
+            @Override public void save(PersistentStealthState state) throws IOException {
+                assertNotEquals(caller, Thread.currentThread());
+                entered.countDown();
+                try {
+                    if (!release.await(5, TimeUnit.SECONDS)) { throw new IOException("test write timeout"); }
+                } catch (InterruptedException exception) {
+                    Thread.currentThread().interrupt();
+                    throw new IOException(exception);
+                }
+            }
+        };
+        var manager = new StealthStateManager(repository, initial);
+        try {
+            var saved = manager.update(state -> state.withEyeProgress(id, new EyeProgress(28_800_000, true)));
+            assertTrue(entered.await(5, TimeUnit.SECONDS));
+            assertTrue(manager.snapshot().eyeProgress(id).unlocked());
+            assertFalse(manager.durableSnapshot().eyeProgress(id).unlocked());
+            release.countDown();
+            saved.join();
+            assertTrue(manager.durableSnapshot().eyeProgress(id).unlocked());
+        } finally { release.countDown(); manager.close(); }
+    }
+
+    @Test
+    void failedWriteCannotGrantDurableUnlockAndSuccessfulRetryCan() {
+        UUID id = UUID.randomUUID();
+        var initial = new PersistentStealthState(Map.of(), Map.of());
+        var fail = new AtomicBoolean(true);
+        var repository = new StealthStateRepository() {
+            @Override public PersistentStealthState load() { return initial; }
+            @Override public void save(PersistentStealthState state) throws IOException {
+                if (fail.get()) { throw new IOException("test disk failure"); }
+            }
+        };
+        var manager = new StealthStateManager(repository, initial);
+        try {
+            assertThrows(CompletionException.class, () -> manager.update(state ->
+                state.withEyeProgress(id, new EyeProgress(28_800_000, true))).join());
+            assertFalse(manager.durableSnapshot().eyeProgress(id).unlocked());
+            fail.set(false);
+            manager.save().join();
+            assertTrue(manager.durableSnapshot().eyeProgress(id).unlocked());
+        } finally { fail.set(false); manager.close(); }
+    }
+}

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

@@ -0,0 +1,57 @@
+package games.dmg.spigotstealth;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import java.io.IOException;
+import java.nio.file.Path;
+import java.util.UUID;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.TimeUnit;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+class StealthStateShutdownTest {
+    @TempDir Path directory;
+
+    @Test
+    void shutdownReturnsWithoutWaitingForDiskButDrainsTheFinalSnapshotAndRejectsLaterMutations() throws Exception {
+        var disk = new YamlStealthStateRepository(directory.resolve("state.yml"));
+        var saving = new CountDownLatch(1);
+        var release = new CountDownLatch(1);
+        StealthStateRepository repository = new StealthStateRepository() {
+            @Override public PersistentStealthState load() throws IOException { return disk.load(); }
+            @Override public void save(PersistentStealthState state) throws IOException {
+                saving.countDown();
+                try {
+                    if (!release.await(5, TimeUnit.SECONDS)) { throw new IOException("Test disk gate timed out"); }
+                } catch (InterruptedException exception) {
+                    Thread.currentThread().interrupt();
+                    throw new IOException(exception);
+                }
+                disk.save(state);
+            }
+        };
+        var states = new StealthStateManager(repository, repository.load());
+        UUID id = UUID.randomUUID();
+        try {
+            states.update(state -> state.withEyeProgress(id, new EyeProgress(1234, false)));
+            assertTrue(saving.await(3, TimeUnit.SECONDS));
+            // A blocked save must not block the lifecycle caller. The test thread still releases the disk on failure.
+            var closing = CompletableFuture.supplyAsync(states::closeAsync).get(1, TimeUnit.SECONDS);
+            assertFalse(closing.isDone(), "shutdown completion must await the queued durable snapshot");
+            assertSame(closing, states.closeAsync());
+            assertThrows(ExecutionException.class, () -> states.update(state ->
+                    state.withEyeProgress(id, new EyeProgress(28_800_000, true))).get(1, TimeUnit.SECONDS));
+            assertEquals(1234, states.snapshot().eyeProgress(id).accumulatedMillis());
+            release.countDown();
+            closing.get(3, TimeUnit.SECONDS);
+            assertEquals(1234, disk.load().eyeProgress(id).accumulatedMillis());
+            assertEquals(disk.load(), states.durableSnapshot());
+        } finally {
+            release.countDown();
+            states.close();
+        }
+    }
+}