fix(test): model native slow duration during source exit

src/nativeTest/java/games/dmg/fantasystick/FrostShardNativeTest.java

@@ -674,6 +674,14 @@ class FrostShardNativeTest {
     }
 
     @Test void sourceExitRemovesOnlyOwnedSlowAndRestoresThePriorNativeLayer() throws Exception {
+        sourceExitWithNativeSlow(false);
+    }
+
+    @Test void nativeTickAgingBeforeSourceExitStillRestoresOnlyTheOwnedPriorSlowLayer() throws Exception {
+        sourceExitWithNativeSlow(true);
+    }
+
+    private void sourceExitWithNativeSlow(boolean ageBeforeExit) throws Exception {
         java.nio.file.Files.writeString(data.resolve("config.yml"), "frost-shard-cooldown-seconds: 0\n");
         try (var f = new FantasyStickLifecycleNativeTest.Fixture(data)) {
             f.plugin.setEnabled(true);
@@ -688,10 +696,21 @@ class FrostShardNativeTest {
             var target = mock(org.bukkit.entity.LivingEntity.class);
             when(target.getUniqueId()).thenReturn(java.util.UUID.randomUUID());
             when(target.getLocation()).thenReturn(new org.bukkit.Location(a.world, 2, 65.6, 0));
+            when(target.getPersistentDataContainer()).thenReturn(
+                new org.bukkit.craftbukkit.persistence.CraftPersistentDataContainer(
+                    new org.bukkit.craftbukkit.persistence.CraftPersistentDataTypeRegistry()));
             var previous = new org.bukkit.potion.PotionEffect(org.bukkit.potion.PotionEffectType.SLOWNESS, 200, 1);
             var current = new java.util.concurrent.atomic.AtomicReference<org.bukkit.potion.PotionEffect>(previous);
-            when(target.getPotionEffect(org.bukkit.potion.PotionEffectType.SLOWNESS)).thenAnswer(call -> current.get());
-            when(target.addPotionEffect(any())).thenAnswer(call -> { current.set(call.getArgument(0)); return true; });
+            var installedAt = new java.util.concurrent.atomic.AtomicLong(System.nanoTime());
+            when(target.getPotionEffect(org.bukkit.potion.PotionEffectType.SLOWNESS)).thenAnswer(call -> {
+                var effect = current.get(); if (effect == null || effect.isInfinite()) return effect;
+                long ticks = Math.max(0, (System.nanoTime() - installedAt.get()) / 50_000_000L);
+                int remaining = (int) Math.max(0, (long) effect.getDuration() - ticks);
+                return remaining == 0 ? null : effect.withDuration(remaining);
+            });
+            when(target.addPotionEffect(any())).thenAnswer(call -> {
+                current.set(call.getArgument(0)); installedAt.set(System.nanoTime()); return true;
+            });
             doAnswer(call -> { current.set(null); return null; }).when(target)
                 .removePotionEffect(org.bukkit.potion.PotionEffectType.SLOWNESS);
             doAnswer(call -> {
@@ -707,6 +726,15 @@ class FrostShardNativeTest {
             PartyBookNativeTest.drain(f); PartyBookNativeTest.drain(f);
             f.dispatcher.accept(new org.bukkit.event.entity.ProjectileHitEvent(projectile, target));
             assertEquals(0, current.get().getAmplifier());
+            if (ageBeforeExit) {
+                var applied = current.get(); Thread.sleep(200);
+                var aged = target.getPotionEffect(org.bukkit.potion.PotionEffectType.SLOWNESS); assertNotNull(aged);
+                assertTrue(aged.getDuration() < applied.getDuration(),
+                    "The native test layer must report remaining duration after real ticks, not a frozen application snapshot");
+                assertEquals(applied.getType(), aged.getType()); assertEquals(applied.getAmplifier(), aged.getAmplifier());
+                assertEquals(applied.isAmbient(), aged.isAmbient()); assertEquals(applied.hasParticles(), aged.hasParticles());
+                assertEquals(applied.hasIcon(), aged.hasIcon());
+            }
             a.core.inventory.setItemInOffHand(null); f.changed(a); PartyBookNativeTest.drain(f); f.awaitCharacterAndReceipt(a);
             ((games.dmg.fantasystick.ability.AbilityEngine) FantasyStickLifecycleNativeTest.Fixture.field(f.plugin, "abilityEngine")).sweep();
             assertNotNull(current.get()); assertEquals(1, current.get().getAmplifier());