fix: prevent overlapping fade and loop playback

README.md

@@ -67,7 +67,7 @@ playback:
   loop-restart-ticks: 2680
 ```
 
-When a selected zone remains selected, Ambient Audio Zone normally sends no new sound packet. In follow-player mode it re-emits only when the calculated fade changes materially, and it uses an entity-attached packet so the sound follows the player. Leaving starts a configurable grace timer; returning before it expires preserves the existing client playback instead of restarting it. `loop-restart-ticks` is a fallback for sounds whose resource-pack definition does not loop; set it to the exact sound length, while resource-pack `loop: true` remains the seamless option. Reloading or editing a zone intentionally replaces its active sound.
+When a selected zone remains selected, Ambient Audio Zone normally sends no new sound packet. In follow-player mode it uses rate-limited fade updates and stops the previous packet before re-emitting, preventing layered copies of the sound. Bukkit has no mutable-volume packet, so these updates are necessarily discrete; resource-pack loops are the smoothest option. Leaving starts a configurable grace timer; returning before it expires preserves the existing client playback instead of restarting it. `loop-restart-ticks` is a fallback for sounds whose resource-pack definition does not loop; set it to the exact sound length, while resource-pack `loop: true` remains the seamless option. Reloading or editing a zone intentionally replaces its active sound.
 
 ## Resource-pack looping note
 

src/main/java/com/lexian/ambientaudio/service/PlaybackService.java

@@ -35,21 +35,21 @@ public final class PlaybackService {
             float volume = volumeFor(zone, player);
             if (sound == null) {
                 play(player, zone, volume);
-                current.put(zone.normalizedName(), new ActiveSound(zone, Long.MAX_VALUE, now, volume));
+                current.put(zone.normalizedName(), new ActiveSound(zone, Long.MAX_VALUE, now, now, volume));
             } else if (zone.loop() && loopRestartTicks > 0 && now - sound.startedAtTick() >= loopRestartTicks) {
                 play(player, zone, volume);
-                current.put(zone.normalizedName(), new ActiveSound(zone, Long.MAX_VALUE, now, volume));
+                current.put(zone.normalizedName(), new ActiveSound(zone, Long.MAX_VALUE, now, now, volume));
-            } else if (followPlayer && Math.abs(sound.volume() - volume) >= 0.05f) {
+            } else if (followPlayer && now - sound.lastPacketTick() >= 40 && Math.abs(sound.volume() - volume) >= 0.10f) {
-                // A sound packet has no mutable volume. Re-emit only when the fade changed materially;
+                // Bukkit has no volume-update packet. Rate-limit fade packets and stop the previous
-                // inside the zone the packet remains attached to the player and is not restarted.
+                // packet first; otherwise repeated entity sound packets overlap on the client.
                 play(player, zone, volume);
-                current.put(zone.normalizedName(), new ActiveSound(zone, Long.MAX_VALUE, sound.startedAtTick(), volume));
+                current.put(zone.normalizedName(), new ActiveSound(zone, Long.MAX_VALUE, sound.startedAtTick(), now, volume));
             }
         }
         for (Iterator<Map.Entry<String, ActiveSound>> it = current.entrySet().iterator(); it.hasNext();) {
             Map.Entry<String, ActiveSound> entry = it.next(); ActiveSound sound = entry.getValue();
-            if (desired.contains(entry.getKey())) { entry.setValue(new ActiveSound(sound.zone(), Long.MAX_VALUE, sound.startedAtTick(), sound.volume())); continue; }
+            if (desired.contains(entry.getKey())) { entry.setValue(new ActiveSound(sound.zone(), Long.MAX_VALUE, sound.startedAtTick(), sound.lastPacketTick(), sound.volume())); continue; }
-            if (sound.stopAtTick() == Long.MAX_VALUE) { entry.setValue(new ActiveSound(sound.zone(), now + leaveGraceTicks, sound.startedAtTick(), sound.volume())); continue; }
+            if (sound.stopAtTick() == Long.MAX_VALUE) { entry.setValue(new ActiveSound(sound.zone(), now + leaveGraceTicks, sound.startedAtTick(), sound.lastPacketTick(), sound.volume())); continue; }
             if (now >= sound.stopAtTick()) { player.stopSound(sound.zone().sound(), sound.zone().category()); it.remove(); }
         }
         if (current.isEmpty()) active.remove(player.getUniqueId());
@@ -63,6 +63,9 @@ public final class PlaybackService {
         } active.clear();
     }
     private void play(Player player, AudioZone zone, float volume) {
+        // A sound event is not a handle. Stop the matching event before re-emitting it so
+        // fade updates and loop restarts cannot layer copies of the same sound.
+        player.stopSound(zone.sound(), zone.category());
         if (followPlayer) player.playSound(player, zone.sound(), zone.category(), volume, zone.pitch());
         else player.playSound(zone.originLocation(player.getWorld()), zone.sound(), zone.category(), zone.volume(), zone.pitch());
     }
@@ -73,5 +76,5 @@ public final class PlaybackService {
         double multiplier = fade == 0 ? (distance == 0 ? 1 : 0) : Math.max(0, 1 - distance / fade);
         return (float) Math.max(0.001, zone.volume() * multiplier);
     }
-    private record ActiveSound(AudioZone zone, long stopAtTick, long startedAtTick, float volume) { }
+    private record ActiveSound(AudioZone zone, long stopAtTick, long startedAtTick, long lastPacketTick, float volume) { }
 }