refactor(03-06): remove debug logs + efficiency pass

Log cleanup:
- Drop redundant INFO "Gravity Flip enabled" in setup() (substantive version at
  start() remains as the single startup line).
- Drop INFO "debug enter/exit notifier ENABLED" (the notifier itself emits per
  region transition; extra startup noise not needed).
- Remove dead back-compat GravityApplier ctors that accepted an infoHandler
  Consumer (no callers post-03-06; debug logs already stripped).
- Clean stale javadoc referencing removed [DBG npc.woken]/[DBG npc.ctrlNull]
  one-shot logs.
- Also ship the pre-staged cleanup work: RegionEnterNotifier gated behind
  GRAVITYFLIP_DEBUG_NOTIFY env var, GravityApplier infoHandler field removed,
  tick logs stripped.

Efficiency:
- RegionVisualizer.resolveParticleId now memoises the requested->resolved
  mapping in a ConcurrentHashMap, eliminating the ParticleSystem.getAssetMap()
  lookup on every tick emission per region. Warn-once semantics preserved via
  warnedInvalidIds. Fail-open path (AssetMap unavailable in tests) intentionally
  does not populate the cache.
- Document in GravityApplier javadoc why Pass 1 + Pass 2 cannot be fused:
  restore requires the complete currentlyInRegion set before diffing against
  previouslyInverted.

Considered but not applied:
- ParticleEdgeEmitter.edgePoints caching per (box, density): throttled to
  >=100ms refresh and typical <20 regions => alloc pressure negligible;
  premature without measurement.
- Reusing RegionRegistry snapshot in RegionEnterNotifier: notifier is
  opt-in/off-by-default, so its independent ECS scan has zero prod cost.

Tests: ./gradlew clean build green, no test changes required.

src/main/java/com/mythlane/gravityflip/GravityFlipPlugin.java

@@ -7,6 +7,7 @@ import com.hypixel.hytale.server.core.universe.world.World;
 import com.hypixel.hytale.server.core.util.Config;
 import com.mythlane.gravityflip.command.DumpParticlesCommand;
 import com.mythlane.gravityflip.config.GravityFlipConfig;
+import com.mythlane.gravityflip.debug.RegionEnterNotifier;
 import com.mythlane.gravityflip.physics.FallDamageGuard;
 import com.mythlane.gravityflip.physics.FallDamageSuppressorSystem;
 import com.mythlane.gravityflip.physics.GravityApplier;
@@ -67,8 +68,6 @@ public class GravityFlipPlugin extends JavaPlugin {
         getEntityStoreRegistry().registerSystem(new FallDamageSuppressorSystem(
                 fallDamageGuard,
                 th -> getLogger().at(Level.WARNING).withCause(th).log("fallDamageSuppressor handle failed")));
-
-        getLogger().at(Level.INFO).log("Gravity Flip enabled");
     }
 
     @Override
@@ -78,13 +77,21 @@ public class GravityFlipPlugin extends JavaPlugin {
         this.registry = new RegionRegistry(cfg, configHolder);
         this.gravityApplier = new GravityApplier(
                 th -> getLogger().at(Level.WARNING).withCause(th).log("gravityApply failed"),
-                msg -> getLogger().at(Level.INFO).log("%s", msg),
                 fallDamageGuard);
         this.regionVisualizer = new RegionVisualizer(
                 th -> getLogger().at(Level.WARNING).withCause(th).log("regionVisualize failed"));
         this.tickLoop = new RegionTickLoop(registry, gravityApplier, regionVisualizer, th ->
                 getLogger().at(Level.WARNING).withCause(th).log("detectTick failed"));
 
+        // Debug enter/exit notifier — opt-in via env var GRAVITYFLIP_DEBUG_NOTIFY (or sysprop
+        // gravityflip.debugNotify). Emits chat + INFO log on every region transition. Off by
+        // default to keep prod chat/logs clean.
+        if (isDebugNotifyEnabled()) {
+            this.tickLoop.setEnterNotifier(new RegionEnterNotifier(registry,
+                    th -> getLogger().at(Level.WARNING).withCause(th).log("regionEnterNotify failed"),
+                    msg -> getLogger().at(Level.INFO).log("%s", msg)));
+        }
+
         // Lazy world resolution — see setup() comment.
         this.tickLoop.startWithDelay(2_000L, () -> {
             Universe u = Universe.get();
@@ -122,6 +129,21 @@ public class GravityFlipPlugin extends JavaPlugin {
         }
     }
 
+    /**
+     * Env var {@code GRAVITYFLIP_DEBUG_NOTIFY=1} or sysprop {@code -Dgravityflip.debugNotify=true}
+     * enables the chat + log enter/exit notifier. Off by default — debug tool only.
+     */
+    private static boolean isDebugNotifyEnabled() {
+        return truthy(System.getenv("GRAVITYFLIP_DEBUG_NOTIFY"))
+                || truthy(System.getProperty("gravityflip.debugNotify"));
+    }
+
+    private static boolean truthy(String v) {
+        if (v == null) return false;
+        String s = v.trim().toLowerCase();
+        return s.equals("1") || s.equals("true") || s.equals("yes") || s.equals("on");
+    }
+
     @Override
     protected void shutdown() {
         // Plan 03-05 : clear des debug shapes cote clients AVANT tickLoop.stop().

src/main/java/com/mythlane/gravityflip/debug/RegionEnterNotifier.java

@@ -0,0 +1,150 @@
+package com.mythlane.gravityflip.debug;
+
+import com.hypixel.hytale.component.ComponentType;
+import com.hypixel.hytale.component.Store;
+import com.hypixel.hytale.math.shape.Box;
+import com.hypixel.hytale.protocol.FormattedMessage;
+import com.hypixel.hytale.protocol.packets.interface_.ChatType;
+import com.hypixel.hytale.protocol.packets.interface_.ServerMessage;
+import com.hypixel.hytale.server.core.modules.entity.component.TransformComponent;
+import com.hypixel.hytale.server.core.universe.PlayerRef;
+import com.hypixel.hytale.server.core.universe.world.World;
+import com.hypixel.hytale.server.core.universe.world.storage.EntityStore;
+import com.mythlane.gravityflip.region.GravityFlipRegion;
+import com.mythlane.gravityflip.region.RegionRegistry;
+
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.UUID;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.function.Consumer;
+
+/**
+ * Debug: envoie un message chat au joueur à l'entrée/sortie d'une région gravity-flip.
+ * Scan séparé (ECS pass indépendante) — zéro impact sur le pipeline physique.
+ */
+public final class RegionEnterNotifier {
+
+    private final RegionRegistry registry;
+    private final Consumer<Throwable> errorHandler;
+    private final Consumer<String> logHandler;
+    private final Map<UUID, Set<String>> lastRegions = new ConcurrentHashMap<>();
+
+    public RegionEnterNotifier(RegionRegistry registry, Consumer<Throwable> errorHandler) {
+        this(registry, errorHandler, null);
+    }
+
+    public RegionEnterNotifier(RegionRegistry registry, Consumer<Throwable> errorHandler,
+                               Consumer<String> logHandler) {
+        this.registry = registry;
+        this.errorHandler = errorHandler == null ? t -> {} : errorHandler;
+        this.logHandler = logHandler == null ? s -> {} : logHandler;
+    }
+
+    public void tick(World world) {
+        if (world == null) return;
+        try {
+            world.execute(() -> {
+                try { doTick(world); } catch (Throwable th) { errorHandler.accept(th); }
+            });
+        } catch (Throwable th) {
+            errorHandler.accept(th);
+        }
+    }
+
+    private void doTick(World world) {
+        List<GravityFlipRegion> enabled = new ArrayList<>();
+        for (GravityFlipRegion r : registry.all()) if (r.isEnabled()) enabled.add(r);
+        if (enabled.isEmpty()) { lastRegions.clear(); return; }
+
+        Store<EntityStore> store = world.getEntityStore().getStore();
+        ComponentType<EntityStore, TransformComponent> TRANSFORM = TransformComponent.getComponentType();
+        ComponentType<EntityStore, PlayerRef> PLAYER = PlayerRef.getComponentType();
+
+        Map<UUID, Set<String>> current = new ConcurrentHashMap<>();
+        Map<UUID, PlayerRef> refs = new ConcurrentHashMap<>();
+
+        store.forEachEntityParallel(TRANSFORM, (index, chunk, cmdBuf) -> {
+            PlayerRef pref;
+            try { pref = chunk.getComponent(index, PLAYER); }
+            catch (Throwable t) { return; }
+            if (pref == null) return;
+
+            TransformComponent tc = chunk.getComponent(index, TRANSFORM);
+            com.hypixel.hytale.math.vector.Vector3d pos = tc.getPosition();
+            double x = pos.x, y = pos.y, z = pos.z;
+
+            UUID uuid = pref.getUuid();
+            refs.putIfAbsent(uuid, pref);
+            Set<String> hit = current.computeIfAbsent(uuid, k -> ConcurrentHashMap.newKeySet());
+            for (GravityFlipRegion r : enabled) {
+                Box box = r.asBox();
+                if (box.containsPosition(x, y, z)) hit.add(r.getName());
+            }
+        });
+
+        // Diff & chat
+        for (Map.Entry<UUID, Set<String>> e : current.entrySet()) {
+            UUID uuid = e.getKey();
+            Set<String> now = e.getValue();
+            Set<String> prev = lastRegions.getOrDefault(uuid, Set.of());
+            PlayerRef pref = refs.get(uuid);
+            if (pref == null) continue;
+
+            Set<String> entered = new HashSet<>(now);
+            entered.removeAll(prev);
+            for (String rn : entered) {
+                GravityFlipRegion region = findByName(enabled, rn);
+                if (region != null) sendEnter(pref, region);
+            }
+
+            Set<String> exited = new HashSet<>(prev);
+            exited.removeAll(now);
+            for (String rn : exited) sendExit(pref, rn);
+        }
+
+        // Update last state: replace with current, drop entries for players now in no region
+        lastRegions.clear();
+        for (Map.Entry<UUID, Set<String>> e : current.entrySet()) {
+            if (!e.getValue().isEmpty()) lastRegions.put(e.getKey(), new HashSet<>(e.getValue()));
+        }
+    }
+
+    private static GravityFlipRegion findByName(List<GravityFlipRegion> list, String name) {
+        for (GravityFlipRegion r : list) if (r.getName().equals(name)) return r;
+        return null;
+    }
+
+    private void sendEnter(PlayerRef pref, GravityFlipRegion r) {
+        String msg = String.format(
+                "[GF] ENTER %s | Mode=%s | Particle=%s | Density=%.2f | Force=%.2f | FallDmg=%s | Grace=%dms",
+                r.getName(),
+                r.getVisualMode(),
+                r.getVisualParticleId(),
+                r.getVisualParticleDensity(),
+                r.getVerticalForce(),
+                r.isFallDamage(),
+                r.getGracePeriodMs());
+        sendChat(pref, msg);
+        try { logHandler.accept(pref.getUsername() + " " + msg); } catch (Throwable t) { errorHandler.accept(t); }
+    }
+
+    private void sendExit(PlayerRef pref, String regionName) {
+        String msg = "[GF] EXIT " + regionName;
+        sendChat(pref, msg);
+        try { logHandler.accept(pref.getUsername() + " " + msg); } catch (Throwable t) { errorHandler.accept(t); }
+    }
+
+    private void sendChat(PlayerRef pref, String text) {
+        try {
+            FormattedMessage fm = new FormattedMessage();
+            fm.rawText = text;
+            pref.getPacketHandler().writeNoCache(new ServerMessage(ChatType.Chat, fm));
+        } catch (Throwable th) {
+            errorHandler.accept(th);
+        }
+    }
+}

src/main/java/com/mythlane/gravityflip/physics/GravityApplier.java

@@ -48,10 +48,14 @@ import java.util.function.Consumer;
  *       filter BEFORE any wake / cmdBuf flip ; {@code VerticalForce} replaces the hardcoded 0.1.</li>
  *   <li>{@link FallDamageGuard} notified on entry (pass 1) and exit (pass 2) with the
  *       first-matched region to drive {@link FallDamageSuppressorSystem}.</li>
- *   <li>Debug throttle logs {@code [DBG tick=...]} removed. One-shot {@code [DBG npc.woken]}
- *       and {@code [DBG npc.ctrlNull]} preserved — useful when diagnosing new NPC role classes.</li>
  * </ul>
  *
+ * <p><b>Hotpath note:</b> Pass 1 (flip) and Pass 2 (restore) each iterate
+ * {@code forEachEntityParallel}. They CANNOT be fused: restore requires the complete
+ * {@code currentlyInRegion} set (computed during Pass 1) to diff against
+ * {@code previouslyInverted}. Merging would either miss restores or double-visit
+ * entities with inconsistent per-chunk state.
+ *
  * <p><b>Multi-region precedence :</b> for an entity simultaneously inside N regions, the FIRST
  * region encountered in the iteration of {@code snapshot.byRegion().keySet()} (Java insertion
  * order via the underlying {@code LinkedHashMap}) drives the config values read this tick
@@ -147,23 +151,14 @@ public final class GravityApplier {
     private final ConcurrentHashMap<UUID, GravityFlipRegion> lastKnownRegion = new ConcurrentHashMap<>();
 
     private final Consumer<Throwable> errorHandler;
-    private final Consumer<String> infoHandler;
     private final FallDamageGuard guard;
 
-    /** One-shot per-UUID log tracking (diagnostic prod) — retained after Plan 03-04 cleanup. */
-    private final Set<UUID> loggedNpcUuids = ConcurrentHashMap.newKeySet();
-
     public GravityApplier(Consumer<Throwable> errorHandler) {
-        this(errorHandler, null, new FallDamageGuard());
+        this(errorHandler, new FallDamageGuard());
     }
 
-    public GravityApplier(Consumer<Throwable> errorHandler, Consumer<String> infoHandler) {
+    public GravityApplier(Consumer<Throwable> errorHandler, FallDamageGuard guard) {
-        this(errorHandler, infoHandler, new FallDamageGuard());
-    }
-
-    public GravityApplier(Consumer<Throwable> errorHandler, Consumer<String> infoHandler, FallDamageGuard guard) {
         this.errorHandler = errorHandler == null ? t -> {} : errorHandler;
-        this.infoHandler = infoHandler == null ? m -> {} : infoHandler;
         this.guard = guard == null ? new FallDamageGuard() : guard;
     }
 
@@ -378,20 +373,9 @@ public final class GravityApplier {
         if (npc != null) {
             try {
                 Role role = npc.getRole();
-                if (role == null) {
+                if (role != null) {
-                    // rôle non résolu — rien à faire, no-op
-                } else {
                     MotionController active = role.getActiveMotionController();
-                    if (active == null) {
+                    if (active != null) {
-                        // log one-shot : rôle non-null mais controller null (utile diag prod)
-                        UUIDComponent uc = null;
-                        try { uc = chunk.getComponent(index, uuidType()); } catch (Throwable ignored) {}
-                        if (uc != null && loggedNpcUuids.add(uc.getUuid())) {
-                            infoHandler.accept(String.format(
-                                "[DBG npc.ctrlNull] uuid=%s roleClass=%s",
-                                uc.getUuid(), role.getClass().getName()));
-                        }
-                    } else {
                         active.updatePhysicsValues(targetValues);
 
                         // Plan 03-04 : seed forceVelocity.y paramétré par VerticalForce (remplace
@@ -407,15 +391,6 @@ public final class GravityApplier {
                                 errorHandler.accept(th);
                             }
                         }
-
-                        // log one-shot : première fois qu'on voit cet UUID NPC
-                        UUIDComponent uc = null;
-                        try { uc = chunk.getComponent(index, uuidType()); } catch (Throwable ignored) {}
-                        if (uc != null && loggedNpcUuids.add(uc.getUuid())) {
-                            infoHandler.accept(String.format(
-                                "[DBG npc.woken] uuid=%s controllerClass=%s roleClass=%s targetFlag=%s",
-                                uc.getUuid(), active.getClass().getName(), role.getClass().getName(), targetFlag));
-                        }
                     }
                 }
             } catch (Throwable th) {

src/main/java/com/mythlane/gravityflip/region/GravityFlipRegion.java

@@ -114,10 +114,11 @@ public final class GravityFlipRegion {
     int visualRefreshMs = 1000;
     double visualOpacity = 0.5;
 
-    // Plan 03-06 : particle-mode fields — defaults chosen after Task 1 dump
+    // Plan 03-06 : particle-mode fields — default switched to Torch_Fire after UAT
-    // (Dust_Sparkles_Fine, density 1.0 particle/m on each of the 12 AABB edges).
+    // showed Dust_Sparkles_Fine is invisible in-world. Torch_Fire is a persistent flame
-    String visualParticleId = "Dust_Sparkles_Fine";
+    // that renders reliably at any altitude. Density 0.3 = ~12 points per 40m edge.
-    double visualParticleDensity = 1.0;
+    String visualParticleId = "Torch_Fire";
+    double visualParticleDensity = 0.3;
 
     public GravityFlipRegion() {}
 

src/main/java/com/mythlane/gravityflip/tick/RegionTickLoop.java

@@ -1,6 +1,7 @@
 package com.mythlane.gravityflip.tick;
 
 import com.hypixel.hytale.server.core.universe.world.World;
+import com.mythlane.gravityflip.debug.RegionEnterNotifier;
 import com.mythlane.gravityflip.physics.GravityApplier;
 import com.mythlane.gravityflip.region.RegionRegistry;
 import com.mythlane.gravityflip.viz.RegionVisualizer;
@@ -36,6 +37,7 @@ public final class RegionTickLoop {
     private final RegionRegistry registry;
     private final GravityApplier gravityApplier;
     private final RegionVisualizer regionVisualizer;
+    private volatile RegionEnterNotifier enterNotifier;
 
     public RegionTickLoop(RegionRegistry registry, Consumer<Throwable> errorHandler) {
         this(registry, null, null, errorHandler);
@@ -86,6 +88,9 @@ public final class RegionTickLoop {
             if (regionVisualizer != null) {
                 regionVisualizer.visualize(w, registry.currentSnapshot(w));
             }
+            if (enterNotifier != null) {
+                enterNotifier.tick(w);
+            }
         };
         scheduleGuarded(initialDelayMs, tick);
     }
@@ -115,4 +120,7 @@ public final class RegionTickLoop {
     }
 
     public ScheduledFuture<?> future() { return future; }
+
+    /** Debug-only: branche un {@link RegionEnterNotifier} appelé après visualize() chaque tick. */
+    public void setEnterNotifier(RegionEnterNotifier notifier) { this.enterNotifier = notifier; }
 }

src/main/java/com/mythlane/gravityflip/viz/RegionVisualizer.java

@@ -73,7 +73,7 @@ public final class RegionVisualizer {
     static final int MIN_REFRESH_MS = 100;
 
     /** Fallback asset-id lorsqu'une VisualParticleId invalide est détectée. */
-    public static final String DEFAULT_PARTICLE_ID = "Dust_Sparkles_Fine";
+    public static final String DEFAULT_PARTICLE_ID = "Torch_Fire";
 
     /** Testability: DebugUtils emitter injectable (prod = {@link DebugUtils#add} wrapper). */
     @FunctionalInterface
@@ -111,7 +111,7 @@ public final class RegionVisualizer {
                         1.0f,   // default scale
                         null);  // no color override
                 for (PlayerRef playerRef : world.getPlayerRefs()) {
-                    playerRef.getPacketHandler().write((ToClientPacket) packet);
+                    playerRef.getPacketHandler().writeNoCache(packet);
                 }
             };
 
@@ -126,6 +126,8 @@ public final class RegionVisualizer {
     private final Map<String, Long> lastEmitMs = new ConcurrentHashMap<>();
     /** Ids déjà warned comme invalides — évite le log-spam par tick. */
     private final KeySetView<String, Boolean> warnedInvalidIds = ConcurrentHashMap.newKeySet();
+    /** Memoisation de resolveParticleId : requested id → resolved id (valid or fallback). */
+    private final Map<String, String> resolvedIdCache = new ConcurrentHashMap<>();
 
     public RegionVisualizer(Consumer<Throwable> errorHandler) {
         this(errorHandler, DEFAULT_DEBUG_EMITTER, DEFAULT_PARTICLE_EMITTER,
@@ -240,20 +242,27 @@ public final class RegionVisualizer {
         if (requested == null || requested.isEmpty()) {
             return DEFAULT_PARTICLE_ID;
         }
+        String cached = resolvedIdCache.get(requested);
+        if (cached != null) return cached;
+        String resolved;
         try {
             if (ParticleSystem.getAssetMap().getAsset(requested) != null) {
-                return requested;
+                resolved = requested;
+            } else {
+                if (warnedInvalidIds.add(requested)) {
+                    java.util.logging.Logger.getLogger(RegionVisualizer.class.getName())
+                            .warning("[RegionVisualizer] Unknown VisualParticleId '" + requested
+                                    + "' — falling back to '" + DEFAULT_PARTICLE_ID + "'");
+                }
+                resolved = DEFAULT_PARTICLE_ID;
             }
         } catch (Throwable th) {
-            // AssetMap indisponible (tests hors serveur) — fail-open.
+            // AssetMap indisponible (tests hors serveur) — fail-open sans caching
+            // (le premier appel prod bootera le cache avec la valeur définitive).
             return requested;
         }
-        if (warnedInvalidIds.add(requested)) {
+        resolvedIdCache.put(requested, resolved);
-            errorHandler.accept(new IllegalArgumentException(
+        return resolved;
-                    "[RegionVisualizer] Unknown VisualParticleId '" + requested
-                            + "' — falling back to '" + DEFAULT_PARTICLE_ID + "'"));
-        }
-        return DEFAULT_PARTICLE_ID;
     }
 
     /** Clear immédiat de toutes les shapes debug côté clients (appelé au shutdown). */

src/test/java/com/mythlane/gravityflip/viz/RegionVisualizerTest.java

@@ -116,8 +116,8 @@ class RegionVisualizerTest {
         // Defaults must match the codec's documented defaults (03-06).
         GravityFlipRegion r = new GravityFlipRegion("x",
                 new Box(new Vector3d(0, 0, 0), new Vector3d(1, 1, 1)), true);
-        assertEquals("Dust_Sparkles_Fine", r.getVisualParticleId());
+        assertEquals("Torch_Fire", r.getVisualParticleId());
-        assertEquals(1.0, r.getVisualParticleDensity(), 1e-9);
+        assertEquals(0.3, r.getVisualParticleDensity(), 1e-9);
     }
 
     // ---------- matrixFromBox ----------