#W# Update: added Distribution/Data/Files to gitignore.

## Summary

`Mobile.DamageEntries` was a `List<DamageEntry>` allocated for every mobile, including the ~99% that never take damage. It is now an inline `ValueLinkList<DamageEntry>` (24 bytes in the `Mobile` object, no separate allocation) ordered least recent → most recent.

- `DamageEntry` implements `IValueLinkListNode<DamageEntry>`.
- `RegisterDamage` moves the entry to the tail in O(1) instead of `Remove` + `Add` on a list.
- Expired entries are always a head prefix, so pruning walks from the head and stops at the first live entry. The `DamageEntries` getter prunes on access.
- `DamageEntries` is exposed as `ref readonly`; enumerate with `foreach` or `.ByDescending()`. Mutation goes through `RegisterDamage` / `ClearDamageEntries`.
- `BaseCreature.GetLootingRights` and `BaseCreature.ComputeBonusDamage` take `in ValueLinkList<DamageEntry>`; all callers compile unchanged. Files that `foreach` over `DamageEntries` need `using Server.Collections;` for the enumerator extension.
- RunUO migration docs (`dev-docs/runuo-migration-docs/09`, `11`) and the `migrate-items-mobiles` skill document the change.

Saves one object and 16 bytes per mobile (~8 MB and 500k gen2 objects on a 500k world). Second of three PRs from the lazy per-mobile collections design (first: #2604). Branched from `main`; the two diffs touch disjoint hunks of `Mobile.cs`.

## Breaking change

- `Mobile.DamageEntries` is no longer a `List<DamageEntry>`. Indexing, `.Clear()`, `.Add()`, `.Remove()` no longer compile; use `foreach`, `.ByDescending()`, `.Count`, `ClearDamageEntries()`, and `RegisterDamage`. Calling a `ValueLinkList` mutator on the `ref readonly` property compiles but operates on a copy while still unlinking the real nodes; do not.
- `BaseCreature.GetLootingRights` and `BaseCreature.ComputeBonusDamage` signatures changed to `(in ValueLinkList<DamageEntry>, …)`.

Save format is untouched: damage entries are not serialized.

## Behavior

Recency order, `allowSelf`, tie-breaking in `FindMostTotal`/`FindLeastTotal` (most recent wins), `Responsible` accounting, and loot-rights ordering are unchanged and covered by the new `DamageEntryTests` and `LootingRightsTests`.

## Testing

- `dotnet build -c Release` clean.
- New `DamageEntryTests` and `LootingRightsTests` plus full `Server.Tests` and `UOContent.Tests`.

.gitignore

@@ -1,4 +1,5 @@
 # Distribution Files
+/Distribution/Data/Files
 /Distribution/Logger
 /Distribution/Logger.*
 /Distribution/ModernUO

Projects/Server.Tests/Tests/Mobiles/DamageEntryTests.cs

@@ -0,0 +1,311 @@
+using System;
+using System.Collections.Generic;
+using Server.Collections;
+using Xunit;
+
+namespace Server.Tests;
+
+[Collection("Sequential Server Tests")]
+public class DamageEntryTests
+{
+    private class TestMobile : Mobile
+    {
+    }
+
+    private class PetMobile : Mobile
+    {
+        public Mobile Master { get; set; }
+
+        public override Mobile GetDamageMaster(Mobile damagee) => Master;
+    }
+
+    private static List<Mobile> Damagers(Mobile victim)
+    {
+        var result = new List<Mobile>();
+        foreach (var de in victim.DamageEntries)
+        {
+            result.Add(de.Damager);
+        }
+
+        return result;
+    }
+
+    [Fact]
+    public void FreshMobile_HasNoEntries()
+    {
+        var m = new TestMobile();
+
+        try
+        {
+            Assert.Equal(0, m.DamageEntries.Count);
+            Assert.Null(m.FindMostRecentDamageEntry(true));
+            Assert.Null(m.FindLeastRecentDamageEntry(true));
+            Assert.Null(m.FindMostTotalDamageEntry(true));
+            Assert.Null(m.FindLeastTotalDamageEntry(true));
+            Assert.Null(m.FindDamageEntryFor(m));
+        }
+        finally
+        {
+            m.Delete();
+        }
+    }
+
+    [Fact]
+    public void RegisterDamage_OrdersLeastRecentToMostRecent()
+    {
+        var victim = new TestMobile();
+        var a = new TestMobile();
+        var b = new TestMobile();
+
+        try
+        {
+            victim.RegisterDamage(10, a);
+            victim.RegisterDamage(20, b);
+            victim.RegisterDamage(5, a); // a becomes most recent again
+
+            Assert.Equal(2, victim.DamageEntries.Count);
+            Assert.Equal(new[] { b, a }, Damagers(victim));
+            Assert.Equal(15, victim.FindDamageEntryFor(a).DamageGiven);
+            Assert.Same(a, victim.FindMostRecentDamager(true));
+            Assert.Same(b, victim.FindLeastRecentDamager(true));
+        }
+        finally
+        {
+            victim.Delete();
+            a.Delete();
+            b.Delete();
+        }
+    }
+
+    [Fact]
+    public void FindRecent_HonorsAllowSelf()
+    {
+        var victim = new TestMobile();
+        var a = new TestMobile();
+
+        try
+        {
+            victim.RegisterDamage(10, a);
+            victim.RegisterDamage(10, victim); // self is most recent
+
+            Assert.Same(victim, victim.FindMostRecentDamager(true));
+            Assert.Same(a, victim.FindMostRecentDamager(false));
+            Assert.Same(a, victim.FindLeastRecentDamager(false));
+        }
+        finally
+        {
+            victim.Delete();
+            a.Delete();
+        }
+    }
+
+    [Fact]
+    public void FindLeastRecent_HonorsAllowSelf()
+    {
+        var victim = new TestMobile();
+        var a = new TestMobile();
+
+        try
+        {
+            victim.RegisterDamage(10, victim); // self is least recent, so the head is the one to skip
+            victim.RegisterDamage(10, a);
+
+            Assert.Same(victim, victim.FindLeastRecentDamager(true));
+            Assert.Same(a, victim.FindLeastRecentDamager(false));
+        }
+        finally
+        {
+            victim.Delete();
+            a.Delete();
+        }
+    }
+
+    [Fact]
+    public void FindTotal_PicksByDamage_MostRecentWinsTies()
+    {
+        var victim = new TestMobile();
+        var a = new TestMobile();
+        var b = new TestMobile();
+        var c = new TestMobile();
+
+        try
+        {
+            victim.RegisterDamage(30, a);
+            victim.RegisterDamage(30, b); // ties a; b is more recent
+            victim.RegisterDamage(1, c);
+
+            Assert.Same(b, victim.FindMostTotalDamager(true));
+            Assert.Same(c, victim.FindLeastTotalDamager(true));
+        }
+        finally
+        {
+            victim.Delete();
+            a.Delete();
+            b.Delete();
+            c.Delete();
+        }
+    }
+
+    [Fact]
+    public void FindLeastTotal_MostRecentWinsTies()
+    {
+        var victim = new TestMobile();
+        var a = new TestMobile();
+        var b = new TestMobile();
+        var c = new TestMobile();
+
+        try
+        {
+            victim.RegisterDamage(30, a);
+            victim.RegisterDamage(5, b);
+            victim.RegisterDamage(5, c); // ties b for the minimum; c is more recent
+
+            Assert.Same(a, victim.FindMostTotalDamager(true));
+            Assert.Same(c, victim.FindLeastTotalDamager(true));
+        }
+        finally
+        {
+            victim.Delete();
+            a.Delete();
+            b.Delete();
+            c.Delete();
+        }
+    }
+
+    [Fact]
+    public void Prune_RemovesExpiredPrefix_KeepsOrder()
+    {
+        var start = Core._now;
+        var victim = new TestMobile();
+        var a = new TestMobile();
+        var b = new TestMobile();
+
+        try
+        {
+            victim.RegisterDamage(10, a);
+
+            Core._now = start + DamageEntry.ExpireDelay + TimeSpan.FromSeconds(1);
+            victim.RegisterDamage(10, b); // a is now expired, b is live
+
+            Assert.Equal(new[] { b }, Damagers(victim));
+            Assert.Null(victim.FindDamageEntryFor(a));
+        }
+        finally
+        {
+            Core._now = start;
+            victim.Delete();
+            a.Delete();
+            b.Delete();
+        }
+    }
+
+    [Fact]
+    public void Prune_AllExpired_EmptiesList()
+    {
+        var start = Core._now;
+        var victim = new TestMobile();
+        var a = new TestMobile();
+        var b = new TestMobile();
+
+        try
+        {
+            victim.RegisterDamage(10, a);
+            victim.RegisterDamage(10, b);
+
+            Core._now = start + DamageEntry.ExpireDelay + TimeSpan.FromSeconds(1);
+
+            Assert.Equal(0, victim.DamageEntries.Count);
+            Assert.Null(victim.FindMostRecentDamageEntry(true));
+        }
+        finally
+        {
+            Core._now = start;
+            victim.Delete();
+            a.Delete();
+            b.Delete();
+        }
+    }
+
+    [Fact]
+    public void ClearDamageEntries_UnlinksEveryNode()
+    {
+        var victim = new TestMobile();
+        var a = new TestMobile();
+        var b = new TestMobile();
+
+        try
+        {
+            var ea = victim.RegisterDamage(10, a);
+            var eb = victim.RegisterDamage(10, b);
+
+            victim.ClearDamageEntries();
+
+            Assert.Equal(0, victim.DamageEntries.Count);
+            Assert.False(ea.OnLinkList);
+            Assert.False(eb.OnLinkList);
+            Assert.Null(ea.Next);
+            Assert.Null(ea.Previous);
+            Assert.Null(eb.Next);
+            Assert.Null(eb.Previous);
+        }
+        finally
+        {
+            victim.Delete();
+            a.Delete();
+            b.Delete();
+        }
+    }
+
+    [Fact]
+    public void FullHitPoints_ClearsEntries()
+    {
+        var victim = new TestMobile();
+        var a = new TestMobile();
+
+        try
+        {
+            victim.RawStr = 50; // HitsMax follows Str for a base Mobile
+            victim.Hits = 10;
+            victim.RegisterDamage(10, a);
+            Assert.Equal(1, victim.DamageEntries.Count);
+
+            // Also stops the HitsTimer the Hits = 10 write started, so the test leaves no timer behind.
+            victim.Hits = victim.HitsMax;
+
+            Assert.Equal(0, victim.DamageEntries.Count);
+        }
+        finally
+        {
+            victim.Delete();
+            a.Delete();
+        }
+    }
+
+    [Fact]
+    public void RegisterDamage_AccumulatesResponsibleMaster()
+    {
+        var victim = new TestMobile();
+        var master = new TestMobile();
+        var pet = new PetMobile { Master = master };
+
+        try
+        {
+            victim.RegisterDamage(10, pet);
+            var entry = victim.RegisterDamage(5, pet);
+
+            Assert.Same(pet, entry.Damager);
+            Assert.Equal(15, entry.DamageGiven);
+            Assert.NotNull(entry.Responsible);
+            Assert.Single(entry.Responsible);
+            Assert.Same(master, entry.Responsible[0].Damager);
+            Assert.Equal(15, entry.Responsible[0].DamageGiven);
+            Assert.False(entry.Responsible[0].OnLinkList); // sub-entries never join the main list
+        }
+        finally
+        {
+            victim.Delete();
+            master.Delete();
+            pet.Delete();
+        }
+    }
+}

Projects/Server/Mobiles/Mobile.cs

@@ -42,7 +42,7 @@ public delegate void PromptCallback(Mobile from, string text);
 
 public delegate void PromptStateCallback<in T>(Mobile from, string text, T state);
 
-public class DamageEntry
+public class DamageEntry : IValueLinkListNode<DamageEntry>
 {
     public DamageEntry(Mobile damager) => Damager = damager;
 
@@ -57,6 +57,11 @@ public class DamageEntry
     public List<DamageEntry> Responsible { get; set; }
 
     public static TimeSpan ExpireDelay { get; set; } = TimeSpan.FromMinutes(2.0);
+
+    // Intrusive links for Mobile._damageEntries. Sub-entries in Responsible never join a list.
+    public DamageEntry Next { get; set; }
+    public DamageEntry Previous { get; set; }
+    public bool OnLinkList { get; set; }
 }
 
 [Flags]
@@ -377,7 +382,6 @@ public partial class Mobile : IHued, IComparable<Mobile>, ISpawnable, IObjectPro
         Aggressors = new List<AggressorInfo>();
         Aggressed = new List<AggressorInfo>();
         NextSkillTime = Core.TickCount;
-        DamageEntries = new List<DamageEntry>();
     }
 
     // Sectors
@@ -958,7 +962,23 @@ public partial class Mobile : IHued, IComparable<Mobile>, ISpawnable, IObjectPro
 
     public static VisibleDamageType VisibleDamageType { get; set; }
 
-    public List<DamageEntry> DamageEntries { get; private set; }
+    private ValueLinkList<DamageEntry> _damageEntries;
+
+    /// <summary>
+    /// Damage entries ordered least recent (head) to most recent (tail). Expired entries are
+    /// pruned on access. Enumerate with <c>foreach</c> (ascending) or <c>.ByDescending()</c>.
+    /// Mutate only through <see cref="RegisterDamage"/> and <see cref="ClearDamageEntries"/>.
+    /// Calling a ValueLinkList mutator on this reference compiles, but operates on a defensive copy
+    /// while still unlinking the real nodes — it silently corrupts the list.
+    /// </summary>
+    public ref readonly ValueLinkList<DamageEntry> DamageEntries
+    {
+        get
+        {
+            PruneExpiredDamageEntries();
+            return ref _damageEntries;
+        }
+    }
 
     [CommandProperty(AccessLevel.GameMaster)]
     public Mobile LastKiller { get; set; }
@@ -1627,7 +1647,7 @@ public partial class Mobile : IHued, IComparable<Mobile>, ISpawnable, IObjectPro
 
     public virtual bool KeepsItemsOnDeath => m_AccessLevel > AccessLevel.Player;
 
-    public bool HasTrade => m_NetState?.Trades.Count > 0;
+    public bool HasTrade => m_NetState?.Trades?.Count > 0;
 
     public bool NoMoveHS { get; set; }
 
@@ -2020,10 +2040,7 @@ public partial class Mobile : IHued, IComparable<Mobile>, ISpawnable, IObjectPro
                     Aggressors[i].CanReportMurder = false;
                 }
 
-                if (DamageEntries.Count > 0)
+                ClearDamageEntries(); // reset damage entries on full HP
-                {
-                    DamageEntries.Clear(); // reset damage entries on full HP
-                }
             }
             else if (CanRegenHits)
             {
@@ -5745,24 +5762,54 @@ public partial class Mobile : IHued, IComparable<Mobile>, ISpawnable, IObjectPro
         }
     }
 
+    // Entries are kept in LastDamage order, so expired entries are always a head prefix.
+    private void PruneExpiredDamageEntries()
+    {
+#if DEBUG
+        for (var node = _damageEntries._first; node != null; node = node.Next)
+        {
+            Debug.Assert(
+                node.Next == null || node.Next.LastDamage >= node.LastDamage,
+                "Damage entries must be ordered by LastDamage ascending."
+            );
+        }
+#endif
+
+        var first = _damageEntries._first;
+
+        if (first?.HasExpired != true)
+        {
+            return;
+        }
+
+        var firstLive = first.Next;
+
+        while (firstLive?.HasExpired == true)
+        {
+            firstLive = firstLive.Next;
+        }
+
+        if (firstLive == null)
+        {
+            _damageEntries.RemoveAll();
+        }
+        else
+        {
+            _damageEntries.RemoveAllBefore(firstLive);
+        }
+    }
+
+    public void ClearDamageEntries() => _damageEntries.RemoveAll();
+
     public Mobile FindMostRecentDamager(bool allowSelf) => FindMostRecentDamageEntry(allowSelf)?.Damager;
 
     public DamageEntry FindMostRecentDamageEntry(bool allowSelf)
     {
-        for (var i = DamageEntries.Count - 1; i >= 0; --i)
+        PruneExpiredDamageEntries();
+
+        for (var de = _damageEntries._last; de != null; de = de.Previous)
         {
-            if (i >= DamageEntries.Count)
+            if (allowSelf || de.Damager != this)
-            {
-                continue;
-            }
-
-            var de = DamageEntries[i];
-
-            if (de.HasExpired)
-            {
-                DamageEntries.RemoveAt(i);
-            }
-            else if (allowSelf || de.Damager != this)
             {
                 return de;
             }
@@ -5775,21 +5822,11 @@ public partial class Mobile : IHued, IComparable<Mobile>, ISpawnable, IObjectPro
 
     public DamageEntry FindLeastRecentDamageEntry(bool allowSelf)
     {
-        for (var i = 0; i < DamageEntries.Count; ++i)
+        PruneExpiredDamageEntries();
+
+        for (var de = _damageEntries._first; de != null; de = de.Next)
         {
-            if (i < 0)
+            if (allowSelf || de.Damager != this)
-            {
-                continue;
-            }
-
-            var de = DamageEntries[i];
-
-            if (de.HasExpired)
-            {
-                DamageEntries.RemoveAt(i);
-                --i;
-            }
-            else if (allowSelf || de.Damager != this)
             {
                 return de;
             }
@@ -5800,24 +5837,17 @@ public partial class Mobile : IHued, IComparable<Mobile>, ISpawnable, IObjectPro
 
     public Mobile FindMostTotalDamager(bool allowSelf) => FindMostTotalDamageEntry(allowSelf)?.Damager;
 
+    // Walks most recent first with a strict comparison so the most recent entry wins ties,
+    // matching the previous reverse-indexed loop.
     public DamageEntry FindMostTotalDamageEntry(bool allowSelf)
     {
+        PruneExpiredDamageEntries();
+
         DamageEntry mostTotal = null;
 
-        for (var i = DamageEntries.Count - 1; i >= 0; --i)
+        for (var de = _damageEntries._last; de != null; de = de.Previous)
         {
-            if (i >= DamageEntries.Count)
+            if ((allowSelf || de.Damager != this) && (mostTotal == null || de.DamageGiven > mostTotal.DamageGiven))
-            {
-                continue;
-            }
-
-            var de = DamageEntries[i];
-
-            if (de.HasExpired)
-            {
-                DamageEntries.RemoveAt(i);
-            }
-            else if ((allowSelf || de.Damager != this) && (mostTotal == null || de.DamageGiven > mostTotal.DamageGiven))
             {
                 mostTotal = de;
             }
@@ -5830,46 +5860,28 @@ public partial class Mobile : IHued, IComparable<Mobile>, ISpawnable, IObjectPro
 
     public DamageEntry FindLeastTotalDamageEntry(bool allowSelf)
     {
-        DamageEntry mostTotal = null;
+        PruneExpiredDamageEntries();
 
-        for (var i = DamageEntries.Count - 1; i >= 0; --i)
+        DamageEntry leastTotal = null;
+
+        for (var de = _damageEntries._last; de != null; de = de.Previous)
         {
-            if (i >= DamageEntries.Count)
+            if ((allowSelf || de.Damager != this) && (leastTotal == null || de.DamageGiven < leastTotal.DamageGiven))
             {
-                continue;
+                leastTotal = de;
-            }
-
-            var de = DamageEntries[i];
-
-            if (de.HasExpired)
-            {
-                DamageEntries.RemoveAt(i);
-            }
-            else if ((allowSelf || de.Damager != this) && (mostTotal == null || de.DamageGiven < mostTotal.DamageGiven))
-            {
-                mostTotal = de;
             }
         }
 
-        return mostTotal;
+        return leastTotal;
     }
 
     public DamageEntry FindDamageEntryFor(Mobile m)
     {
-        for (var i = DamageEntries.Count - 1; i >= 0; --i)
+        PruneExpiredDamageEntries();
+
+        for (var de = _damageEntries._last; de != null; de = de.Previous)
         {
-            if (i >= DamageEntries.Count)
+            if (de.Damager == m)
-            {
-                continue;
-            }
-
-            var de = DamageEntries[i];
-
-            if (de.HasExpired)
-            {
-                DamageEntries.RemoveAt(i);
-            }
-            else if (de.Damager == m)
             {
                 return de;
             }
@@ -5887,8 +5899,13 @@ public partial class Mobile : IHued, IComparable<Mobile>, ISpawnable, IObjectPro
         de.DamageGiven += amount;
         de.LastDamage = Core.Now;
 
-        DamageEntries.Remove(de);
+        // Move to the tail so the list stays in LastDamage order.
-        DamageEntries.Add(de);
+        if (de.OnLinkList)
+        {
+            _damageEntries.Remove(de);
+        }
+
+        _damageEntries.AddLast(de);
 
         var master = from.GetDamageMaster(this);
 
@@ -6478,9 +6495,6 @@ public partial class Mobile : IHued, IComparable<Mobile>, ISpawnable, IObjectPro
                     m_DexLock = (StatLockType)reader.ReadByte();
                     m_IntLock = (StatLockType)reader.ReadByte();
 
-                    _statMods = new List<StatMod>();
-                    _skillMods = new List<SkillMod>();
-
                     if (version < 32)
                     {
                         if (reader.ReadBool())
@@ -7813,13 +7827,10 @@ public partial class Mobile : IHued, IComparable<Mobile>, ISpawnable, IObjectPro
         m_FollowersMax = 5;
         Skills = new Skills(this);
         Items = new List<Item>();
-        _statMods = new List<StatMod>();
-        _skillMods = new List<SkillMod>();
         Map = Map.Internal;
         AutoPageNotify = true;
         Aggressors = new List<AggressorInfo>();
         Aggressed = new List<AggressorInfo>();
-        DamageEntries = new List<DamageEntry>();
 
         NextSkillTime = Core.TickCount;
     }

Projects/Server/Network/MovementThrottle.cs

@@ -50,9 +50,6 @@ public static class MovementThrottle
     private const int ClientMaxUnackedMovements = 5;
     private const int MaxQueueWithUnmodifiedClient = ClientMaxUnackedMovements - 1;  // 4
 
-    // Debug logging - enable for testing speed hack detection
-    private static bool _debugLogging = false;
-
     // Track NetStates with queued movements for efficient processing
     private static readonly HashSet<NetState> _netStatesWithQueuedMovements = new(256);
 
@@ -83,15 +80,9 @@ public static class MovementThrottle
 
     public static void Configure()
     {
-        _maxCredit = ServerConfiguration.GetOrUpdateSetting(
+        _maxCredit = ServerConfiguration.GetOrUpdateSetting("movementThrottle.maxCredit", _maxCredit);
-            "movementThrottle.maxCredit",
+        _maxRttBonus = ServerConfiguration.GetOrUpdateSetting("movementThrottle.maxRttBonus", _maxRttBonus);
-            _maxCredit
+        _hardQueueLimit = ServerConfiguration.GetOrUpdateSetting("movementThrottle.hardQueueLimit", _hardQueueLimit);
-        );
-
-        _hardQueueLimit = ServerConfiguration.GetOrUpdateSetting(
-            "movementThrottle.hardQueueLimit",
-            _hardQueueLimit
-        );
 
         _movementHistorySize = ServerConfiguration.GetOrUpdateSetting(
             "movementThrottle.movementHistorySize",
@@ -103,6 +94,13 @@ public static class MovementThrottle
             _minSamplesForRate
         );
 
+        _maxChainGap = ServerConfiguration.GetOrUpdateSetting("movementThrottle.maxChainGap", _maxChainGap);
+
+        _speedHackNotificationCooldown = ServerConfiguration.GetOrUpdateSetting(
+            "movementThrottle.speedHackNotificationCooldown",
+            _speedHackNotificationCooldown
+        );
+
         _suspiciousRateThreshold = (float)ServerConfiguration.GetOrUpdateSetting(
             "movementThrottle.suspiciousRateThreshold",
             _suspiciousRateThreshold
@@ -112,11 +110,6 @@ public static class MovementThrottle
             "movementThrottle.definiteRateThreshold",
             _definiteRateThreshold
         );
-
-        _debugLogging = ServerConfiguration.GetOrUpdateSetting(
-            "movementThrottle.debugLogging",
-            _debugLogging
-        );
     }
 
     /// <summary>
@@ -191,15 +184,16 @@ public static class MovementThrottle
             // Credit can go negative up to -dynamicCredit (debt limit)
             if (ns._movementCredit - earlyAmount >= -dynamicCredit)
             {
-                var prevCredit = ns._movementCredit;
                 // Use credit to cover early arrival
                 ns._movementCredit -= earlyAmount;
 
-                if (_debugLogging && ns._movementLogging)
+                if (ns._movementLogging)
                 {
+                    var prevCredit = ns._movementCredit + earlyAmount;
+
                     logger.Debug(
                         "[Credit] {Name}: delta={Delta}ms early={Early}ms credit={PrevCredit}->{Credit}/{MaxCredit} action=execute",
-                        mobile.RawName, delta, earlyAmount, prevCredit, ns._movementCredit, dynamicCredit
+                        mobile, delta, earlyAmount, prevCredit, ns._movementCredit, dynamicCredit
                     );
                 }
 
@@ -208,11 +202,11 @@ public static class MovementThrottle
                 return;
             }
 
-            if (_debugLogging && ns._movementLogging)
+            if (ns._movementLogging)
             {
                 logger.Debug(
                     "[Credit] {Name}: delta={Delta}ms early={Early}ms credit={Credit}/{MaxCredit} EXHAUSTED -> queue",
-                    mobile.RawName, delta, earlyAmount, ns._movementCredit, dynamicCredit
+                    mobile, delta, earlyAmount, ns._movementCredit, dynamicCredit
                 );
             }
 
@@ -227,11 +221,11 @@ public static class MovementThrottle
             var prevCredit = ns._movementCredit;
             ns._movementCredit = Math.Min(ns._movementCredit + delta, dynamicCredit);
 
-            if (_debugLogging && ns._movementLogging && ns._movementCredit != prevCredit)
+            if (ns._movementLogging && ns._movementCredit != prevCredit)
             {
                 logger.Debug(
                     "[Credit] {Name}: delta=+{Delta}ms credit={PrevCredit}->{Credit}/{MaxCredit} action=execute",
-                    mobile.RawName, delta, prevCredit, ns._movementCredit, dynamicCredit
+                    mobile, delta, prevCredit, ns._movementCredit, dynamicCredit
                 );
             }
         }
@@ -247,12 +241,9 @@ public static class MovementThrottle
     {
         if (!mobile.Move(dir))
         {
-            if (_debugLogging && ns._movementLogging)
+            if (ns._movementLogging)
             {
-                logger.Debug(
+                logger.Debug("[Execute] {Name}: Move FAILED dir={Dir} seq={Seq} -> reject+reset", mobile, dir, seq);
-                    "[Execute] {Name}: Move FAILED dir={Dir} seq={Seq} -> reject+reset",
-                    mobile.RawName, dir, seq
-                );
             }
 
             // Movement failed (blocked, paralyzed, frozen, etc.)
@@ -260,11 +251,11 @@ public static class MovementThrottle
             return;
         }
 
-        if (_debugLogging && ns._movementLogging)
+        if (ns._movementLogging)
         {
             logger.Debug(
                 "[Execute] {Name}: Move OK dir={Dir} seq={Seq} nextMove={NextMove}ms",
-                mobile.RawName, dir, seq, ns._nextMovementTime - Core.TickCount
+                mobile, dir, seq, ns._nextMovementTime - Core.TickCount
             );
         }
 
@@ -304,11 +295,11 @@ public static class MovementThrottle
         ns._hasQueuedMovements = true;
         _netStatesWithQueuedMovements.Add(ns);
 
-        if (_debugLogging && ns._movementLogging)
+        if (ns._movementLogging)
         {
             logger.Debug(
                 "[Queue] {Name}: enqueued dir={Dir} seq={Seq} (depth={Depth})",
-                ns.Mobile?.RawName, dir, seq, ns._movementQueue.Count
+                ns.Mobile, dir, seq, ns._movementQueue.Count
             );
         }
     }
@@ -320,7 +311,6 @@ public static class MovementThrottle
     {
         ns.SendMovementRej(seq, mobile);
         ns.ResetMovementState();
-        _netStatesWithQueuedMovements.Remove(ns);
     }
 
     /// <summary>
@@ -333,20 +323,18 @@ public static class MovementThrottle
             return;
         }
 
-        // Process each NetState with queued movements
+        foreach (var ns in _netStatesWithQueuedMovements)
-        // Use a snapshot to avoid modification during iteration
-        var toProcess = new List<NetState>(_netStatesWithQueuedMovements);
-
-        for (var i = 0; i < toProcess.Count; i++)
         {
-            var ns = toProcess[i];
+            if (ns.Running)
-            if (!ns.Running)
             {
-                _netStatesWithQueuedMovements.Remove(ns);
+                ProcessMovementQueue(ns);
-                continue;
+                if (ns._hasQueuedMovements)
+                {
+                    continue;
+                }
             }
 
-            ProcessMovementQueue(ns);
+            _netStatesWithQueuedMovements.Remove(ns);
         }
     }
 
@@ -356,6 +344,7 @@ public static class MovementThrottle
     public static void ProcessMovementQueue(NetState ns)
     {
         var mobile = ns.Mobile;
+
         if (mobile?.Deleted != false)
         {
             ClearQueue(ns);
@@ -374,7 +363,7 @@ public static class MovementThrottle
         while (ns._movementQueue?.Count > 0)
         {
             // Check if it's time to execute
-            if (now < ns._nextMovementTime)
+            if (now - ns._nextMovementTime < 0)
             {
                 // Not yet - leave remaining items in queue for next Slice
                 break;
@@ -394,11 +383,11 @@ public static class MovementThrottle
             // Execute the move
             if (!mobile.Move(movement.Direction))
             {
-                if (_debugLogging && ns._movementLogging)
+                if (ns._movementLogging)
                 {
                     logger.Debug(
                         "[Queue] {Name}: dequeued FAILED dir={Dir} (remaining={Remaining})",
-                        mobile.RawName, movement.Direction, remaining
+                        mobile, movement.Direction, remaining
                     );
                 }
 
@@ -407,12 +396,12 @@ public static class MovementThrottle
                 return;
             }
 
-            if (_debugLogging && ns._movementLogging)
+            if (ns._movementLogging)
             {
                 var waited = now - ns._nextMovementTime;
                 logger.Debug(
                     "[Queue] {Name}: dequeued OK dir={Dir} (remaining={Remaining}, waited={Waited}ms)",
-                    mobile.RawName, movement.Direction, remaining, waited >= 0 ? waited : 0
+                    mobile, movement.Direction, remaining, waited >= 0 ? waited : 0
                 );
             }
 
@@ -430,10 +419,6 @@ public static class MovementThrottle
 
         // Update tracking
         ns._hasQueuedMovements = ns._movementQueue?.Count > 0;
-        if (!ns._hasQueuedMovements)
-        {
-            _netStatesWithQueuedMovements.Remove(ns);
-        }
     }
 
     /// <summary>
@@ -469,7 +454,6 @@ public static class MovementThrottle
     {
         ns._movementQueue?.Clear();
         ns._hasQueuedMovements = false;
-        _netStatesWithQueuedMovements.Remove(ns);
     }
 
     // Maximum expected packets per second (mounted running = 100ms = 10/sec, plus tolerance)
@@ -484,7 +468,7 @@ public static class MovementThrottle
         logger.Information(
             "Movement queue overflow: {Character} ({Account}) | " +
             "Queue reached hard limit: {Limit} | IP: {IP}",
-            mobile?.RawName ?? "Unknown",
+            mobile,
             ns.Account?.Username ?? "Unknown",
             _hardQueueLimit,
             ns.Address
@@ -516,7 +500,7 @@ public static class MovementThrottle
     private static void RecordMovement(NetState ns, long now, int cost, Direction dir, Mobile mobile)
     {
         // Calculate interval since last movement
-        var interval = ns._lastMovementRecordTime > 0
+        var interval = ns._hasMovementRecord
             ? (int)(now - ns._lastMovementRecordTime)
             : -1; // -1 indicates first movement (no previous time)
 
@@ -525,6 +509,7 @@ public static class MovementThrottle
         if (interval <= 0 || interval > _maxChainGap)
         {
             ns._lastMovementRecordTime = now;
+            ns._hasMovementRecord = true;
 
             // Use RTT to distinguish "stopped moving" vs "lagged"
             // - Stable low-latency connection with gap >> RTT → player stopped, reset history
@@ -544,19 +529,19 @@ public static class MovementThrottle
                 // A large gap followed by a burst of packets = likely lag recovery, not speed hack
                 ns._lastGapDuration = interval;
 
-                if (_debugLogging && mobile?.RawName != null)
+                if (ns._movementLogging)
                 {
                     var action = shouldReset ? "history reset" : "history preserved (possible lag)";
                     logger.Debug(
                         "[Movement] {Name}: SKIP recording (gap {Gap}ms > {MaxGap}ms, " +
                         "RTT={RTT}ms stable={Stable} → {Action})",
-                        mobile.RawName, interval, _maxChainGap, avgRtt, ns.HasStableConnection, action
+                        mobile, interval, _maxChainGap, avgRtt, ns.HasStableConnection, action
                     );
                 }
             }
-            else if (_debugLogging && mobile?.RawName != null)
+            else if (ns._movementLogging)
             {
-                logger.Debug("[Movement] {Name}: SKIP recording (first in chain)", mobile.RawName);
+                logger.Debug("[Movement] {Name}: SKIP recording (first in chain)", mobile);
             }
 
             return;
@@ -572,12 +557,9 @@ public static class MovementThrottle
         // the next real move's interval artificially short, inflating rate.
         if (cost == 0)
         {
-            if (_debugLogging && mobile?.RawName != null)
+            if (ns._movementLogging)
             {
-                logger.Debug(
+                logger.Debug("[Movement] {Name}: SKIP direction-only change (preserves interval measurement)", mobile);
-                    "[Movement] {Name}: SKIP direction-only change (preserves interval measurement)",
-                    mobile.RawName
-                );
             }
             return;
         }
@@ -613,15 +595,16 @@ public static class MovementThrottle
         }
 
         ns._lastMovementRecordTime = now;
+        ns._hasMovementRecord = true;
 
         // Debug logging
-        if (_debugLogging && mobile?.RawName != null)
+        if (ns._movementLogging)
         {
             var historyCount = ns._movementHistoryFull ? _movementHistorySize : ns._movementHistoryIndex;
             logger.Debug(
                 "[Movement] {Name}: interval={Interval}ms target={Target}ms queue={Queue} " +
                 "flags={Flags} history={History}/{MaxHistory} RTT={RTT}ms",
-                mobile.RawName, interval, cost, record.QueueDepth,
+                mobile, interval, cost, record.QueueDepth,
                 flags, historyCount, _movementHistorySize, ns.AverageRtt
             );
         }
@@ -814,7 +797,7 @@ public static class MovementThrottle
         var averageRtt = ns.AverageRtt;
 
         // Detailed rate breakdown for debugging
-        if (_debugLogging)
+        if (ns._movementLogging)
         {
             logger.Debug("[MovementAnalysis] Rate={Rate:F3}, Samples={Samples}, RTT={RTT}ms",
                 rate, sampleCount, averageRtt);
@@ -977,19 +960,19 @@ public static class MovementThrottle
         var verdict = AnalyzeMovement(ns, out var rate, out var sampleCount, out var confidence);
 
         // Debug logging
-        if (_debugLogging && ns.Mobile?.RawName != null)
+        if (ns._movementLogging)
         {
             var (burstSize, _) = DetectRecentBurst(ns);
-            var probeStatus = ns._rttProbeTime > 0 ? "pending" : "idle";
+            var probeStatus = ns._rttProbePending ? "pending" : "idle";
             var queueDepth = ns._movementQueue?.Count ?? 0;
             logger.Debug(
                 "[RateCheck] {Name}: rate={Rate:F3} samples={Samples} verdict={Verdict} " +
                 "confidence={Confidence:P0} queue={Queue} burst={Burst} sustained={Sustained}s",
-                ns.Mobile.RawName, rate, sampleCount, verdict, confidence, queueDepth, burstSize, ns._consecutiveHighRateSeconds
+                ns.Mobile, rate, sampleCount, verdict, confidence, queueDepth, burstSize, ns._consecutiveHighRateSeconds
             );
             logger.Debug(
                 "    RTT: avg={Avg}ms last={Last}ms var={Var} samples={RttSamples} stable={Stable} probe={Probe}",
-                ns.AverageRtt, ns._lastRtt, ns._rttVariance, ns._rttSampleCount, ns.HasStableConnection, probeStatus
+                ns.AverageRtt, ns.LastRtt, ns._rttVariance, ns._rttSampleCount, ns.HasStableConnection, probeStatus
             );
         }
 
@@ -1025,11 +1008,11 @@ public static class MovementThrottle
 
         if (shouldNotify)
         {
-            if (_debugLogging)
+            if (ns._movementLogging)
             {
                 logger.Debug(
                     "[ALERT] {Urgency} - {Name}: rate={Rate:F3} verdict={Verdict} confidence={Confidence:P0}",
-                    urgency, ns.Mobile?.RawName, rate, verdict, confidence
+                    urgency, ns.Mobile, rate, verdict, confidence
                 );
             }
             NotifyStaff(ns, rate, sampleCount, confidence, verdict, urgency);
@@ -1054,11 +1037,12 @@ public static class MovementThrottle
         var now = Core.TickCount;
 
         // Rate-limit notifications per player
-        if (now - ns._lastSpeedHackNotification < _speedHackNotificationCooldown)
+        if (ns._speedHackNotified && now - ns._lastSpeedHackNotification < _speedHackNotificationCooldown)
         {
             return;
         }
 
+        ns._speedHackNotified = true;
         ns._lastSpeedHackNotification = now;
 
         var mobile = ns.Mobile;
@@ -1070,7 +1054,7 @@ public static class MovementThrottle
             "PacketRate: {PacketRate}/s (peak: {PeakRate}/s) | RTT: {Rtt}ms (stable: {Stable}) | " +
             "Sustained: {Sustained}s | Queue: {Queue} | Location: {Location} Map: {Map} | IP: {IP}",
             urgency,
-            mobile?.RawName ?? "Unknown",
+            mobile,
             ns.Account?.Username ?? "Unknown",
             rate,
             sampleCount,
@@ -1138,7 +1122,7 @@ public static class MovementThrottle
             Verdict = verdict,
             Confidence = confidence,
             AverageRtt = ns.AverageRtt,
-            LastRtt = ns._lastRtt,
+            LastRtt = ns.LastRtt,
             RttVariance = ns._rttVariance,
             StableConnection = ns.HasStableConnection,
             RttSampleCount = ns._rttSampleCount,

Projects/Server/Network/NetState/NetState.Movement.cs

@@ -15,7 +15,6 @@
 
 using System;
 using System.Collections.Generic;
-using System.Diagnostics;
 using System.Runtime.InteropServices;
 using Server.Logging;
 
@@ -70,23 +69,24 @@ public partial class NetState
     internal Queue<QueuedMovement> _movementQueue;          // Lazy initialized
     internal long _movementCredit;                          // Credit buffer for timing jitter
     internal long _nextMovementTime = Core.TickCount;       // When next movement is allowed
-    internal int _sustainedQueueDepth;                      // Tracks sustained high queue depth
+    internal long _lastQueueDepthCheck = Core.TickCount;    // Throttle depth check frequency
-    internal long _lastQueueDepthCheck;                     // Throttle depth check frequency
     internal bool _hasQueuedMovements;                      // Fast check for Slice()
 
     // Movement history for rate-based speed hack detection (lazy initialized)
     internal MovementRecord[] _movementHistory;             // Circular buffer
     internal int _movementHistoryIndex;                     // Next write position (also serves as count until full)
     internal bool _movementHistoryFull;                     // True once buffer has wrapped
-    internal long _lastMovementRecordTime;                  // For calculating intervals
+    internal long _lastMovementRecordTime;                  // For calculating intervals (valid only when _hasMovementRecord)
+    internal bool _hasMovementRecord;                       // False until the first movement in a chain is seen
 
     // Detection state
     internal int _consecutiveHighRateSeconds;               // Sustained detection counter
-    internal long _lastSpeedHackNotification;               // Rate-limit notifications
+    internal long _lastSpeedHackNotification;               // Rate-limit notifications (valid only when _speedHackNotified)
+    internal bool _speedHackNotified;                       // False until the first notification is sent
     internal int _lastGapDuration;                          // Duration of last gap > maxChainGap (for burst forgiveness)
 
     // Movement packet rate tracking (for speed hack detection)
-    internal long _movementWindowStart;                     // Start of current 1-second window
+    internal long _movementWindowStart = Core.TickCount;    // Start of current 1-second window
     internal int _movementsInWindow;                        // Count in current window
     internal int _peakMovementRate;                         // Highest rate seen (packets/sec)
 
@@ -100,10 +100,9 @@ public partial class NetState
         _nextMovementTime = Core.TickCount;
         _movementCredit = 0;
         _hasQueuedMovements = false;
-        _sustainedQueueDepth = 0;
 
         // Reset movement history - next movement starts a new chain
-        _lastMovementRecordTime = 0;
+        _hasMovementRecord = false;
         _movementHistoryIndex = 0;
         _movementHistoryFull = false;
 
@@ -113,7 +112,7 @@ public partial class NetState
         _rttProbeInterval = RttProbeIntervalNormal;
 
         // Reset packet rate window
-        _movementWindowStart = 0;
+        _movementWindowStart = Core.TickCount;
         _movementsInWindow = 0;
     }
 
@@ -165,17 +164,19 @@ public partial class NetState
     private const long MaxStableLatency = 200;            // Max RTT (ms) for "stable" connection
 
     // RTT state
-    internal long _rttProbeTime;                            // When we sent the probe (0 = not waiting)
+    internal bool _rttProbePending;                         // True while waiting for a probe response
-    internal long _lastRtt;                                 // Most recent RTT measurement
+    internal long _rttProbeTime;                            // When we sent the probe (valid only when _rttProbePending)
     internal long[] _rttHistory;                            // Rolling history (lazy init)
     internal int _rttHistoryIndex;                          // Current position in history
     internal int _rttSampleCount;                           // Number of samples collected (saturates at RttHistorySize)
     internal long _rttVariance;                             // Calculated variance for stability
-    internal long _nextRttProbe;                            // When to send next probe
+    internal long _nextRttProbe = Core.TickCount;           // When to send next probe
     internal int _rttProbeInterval = RttProbeIntervalNormal; // Current probe interval
 
-    // High-resolution timestamp for RTT measurement (Stopwatch ticks, not game loop ticks)
+    /// <summary>
-    private long _rttProbeTimestampHiRes;
+    /// Gets the most recent RTT measurement, or 0 if none has been recorded.
+    /// </summary>
+    public long LastRtt => _rttSampleCount > 0 ? _rttHistory[(_rttHistoryIndex - 1) & (RttHistorySize - 1)] : 0;
 
     /// <summary>
     /// Sets the RTT probe interval based on suspicion level.
@@ -206,23 +207,22 @@ public partial class NetState
         var now = Core.TickCount;
 
         // Don't send if we're still waiting for a response
-        if (_rttProbeTime > 0)
+        if (_rttProbePending)
         {
             // Timeout after 10 seconds - connection is probably dead or very laggy
             if (now - _rttProbeTime > 10000)
             {
-                _rttProbeTime = 0;
+                _rttProbePending = false;
-                _rttProbeTimestampHiRes = 0;
             }
             return;
         }
 
         // First probe: send immediately when player starts moving
         // Subsequent probes: send when interval has passed
-        if (_nextRttProbe == 0 || now >= _nextRttProbe)
+        if (now - _nextRttProbe >= 0)
         {
+            _rttProbePending = true;
             _rttProbeTime = now;
-            _rttProbeTimestampHiRes = Stopwatch.GetTimestamp();
             _nextRttProbe = now + _rttProbeInterval + Utility.Random(RttProbeJitter);
 
             if (_movementLogging)
@@ -242,10 +242,9 @@ public partial class NetState
     /// </summary>
     public void RecordRttMeasurement()
     {
-        var nowHiRes = Stopwatch.GetTimestamp();
         var now = Core.TickCount;
 
-        if (_rttProbeTime <= 0)
+        if (!_rttProbePending)
         {
             // Not expecting a response (client-initiated version send) - ignore silently
             return;
@@ -253,19 +252,15 @@ public partial class NetState
 
         var rtt = now - _rttProbeTime;
 
-        // High-resolution RTT in microseconds
-        var rttHiResUs = (nowHiRes - _rttProbeTimestampHiRes) * 1_000_000 / Stopwatch.Frequency;
-
         if (_movementLogging)
         {
             movementLogger.Debug(
-                "[RTT-Response] {Account}: {Rtt}ms (HiRes: {RttHiRes:F2}ms)",
+                "[RTT-Response] {Account}: {Rtt}ms",
-                Account?.Username ?? _toString, rtt, rttHiResUs / 1000.0
+                Account?.Username ?? _toString, rtt
             );
         }
 
-        _rttProbeTime = 0;
+        _rttProbePending = false;
-        _rttProbeTimestampHiRes = 0;
 
         // Sanity check - RTT should be positive and reasonable
         if (rtt is <= 0 or > 10000)
@@ -285,7 +280,6 @@ public partial class NetState
 
         // Update history
         _rttHistory[_rttHistoryIndex++ & (RttHistorySize - 1)] = rtt;
-        _lastRtt = rtt;
 
         // Track sample count (saturates at buffer size)
         if (_rttSampleCount < RttHistorySize)

Projects/Server/Network/NetState/NetState.cs

@@ -44,7 +44,7 @@ public partial class NetState : IComparable<NetState>, IValueLinkListNode<NetSta
 
     private static readonly Queue<NetState> _connectingQueue = new(2048);
     private static readonly HashSet<NetState> _instances = new(2048);
-    public static IReadOnlySet<NetState> Instances => _instances;
+    public static HashSet<NetState> Instances => _instances;
 
     private readonly string _toString;
     private ClientVersion _version;
@@ -109,9 +109,6 @@ public partial class NetState : IComparable<NetState>, IValueLinkListNode<NetSta
         Address = address;
 
         Seeded = false;
-        HuePickers = [];
-        Menus = [];
-        Trades = [];
         NextActivityCheck = Core.TickCount + 30000;
         ConnectedOn = Core.Now;
         _toString = address?.ToString() ?? "(error)";
@@ -166,7 +163,7 @@ public partial class NetState : IComparable<NetState>, IValueLinkListNode<NetSta
 
     public bool BlockAllPackets { get; set; }
 
-    public List<SecureTrade> Trades { get; }
+    public List<SecureTrade> Trades { get; private set; }
 
     public bool Seeded { get; set; }
 
@@ -260,8 +257,18 @@ public partial class NetState : IComparable<NetState>, IValueLinkListNode<NetSta
 
     public void ValidateAllTrades()
     {
+        if (Trades == null)
+        {
+            return;
+        }
+
         for (var i = Trades.Count - 1; i >= 0; --i)
         {
+            if (Trades == null)
+            {
+                break;
+            }
+
             if (i >= Trades.Count)
             {
                 continue;
@@ -280,8 +287,18 @@ public partial class NetState : IComparable<NetState>, IValueLinkListNode<NetSta
 
     public void CancelAllTrades()
     {
+        if (Trades == null)
+        {
+            return;
+        }
+
         for (var i = Trades.Count - 1; i >= 0; --i)
         {
+            if (Trades != null)
+            {
+                break;
+            }
+
             if (i < Trades.Count)
             {
                 Trades[i].Cancel();
@@ -291,11 +308,21 @@ public partial class NetState : IComparable<NetState>, IValueLinkListNode<NetSta
 
     public void RemoveTrade(SecureTrade trade)
     {
-        Trades.Remove(trade);
+        Trades?.Remove(trade);
+
+        if (Trades?.Count == 0)
+        {
+            Trades = null;
+        }
     }
 
     public SecureTrade FindTrade(Mobile m)
     {
+        if (Trades == null)
+        {
+            return null;
+        }
+
         for (var i = 0; i < Trades.Count; ++i)
         {
             var trade = Trades[i];
@@ -311,6 +338,11 @@ public partial class NetState : IComparable<NetState>, IValueLinkListNode<NetSta
 
     public SecureTradeContainer FindTradeContainer(Mobile m)
     {
+        if (Trades == null)
+        {
+            return null;
+        }
+
         for (var i = 0; i < Trades.Count; ++i)
         {
             var trade = Trades[i];
@@ -336,7 +368,11 @@ public partial class NetState : IComparable<NetState>, IValueLinkListNode<NetSta
     {
         var newTrade = new SecureTrade(Mobile, state.Mobile);
 
+        Trades ??= [];
+
         Trades.Add(newTrade);
+
+        state.Trades ??= [];
         state.Trades.Add(newTrade);
 
         return newTrade.From.Container;
@@ -1176,8 +1212,16 @@ public partial class NetState : IComparable<NetState>, IValueLinkListNode<NetSta
 
         var a = Account;
 
-        Menus.Clear();
+        Menus?.Clear();
-        HuePickers.Clear();
+        Menus = null;
+
+        HuePickers?.Clear();
+        HuePickers = null;
+
+        // Just in case, but should already be nulled when Mobile.NetState is set to null and CancelAllTrades is called.
+        Trades?.Clear();
+        Trades = null;
+
         Account = null;
         ServerInfo = null;
         CityInfo = null;

Projects/UOContent.Tests/Fixtures/TestServerInitializer.cs

@@ -103,6 +103,7 @@ internal static class TestServerInitializer
             // Registers the Accounts entity persistence; without it no test can construct an Account.
             Server.Accounting.Accounts.Configure();
             RaceDefinitions.Configure();
+            Server.Movement.Movement.Configure();
             MovementImpl.Configure();
             PathFollower.Configure();
             World.Load();

Projects/UOContent.Tests/Tests/Mobiles/AI/AcquisitionTests.cs

@@ -0,0 +1,211 @@
+using System;
+using System.Collections.Generic;
+using Server;
+using Server.Mobiles;
+using Xunit;
+
+namespace UOContent.Tests.Mobiles.AI;
+
+// Pins the reacquire gate and the AcquireOnApproachDelay gradient: every scan re-arms the
+// full ReacquireDelay; enemy movement clamps the deadline to the approach delay (Zero =
+// prodded scan); an illegal deadline self-heals.
+[Collection("Sequential Pathfinding Tests")]
+public class AcquisitionTests : IDisposable
+{
+    private readonly List<Mobile> _created = new();
+
+    public void Dispose()
+    {
+        foreach (var m in _created)
+        {
+            m?.Delete();
+        }
+
+        _created.Clear();
+    }
+
+    private sealed class WildStub : BaseCreature
+    {
+        public WildStub() : base(AIType.AI_Melee, FightMode.Closest, 16, 1) => Body = 0xC9;
+
+        public override void GetSpeeds(out double activeSpeed, out double passiveSpeed)
+        {
+            activeSpeed = 0.3;
+            passiveSpeed = 0.6;
+        }
+    }
+
+    private sealed class TargetStub : Mobile
+    {
+        public TargetStub() => Body = 0x190;
+    }
+
+    private WildStub Spawn(Map map, Point3D loc)
+    {
+        var bc = new WildStub();
+        bc.MoveToWorld(loc, map);
+        bc.AIObject.AITimer?.Stop();
+        _created.Add(bc);
+        return bc;
+    }
+
+    [Fact]
+    public void EmptyScan_HonorsReacquireDelay()
+    {
+        var map = Map.Maps[1];
+        Assert.NotNull(map);
+        map.GetAverageZ(1500, 1600, out _, out var z, out _);
+
+        var bc = Spawn(map, new Point3D(1500, 1600, (sbyte)z));
+        bc.NextReacquireTime = Core.TickCount;
+
+        Assert.False(bc.AIObject.AcquireFocusMob(bc.RangePerception, FightMode.Closest, false, false, true));
+        Assert.InRange(bc.NextReacquireTime - Core.TickCount, 5000, 10000);
+    }
+
+    [Fact]
+    public void WedgedGate_SelfHeals()
+    {
+        var map = Map.Maps[1];
+        Assert.NotNull(map);
+        map.GetAverageZ(1500, 1600, out _, out var z, out _);
+
+        var bc = Spawn(map, new Point3D(1500, 1600, (sbyte)z));
+
+        var target = new TargetStub();
+        target.DefaultMobileInit();
+        target.MoveToWorld(new Point3D(1497, 1600, (sbyte)z), map);
+        _created.Add(target);
+
+        // Illegal deadline (beyond ReacquireDelay): must read as open, not block forever.
+        bc.NextReacquireTime = Core.TickCount + 60000;
+
+        Assert.True(bc.AIObject.AcquireFocusMob(bc.RangePerception, FightMode.Closest, false, false, true));
+        Assert.Equal(target, bc.FocusMob);
+    }
+
+    [Theory]
+    [InlineData(false, 5, true)]  // an enemy moving inside approach range (10) clamps the deadline
+    [InlineData(true, 5, false)]  // a same-team wild creature is not an enemy — ignored
+    [InlineData(false, 12, false)] // inside RangePerception but outside approach range — poll only
+    [InlineData(false, 20, false)] // outside approach range (10) is ignored
+    public void MovementClampsScanDeadlineOnlyForEnemiesInRange(bool wildMover, int distance, bool notices)
+    {
+        var map = Map.Maps[1];
+        Assert.NotNull(map);
+        map.GetAverageZ(1500, 1600, out _, out var z, out _);
+
+        var bc = Spawn(map, new Point3D(1500, 1600, (sbyte)z));
+        bc.NextReacquireTime = Core.TickCount + 8000;
+
+        Mobile mover;
+        if (wildMover)
+        {
+            mover = Spawn(map, new Point3D(1500 - distance, 1600, (sbyte)z));
+        }
+        else
+        {
+            mover = new TargetStub { Player = true };
+            mover.DefaultMobileInit();
+            mover.MoveToWorld(new Point3D(1500 - distance, 1600, (sbyte)z), map);
+            _created.Add(mover);
+        }
+
+        bc.OnMovement(mover, new Point3D(1400, 1600, (sbyte)z));
+
+        var remaining = bc.NextReacquireTime - Core.TickCount;
+
+        if (notices)
+        {
+            // Clamped to the approach delay (2s), never opened outright.
+            Assert.InRange(remaining, 1, (long)bc.AcquireOnApproachDelay.TotalMilliseconds);
+        }
+        else
+        {
+            Assert.True(remaining > 5000);
+        }
+    }
+
+    private sealed class InstantStub : BaseCreature
+    {
+        public InstantStub() : base(AIType.AI_Melee, FightMode.Closest, 16, 1) => Body = 0xC9;
+
+        public override TimeSpan AcquireOnApproachDelay => TimeSpan.Zero;
+
+        public override void GetSpeeds(out double activeSpeed, out double passiveSpeed)
+        {
+            activeSpeed = 0.3;
+            passiveSpeed = 0.6;
+        }
+    }
+
+    [Fact]
+    public void ZeroApproachDelay_OpensGateImmediately()
+    {
+        var map = Map.Maps[1];
+        Assert.NotNull(map);
+        map.GetAverageZ(1500, 1600, out _, out var z, out _);
+
+        var bc = new InstantStub();
+        bc.MoveToWorld(new Point3D(1500, 1600, (sbyte)z), map);
+        bc.AIObject.AITimer?.Stop();
+        _created.Add(bc);
+        bc.NextReacquireTime = Core.TickCount + 8000;
+
+        var mover = new TargetStub { Player = true };
+        mover.DefaultMobileInit();
+        mover.MoveToWorld(new Point3D(1495, 1600, (sbyte)z), map);
+        _created.Add(mover);
+
+        bc.OnMovement(mover, new Point3D(1400, 1600, (sbyte)z));
+
+        // Zero = the gate opens and the AI is prodded to think now; no direct engage.
+        Assert.True(Core.TickCount - bc.NextReacquireTime >= 0);
+        Assert.Null(bc.Combatant);
+        Assert.True(bc.AIObject.AITimer.Running);
+    }
+
+    [Fact]
+    public void RepeatedMovement_DoesNotShortenBelowApproachDelay()
+    {
+        var map = Map.Maps[1];
+        Assert.NotNull(map);
+        map.GetAverageZ(1500, 1600, out _, out var z, out _);
+
+        var bc = Spawn(map, new Point3D(1500, 1600, (sbyte)z));
+        bc.NextReacquireTime = Core.TickCount + 8000;
+
+        var mover = new TargetStub { Player = true };
+        mover.DefaultMobileInit();
+        mover.MoveToWorld(new Point3D(1495, 1600, (sbyte)z), map);
+        _created.Add(mover);
+
+        bc.OnMovement(mover, new Point3D(1400, 1600, (sbyte)z));
+        var afterFirst = bc.NextReacquireTime;
+
+        bc.OnMovement(mover, new Point3D(1496, 1600, (sbyte)z));
+
+        Assert.Equal(afterFirst, bc.NextReacquireTime);
+    }
+
+    [Fact]
+    public void SuccessfulAcquire_HoldsFullDelay()
+    {
+        var map = Map.Maps[1];
+        Assert.NotNull(map);
+        map.GetAverageZ(1500, 1600, out _, out var z, out _);
+
+        var bc = Spawn(map, new Point3D(1500, 1600, (sbyte)z));
+
+        var target = new TargetStub();
+        target.DefaultMobileInit();
+        target.MoveToWorld(new Point3D(1497, 1600, (sbyte)z), map);
+        _created.Add(target);
+
+        bc.NextReacquireTime = Core.TickCount;
+
+        Assert.True(bc.AIObject.AcquireFocusMob(bc.RangePerception, FightMode.Closest, false, false, true));
+        Assert.Equal(target, bc.FocusMob);
+        Assert.True(bc.NextReacquireTime - Core.TickCount > 5000);
+    }
+}

Projects/UOContent.Tests/Tests/Mobiles/AI/ApproachTargetTests.cs

@@ -40,7 +40,7 @@ public class ApproachTargetTests
         for (var i = 0; i < maxTicks; i++)
         {
             ai.NextMove = 0;
-            ai.WalkMobileRange(target, 1, false, 1, 2);
+            ai.WalkMobileRange(target, 1, 1, 2);
             if (bc.InRange(target, arriveDist))
             {
                 return true;
@@ -123,7 +123,7 @@ public class ApproachTargetTests
         for (var i = 0; i < 200; i++)
         {
             ai.NextMove = 0;
-            ai.MoveTo(target, false, 1);
+            ai.MoveTo(target, 1);
             if (bc.InRange(target, 1))
             {
                 arrived = true;
@@ -154,7 +154,7 @@ public class ApproachTargetTests
         for (var i = 0; i < 60; i++)
         {
             ai.NextMove = 0;
-            ai.MoveTo(target, true, 1);
+            ai.MoveTo(target, 1);
 
             // Target walks west every other tick for its first several steps, then stops,
             // so a same-speed chaser eventually closes the gap.
@@ -214,7 +214,7 @@ public class ApproachTargetTests
         for (var i = 0; i < 120; i++)
         {
             ai.NextMove = 0;
-            ai.MoveTo(target, false, 1);
+            ai.MoveTo(target, 1);
         }
 
         // After giving up, the creature must idle (not oscillate) while the goal is still.
@@ -223,7 +223,7 @@ public class ApproachTargetTests
         for (var i = 0; i < 20; i++)
         {
             ai.NextMove = 0;
-            ai.MoveTo(target, false, 1);
+            ai.MoveTo(target, 1);
             if (bc.Location != idleStart)
             {
                 stayedIdle = false;

Projects/UOContent.Tests/Tests/Mobiles/AI/GuardFollowTests.cs

@@ -0,0 +1,96 @@
+using System.Collections.Generic;
+using Server;
+using Server.Mobiles;
+using Xunit;
+
+namespace UOContent.Tests.Mobiles.AI;
+
+// Guard-following may pathfind, so this shares the pathfinding collection.
+[Collection("Sequential Pathfinding Tests")]
+public class GuardFollowTests
+{
+    [Fact]
+    public void GuardFollow_StepsTowardMaster_AndRegistersMoveIntent()
+    {
+        var map = Map.Maps[1];
+        Assert.NotNull(map);
+        map.GetAverageZ(1500, 1600, out _, out var z, out _);
+
+        var master = new PlayerMobile(World.NewMobile);
+        master.DefaultMobileInit();
+        master.MoveToWorld(new Point3D(1494, 1600, (sbyte)z), map);
+
+        var pet = new PetTestStub();
+        pet.MoveToWorld(new Point3D(1500, 1600, (sbyte)z), map); // 6 tiles east, open terrain
+        pet.SetControlMaster(master);
+
+        var ai = pet.AIObject;
+        ai.AITimer?.Stop(); // drive manually
+        pet.ControlOrder = OrderType.Guard;
+        ai.AITimer?.Stop(); // the order change may restart the timer
+
+        var start = pet.Location;
+        ai.NextMove = 0;
+        ai.Obey();
+
+        var moved = pet.Location != start;
+        var hasIntent = ai.TryGetMoveWake(out _);
+        var currentSpeed = pet.CurrentSpeed;
+        var currentMoveSpeed = pet.CurrentMoveSpeed;
+
+        pet.Delete();
+        master.Delete();
+
+        Assert.True(moved, "a guarding pet beyond guard range must step toward its master");
+        // Without a move intent, guard-following only steps on the think grid.
+        Assert.True(hasIntent, "guard-following must register a move intent");
+
+        // AOS return sprint on both clocks; the per-step speed flip must not undo it.
+        Assert.Equal(0.1, currentSpeed);
+        Assert.Equal(0.1, currentMoveSpeed);
+    }
+
+    [Fact]
+    public void GuardReturn_PreAOS_RunsActive()
+    {
+        var previous = Core.Expansion;
+
+        try
+        {
+            Core.Expansion = Expansion.UOR;
+
+            var map = Map.Maps[1];
+            Assert.NotNull(map);
+            map.GetAverageZ(1500, 1600, out _, out var z, out _);
+
+            var master = new PlayerMobile(World.NewMobile);
+            master.DefaultMobileInit();
+            master.MoveToWorld(new Point3D(1494, 1600, (sbyte)z), map);
+
+            var pet = new PetTestStub();
+            pet.MoveToWorld(new Point3D(1500, 1600, (sbyte)z), map);
+            pet.SetControlMaster(master);
+
+            var ai = pet.AIObject;
+            ai.AITimer?.Stop();
+            pet.ControlOrder = OrderType.Guard;
+            ai.AITimer?.Stop();
+            pet.SetCurrentSpeedToPassive(); // a stale passive state must not persist
+
+            ai.NextMove = 0;
+            ai.Obey();
+
+            var currentSpeed = pet.CurrentSpeed;
+
+            pet.Delete();
+            master.Delete();
+
+            // No sprint pre-AOS: the return runs active.
+            Assert.Equal(0.2, currentSpeed);
+        }
+        finally
+        {
+            Core.Expansion = previous;
+        }
+    }
+}

Projects/UOContent.Tests/Tests/Mobiles/AI/GuardOrderTests.cs

@@ -0,0 +1,137 @@
+using System;
+using System.Collections.Generic;
+using Server;
+using Server.Mobiles;
+using Xunit;
+
+namespace UOContent.Tests.Mobiles.AI;
+
+// A guarding pet fights without leaving the Guard order, retargets toward the master's
+// closest aggressor, and stands down when nothing threatens. Scene: the open
+// (1495..1500, 1600) Trammel segment; targets are adjacent so no pathfinding runs.
+[Collection("Sequential UOContent Tests")]
+public class GuardOrderTests : IDisposable
+{
+    private readonly List<Mobile> _created = new();
+
+    private sealed class AggressorStub : Mobile
+    {
+        public AggressorStub() => Body = 0xC9;
+    }
+
+    public void Dispose()
+    {
+        foreach (var m in _created)
+        {
+            m?.Delete();
+        }
+
+        _created.Clear();
+    }
+
+    private (PlayerMobile master, PetTestStub pet) SpawnGuardingPet(out Map map, out int z)
+    {
+        map = Map.Maps[1];
+        Assert.NotNull(map);
+        map.GetAverageZ(1500, 1600, out _, out z, out _);
+
+        var master = new PlayerMobile(World.NewMobile);
+        master.DefaultMobileInit();
+        master.MoveToWorld(new Point3D(1500, 1600, (sbyte)z), map);
+        _created.Add(master);
+
+        var pet = new PetTestStub();
+        pet.MoveToWorld(new Point3D(1499, 1600, (sbyte)z), map);
+        pet.SetControlMaster(master);
+        _created.Add(pet);
+
+        pet.AIObject.AITimer?.Stop(); // drive manually
+        pet.ControlOrder = OrderType.Guard;
+        pet.AIObject.AITimer?.Stop(); // the order change restarts the timer
+
+        return (master, pet);
+    }
+
+    private AggressorStub SpawnAggressor(PetTestStub pet, Point3D loc, Mobile attacking)
+    {
+        var aggr = new AggressorStub();
+        aggr.MoveToWorld(loc, pet.Map);
+        _created.Add(aggr);
+
+        // Setup guard: the scene must stay LOS-clear and the combatant must not be vetoed.
+        Assert.True(pet.InLOS(aggr), $"no LOS from pet to aggressor at {loc}");
+
+        if (attacking != null)
+        {
+            aggr.Combatant = attacking;
+            Assert.Same(attacking, aggr.Combatant);
+        }
+
+        return aggr;
+    }
+
+    [Fact]
+    public void GuardEngage_KeepsGuardOrder()
+    {
+        var (master, pet) = SpawnGuardingPet(out _, out var z);
+        var aggr = SpawnAggressor(pet, new Point3D(1498, 1600, (sbyte)z), master);
+
+        pet.AIObject.Obey();
+
+        Assert.Same(aggr, pet.Combatant);
+        Assert.Equal(OrderType.Guard, pet.ControlOrder);
+        Assert.Equal(OrderType.Guard, pet.AIObject.PersistentOrder);
+    }
+
+    [Fact]
+    public void Guard_RetargetsToAggressorClosestToMaster()
+    {
+        var (master, pet) = SpawnGuardingPet(out _, out var z);
+        var far = SpawnAggressor(pet, new Point3D(1495, 1600, (sbyte)z), master);
+        var near = SpawnAggressor(pet, new Point3D(1498, 1600, (sbyte)z), master);
+
+        pet.Combatant = far; // already fighting the far aggressor
+
+        pet.AIObject.Obey();
+
+        Assert.Same(near, pet.Combatant); // defends the master, not the current fight
+        Assert.Equal(OrderType.Guard, pet.ControlOrder);
+    }
+
+    [Fact]
+    public void ExplicitAttack_ResumesGuard_WithoutChainingIntoAttack()
+    {
+        var (master, pet) = SpawnGuardingPet(out _, out var z);
+
+        // Explicit kill order on a target that then becomes invalid.
+        var victim = SpawnAggressor(pet, new Point3D(1498, 1600, (sbyte)z), null);
+        pet.ControlTarget = victim;
+        pet.ControlOrder = OrderType.Attack;
+        victim.Hidden = true;
+
+        // A second aggressor is still after the master; FightMode.Closest would chain it.
+        var aggr2 = SpawnAggressor(pet, new Point3D(1497, 1600, (sbyte)z), master);
+
+        pet.AIObject.Obey(); // attack completes -> resume the persistent Guard
+
+        Assert.Equal(OrderType.Guard, pet.ControlOrder);
+
+        pet.AIObject.Obey(); // the guard scan engages the remaining aggressor in-order
+
+        Assert.Same(aggr2, pet.Combatant);
+        Assert.Equal(OrderType.Guard, pet.ControlOrder);
+    }
+
+    [Fact]
+    public void PeacefulGuard_StandsDown()
+    {
+        var (_, pet) = SpawnGuardingPet(out _, out _);
+        Assert.True(pet.Warmode); // the guard order opens in war stance
+
+        pet.AIObject.Obey(); // nothing to guard against
+
+        Assert.False(pet.Warmode);
+        Assert.Null(pet.Combatant);
+        Assert.Null(pet.FocusMob);
+    }
+}

Projects/UOContent.Tests/Tests/Mobiles/AI/PetPacingTests.cs

@@ -0,0 +1,222 @@
+using System;
+using System.Collections.Generic;
+using Server;
+using Server.Mobiles;
+using Xunit;
+
+namespace UOContent.Tests.Mobiles.AI;
+
+// Pet order handlers own the speed clocks; combat chases and herding keep their own pacing.
+[Collection("Sequential UOContent Tests")]
+public class PetPacingTests : IDisposable
+{
+    private readonly List<Mobile> _created = new();
+
+    private (PlayerMobile master, PetTestStub pet) Spawn(Point3D masterLoc, Point3D petLoc)
+    {
+        var pair = PetTestSetup.SpawnControlledPet(masterLoc, petLoc);
+        _created.Add(pair.master);
+        _created.Add(pair.pet);
+        return pair;
+    }
+
+    public void Dispose()
+    {
+        foreach (var m in _created)
+        {
+            m?.Delete();
+        }
+
+        _created.Clear();
+    }
+
+    // Movement orders run active, resting orders run passive; the move clock follows.
+    [Fact]
+    public void OrderIssue_SetsThinkClock()
+    {
+        var (master, pet) = Spawn(new Point3D(1000, 1000, 0), new Point3D(1001, 1000, 0));
+        pet.SetMoveSpeed(0.3, 0.9);
+        pet.SetCurrentSpeedToPassive();
+
+        pet.ControlOrder = OrderType.Come;
+        Assert.Equal(0.2, pet.CurrentSpeed);
+        Assert.Equal(0.3, pet.CurrentMoveSpeed); // verbatim active -> activeMove
+
+        pet.ControlOrder = OrderType.Stay;
+        Assert.Equal(0.4, pet.CurrentSpeed);
+        Assert.Equal(0.9, pet.CurrentMoveSpeed);
+
+        pet.ControlTarget = master;
+        pet.ControlOrder = OrderType.Follow;
+        Assert.Equal(0.2, pet.CurrentSpeed);
+
+        pet.ControlOrder = OrderType.Guard;
+        Assert.Equal(0.2, pet.CurrentSpeed);
+    }
+
+    // AOS: following the master sprints at a bespoke 0.1 on both clocks.
+    [Fact]
+    public void FollowMaster_ObeySprints()
+    {
+        var (master, pet) = Spawn(new Point3D(1000, 1000, 0), new Point3D(1001, 1000, 0));
+        pet.SetMoveSpeed(0.3, 0.9);
+        pet.AIObject.AITimer?.Stop();
+
+        pet.ControlTarget = master;
+        pet.ControlOrder = OrderType.Follow; // fixture era is EJ
+        pet.AIObject.Obey();
+
+        Assert.Equal(0.1, pet.CurrentSpeed);
+        Assert.Equal(0.1, pet.CurrentMoveSpeed);
+    }
+
+    // At the master's side a guarding pet stays active: no stale-warmode passive, no sprint.
+    [Fact]
+    public void GuardAtMastersSide_IsActive()
+    {
+        var (_, pet) = Spawn(new Point3D(1000, 1000, 0), new Point3D(1001, 1000, 0));
+        pet.SetMoveSpeed(0.3, 0.9);
+        pet.AIObject.AITimer?.Stop();
+        pet.SetCurrentSpeedToPassive();
+
+        pet.ControlOrder = OrderType.Guard;
+        pet.AIObject.Obey(); // nothing to guard against, master adjacent
+
+        Assert.Equal(0.2, pet.CurrentSpeed);
+        Assert.Equal(0.3, pet.CurrentMoveSpeed);
+    }
+
+    // A pet chasing a combatant keeps the move table.
+    [Fact]
+    public void CombatChasingPet_KeepsMoveTable()
+    {
+        var (_, pet) = Spawn(new Point3D(1000, 1000, 0), new Point3D(1001, 1000, 0));
+        var target = new PetTestStub();
+        target.MoveToWorld(new Point3D(1003, 1000, 0), Map.Felucca);
+        _created.Add(target);
+
+        pet.SetMoveSpeed(0.3, 0.9);
+        pet.ControlOrder = OrderType.Guard;
+        pet.Combatant = target;
+        pet.SetCurrentSpeedToActive();
+
+        Assert.Equal(0.3, pet.CurrentMoveSpeed);
+    }
+
+    // Herding overrides order pacing.
+    [Fact]
+    public void HerdedObeyingPet_KeepsHerdingPace()
+    {
+        var (_, pet) = Spawn(new Point3D(1000, 1000, 0), new Point3D(1001, 1000, 0));
+        pet.SetMoveSpeed(0.45, 0.9);
+        pet.SetCurrentSpeedToPassive();
+
+        pet.TargetLocation = new Point2D(1010, 1010);
+
+        Assert.Equal(0.3, pet.CurrentMoveSpeed); // fixed herding pace
+    }
+
+    private sealed class ThinkProbe : PetTestStub
+    {
+        public int Thinks;
+
+        public override void OnThink()
+        {
+            Thinks++;
+            base.OnThink();
+        }
+    }
+
+    private (PlayerMobile master, ThinkProbe pet) SpawnProbe()
+    {
+        var master = new PlayerMobile(World.NewMobile);
+        master.DefaultMobileInit();
+        master.MoveToWorld(new Point3D(1000, 1000, 0), Map.Felucca);
+        _created.Add(master);
+
+        var pet = new ThinkProbe();
+        pet.MoveToWorld(new Point3D(1001, 1000, 0), Map.Felucca);
+        pet.SetControlMaster(master);
+        _created.Add(pet);
+
+        return (master, pet);
+    }
+
+    // Advances time in 8ms lockstep so the wheel and Core.TickCount stay in sync.
+    private static void RunFor(long ms)
+    {
+        var deadline = Core._tickCount + ms;
+
+        while (Core._tickCount < deadline)
+        {
+            Core._tickCount += 8;
+            Timer.Slice(Core._tickCount);
+        }
+    }
+
+    private static bool RunUntil(Func<bool> condition, long maxMs)
+    {
+        var deadline = Core._tickCount + maxMs;
+
+        while (Core._tickCount < deadline)
+        {
+            if (condition())
+            {
+                return true;
+            }
+
+            Core._tickCount += 8;
+            Timer.Slice(Core._tickCount);
+        }
+
+        return condition();
+    }
+
+    // Runs past the spawn stagger; returns right after a think with the next 0.4s away.
+    private ThinkProbe SettledProbe(out PlayerMobile master)
+    {
+        Core._tickCount = 0;
+        Timer.Init(0);
+
+        var (m, pet) = SpawnProbe();
+        master = m;
+        pet.ForceIdle = true; // no wandering; pure cadence
+        pet.ControlOrder = OrderType.Stay;
+
+        var settled = RunUntil(() => pet.Thinks >= 2, 8000);
+        Assert.True(settled, "the AI must reach a steady think cadence");
+
+        return pet;
+    }
+
+    [Fact]
+    public void OrderChange_WakesStaleThinkTimer()
+    {
+        var pet = SettledProbe(out var master);
+        var thinksBefore = pet.Thinks;
+
+        RunFor(200); // mid-wait, next think ~200ms out
+        Assert.Equal(thinksBefore, pet.Thinks);
+
+        pet.ControlTarget = master;
+        pet.ControlOrder = OrderType.Follow;
+
+        RunFor(80);
+        Assert.True(pet.Thinks > thinksBefore, "a fresh order must wake the AI promptly");
+    }
+
+    [Fact]
+    public void SpeedUp_ReschedulesPendingWake()
+    {
+        var pet = SettledProbe(out _);
+        var thinksBefore = pet.Thinks;
+
+        RunFor(200); // mid-wait, next think ~200ms out
+        Assert.Equal(thinksBefore, pet.Thinks);
+
+        pet.CurrentSpeed = 0.1;
+
+        RunFor(120);
+        Assert.True(pet.Thinks > thinksBefore, "a speed-up must reschedule the pending wake");
+    }
+}

Projects/UOContent.Tests/Tests/Mobiles/AI/RunFlagTests.cs

@@ -0,0 +1,162 @@
+using System.Collections.Generic;
+using Server;
+using Server.Mobiles;
+using Xunit;
+
+namespace UOContent.Tests.Mobiles.AI;
+
+// The Running bit is derived from the step pace: a step shorter than the client's walk
+// interpolation (400ms on foot, 200ms mounted/flying) is flagged as a run.
+[Collection("Sequential Pathfinding Tests")]
+public class RunFlagTests : System.IDisposable
+{
+    private readonly List<Mobile> _created = new();
+
+    private PetTestStub Spawn(double activeMove)
+    {
+        var pet = new PetTestStub();
+        pet.MoveToWorld(new Point3D(1000, 1000, 0), Map.Felucca);
+        pet.AIObject.AITimer?.Stop();
+        pet.SetMoveSpeed(activeMove, activeMove * 3);
+        pet.SetCurrentSpeedToActive();
+        pet.LastMoveTime = Core.TickCount; // mid-cadence unless a test says otherwise
+        _created.Add(pet);
+        return pet;
+    }
+
+    public void Dispose()
+    {
+        foreach (var m in _created)
+        {
+            m?.Delete();
+        }
+
+        _created.Clear();
+    }
+
+    [Theory]
+    [InlineData(0.3, true)]
+    [InlineData(0.125, true)]
+    [InlineData(0.4, false)]
+    [InlineData(0.45, false)]
+    [InlineData(1.05, false)]
+    public void FootCreature_RunsOnlyWhenFasterThanWalk(double activeMove, bool expected)
+    {
+        var pet = Spawn(activeMove);
+
+        Assert.Equal(activeMove, pet.CurrentMoveSpeed);
+        Assert.Equal(expected, pet.AIObject.ShouldRun());
+    }
+
+    [Theory]
+    [InlineData(0.3, false)]
+    [InlineData(0.15, true)]
+    public void FlyingCreature_UsesMountThresholds(double activeMove, bool expected)
+    {
+        var pet = Spawn(activeMove);
+        pet.Flying = true;
+
+        Assert.Equal(expected, pet.AIObject.ShouldRun());
+    }
+
+    [Fact]
+    public void BadlyHurt_SlowsBelowWalk_DropsToWalk()
+    {
+        var pet = Spawn(0.35);
+        Assert.True(pet.AIObject.ShouldRun());
+
+        // The hurt inflation is on the observed step pace, so the flag follows it.
+        pet.SetHits(100);
+        pet.Hits = 5;
+        pet.SetStam(100);
+        pet.Stam = 5;
+
+        Assert.False(pet.AIObject.ShouldRun());
+    }
+
+    [Theory]
+    [InlineData(0.3, true)]
+    [InlineData(0.45, false)]
+    public void DoMove_StampsRunningBit(double activeMove, bool expected)
+    {
+        var map = Map.Maps[1];
+        Assert.NotNull(map);
+        map.GetAverageZ(1500, 1600, out _, out var z, out _);
+
+        var pet = Spawn(activeMove);
+        pet.MoveToWorld(new Point3D(1500, 1600, (sbyte)z), map);
+
+        var ai = pet.AIObject;
+        ai.NextMove = 0;
+        var start = pet.Location;
+
+        Assert.True(ai.DoMove(Direction.West));
+        Assert.NotEqual(start, pet.Location);
+        Assert.Equal(expected, (pet.Direction & Direction.Running) != 0);
+    }
+
+    // An isolated step (after standing at least a walk interval) renders alone and darts
+    // if run-flagged, so it walks; continuing cadences and true sprinters keep the flag.
+    [Fact]
+    public void IsolatedStep_DropsToWalk()
+    {
+        var pet = Spawn(0.3);
+        pet.LastMoveTime = Core.TickCount - 1000;
+
+        Assert.False(pet.AIObject.ShouldRun());
+    }
+
+    [Fact]
+    public void IsolatedStep_SprinterStillRuns()
+    {
+        var pet = Spawn(0.125);
+        pet.LastMoveTime = Core.TickCount - 1000;
+
+        Assert.True(pet.AIObject.ShouldRun());
+    }
+
+    [Fact]
+    public void StallDoesNotBankCatchUpSteps()
+    {
+        var map = Map.Maps[1];
+        Assert.NotNull(map);
+        map.GetAverageZ(1500, 1600, out _, out var z, out _);
+
+        var pet = Spawn(0.3);
+        pet.MoveToWorld(new Point3D(1500, 1600, (sbyte)z), map);
+
+        var ai = pet.AIObject;
+        ai.NextMove = Core.TickCount - 1000;
+
+        Assert.True(ai.DoMove(Direction.West));
+
+        // A stall must restart the cadence at full pace: banked catch-up steps
+        // release as a burst the client renders as a sprint/teleport.
+        Assert.False(ai.CanMoveNow(out _));
+        Assert.True(ai.NextMove - Core.TickCount > 250);
+    }
+
+    [Fact]
+    public void LateStepDoesNotEarnAQuickerFollowUp()
+    {
+        var map = Map.Maps[1];
+        Assert.NotNull(map);
+        map.GetAverageZ(1500, 1600, out _, out var z, out _);
+
+        var pet = Spawn(0.3);
+        pet.MoveToWorld(new Point3D(1500, 1600, (sbyte)z), map);
+
+        pet.Warmode = true; // keep the active move clock through the step
+
+        var ai = pet.AIObject;
+        // The step lands 200ms past the budget — under one period, the reactive
+        // mirroring case (think grid vs budget deadline misalignment).
+        ai.NextMove = Core.TickCount - 200;
+
+        Assert.True(ai.DoMove(Direction.West));
+
+        // The debt must not be repaid: a sub-period catch-up step follows ~100ms
+        // behind and renders as a dart pair beside the player.
+        Assert.True(ai.NextMove - Core.TickCount > 250);
+    }
+}

Projects/UOContent.Tests/Tests/Mobiles/LootingRightsTests.cs

@@ -0,0 +1,146 @@
+using System.Collections.Generic;
+using Server.Mobiles;
+using Xunit;
+
+namespace Server.Tests;
+
+/// <summary>
+/// Pins the looting-rights rules that the inline damage entry list has to keep producing: the
+/// returned stores are sorted by damage descending, the first (least recent) damager takes the
+/// 1.25x bonus, the hitsMax band decides who clears the threshold, and a pet's damage is credited
+/// to its damage master rather than to the pet.
+/// </summary>
+[Collection("Sequential UOContent Tests")]
+public class LootingRightsTests
+{
+    private class TestMobile : Mobile
+    {
+    }
+
+    private class PetMobile : Mobile
+    {
+        public Mobile Master { get; set; }
+
+        public override Mobile GetDamageMaster(Mobile damagee) => Master;
+    }
+
+    // GetLootingRights only ever credits mobiles flagged as players.
+    private static TestMobile NewPlayer() => new() { Player = true };
+
+    private static DamageStore FindStore(List<DamageStore> rights, Mobile m)
+    {
+        for (var i = 0; i < rights.Count; i++)
+        {
+            if (rights[i].m_Mobile == m)
+            {
+                return rights[i];
+            }
+        }
+
+        return null;
+    }
+
+    [Fact]
+    public void TwoPlayerDamagers_SortDescending_AndTheFirstDamagerTakesTheBonus()
+    {
+        var victim = new TestMobile();
+        var first = NewPlayer();
+        var second = NewPlayer();
+
+        try
+        {
+            victim.RegisterDamage(100, first);
+            victim.RegisterDamage(40, second); // second is the most recent, first is the "first damager"
+
+            // hitsMax < 200 puts the bar at topDamage / 2.
+            var rights = BaseCreature.GetLootingRights(victim.DamageEntries, 100);
+
+            Assert.Equal(2, rights.Count);
+
+            // Sorted by damage descending.
+            Assert.True(rights[0].m_Damage >= rights[1].m_Damage);
+            Assert.Same(first, rights[0].m_Mobile);
+            Assert.Same(second, rights[1].m_Mobile);
+
+            // The first damager - the least recent entry - gets the 1.25x bonus; nobody else does.
+            Assert.Equal(125, rights[0].m_Damage);
+            Assert.Equal(40, rights[1].m_Damage);
+
+            // topDamage 125 / 2 = 62, so 40 is below the bar.
+            Assert.True(rights[0].m_HasRight);
+            Assert.False(rights[1].m_HasRight);
+        }
+        finally
+        {
+            victim.Delete();
+            first.Delete();
+            second.Delete();
+        }
+    }
+
+    [Fact]
+    public void HitsMaxBand_MovesTheRightsThreshold()
+    {
+        var victim = new TestMobile();
+        var first = NewPlayer();
+        var second = NewPlayer();
+
+        try
+        {
+            victim.RegisterDamage(100, first);
+            victim.RegisterDamage(40, second);
+
+            // hitsMax >= 200 drops the bar to topDamage / 4 = 31, which 40 clears.
+            var rights = BaseCreature.GetLootingRights(victim.DamageEntries, 200);
+
+            Assert.Equal(2, rights.Count);
+            Assert.True(rights[0].m_HasRight);
+            Assert.True(rights[1].m_HasRight);
+            Assert.Same(second, rights[1].m_Mobile);
+        }
+        finally
+        {
+            victim.Delete();
+            first.Delete();
+            second.Delete();
+        }
+    }
+
+    [Fact]
+    public void PetDamage_CreditsTheMaster_NotThePet()
+    {
+        var victim = new TestMobile();
+        var master = NewPlayer();
+        var pet = new PetMobile { Master = master };
+        var wild = new TestMobile(); // no damage master, and not a player
+
+        try
+        {
+            victim.RegisterDamage(50, pet);
+            victim.RegisterDamage(20, wild);
+
+            var rights = BaseCreature.GetLootingRights(victim.DamageEntries, 100);
+
+            // The master is credited through the entry's Responsible sub-entry, and is the only one.
+            Assert.Single(rights);
+
+            var masterStore = FindStore(rights, master);
+            Assert.NotNull(masterStore);
+            Assert.Equal(62, masterStore.m_Damage); // 50, then the first-damager 1.25x bonus
+            Assert.True(masterStore.m_HasRight);
+
+            // The pet's own damage was fully handed to the master, so it earns no store.
+            Assert.Null(FindStore(rights, pet));
+
+            // A non-player damager earns nothing even when its damage was never reassigned.
+            Assert.Null(FindStore(rights, wild));
+        }
+        finally
+        {
+            victim.Delete();
+            master.Delete();
+            pet.Delete();
+            wild.Delete();
+        }
+    }
+}

Projects/UOContent/Engines/CannedEvil/ChampionSpawn.cs

@@ -18,6 +18,7 @@ using System.Net;
 using System.Collections.Generic;
 using System.Runtime.InteropServices;
 using ModernUO.Serialization;
+using Server.Collections;
 using Server.Engines.Virtues;
 using Server.Gumps;
 using Server.Items;
@@ -1181,11 +1182,6 @@ public partial class ChampionSpawn : Item
 
         foreach (var de in m.DamageEntries)
         {
-            if (de.HasExpired)
-            {
-                continue;
-            }
-
             var damager = de.Damager;
             var master = damager.GetDamageMaster(m);
 

Projects/UOContent/Engines/Factions/Mobiles/Guards/GuardAI.cs

@@ -359,14 +359,14 @@ namespace Server.Factions
             {
               if (m_Mobile.InRange( m, 1 ))
                 RunFrom( m );
-              else if (!m_Mobile.InRange( m, m_Mobile.RangeFight > 2 ? m_Mobile.RangeFight : 2 ) && !MoveTo( m, true, 1 ))
+              else if (!m_Mobile.InRange( m, m_Mobile.RangeFight > 2 ? m_Mobile.RangeFight : 2 ) && !MoveTo(m, 1))
                 OnFailedMove();
             }
             else
             {*/
             if (!Mobile.InRange(m, Mobile.RangeFight))
             {
-                if (!MoveTo(m, true, 1))
+                if (!MoveTo(m, 1))
                 {
                     OnFailedMove();
                 }

Projects/UOContent/Engines/Harvest/Core/HarvestSystem.cs

@@ -219,7 +219,7 @@ namespace Server.Engines.Harvest
                             }
                             else
                             {
-                                item.Delete();
+                                bonusItem?.Delete();
                             }
                         }
 

Projects/UOContent/Engines/Pathing/PathFollower.cs

@@ -83,7 +83,7 @@ public class PathFollower
     public static bool Check(Point3D loc, Point3D goal, int range) =>
         Utility.InRange(loc, goal, range) && (range > 1 || (loc.Z - goal.Z).Abs() < 16);
 
-    public bool Follow(bool run, int range)
+    public bool Follow(int range)
     {
         var goal = GetGoalLocation();
         Direction d;
@@ -97,13 +97,13 @@ public class PathFollower
 
         if (!(Enabled && m_Path.Success))
         {
-            d = m_From.GetDirectionTo(goal, run);
+            d = m_From.GetDirectionTo(goal);
             m_From.SetDirection(d);
 
             return Move(d) is MoveResult.Success or MoveResult.SuccessAutoTurn && Check(m_From.Location, goal, range);
         }
 
-        d = m_From.GetDirectionTo(m_Next, run);
+        d = m_From.GetDirectionTo(m_Next);
         m_From.SetDirection(d);
         var res = Move(d);
 

Projects/UOContent/Mobiles/AI/AnimalAI.cs

@@ -38,7 +38,7 @@ public class AnimalAI : BaseAI
             return true;
         }
 
-        if (!WalkMobileRange(combatant, 1, false, Mobile.RangeFight, Mobile.RangeFight))
+        if (!WalkMobileRange(combatant, 1, Mobile.RangeFight, Mobile.RangeFight))
         {
             if (Mobile.GetDistanceToSqrt(combatant) > Mobile.RangePerception + 1)
             {

Projects/UOContent/Mobiles/AI/ArcherAI.cs

@@ -17,7 +17,7 @@ public class ArcherAI : BaseAI
 
         if (AcquireFocusMob(Mobile.RangePerception, Mobile.FightMode, false, false, true))
         {
-            this.DebugSayFormatted($"I have detected {Mobile.FocusMob.Name} and I will attack");
+            this.DebugSayFormatted($"I have detected {Mobile.FocusMob.Name}, attacking");
 
             Mobile.Combatant = Mobile.FocusMob;
             Action = ActionType.Combat;
@@ -43,7 +43,7 @@ public class ArcherAI : BaseAI
             return true;
         }
 
-        if (!WalkMobileRange(combatant, 1, false, Mobile.RangeFight, Mobile.Weapon.MaxRange))
+        if (!WalkMobileRange(combatant, 1, Mobile.RangeFight, Mobile.Weapon.MaxRange))
         {
             this.DebugSayFormatted($"I am still not in range of {combatant.Name}");
 

Projects/UOContent/Mobiles/AI/BaseAI/AIGroupMovement.cs

@@ -63,7 +63,7 @@ public abstract partial class BaseAI
         return crowding;
     }
 
-    public static bool MoveToWithGroup(BaseAI ai, Mobile target, bool run, int range)
+    public static bool MoveToWithGroup(BaseAI ai, Mobile target, int range)
     {
         if (Core.TickCount - _lastGroupUpdateTime > 1000)
         {
@@ -79,7 +79,7 @@ public abstract partial class BaseAI
             if (optimalPosition == Point3D.Zero)
             {
 
-                return ai.MoveToWithCollisionAvoidance(target, run, range);
+                return ai.MoveToWithCollisionAvoidance(target, range);
             }
 
             _reservedPositions[mobile] = optimalPosition;
@@ -99,7 +99,7 @@ public abstract partial class BaseAI
             }
 
             // A blocked or wall-slid step is not progress — route around the obstacle.
-            return ai.ApproachTarget(target, run, range);
+            return ai.ApproachTarget(target, range);
         }
         finally
         {

Projects/UOContent/Mobiles/AI/BaseAI/AIMovement.cs

@@ -18,6 +18,7 @@ using System.Runtime.CompilerServices;
 using Server.Collections;
 using Server.Items;
 using MoveImpl = Server.Movement.MovementImpl;
+using Moves = Server.Movement.Movement;
 
 namespace Server.Mobiles;
 
@@ -43,7 +44,6 @@ public abstract partial class BaseAI
     // live, the AITimer wakes at NextMove between think ticks to advance the step.
     private Mobile _moveIntentTarget;
     private IPoint3D _moveIntentPoint;
-    private bool _moveIntentRun;
     private int _moveIntentRange;
     private long _moveIntentExpire;
 
@@ -74,23 +74,42 @@ public abstract partial class BaseAI
         return Core.TickCount - NextMove >= 0;
     }
 
-    // Accumulative full-step budget: long-run pacing averages CurrentMoveSpeed exactly
+    // Seconds per step as the client observes it: the move clock plus the hurt inflation.
-    // regardless of timer-grid jitter; snap-to-now caps stall catch-up at one step.
+    private double EffectiveStepDelay()
-    private void ConsumeMoveBudget()
     {
         var stepDelay = Mobile.CurrentMoveSpeed;
 
-        if (!(Core.AOS && IsFollowingMaster()))
+        return Core.AOS && IsFollowingMaster() ? stepDelay : BadlyHurtMoveDelay(Mobile, stepDelay);
+    }
+
+    // The Running bit only selects the client's per-step interpolation (walk 400ms / run
+    // 200ms on foot, 200/100 mounted). A step shorter than the walk time must run or the
+    // client falls behind and snaps — but an isolated step (after standing at least a walk
+    // interval) renders alone and darts if run-flagged, so it goes out as a walk. A true
+    // sprinter always runs: a walk-rendered first step would flood the client's queue.
+    public bool ShouldRun()
+    {
+        var mounted = Mobile.Mounted || Mobile.Flying;
+        var walkDelay = mounted ? Moves.WalkMountDelay : Moves.WalkFootDelay;
+        var pace = EffectiveStepDelay() * 1000;
+
+        if (pace >= walkDelay)
         {
-            stepDelay = BadlyHurtMoveDelay(Mobile, stepDelay);
+            return false;
         }
 
-        NextMove += Math.Max(50, (long)(stepDelay * 1000));
+        var runDelay = mounted ? Moves.RunMountDelay : Moves.RunFootDelay;
 
-        if (Core.TickCount - NextMove > 0)
+        return pace < runDelay || Core.TickCount - Mobile.LastMoveTime < walkDelay;
-        {
+    }
-            NextMove = Core.TickCount;
+
-        }
+    // One step per period, paced from the step just taken — no debt accrual: repaying a
+    // late step with a quicker follow-up puts two steps ~100ms apart, which renders as a
+    // dart. In continuous pursuit the move-wake lands within wheel resolution of this
+    // deadline, so the only cost is single-digit-ms drift per step.
+    private void ConsumeMoveBudget()
+    {
+        NextMove = Core.TickCount + Math.Max(50, (long)(EffectiveStepDelay() * 1000));
     }
 
     public virtual bool CheckMove() => !(Mobile.Deleted || Mobile.DisallowAllMoves);
@@ -108,6 +127,8 @@ public abstract partial class BaseAI
             return MoveResult.BadState;
         }
 
+        d = (d & Direction.Mask) | (ShouldRun() ? Direction.Running : 0);
+
         if ((Mobile.Direction & Direction.Mask) != (d & Direction.Mask))
         {
             Mobile.Direction = d;
@@ -118,18 +139,17 @@ public abstract partial class BaseAI
 
         if (TryMove(d))
         {
-            // Writes the think clock only; hurt slowdown applies in ConsumeMoveBudget.
+            // Obeying pets are paced by their order handlers.
-            if (Core.AOS && IsFollowingMaster())
+            if (!IsObeyingMoveOrder())
             {
-                Mobile.CurrentSpeed = 0.1;
+                if (Mobile.Warmode || Mobile.Combatant != null)
-            }
+                {
-            else if (Mobile.Warmode || Mobile.Combatant != null)
+                    Mobile.SetCurrentSpeedToActive();
-            {
+                }
-                Mobile.SetCurrentSpeedToActive();
+                else
-            }
+                {
-            else
+                    Mobile.SetCurrentSpeedToPassive();
-            {
+                }
-                Mobile.SetCurrentSpeedToPassive();
             }
 
             ConsumeMoveBudget();
@@ -335,7 +355,7 @@ public abstract partial class BaseAI
     /// best-distance stall counter idles the creature if an in-range goal is genuinely
     /// unreachable, without ever abandoning a real chase or detour.
     /// </summary>
-    protected bool ApproachTarget(Mobile target, bool run, int range)
+    protected bool ApproachTarget(Mobile target, int range)
     {
         if (Mobile.Deleted || Mobile.DisallowAllMoves || target?.Deleted != false)
         {
@@ -362,7 +382,7 @@ public abstract partial class BaseAI
             ResetApproach(); // target moved — try again fresh
         }
 
-        RenewMoveIntent(target, null, run, range);
+        RenewMoveIntent(target, null, range);
 
         // FAST PATH: greedy step toward the target, counted as success ONLY when the move
         // fully succeeded (not an auto-turn sidestep) and actually got us closer. An
@@ -374,7 +394,7 @@ public abstract partial class BaseAI
         if (Path == null && Mobile.InLOS(target))
         {
             var distBefore = Mobile.GetDistanceToSqrt(target);
-            var res = DoMoveImpl(Mobile.GetDirectionTo(target, run), true);
+            var res = DoMoveImpl(Mobile.GetDirectionTo(target), true);
 
             if (res == MoveResult.BadState)
             {
@@ -403,7 +423,7 @@ public abstract partial class BaseAI
         var couldMove = CanMoveNow(out _) && !IsInBadState();
         var locBefore = Mobile.Location;
 
-        if (Path.Follow(run, range))
+        if (Path.Follow(range))
         {
             ResetApproach();
             return true;
@@ -422,7 +442,7 @@ public abstract partial class BaseAI
     /// Walks toward a fixed point (e.g. a target's last-known position), pathfinding around
     /// obstacles. Returns false on arrival or when genuinely unable to make progress.
     /// </summary>
-    public bool MoveToPoint(IPoint3D goal, bool run)
+    public bool MoveToPoint(IPoint3D goal)
     {
         if (Mobile.Deleted || Mobile.DisallowAllMoves || goal == null)
         {
@@ -435,12 +455,12 @@ public abstract partial class BaseAI
             Path = new PathFollower(Mobile, goal) { Mover = DoMoveImpl };
         }
 
-        RenewMoveIntent(null, goal, run, 1);
+        RenewMoveIntent(null, goal, 1);
 
         var couldMove = CanMoveNow(out _) && !IsInBadState();
         var locBefore = Mobile.Location;
 
-        if (Path.Follow(run, 1))
+        if (Path.Follow(1))
         {
             Path = null;
             ClearMoveIntent();
@@ -516,11 +536,10 @@ public abstract partial class BaseAI
         _approachGaveUp = false;
     }
 
-    private void RenewMoveIntent(Mobile target, IPoint3D point, bool run, int range)
+    private void RenewMoveIntent(Mobile target, IPoint3D point, int range)
     {
         _moveIntentTarget = target;
         _moveIntentPoint = point;
-        _moveIntentRun = run;
         _moveIntentRange = range;
 
         // A live pursuit renews every think tick; unrenewed intent dies on its own.
@@ -541,8 +560,7 @@ public abstract partial class BaseAI
     {
         nextMove = NextMove;
 
-        return (_moveIntentTarget != null || _moveIntentPoint != null) &&
+        return (_moveIntentTarget != null || _moveIntentPoint != null) && Core.TickCount - _moveIntentExpire < 0;
-               Core.TickCount - _moveIntentExpire < 0;
     }
 
     /// <summary>
@@ -558,26 +576,21 @@ public abstract partial class BaseAI
 
         if (_moveIntentTarget != null)
         {
-            ApproachTarget(_moveIntentTarget, _moveIntentRun, _moveIntentRange);
+            ApproachTarget(_moveIntentTarget, _moveIntentRange);
         }
         else
         {
-            MoveToPoint(_moveIntentPoint, _moveIntentRun);
+            MoveToPoint(_moveIntentPoint);
         }
     }
 
-    public virtual bool MoveTo(Mobile m, bool run, int range)
+    public virtual bool MoveTo(Mobile m, int range)
     {
         if (Mobile.Deleted || Mobile.DisallowAllMoves || m?.Deleted != false)
         {
             return false;
         }
 
-        var distance = (int)Mobile.GetDistanceToSqrt(m);
-        var distanceThreshold = Core.AOS && IsFollowingMaster() ? 1 : 5;
-
-        var shouldRun = run && distance > distanceThreshold;
-
         if (Mobile.InRange(m, range))
         {
             ResetApproach();
@@ -586,10 +599,10 @@ public abstract partial class BaseAI
 
         if (UseGroupMovement(m, range))
         {
-            return MoveToWithGroup(this, m, shouldRun, range);
+            return MoveToWithGroup(this, m, range);
         }
 
-        return ApproachTarget(m, shouldRun, range);
+        return ApproachTarget(m, range);
     }
 
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
@@ -599,12 +612,15 @@ public abstract partial class BaseAI
         Mobile.ControlTarget == Mobile.ControlMaster &&
         Mobile.Combatant == null;
 
-    private bool MoveToWithCollisionAvoidance(Mobile target, bool run, int range)
+    // A pet executing a movement order outside combat; its order handler owns its speed.
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public bool IsObeyingMoveOrder() =>
+        Mobile.Controlled &&
+        Mobile.Combatant == null &&
+        Mobile.ControlOrder is OrderType.Come or OrderType.Follow or OrderType.Guard;
+
+    private bool MoveToWithCollisionAvoidance(Mobile target, int range)
     {
-        var distance = (int)Mobile.GetDistanceToSqrt(target);
-
-        var shouldRun = run && distance > 5;
-
         var direction = Mobile.GetDirectionTo(target);
 
         // Wall-slide auto-turns must not count as progress, or a creature pinned on
@@ -635,10 +651,10 @@ public abstract partial class BaseAI
 
         // Tactical sidesteps exhausted — route around the obstacle via the centralized
         // approach primitive (persistent PathFollower, no oscillation).
-        return ApproachTarget(target, shouldRun, range);
+        return ApproachTarget(target, range);
     }
 
-    public virtual bool WalkMobileRange(Mobile m, int iSteps, bool run, int iWantDistMin, int iWantDistMax)
+    public virtual bool WalkMobileRange(Mobile m, int iSteps, int iWantDistMin, int iWantDistMax)
     {
         if (Mobile.Deleted || Mobile.DisallowAllMoves || m == null)
         {
@@ -649,14 +665,12 @@ public abstract partial class BaseAI
         {
             var iCurrDist = (int)Mobile.GetDistanceToSqrt(m);
 
-            var shouldRun = run && iCurrDist > 5;
-
             if (iCurrDist >= iWantDistMin && iCurrDist <= iWantDistMax)
             {
                 return true;
             }
 
-            if (!MoveTowardsOrAwayFrom(m, shouldRun, iCurrDist, iWantDistMax))
+            if (!MoveTowardsOrAwayFrom(m, iCurrDist, iWantDistMax))
             {
                 return false;
             }
@@ -667,18 +681,16 @@ public abstract partial class BaseAI
         return dist >= iWantDistMin && dist <= iWantDistMax;
     }
 
-    private bool MoveTowardsOrAwayFrom(Mobile m, bool run, int iCurrDist, int iWantDistMax)
+    private bool MoveTowardsOrAwayFrom(Mobile m, int iCurrDist, int iWantDistMax)
     {
-        var shouldRun = run && iCurrDist > 5;
-
         if (iCurrDist > iWantDistMax)
         {
             // Too far: approach via the centralized progress-based primitive.
-            return ApproachTarget(m, shouldRun, iWantDistMax);
+            return ApproachTarget(m, iWantDistMax);
         }
 
         // Too close: back away. Retreat keeps the simple greedy behavior (out of scope).
-        if (DoMove(m.GetDirectionTo(Mobile, shouldRun), true))
+        if (DoMove(m.GetDirectionTo(Mobile), true))
         {
             Path = null;
             return true;

Projects/UOContent/Mobiles/AI/BaseAI/AITimer.cs

@@ -26,11 +26,13 @@ public sealed class AITimer : Timer
 {
     private readonly BaseAI _owner;
     private long _nextThink;
+    private long _nextWake; // when the pending wheel entry fires
+    private bool _inTick;
     private int _detectHiddenMinDelay;
     private int _detectHiddenMaxDelay;
 
-    public AITimer(BaseAI owner) : base(TimeSpan.FromMilliseconds(Utility.Random(3000)),
+    // The initial delay is irrelevant: Activate is the only start path and sets its own.
-        TimeSpan.FromSeconds(owner.Mobile.CurrentSpeed))
+    public AITimer(BaseAI owner) : base(TimeSpan.Zero, TimeSpan.FromSeconds(owner.Mobile.CurrentSpeed))
     {
         _owner = owner;
         _owner._nextDetectHidden = Core.TickCount;
@@ -40,8 +42,34 @@ public sealed class AITimer : Timer
     public void Activate()
     {
         _nextThink = Core.TickCount;
-        Interval = TimeSpan.FromSeconds(_owner.Mobile.CurrentSpeed);
+
+        if (Running)
+        {
+            return;
+        }
+
+        // Short random spread: the creature responds within a think while a sector's
+        // worth of timers avoids a same-tick burst; the idle think jitter keeps the
+        // cohort apart from there.
+        Delay = TimeSpan.FromMilliseconds(Utility.Random(256));
         Start();
+        _nextWake = Core.TickCount + (long)Delay.TotalMilliseconds;
+    }
+
+    // Think now. A think grants no action: steps, swings, casts, and abilities keep their own gates.
+    public void Prod()
+    {
+        _nextThink = Core.TickCount;
+
+        if (Running)
+        {
+            Reschedule();
+            return;
+        }
+
+        Delay = TimeSpan.Zero;
+        Start();
+        _nextWake = Core.TickCount + (long)Delay.TotalMilliseconds;
     }
 
     // A speed-up must not wait out a stale, longer think deadline.
@@ -52,12 +80,53 @@ public sealed class AITimer : Timer
         if (candidate - _nextThink < 0)
         {
             _nextThink = candidate;
+            Reschedule();
+        }
+    }
+
+    // Moves the pending wake earlier. Interval is only read after the next fire,
+    // so this needs Stop, Delay = remaining, Start.
+    private void Reschedule()
+    {
+        if (_inTick || !Running)
+        {
+            return; // ScheduleNext handles it at tick end
         }
 
-        Interval = TimeSpan.FromSeconds(_owner.Mobile.CurrentSpeed);
+        var now = Core.TickCount;
+        var deadline = _nextThink;
+
+        if (_owner.TryGetMoveWake(out var nextMove) && nextMove - now > 0 && nextMove - deadline < 0)
+        {
+            deadline = nextMove;
+        }
+
+        if (deadline - _nextWake >= 0)
+        {
+            return; // pending wake is already early enough
+        }
+
+        Stop();
+        Delay = TimeSpan.FromMilliseconds(Math.Max(0, deadline - now));
+        Start();
+        _nextWake = now + (long)Delay.TotalMilliseconds;
     }
 
     protected override void OnTick()
+    {
+        _inTick = true;
+
+        try
+        {
+            OnTickCore();
+        }
+        finally
+        {
+            _inTick = false;
+        }
+    }
+
+    private void OnTickCore()
     {
         if (ShouldStop())
         {
@@ -83,7 +152,18 @@ public sealed class AITimer : Timer
             }
 
             // Cadence from the post-decision speed (decisions may flip active/passive).
-            _nextThink = Core.TickCount + (long)(_owner.Mobile.CurrentSpeed * 1000);
+            var period = (long)(_owner.Mobile.CurrentSpeed * 1000);
+            _nextThink = Core.TickCount + period;
+
+            // Idle cadence drifts: a zero-mean jitter random-walks think phases apart, so
+            // creatures spawned or woken together cannot stay in lock-step (a one-shot
+            // spread can collide and identical periods never separate). Engaged cadence
+            // stays exact — pursuit timing anchors to real step times.
+            if (_owner.Mobile.CurrentSpeed == _owner.Mobile.PassiveSpeed)
+            {
+                var jitter = (int)(period >> 3);
+                _nextThink += Utility.RandomMinMax(-jitter, jitter);
+            }
         }
         else
         {
@@ -111,6 +191,7 @@ public sealed class AITimer : Timer
 
         // The wheel rounds up to its 8ms resolution; a non-positive delay becomes one turn.
         Interval = TimeSpan.FromMilliseconds(delay);
+        _nextWake = now + (long)Interval.TotalMilliseconds;
     }
 
     private bool ShouldStop()

Projects/UOContent/Mobiles/AI/BaseAI/BaseAI.cs

@@ -64,7 +64,7 @@ public abstract partial class BaseAI
 
         if (!m.PlayerRangeSensitive || !World.Loading && m.Map != null && m.Map != Map.Internal && m.Map.GetSector(m.Location).Active)
         {
-            AITimer.Start();
+            AITimer.Activate();
         }
 
         if (Action != ActionType.Wander)
@@ -442,7 +442,7 @@ public abstract partial class BaseAI
         var master = Mobile.SummonMaster;
         if (master != null && master.Map == Mobile.Map && master.InRange(Mobile, Mobile.RangePerception))
         {
-            MoveTo(master, false, 1);
+            MoveTo(master, 1);
         }
     }
 
@@ -592,7 +592,7 @@ public abstract partial class BaseAI
         }
 
         _lkpGoal ??= _lkpLocation;
-        return MoveToPoint(_lkpGoal, false);
+        return MoveToPoint(_lkpGoal);
     }
 
     private void ClearLastKnown()
@@ -644,7 +644,7 @@ public abstract partial class BaseAI
                 _herdGoal = new Point3D(target.X, target.Y, Mobile.Map?.GetAverageZ(target.X, target.Y) ?? Mobile.Z);
             }
 
-            MoveToPoint(_herdGoal, false);
+            MoveToPoint(_herdGoal);
             return true;
         }
 
@@ -798,7 +798,7 @@ public abstract partial class BaseAI
     {
         if (AcquireFocusMob(Mobile.RangePerception * 2, FightMode.Closest, true, false, true))
         {
-            if (WalkMobileRange(Mobile.FocusMob, 1, false, Mobile.RangePerception, Mobile.RangePerception * 2))
+            if (WalkMobileRange(Mobile.FocusMob, 1, Mobile.RangePerception, Mobile.RangePerception * 2))
             {
                 DebugSay("I backed off to safety. Wandering...");
 
@@ -850,22 +850,24 @@ public abstract partial class BaseAI
             return false;
         }
 
-        if (Core.TickCount - Mobile.NextReacquireTime < 0)
+        var reacquireDelay = (long)Mobile.ReacquireDelay.TotalMilliseconds;
+        var gateRemaining = Mobile.NextReacquireTime - Core.TickCount;
+
+        if (gateRemaining > 0 && gateRemaining <= reacquireDelay)
         {
             Mobile.FocusMob = null;
             return false;
         }
 
-        Mobile.NextReacquireTime = Core.TickCount + (int)Mobile.ReacquireDelay.TotalMilliseconds;
+        DebugSay("Acquiring new target...", 0);
 
-        DebugSay("Acquiring new target...");
+        var acquired = AcquireNewFocusMob(Mobile.Map, iRange, acqType, bPlayerOnly, bFacFriend, bFacFoe);
 
-        if (Mobile.Map == null)
+        // Reaction time is the approach path (BaseCreature.ScheduleAcquireOnApproach),
-        {
+        // not this poll — every scan honors the full delay.
-            return Mobile.FocusMob != null;
+        Mobile.NextReacquireTime = Core.TickCount + reacquireDelay;
-        }
 
-        return AcquireNewFocusMob(Mobile.Map, iRange, acqType, bPlayerOnly, bFacFriend, bFacFoe);
+        return acquired;
     }
 
     private bool HandleBardProvoked()
@@ -941,8 +943,10 @@ public abstract partial class BaseAI
 
     private bool AcquireNewFocusMob(Map map, int iRange, FightMode acqType, bool bPlayerOnly, bool bFacFriend, bool bFacFoe)
     {
-        Mobile newFocusMob = null, enemySummonMob = null;
+        Mobile newFocusMob = null;
-        double val = double.MinValue, enemySummonVal = double.MinValue;
+        Mobile enemySummonMob = null;
+        var val = double.MinValue;
+        var enemySummonVal = double.MinValue;
 
         foreach (var m in map.GetMobilesInRange(Mobile.Location, iRange))
         {

Projects/UOContent/Mobiles/AI/BaseAI/PetOrderHandlers.cs

@@ -26,7 +26,7 @@ public abstract partial class BaseAI
             return;
         }
 
-        Activate();
+        AITimer.Prod();
 
         switch (Mobile.ControlOrder)
         {
@@ -36,6 +36,10 @@ public abstract partial class BaseAI
                     break;
                 }
             case OrderType.Come:
+                {
+                    Mobile.SetCurrentSpeedToActive();
+                    break;
+                }
             case OrderType.Drop:
             case OrderType.Friend:
             case OrderType.Unfriend:
@@ -135,6 +139,7 @@ public abstract partial class BaseAI
         Mobile.FocusMob = null;
         Mobile.Warmode = false;
         Mobile.Combatant = null;
+        Mobile.SetCurrentSpeedToPassive();
     }
 
     private void HandleTransferOrder()
@@ -148,6 +153,7 @@ public abstract partial class BaseAI
         Mobile.FocusMob = null;
         Mobile.Warmode = false;
         Mobile.Combatant = null;
+        Mobile.SetCurrentSpeedToPassive();
         Mobile.PlaySound(Mobile.GetIdleSound());
         _commandIssuer = null;
     }
@@ -162,9 +168,16 @@ public abstract partial class BaseAI
         _commandIssuer?.RevealingAction();
         Mobile.FocusMob = null;
         Mobile.Warmode = true;
-        Mobile.PlaySound(Mobile.GetAttackSound());
+        Mobile.SetCurrentSpeedToActive();
-        Mobile.ControlMaster?.SendLocalizedMessage(1049671, Mobile.Name);
+
-        // ~1_NAME~ is now guarding you.
+        // Resuming the persistent order must not replay the flourish.
+        if (!_resolvingOrder)
+        {
+            Mobile.PlaySound(Mobile.GetAttackSound());
+            Mobile.ControlMaster?.SendLocalizedMessage(1049671, Mobile.Name);
+            // ~1_NAME~ is now guarding you.
+        }
+
         _commandIssuer = null;
     }
 
@@ -191,6 +204,7 @@ public abstract partial class BaseAI
         }
 
         Mobile.Warmode = true;
+        Mobile.SetCurrentSpeedToActive();
         Mobile.PlaySound(Mobile.GetAttackSound());
         _commandIssuer = null;
     }
@@ -206,6 +220,7 @@ public abstract partial class BaseAI
         Mobile.FocusMob = null;
         Mobile.Warmode = false;
         Mobile.Combatant = null;
+        Mobile.SetCurrentSpeedToActive();
         Mobile.PlaySound(Mobile.GetIdleSound());
         _commandIssuer = null;
     }
@@ -221,6 +236,7 @@ public abstract partial class BaseAI
         Mobile.FocusMob = null;
         Mobile.Warmode = false;
         Mobile.Combatant = null;
+        Mobile.SetCurrentSpeedToPassive();
         Mobile.PlaySound(Mobile.GetIdleSound());
         _commandIssuer = null;
         // Home (the stay anchor) is owned by SetPersistentOrder, not this handler.

Projects/UOContent/Mobiles/AI/BaseAI/PetOrders.cs

@@ -84,7 +84,7 @@ public abstract partial class BaseAI
             return true;
         }
 
-        WalkMobileRange(Mobile.ControlMaster, 1, false, 1, 2);
+        WalkMobileRange(Mobile.ControlMaster, 1, 1, 2);
 
         if (Mobile.GetDistanceToSqrt(Mobile.ControlMaster) <= 2)
         {
@@ -128,9 +128,15 @@ public abstract partial class BaseAI
 
         this.DebugSayFormatted($"I am ordered to follow {Mobile.ControlTarget?.Name}.");
 
+        // AOS: sprint after the master (bespoke 0.1 paces both clocks).
+        if (Core.AOS && Mobile.ControlTarget == Mobile.ControlMaster && Mobile.Combatant == null)
+        {
+            Mobile.CurrentSpeed = 0.1;
+        }
+
         if (currentDistance > 1)
         {
-            WalkMobileRange(Mobile.ControlTarget, 1, currentDistance > 2, 1, 2);
+            WalkMobileRange(Mobile.ControlTarget, 1, 1, 2);
         }
     }
 
@@ -291,14 +297,13 @@ public abstract partial class BaseAI
             return true;
         }
 
-        FindCombatant();
+        var combatant = FindGuardTarget();
 
-        if (IsValidCombatant(Mobile.Combatant))
+        if (combatant != null)
         {
-            var combatant = Mobile.Combatant;
-
             this.DebugSayFormatted($"Attacking target: {combatant.Name}");
 
+            // Engage without leaving the Guard order so tags, recall handling, and retargeting persist.
             Mobile.Combatant = combatant;
             Mobile.FocusMob = combatant;
             Action = ActionType.Combat;
@@ -309,16 +314,30 @@ public abstract partial class BaseAI
         {
             this.DebugSayFormatted($"Guarding my master, {controlMaster.Name}.");
 
-            var guardLocation = controlMaster.Location;
+            // Stand down; a stale Warmode would skew the return pace.
+            Mobile.FocusMob = null;
+            Mobile.Warmode = false;
+            Mobile.Combatant = null;
 
-            var distance = (int)Mobile.GetDistanceToSqrt(guardLocation);
+            var distance = (int)Mobile.GetDistanceToSqrt(controlMaster);
 
             if (distance > 3)
             {
-                DoMove(Mobile.GetDirectionTo(guardLocation));
+                // AOS: sprint back (bespoke 0.1 paces both clocks); earlier eras run active.
+                if (Core.AOS)
+                {
+                    Mobile.CurrentSpeed = 0.1;
+                }
+                else
+                {
+                    Mobile.SetCurrentSpeedToActive();
+                }
+
+                WalkMobileRange(controlMaster, 1, 1, 3);
             }
             else
             {
+                Mobile.SetCurrentSpeedToActive(); // alert at the master's side
                 WalkRandom(3, 1, 1);
             }
         }
@@ -359,67 +378,83 @@ public abstract partial class BaseAI
         Mobile.ControlTarget = Mobile.ControlMaster;
         ResumePersistentOrder();
 
-        if (Mobile.FightMode is FightMode.Closest or FightMode.Aggressor)
+        // A resumed Guard engages through its own scan; other fallbacks chain an explicit Attack.
+        if (Mobile.ControlOrder == OrderType.Guard ||
+            Mobile.FightMode is not (FightMode.Closest or FightMode.Aggressor))
         {
-            FindCombatant();
+            return;
+        }
+
+        var next = FindGuardTarget();
+
+        if (next != null)
+        {
+            Mobile.ControlTarget = next;
+            Mobile.ControlOrder = OrderType.Attack;
+            Mobile.Combatant = next;
+
+            this.DebugSayFormatted($"{next.Name} is still hostile! Engaging...");
+
+            Think();
         }
     }
 
-    private void FindCombatant()
+    /// <summary>
+    /// Selects the aggressor closest to the master. The current combatant is kept
+    /// unless a strictly closer one exists. Never mutates order state.
+    /// </summary>
+    private Mobile FindGuardTarget()
     {
         var controlMaster = Mobile.ControlMaster;
+        var anchor = controlMaster ?? Mobile;
+
+        var current = Mobile.Combatant;
+        var best = current != controlMaster && IsValidCombatant(current) ? current : null;
+        var bestDist = best?.GetDistanceToSqrt(anchor) ?? double.MaxValue;
 
         foreach (var aggr in Mobile.GetMobilesInRange(Mobile.RangePerception))
         {
-            if (!Mobile.CanSee(aggr) || aggr.IsDeadBondedPet || !aggr.Alive)
+            if (aggr == best || aggr == Mobile || aggr == controlMaster ||
+                aggr.IsDeadBondedPet || !aggr.Alive ||
+                aggr.Combatant != Mobile && (controlMaster == null || aggr.Combatant != controlMaster))
             {
                 continue;
             }
 
-            var isAttackingPet = aggr.Combatant == Mobile;
+            var dist = aggr.GetDistanceToSqrt(anchor);
-            var isAttackingMaster = controlMaster != null && aggr.Combatant == controlMaster;
 
-            if (isAttackingPet || isAttackingMaster)
+            if (dist < bestDist && Mobile.CanSee(aggr) && Mobile.InLOS(aggr))
             {
-                if (Mobile.InLOS(aggr))
+                best = aggr;
-                {
+                bestDist = dist;
-                    Mobile.ControlTarget = aggr;
-                    Mobile.ControlOrder = OrderType.Attack;
-                    Mobile.Combatant = aggr;
-
-                    var target = isAttackingMaster ? "master" : "me";
-                    this.DebugSayFormatted($"{aggr.Name} is attacking my {target}! Engaging...");
-
-                    Think();
-                    return;
-                }
             }
         }
 
-        if (controlMaster?.Aggressors != null)
+        var aggressors = controlMaster?.Aggressors;
-        {
-            for (var i = 0; i < controlMaster.Aggressors.Count; i++)
-            {
-                var aggressor = controlMaster.Aggressors[i].Attacker;
 
-                if (aggressor?.Deleted != false || !aggressor.Alive || aggressor.IsDeadBondedPet)
+        if (aggressors != null)
+        {
+            for (var i = 0; i < aggressors.Count; i++)
+            {
+                var aggressor = aggressors[i].Attacker;
+
+                if (aggressor == best || aggressor?.Deleted != false || !aggressor.Alive ||
+                    aggressor.IsDeadBondedPet || !Mobile.InRange(aggressor, Mobile.RangePerception))
                 {
                     continue;
                 }
 
-                if (Mobile.InRange(aggressor, Mobile.RangePerception) && Mobile.CanSee(aggressor) && Mobile.InLOS(aggressor))
+                var dist = aggressor.GetDistanceToSqrt(anchor);
+
+                if (dist < bestDist && Mobile.CanSee(aggressor) && Mobile.InLOS(aggressor))
                 {
-                    Mobile.ControlTarget = aggressor;
+                    best = aggressor;
-                    Mobile.ControlOrder = OrderType.Attack;
+                    bestDist = dist;
-                    Mobile.Combatant = aggressor;
-
-                    this.DebugSayFormatted($"{aggressor.Name} recently attacked my master! Retaliating...");
-
-                    Think();
-                    return;
                 }
             }
         }
+
+        return best;
     }
 
     public virtual bool DoOrderRelease()

Projects/UOContent/Mobiles/AI/BerserkAI.cs

@@ -12,7 +12,7 @@ public class BerserkAI : BaseAI
 
         if (AcquireFocusMob(Mobile.RangePerception, FightMode.Closest, false, true, true))
         {
-            this.DebugSayFormatted($"I have detected {Mobile.FocusMob.Name} and I will attack");
+            this.DebugSayFormatted($"I have detected {Mobile.FocusMob.Name}, attacking");
 
             Mobile.Combatant = Mobile.FocusMob;
             Action = ActionType.Combat;
@@ -38,7 +38,7 @@ public class BerserkAI : BaseAI
             return true;
         }
 
-        if (!WalkMobileRange(combatant, 1, false, Mobile.RangeFight, Mobile.RangeFight))
+        if (!WalkMobileRange(combatant, 1, Mobile.RangeFight, Mobile.RangeFight))
         {
             this.DebugSayFormatted($"I am still not in range of {combatant.Name}");
 

Projects/UOContent/Mobiles/AI/HealerAI.cs

@@ -81,7 +81,7 @@ public class HealerAI : BaseAI
             return true;
         }
 
-        WalkMobileRange(Mobile.FocusMob, 1, false, 4, 7);
+        WalkMobileRange(Mobile.FocusMob, 1, 4, 7);
 
         // TODO: Should it be able to do this?
         if (Mobile.TriggerAbility(MonsterAbilityTrigger.CombatAction, Mobile.Combatant))

Projects/UOContent/Mobiles/AI/MageAI.cs

@@ -171,7 +171,7 @@ public class MageAI : BaseAI
     {
         if (!SmartAI)
         {
-            if (!MoveTo(m, false, Mobile.RangeFight))
+            if (!MoveTo(m, Mobile.RangeFight))
             {
                 OnFailedMove();
             }
@@ -185,14 +185,14 @@ public class MageAI : BaseAI
             {
                 RunFrom(m);
             }
-            else if (!Mobile.InRange(m, Math.Max(Mobile.RangeFight, 2)) && !MoveTo(m, false, 1))
+            else if (!Mobile.InRange(m, Math.Max(Mobile.RangeFight, 2)) && !MoveTo(m, 1))
             {
                 OnFailedMove();
             }
         }
         else if (!Mobile.InRange(m, Mobile.RangeFight))
         {
-            if (!MoveTo(m, false, 1))
+            if (!MoveTo(m, 1))
             {
                 OnFailedMove();
             }
@@ -701,7 +701,7 @@ public class MageAI : BaseAI
         {
             DebugSay("I cannot see my target, moving to regain line of sight");
 
-            if (!MoveTo(c, false, 1))
+            if (!MoveTo(c, 1))
             {
                 OnFailedMove();
             }
@@ -1039,7 +1039,7 @@ public class MageAI : BaseAI
                 // target can be invoked.
                 if (!Mobile.InLOS(toTarget))
                 {
-                    MoveTo(toTarget, true, 1);
+                    MoveTo(toTarget, 1);
                 }
                 else
                 {

Projects/UOContent/Mobiles/AI/MeleeAI.cs

@@ -1,3 +1,5 @@
+using System.Runtime.CompilerServices;
+
 namespace Server.Mobiles;
 
 public class MeleeAI : BaseAI
@@ -14,6 +16,7 @@ public class MeleeAI : BaseAI
         if (AcquireFocusMob(Mobile.RangePerception, Mobile.FightMode, false, false, true))
         {
             this.DebugSayFormatted($"I have detected {Mobile.FocusMob.Name}, attacking");
+
             Mobile.Combatant = Mobile.FocusMob;
             Action = ActionType.Combat;
         }
@@ -65,13 +68,9 @@ public class MeleeAI : BaseAI
         return true;
     }
 
-    private bool IsValidCombatant(Mobile combatant)
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    {
+    private bool IsValidCombatant(Mobile combatant) =>
-        return combatant?.Deleted == false 
+        combatant?.Deleted == false && combatant.Map == Mobile.Map && combatant.Alive && !combatant.IsDeadBondedPet;
-               && combatant.Map == Mobile.Map 
-               && combatant.Alive 
-               && !combatant.IsDeadBondedPet;
-    }
 
     private bool HandleOutOfRangeCombatant(Mobile combatant)
     {
@@ -99,7 +98,7 @@ public class MeleeAI : BaseAI
 
     private bool AttemptMoveToCombatant(Mobile combatant)
     {
-        if (MoveTo(combatant, false, Mobile.RangeFight))
+        if (MoveTo(combatant, Mobile.RangeFight))
         {
             return true;
         }
@@ -127,7 +126,8 @@ public class MeleeAI : BaseAI
     {
         if (AcquireFocusMob(Mobile.RangePerception, Mobile.FightMode, false, false, true))
         {
-            this.DebugSayFormatted($"I have detected {Mobile.FocusMob.Name}, attacking.");
+            this.DebugSayFormatted($"I have detected {Mobile.FocusMob.Name}, attacking");
+
             Mobile.Combatant = Mobile.FocusMob;
             Action = ActionType.Combat;
         }

Projects/UOContent/Mobiles/AI/PredatorAI.cs

@@ -41,7 +41,7 @@ public class PredatorAI : BaseAI
             return true;
         }
 
-        if (!WalkMobileRange(combatant, 1, false, Mobile.RangeFight, Mobile.RangeFight))
+        if (!WalkMobileRange(combatant, 1, Mobile.RangeFight, Mobile.RangeFight))
         {
             if (Mobile.GetDistanceToSqrt(combatant) > Mobile.RangePerception + 1)
             {
@@ -70,7 +70,7 @@ public class PredatorAI : BaseAI
         }
         else if (AcquireFocusMob(Mobile.RangePerception * 2, FightMode.Closest, true, false, true))
         {
-            if (WalkMobileRange(Mobile.FocusMob, 1, false, Mobile.RangePerception, Mobile.RangePerception * 2))
+            if (WalkMobileRange(Mobile.FocusMob, 1, Mobile.RangePerception, Mobile.RangePerception * 2))
             {
                 DebugSay("Well, here I am safe");
 

Projects/UOContent/Mobiles/AI/ThiefAI.cs

@@ -43,7 +43,7 @@ public class ThiefAI : BaseAI
             return true;
         }
 
-        if (!WalkMobileRange(combatant, 1, false, Mobile.RangeFight, Mobile.RangeFight))
+        if (!WalkMobileRange(combatant, 1, Mobile.RangeFight, Mobile.RangeFight))
         {
             this.DebugSayFormatted($"I should be closer to {combatant.Name}");
         }

Projects/UOContent/Mobiles/BaseCreature.cs

@@ -750,8 +750,9 @@ namespace Server.Mobiles
 
         /// <summary>
         /// Resolved seconds per step: a verbatim active/passive <see cref="CurrentSpeed"/>
-        /// maps to the matching movement value; a bespoke pace stays fused to both clocks.
+        /// maps to the matching movement value; a bespoke pace (e.g. the pet-order 0.1 sprint)
-        /// A herded creature is always driven at <see cref="HerdingMoveSpeed"/>.
+        /// stays fused to both clocks. A herded creature is always driven at
+        /// <see cref="HerdingMoveSpeed"/>.
         /// </summary>
         [CommandProperty(AccessLevel.GameMaster)]
         public double CurrentMoveSpeed
@@ -845,6 +846,8 @@ namespace Server.Mobiles
         [CommandProperty(AccessLevel.GameMaster)]
         public Point3D ControlDest { get; set; }
 
+        // Fires on every assignment, not only changes: a reissued order is a command
+        // (retarget, break off combat, re-anchor Home). Handlers receive the previous order.
         [CommandProperty(AccessLevel.GameMaster)]
         public OrderType ControlOrder
         {
@@ -933,21 +936,50 @@ namespace Server.Mobiles
 
         public virtual bool GivesMLMinorArtifact => false;
 
-        /* To save on cpu usage, RunUO creatures only reacquire creatures under the following circumstances:
-         *  - 10 seconds have elapsed since the last time it tried
-         *  - The creature was attacked
-         *  - Some creatures, like dragons, will reacquire when they see someone move
-         *
-         * This functionality appears to be implemented on OSI as well
-         */
-
         public long NextReacquireTime { get; set; }
 
         public virtual TimeSpan ReacquireDelay => TimeSpan.FromSeconds(10.0);
-        public virtual bool ReacquireOnMovement => false;
+
-        public virtual bool AcquireOnApproach => m_Paragon;
+        // Reaction-time gradient: an enemy moving inside AcquireOnApproachRange pulls the
+        // next scan to at most this far away. Zero (paragons) scans on the very next
+        // think; larger is dumber; pure ReacquireDelay is the oblivious floor.
+        public virtual TimeSpan AcquireOnApproachDelay => m_Paragon ? TimeSpan.Zero : TimeSpan.FromSeconds(2.0);
+
+        // Reactive range is tighter than the periodic scan's RangePerception: approach
+        // aggro starts on-screen; the ReacquireDelay poll keeps the wide ambient sweep.
         public virtual int AcquireOnApproachRange => 10;
 
+        // Clamps the scan deadline rather than opening the gate: repeated steps cannot
+        // shorten it further, so an armed creature scans once per delay period.
+        private void ScheduleAcquireOnApproach()
+        {
+            var delay = (long)AcquireOnApproachDelay.TotalMilliseconds;
+            var deadline = Core.TickCount + delay;
+
+            if (deadline - NextReacquireTime < 0)
+            {
+                NextReacquireTime = deadline;
+            }
+
+            if (delay <= 0)
+            {
+                // Zero: think now — the ranked scan engages within a wheel turn. Prod is
+                // spam-safe; the Combatant == null guard stops the prods once engaged.
+                AIObject?.AITimer?.Prod();
+            }
+        }
+
+        // IsEnemy first — it cheaply rejects the common case (a same-team wild creature
+        // wandering past); CanBeHarmful covers hidden movers via CanSee.
+        private bool ShouldAcquireOnApproach(Mobile m) =>
+            Combatant == null &&
+            !Controlled && !Summoned && !BardPacified &&
+            FightMode != FightMode.None && FightMode != FightMode.Aggressor &&
+            InRange(m.Location, AcquireOnApproachRange) &&
+            IsEnemy(m) && CanBeHarmful(m, false);
+
+        public virtual bool ReacquireOnMovement => false;
+
         public static bool Summoning { get; set; }
 
         public virtual bool IsDispellable => Summoned && !IsAnimatedDead;
@@ -2021,6 +2053,8 @@ namespace Server.Mobiles
         {
             base.Deserialize(reader);
 
+            NextReacquireTime = Core.TickCount;
+
             var version = reader.ReadInt();
 
             m_CurrentAI = (AIType)reader.ReadInt();
@@ -2852,15 +2886,9 @@ namespace Server.Mobiles
 
         public override void OnMovement(Mobile m, Point3D oldLocation)
         {
-            if (AcquireOnApproach && !Controlled && !Summoned && !BardPacified && FightMode != FightMode.Aggressor)
+            if (ShouldAcquireOnApproach(m))
             {
-                if (InRange(m.Location, AcquireOnApproachRange) && !InRange(oldLocation, AcquireOnApproachRange) &&
+                ScheduleAcquireOnApproach();
-                    CanBeHarmful(m) && IsEnemy(m))
-                {
-                    Combatant = FocusMob = m;
-                    AIObject?.MoveTo(m, true, 1);
-                    DoHarmful(m);
-                }
             }
             else if (ReacquireOnMovement)
             {
@@ -3095,14 +3123,12 @@ namespace Server.Mobiles
             return base.OnBeforeDeath();
         }
 
-        public int ComputeBonusDamage(List<DamageEntry> list, Mobile m)
+        public int ComputeBonusDamage(in ValueLinkList<DamageEntry> list, Mobile m)
         {
             var bonus = 0;
 
-            for (var i = list.Count - 1; i >= 0; --i)
+            foreach (var de in list.ByDescending())
             {
-                var de = list[i];
-
                 if (de.Damager == m || de.Damager is not BaseCreature bc)
                 {
                     continue;
@@ -3139,26 +3165,15 @@ namespace Server.Mobiles
             Combatant is PlayerMobile ||
             Combatant is BaseCreature { Controlled: true } bc && bc.GetMaster() is PlayerMobile;
 
-        public static List<DamageStore> GetLootingRights(List<DamageEntry> damageEntries, int hitsMax)
+        // Iterates most recent first, matching the previous reverse-indexed loop. The list is
+        // already pruned of expired entries by the Mobile.DamageEntries getter.
+        public static List<DamageStore> GetLootingRights(in ValueLinkList<DamageEntry> damageEntries, int hitsMax)
         {
             var rights = new List<DamageStore>();
             DamageStore firstDamager = null;
 
-            for (var i = damageEntries.Count - 1; i >= 0; --i)
+            foreach (var de in damageEntries.ByDescending())
             {
-                if (i >= damageEntries.Count)
-                {
-                    continue;
-                }
-
-                var de = damageEntries[i];
-
-                if (de.HasExpired)
-                {
-                    damageEntries.RemoveAt(i);
-                    continue;
-                }
-
                 var damage = de.DamageGiven;
 
                 var respList = de.Responsible;

Projects/UOContent/Mobiles/Familiars/BaseFamiliar.cs

@@ -92,7 +92,7 @@ public abstract partial class BaseFamiliar : BaseCreature
             Hidden = m_LastHidden = master.Hidden;
         }
 
-        if (AIObject?.WalkMobileRange(master, 5, false, 1, 1) == true)
+        if (AIObject?.WalkMobileRange(master, 5, 1, 1) == true)
         {
             Warmode = master.Warmode;
             Combatant = master.Combatant;

Projects/UOContent/Mobiles/Monsters/LBR/Meers/EnragedCreatures.cs

@@ -108,7 +108,7 @@ namespace Server.Mobiles
             */
             else if (!Combat(this))
             {
-                AIObject?.MoveTo(SummonMaster, false, 5);
+                AIObject?.MoveTo(SummonMaster, 5);
             }
             /*
               On OSI, if the summon attacks a mobile, the summoner meer also

Projects/UOContent/Mobiles/Special/Harrower.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using ModernUO.Serialization;
+using Server.Collections;
 using Server.Engines.CannedEvil;
 using Server.Engines.Virtues;
 using Server.Items;

Projects/UOContent/Network/Packets/IncomingPlayerPackets.cs

@@ -86,11 +86,17 @@ public static class IncomingPlayerPackets
     public static void HuePickerResponse(NetState state, SpanReader reader)
     {
         var serial = reader.ReadUInt32();
-        _ = reader.ReadInt16(); // Item ID
+        reader.ReadInt16(); // Item ID
         var hue = Utility.ClipDyedHue(reader.ReadInt16() & 0x3FFF);
 
-        foreach (var huePicker in state.HuePickers)
+        if (state.HuePickers == null)
         {
+            return;
+        }
+
+        for (var i = 0; i < state.HuePickers.Count; i++)
+        {
+            var huePicker = state.HuePickers[i];
             if (huePicker.Serial == serial)
             {
                 state.RemoveHuePicker(huePicker);
@@ -287,13 +293,18 @@ public static class IncomingPlayerPackets
     public static void MenuResponse(NetState state, SpanReader reader)
     {
         var serial = reader.ReadUInt32();
-        int menuID = reader.ReadInt16();
+        reader.ReadInt16(); // menu id
         int index = reader.ReadInt16();
-        int itemID = reader.ReadInt16();
+        reader.ReadInt16(); // item id
-        int hue = reader.ReadInt16();
+        reader.ReadInt16(); // hue
 
         index -= 1; // convert from 1-based to 0-based
 
+        if (state.Menus == null)
+        {
+            return;
+        }
+
         for (var i = 0; i < state.Menus.Count; i++)
         {
             var menu = state.Menus[i];

Projects/UOContent/Regions/BaseRegion.cs

@@ -113,7 +113,7 @@ public class BaseRegion : Region
                         m_RectBuffer2.RemoveAt(k);
 
                         var sz = rect.Start.Z;
-                        var ez = rect.End.X;
+                        var ez = rect.End.Z;
 
                         if (l1 < l2)
                         {

Projects/UOContent/Spells/Ninjitsu/MirrorImage.cs

@@ -238,10 +238,7 @@ namespace Server.Mobiles
 
             if (master?.Map == Mobile.Map && master?.InRange(Mobile, Mobile.RangePerception) == true)
             {
-                var iCurrDist = (int)Mobile.GetDistanceToSqrt(master);
+                WalkMobileRange(master, 2, 0, 1);
-                var bRun = iCurrDist > 5;
-
-                WalkMobileRange(master, 2, bRun, 0, 1);
             }
             else
             {

dev-docs/claude-skills/migrate-from-runuo/migrate-items-mobiles.md

@@ -29,6 +29,9 @@ description: >
 - `BaseCreature(AI, Fight, 10, 1, 0.2, 0.4)` -> `BaseCreature(AI, Fight)` (extra params default)
 - `Name = "text"` -> `public override string DefaultName => "text";`
 - Expression-bodied overrides: `public override int Meat { get { return 1; } }` -> `public override int Meat => 1;`
+- AI movement calls lose the `run` flag: `MoveTo(m, true, range)` -> `MoveTo(m, range)` (also `WalkMobileRange`, `ApproachTarget`, `MoveToPoint`, `PathFollower.Follow`); the Running bit is derived from step pace -> `dev-docs/runuo-migration-docs/09-items-mobiles-creatures.md` § AI Movement
+- `AcquireOnApproach` (bool) -> `AcquireOnApproachDelay` (TimeSpan; `Zero` = old instant behavior) -> same doc § Target Acquisition
+- `DamageEntries` is an inline `ref readonly ValueLinkList<DamageEntry>`, not a `List`: indexer/`Add`/`Remove`/`Clear` -> `foreach` / `.ByDescending()` (needs `using Server.Collections;`) and `ClearDamageEntries()`; `GetLootingRights` takes it by `in` -> same doc § Damage Entries
 
 ## Anti-Patterns
 - Using `_field--` instead of `Property--` (bypasses MarkDirty tracking)

dev-docs/claude-skills/modernuo-content-patterns.md

@@ -27,8 +27,18 @@ description: >
    (`ActiveSpeed`/`PassiveSpeed`, seconds per AI decision) and move
    (`ActiveMoveSpeed`/`PassiveMoveSpeed`, seconds per step; inherits think until
    overridden). Prefer `npc-speeds.json` buckets (`SpeedClass`); `SetSpeed()` sets think
-   AND clears move overrides, `SetMoveSpeed()` sets move only -- see
+   AND clears move overrides, `SetMoveSpeed()` sets move only. The client `Running` bit is
-   `dev-docs/content-patterns.md` § Creature Speeds
+   derived from the step pace (`BaseAI.ShouldRun`); movement APIs take no run argument --
+   see `dev-docs/content-patterns.md` § Creature Speeds. Reaction time to approaching
+   enemies is `AcquireOnApproachDelay` (TimeSpan gradient; `Zero` = paragon snap, 2s
+   default, `ReacquireDelay`-only = oblivious) -- see § Target Acquisition
+8. **`OnThink` overrides must be excess-call tolerant** -- it fires more often than the
+   think cadence (player commands prod it; speed-ups reschedule it). Gate consequential
+   work on a tick-count deadline (subtraction form) or make it idempotent; bare per-call
+   random rolls are cosmetics-only. `MonsterAbility` is under the same contract: the
+   trigger cooldown is the rate limit, `ChanceToTrigger` is per-sample jitter, and a
+   zero-cooldown `Think`/`CombatAction` ability triggers every sampled think -- see
+   `dev-docs/content-patterns.md` § OnThink: the excess-call contract
 
 ## New Item Template
 

dev-docs/content-patterns.md

@@ -283,6 +283,91 @@ ClearMoveSpeed();            // back to inheriting the think clock
 All four are `[props`-tunable per instance (move values: set `0` to re-inherit); per-instance
 move overrides serialize. Being badly hurt slows steps, never decisions (RunUO parity).
 
+The client's `Running` bit is derived from the step pace, never passed by callers
+(`BaseAI.ShouldRun`, stamped in `DoMoveImpl`): a step shorter than the client's walk
+interpolation — 400 ms on foot, 200 ms mounted/flying (`Movement.WalkFootDelay` /
+`WalkMountDelay`) — is flagged as a run, or the client falls behind and snaps. An isolated
+step (resuming after at least a walk interval standing) goes out as a walk regardless of
+pace — the client renders each step alone, so a run-flagged single step darts — unless the
+pace beats the run interpolation (a true sprinter), where a walk-rendered first step would
+flood the client's step queue. Movement APIs (`MoveTo`, `WalkMobileRange`,
+`ApproachTarget`, `MoveToPoint`) take no run argument; to make a creature run, make it
+fast. Creatures step at most once per `CurrentMoveSpeed` period, paced from the step just
+taken — a stall never banks catch-up steps, so a resumed chase restarts at full pace.
+
+### Target Acquisition: the reaction-time gradient
+
+Acquisition is event-driven, not polled. The periodic scan (`AcquireFocusMob`) is gated by
+`ReacquireDelay` (10 s default) and every scan re-arms it in full, success or failure — it
+is target stickiness plus the fallback for what movement cannot signal (reveals, doors,
+summons). Reaction time comes from `BaseCreature.OnMovement`: an enemy moving inside
+`AcquireOnApproachRange` (10 — on-screen; the periodic scan keeps the wider
+`RangePerception`) clamps the next scan to
+at most **`AcquireOnApproachDelay`** — the intelligence gradient. `TimeSpan.Zero`
+(paragons) also prods the AI, so the ranked scan engages within a timer-wheel turn; the
+2 s default reads as "took a beat to notice you"; larger is dumber; a creature that
+overrides the delay above `ReacquireDelay` is effectively oblivious to approach. Repeated
+steps cannot shorten the clamp, so an armed creature scans once per delay period, not once
+per step or think. `ReacquireOnMovement` remains the broader hook (any mover, no enemy
+check, scan next think). The gate self-heals: a deadline further out than `ReacquireDelay`
+is illegal and reads as open, so no wedged or wrapped value can silence acquisition beyond
+one delay period.
+
+### OnThink: the excess-call contract
+
+`OnThink()` is a scheduler pass, not an action. The AI timer calls it *at least* at the
+think cadence (`CurrentSpeed`), but it can and does fire more often: a player command
+wakes the AI immediately (`AITimer.Prod()`), a speed-up reschedules the pending wake, and
+players run command macros that drive extra thinks deliberately (order spam is spam-safe
+by design — reaction, never action). RunUO had the same property (its timer restarted
+with a random delay on every speed change), so this has never been a fixed-rate callback.
+
+**Every `OnThink` override must be excess-call tolerant.** An extra call must never grant
+an extra action:
+
+- Gate consequential work on its own deadline field, compared in subtraction form
+  (`Core.TickCount - _nextX >= 0` — see `tick-counts.md`), or make it idempotent.
+- Never pace a consequential action with a bare per-call `Utility.RandomDouble()` roll —
+  its frequency then scales with think rate, which players can influence. Per-call rolls
+  are acceptable only for pure cosmetics (idle animations, flavor sounds).
+- The engine already gates the expensive things: steps (the `NextMove` budget), weapon
+  swings, spell casts, detect-hidden, and the base `BaseCreature.OnThink` actions (heal,
+  rummage, aura) all carry their own clocks. Follow that pattern.
+
+```csharp
+private long _nextSpecial;
+
+public override void OnThink()
+{
+    base.OnThink();
+
+    if (Core.TickCount - _nextSpecial >= 0)
+    {
+        DoSpecial();
+        _nextSpecial = Core.TickCount + 5000; // the real rate limit lives here
+    }
+}
+```
+
+### MonsterAbility: same contract
+
+`MonsterAbility.CanTrigger` is sampled once per think for `Think`- and
+`CombatAction`-triggered abilities, so abilities live under the same rule:
+
+- **`MinTriggerCooldown`/`MaxTriggerCooldown` is the real rate limit** — the floor holds
+  no matter how often thinks fire. Always give a triggered ability a real cooldown.
+- **`ChanceToTrigger` is a per-sample roll**: above the cooldown floor, the expected
+  trigger delay shrinks as think rate rises. Treat the chance as flavor jitter, never as
+  the rate limiter, and keep cooldowns long relative to the think interval so the jitter
+  stays negligible (fire breath — chance 0.5, cooldown 30–45s — varies under 1% between
+  natural and spammed think rates).
+- A **zero-cooldown ability records no cooldown at all** and triggers on every sampled
+  think that passes its chance — only ever correct for passive alteration hooks, never
+  for `Think`/`CombatAction` triggers.
+- An ability that breaks pet orders (fear-style effects) must own its duration explicitly
+  (a hold state, or a "refuses orders until" deadline checked in the order handlers) —
+  pets react to re-issued commands immediately, so think latency is not a hold.
+
 ---
 
 ## New Spell

dev-docs/runuo-migration-docs/09-items-mobiles-creatures.md

@@ -474,6 +474,88 @@ The extra parameters (RangePerception, RangeFight, ActiveSpeed, PassiveSpeed) ha
 | `Name = "a creature"` in constructor | `public override string DefaultName => "a creature";` |
 | `get { return value; }` | `=> value;` expression-bodied |
 
+## AI Movement: No `run` Argument
+
+RunUO's movement calls took a `run` flag that callers set inconsistently (`true` in
+combat, `false` for pets, gated by `dist > 5` inside `MoveTo`). The flag only selects the
+client's per-step animation time, so ModernUO derives it from the creature's step pace
+(`BaseAI.ShouldRun`) and the parameter is gone:
+
+```csharp
+// RunUO
+MoveTo(combatant, true, m_Mobile.RangeFight);
+WalkMobileRange(m_Mobile.ControlMaster, 1, false, 0, 1);
+
+// ModernUO
+MoveTo(combatant, Mobile.RangeFight);
+WalkMobileRange(Mobile.ControlMaster, 1, 0, 1);
+```
+
+`ApproachTarget`, `MoveToPoint` and `PathFollower.Follow` lose the argument the same way.
+To make a creature run, make it fast (`SetMoveSpeed` / `npc-speeds.json`), not flagged.
+An isolated step (after the creature stood for at least a walk interval) goes out as a
+walk regardless of pace — only a continuing cadence, or a pace faster than the run
+interpolation, flags run.
+
+## Target Acquisition: `AcquireOnApproach` Is a Delay
+
+RunUO's `AcquireOnApproach` bool (paragon insta-aggro on approach) is now
+`AcquireOnApproachDelay`, a `TimeSpan` reaction-time gradient that applies to every
+creature — enemy movement inside `AcquireOnApproachRange` schedules a scan within the
+delay instead of waiting out the 10 s `ReacquireDelay` poll:
+
+```csharp
+// RunUO
+public override bool AcquireOnApproach => true;
+
+// ModernUO — Zero is the old instant behavior; larger values are dumber
+public override TimeSpan AcquireOnApproachDelay => TimeSpan.Zero;
+```
+
+`AcquireOnApproachRange` stays 10 for all creatures (reactive aggro is on-screen; the
+periodic `ReacquireDelay` scan still sweeps the full `RangePerception`). The
+acquired target comes from the normal FightMode-ranked scan, not from whichever mobile
+happened to move. See `content-patterns.md` § Target Acquisition.
+
+## Damage Entries: Inline `ValueLinkList`, Not `List<DamageEntry>`
+
+RunUO's `Mobile.DamageEntries` was a `List<DamageEntry>` allocated for every mobile.
+ModernUO keeps damage entries in an inline `ValueLinkList<DamageEntry>` struct held by
+the mobile itself, ordered least recent → most recent, so a mobile that never takes
+damage owns no list object and `RegisterDamage` relinks in O(1). The property is
+`ref readonly`; expired entries are pruned when it is read.
+
+```csharp
+// RunUO
+for (var i = m.DamageEntries.Count - 1; i >= 0; --i)
+{
+    var de = m.DamageEntries[i];          // indexer
+    ...
+}
+m.DamageEntries.Clear();
+var rights = BaseCreature.GetLootingRights(m.DamageEntries, m.HitsMax); // List<DamageEntry>
+
+// ModernUO — needs `using Server.Collections;` for the enumerator extensions
+foreach (var de in m.DamageEntries.ByDescending()) // most recent first
+{
+    ...
+}
+foreach (var de in m.DamageEntries)                // least recent first
+{
+    ...
+}
+m.ClearDamageEntries();
+var rights = BaseCreature.GetLootingRights(m.DamageEntries, m.HitsMax); // in ValueLinkList<DamageEntry>
+```
+
+What no longer compiles: the indexer, `.Add`, `.Remove`, `.RemoveAt`, `.Clear`, and
+passing the property where a `List<DamageEntry>` is expected. `.Count`,
+`FindDamageEntryFor`, `FindMostRecentDamager` and the other `Find*` methods, and
+`RegisterDamage` are unchanged. `DamageEntry` now carries `Next`/`Previous`/`OnLinkList`
+link fields; never set them yourself, and never call a `ValueLinkList` mutator on the
+`ref readonly` property — it compiles against a copy and corrupts the node's link state.
+Mutate only through `RegisterDamage` and `ClearDamageEntries`.
+
 ## Item Name Changes
 
 ```csharp

dev-docs/runuo-migration-docs/11-api-reference.md

@@ -130,6 +130,13 @@ Alphabetical by RunUO API name. Use Ctrl+F / Cmd+F to search.
 | `writer.WriteEncodedInt(value)` | `writer.WriteEncodedInt(value)` | Same |
 | `InvalidateProperties()` | `InvalidateProperties()` | Same, or use `[InvalidateProperties]` |
 | `this.MarkDirty()` | `this.MarkDirty()` | NEW — required in custom setters |
+| `MoveTo(m, run, range)` | `MoveTo(m, range)` | `run` removed; the Running bit is derived from the step pace (`BaseAI.ShouldRun`) |
+| `WalkMobileRange(m, steps, run, min, max)` | `WalkMobileRange(m, steps, min, max)` | Same |
+| `PathFollower.Follow(run, range)` | `Follow(range)` | Same |
+| `AcquireOnApproach` (bool) | `AcquireOnApproachDelay` (TimeSpan) | Reaction-time gradient; `Zero` = old instant behavior |
+| `m.DamageEntries` (`List<DamageEntry>`) | `m.DamageEntries` (`ref readonly ValueLinkList<DamageEntry>`) | Inline, least→most recent; `foreach` / `.ByDescending()` only, needs `using Server.Collections;`; no indexer, `Add`, `Remove`, `Clear` |
+| `m.DamageEntries.Clear()` | `m.ClearDamageEntries()` | |
+| `GetLootingRights(List<DamageEntry>, int)` | `GetLootingRights(in ValueLinkList<DamageEntry>, int)` | Callers passing `m.DamageEntries` compile unchanged |
 
 ## Networking