fix: restore pet obedience pacing and reschedule stale AI wakes

Pets slowed dramatically after #2591 (issue #2593): the per-step budget grew
from half a think interval to the full RunUO-parity move table, and a guarding
pet resolves passive (OnCombatantChange clears Warmode whenever the combatant
clears), putting Guard/Come at ~1.05s/step for Medium-bucket pets. Order
changes and speed-ups also waited out the previously scheduled AITimer wake,
because the timer wheel reads Interval only after the next fire.

- CurrentMoveSpeed: a controlled pet executing a master's movement order
  (Come/Follow/Guard, no combatant) paces steps on the think clock — the
  wild-creature move table no longer slows obedience. Combat chases and
  herding keep their own pacing.
- AITimer: track the pending wake and reschedule (Stop, Delay = remaining,
  Start) when a speed-up or fresh order moves the earliest deadline up;
  changes inside a tick still flow through ScheduleNext. New Prod() wakes the
  AI immediately on player commands, including from a stopped timer (stable
  claims no longer wait out the random construction stagger).
- DoOrderGuard: guard-following routes through WalkMobileRange so it registers
  a move intent (between-think move wakes) and paths around obstacles instead
  of bare greedy stepping quantized to the think grid.

Closes #2593

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

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

@@ -0,0 +1,48 @@
+using System.Collections.Generic;
+using Server;
+using Server.Mobiles;
+using Xunit;
+
+namespace UOContent.Tests.Mobiles.AI;
+
+// Guard-order following drives real movement primitives (and may pathfind), so it shares
+// the pathfinding sequential collection like ApproachTargetTests.
+[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 _);
+
+        pet.Delete();
+        master.Delete();
+
+        Assert.True(moved, "a guarding pet beyond guard range must step toward its master");
+        // Between-think move wakes require a registered move intent; bare greedy stepping
+        // quantizes guard-following to the think grid (issue #2593).
+        Assert.True(hasIntent, "guard-following must register a move intent");
+    }
+}

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

@@ -0,0 +1,193 @@
+using System;
+using System.Collections.Generic;
+using Server;
+using Server.Mobiles;
+using Xunit;
+
+namespace UOContent.Tests.Mobiles.AI;
+
+// Pins the pet-obedience pacing policy (issue #2593): a controlled pet executing a
+// master's movement order paces its steps on the think clock, not the wild-creature
+// move table; 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();
+    }
+
+    [Fact]
+    public void ObeyingPet_PacesStepsOnThinkClock()
+    {
+        var (master, pet) = Spawn(new Point3D(1000, 1000, 0), new Point3D(1001, 1000, 0));
+        pet.SetMoveSpeed(0.3, 0.9); // wild-creature table pace; must not slow obedience
+        pet.SetCurrentSpeedToPassive();
+
+        Assert.Equal(OrderType.Come, pet.ControlOrder);
+        Assert.Equal(0.4, pet.CurrentMoveSpeed);
+
+        pet.ControlOrder = OrderType.Guard;
+        Assert.Equal(0.4, pet.CurrentMoveSpeed);
+
+        pet.ControlTarget = master;
+        pet.ControlOrder = OrderType.Follow;
+        Assert.Equal(0.4, pet.CurrentMoveSpeed);
+    }
+
+    // Boundary guard: 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);
+    }
+
+    // Boundary guard: herding overrides obedience 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 simulated time in 8ms lockstep with the wheel, like the real event loop,
+    // so wake schedules 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 random spawn-stagger delay to a known think-tick anchor: returns
+    // right after a think fires, with the next one a full passive cadence (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;
+
+        // Mid-wait on the passive cadence: the next think is ~200ms out.
+        RunFor(200);
+        Assert.Equal(thinksBefore, pet.Thinks);
+
+        // The player issues a command; the pet must not wait out the stale wake.
+        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;
+
+        // Mid-wait on the passive cadence: the next think is ~200ms out.
+        RunFor(200);
+        Assert.Equal(thinksBefore, pet.Thinks);
+
+        // The pet is sped up (e.g. a buff): the next think must move up to the new
+        // 0.1s cadence instead of waiting out the stale 0.4s deadline.
+        pet.CurrentSpeed = 0.1;
+
+        RunFor(120);
+        Assert.True(pet.Thinks > thinksBefore, "a speed-up must reschedule the pending wake");
+    }
+}

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

@@ -26,6 +26,8 @@ public sealed class AITimer : Timer
 {
     private readonly BaseAI _owner;
     private long _nextThink;
+    private long _nextWake; // when the pending wheel entry fires; the wheel cannot tell us
+    private bool _inTick;
     private int _detectHiddenMinDelay;
     private int _detectHiddenMaxDelay;
 
@@ -40,8 +42,31 @@ public sealed class AITimer : Timer
     public void Activate()
     {
         _nextThink = Core.TickCount;
-        Interval = TimeSpan.FromSeconds(_owner.Mobile.CurrentSpeed);
+
+        if (Running)
+        {
+            return;
+        }
+
+        Start(); // keeps the current Delay: the construction stagger for spawn/sector wakes
+        _nextWake = Core.TickCount + (long)Delay.TotalMilliseconds;
+    }
+
+    // A fresh command must not wait out the previous cadence: think now. Pets are exempt
+    // from sector deactivation, so dropping the stagger Delay here cannot bunch sector wakes.
+    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 +77,54 @@ public sealed class AITimer : Timer
         if (candidate - _nextThink < 0)
         {
             _nextThink = candidate;
+            Reschedule();
+        }
+    }
+
+    // Restarts the timer when the new earliest deadline lands before the pending wake.
+    // The wheel reads Interval only after the next fire, so moving a pending wake earlier
+    // requires Stop, Delay = remaining, Start.
+    private void Reschedule()
+    {
+        if (_inTick || !Running)
+        {
+            return; // ScheduleNext reads the updated deadlines 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; // the pending wake is already at or before the new deadline
+        }
+
+        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())
         {
@@ -111,6 +178,7 @@ 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)

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

@@ -26,7 +26,8 @@ public abstract partial class BaseAI
             return;
         }
 
-        Activate();
+        // A fresh command wakes the AI immediately — never wait out the previous cadence.
+        AITimer.Prod();
 
         switch (Mobile.ControlOrder)
         {

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

@@ -309,13 +309,13 @@ public abstract partial class BaseAI
         {
             this.DebugSayFormatted($"Guarding my master, {controlMaster.Name}.");
 
-            var guardLocation = controlMaster.Location;
-
-            var distance = (int)Mobile.GetDistanceToSqrt(guardLocation);
+            var distance = (int)Mobile.GetDistanceToSqrt(controlMaster);
 
             if (distance > 3)
             {
-                DoMove(Mobile.GetDirectionTo(guardLocation));
+                // Through the approach primitive so guard-following registers a move
+                // intent (between-think move wakes) and paths around obstacles.
+                WalkMobileRange(controlMaster, 1, true, 1, 3);
             }
             else
             {

Projects/UOContent/Mobiles/BaseCreature.cs

@@ -751,7 +751,8 @@ 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.
-        /// A herded creature is always driven at <see cref="HerdingMoveSpeed"/>.
+        /// A herded creature is always driven at <see cref="HerdingMoveSpeed"/>; a pet
+        /// executing a master's movement order paces on the think clock.
         /// </summary>
         [CommandProperty(AccessLevel.GameMaster)]
         public double CurrentMoveSpeed
@@ -763,6 +764,14 @@ namespace Server.Mobiles
                     return HerdingMoveSpeed;
                 }
 
+                // Obedience is never slowed by the wild-creature move table; combat
+                // chases (combatant set) keep it.
+                if (Controlled && Combatant == null &&
+                    ControlOrder is OrderType.Come or OrderType.Follow or OrderType.Guard)
+                {
+                    return _currentSpeed;
+                }
+
                 return _currentSpeed == _activeSpeed ? ActiveMoveSpeed
                     : _currentSpeed == _passiveSpeed ? PassiveMoveSpeed
                     : _currentSpeed;