Merge phase/40-clock-tempo.

src/HSchool.Simulation/ClockSpeed.cs

@@ -6,8 +6,8 @@ namespace HSchool.Simulation;
 /// </summary>
 public static class ClockSpeed
 {
-    /// <summary>×½, ×1, ×2, ×3, ×4.</summary>
-    public static ReadOnlySpan<double> Multipliers => [0.5d, 1d, 2d, 3d, 4d];
+    /// <summary>×½, ×1, ×2, ×5, ×10.</summary>
+    public static ReadOnlySpan<double> Multipliers => [0.5d, 1d, 2d, 5d, 10d];
 
     /// <summary>Index of ×1, the speed a school starts at.</summary>
     public const int DefaultIndex = 1;
@@ -18,4 +18,22 @@ public static class ClockSpeed
 
     /// <summary>Multiplier for a validated index; out-of-range values fall back to ×1.</summary>
     public static double MultiplierAt(int index) => IsValid(index) ? Multipliers[index] : Multipliers[DefaultIndex];
+
+    /// <summary>
+    /// Calendar impulses between heavy-system ticks. ×5 and ×10 stride so walking and needs keep
+    /// one game minute per heavy step instead of twenty tiny ones per second.
+    /// </summary>
+    public static int HeavySystemsStride(int speedIndex) => speedIndex switch
+    {
+        3 => 4,
+        4 => 2,
+        _ => 1,
+    };
+
+    /// <summary>
+    /// Game minutes passed into presence, needs and learning on a heavy tick. High speeds use a
+    /// fixed one-minute quantum; lower speeds pass the impulse's own advance.
+    /// </summary>
+    public static double HeavyGameMinutes(int speedIndex, double impulseMinutes) =>
+        speedIndex is 3 or 4 ? 1d : impulseMinutes;
 }

src/HSchool.Simulation/School.cs

@@ -116,6 +116,12 @@ public sealed class School : IDisposable
 
     internal int DecisionBudget { get; set; }
 
+    internal int HeavySystemsInvocations { get; private set; }
+
+    internal double LastHeavyGameMinutes { get; private set; }
+
+    private int _impulseCounter;
+
     public int PendingDecisionCount => DecisionQueue.Count;
 
     /// <summary>
@@ -303,24 +309,14 @@ public sealed class School : IDisposable
                 LastDecisionSlot = null;
             }
 
-            PresenceSystem.Apply(this, gameMinutes);
-            foreach (var id in ActivitySystem.Apply(this, gameMinutes))
-            {
-                PresenceSystem.Enqueue(this, id);
-            }
+            SyncWeather(force: false);
 
-            PersonDayLog.Sync(this);
-
-            if (Catalog is not null)
+            _impulseCounter++;
+            var stride = ClockSpeed.HeavySystemsStride(Clock.SpeedIndex);
+            if (_impulseCounter % stride == 0)
             {
-                var below = PresenceSystem.BelowThreshold(this);
-                SyncWeather(force: false);
-                NeedDecay.Apply(World, Catalog, gameMinutes);
-                WarmthDecay.Apply(this, gameMinutes);
-                PresenceSystem.EnqueueNewlyUrgent(this, below);
-                PresenceSystem.DrainDecisions(this);
-                LessonLearningSystem.Apply(this, gameMinutes);
-                peopleChanged |= ApparelWear.Apply(this, gameMinutes, before);
+                var heavyMinutes = ClockSpeed.HeavyGameMinutes(Clock.SpeedIndex, gameMinutes);
+                peopleChanged |= ApplyHeavySystems(heavyMinutes);
             }
         }
         else
@@ -331,6 +327,34 @@ public sealed class School : IDisposable
         return peopleChanged;
     }
 
+    private bool ApplyHeavySystems(double gameMinutes)
+    {
+        HeavySystemsInvocations++;
+        LastHeavyGameMinutes = gameMinutes;
+
+        var peopleChanged = false;
+        PresenceSystem.Apply(this, gameMinutes);
+        foreach (var id in ActivitySystem.Apply(this, gameMinutes))
+        {
+            PresenceSystem.Enqueue(this, id);
+        }
+
+        PersonDayLog.Sync(this);
+
+        if (Catalog is not null)
+        {
+            var below = PresenceSystem.BelowThreshold(this);
+            NeedDecay.Apply(World, Catalog, gameMinutes);
+            WarmthDecay.Apply(this, gameMinutes);
+            PresenceSystem.EnqueueNewlyUrgent(this, below);
+            PresenceSystem.DrainDecisions(this);
+            LessonLearningSystem.Apply(this, gameMinutes);
+            peopleChanged |= ApparelWear.Apply(this, gameMinutes, Clock.Time.AddMinutes(-gameMinutes));
+        }
+
+        return peopleChanged;
+    }
+
     /// <summary>
     /// Recomputes the street from the preset, seed and current time. Commits when the clock
     /// tenths or precipitation change, so warmth does not jitter every tick. A skip must force

src/HSchool.Simulation/SimulationOptions.cs

@@ -14,7 +14,7 @@ public sealed class SimulationOptions
     public int MaxSchools { get; set; } = 6;
 
     /// <summary>Base speed of the game clock: real seconds are multiplied by this many game minutes.</summary>
-    public double GameMinutesPerRealSecond { get; set; } = 5d;
+    public double GameMinutesPerRealSecond { get; set; } = 1d;
 
     /// <summary>Prefilled start of a new school; the client shows it in the creation form.</summary>
     public DateTime DefaultStartDate