Wire grade trail notices, dress mark factor, and truancy summons weights.

Lesson multipliers stay explicit in tests; poor marks and unexcused absences toast and may auto-summon, while illness stays excused.

src/HSchool.People/GradeTrail.cs

@@ -0,0 +1,90 @@
+using HSchool.Content;
+
+namespace HSchool.People;
+
+/// <summary>
+/// Pure trail checks over recent marks and attendance. Simulation decides when to notice or summon.
+/// </summary>
+public static class GradeTrail
+{
+    public static float? AverageMark(Person person)
+    {
+        ArgumentNullException.ThrowIfNull(person);
+        var list = person.LessonMarks;
+        if (list is null || list.Count == 0)
+        {
+            return null;
+        }
+
+        var total = 0;
+        foreach (var row in list)
+        {
+            total += row.Value;
+        }
+
+        return total / (float)list.Count;
+    }
+
+    public static int TruancyCount(Person person)
+    {
+        ArgumentNullException.ThrowIfNull(person);
+        var list = person.Attendance;
+        if (list is null || list.Count == 0)
+        {
+            return 0;
+        }
+
+        var count = 0;
+        foreach (var row in list)
+        {
+            if (row.Status == AttendanceStatuses.Absent
+                && (row.AbsenceReason is null
+                    || row.AbsenceReason.Equals(AbsenceReasons.Truancy, StringComparison.Ordinal)))
+            {
+                count++;
+            }
+        }
+
+        return count;
+    }
+
+    public static bool HasPoorMarks(Person person, BehaviorDef rules)
+    {
+        ArgumentNullException.ThrowIfNull(person);
+        ArgumentNullException.ThrowIfNull(rules);
+        if (rules.PoorMarkTrailMinMarks <= 0 || rules.PoorMarkTrailMaxAverage <= 0f)
+        {
+            return false;
+        }
+
+        var list = person.LessonMarks;
+        if (list is null || list.Count < rules.PoorMarkTrailMinMarks)
+        {
+            return false;
+        }
+
+        return AverageMark(person) is { } average && average <= rules.PoorMarkTrailMaxAverage;
+    }
+
+    public static bool HasTruancyTrail(Person person, BehaviorDef rules)
+    {
+        ArgumentNullException.ThrowIfNull(person);
+        ArgumentNullException.ThrowIfNull(rules);
+        if (rules.TruancyTrailMinCount <= 0)
+        {
+            return false;
+        }
+
+        return TruancyCount(person) >= rules.TruancyTrailMinCount;
+    }
+
+    public static bool IsPoor(Person person, BehaviorDef rules) =>
+        HasPoorMarks(person, rules) || HasTruancyTrail(person, rules);
+
+    /// <summary>
+    /// Illness absences are excused for summons / offense memory. Truancy and unknown reasons are not.
+    /// </summary>
+    public static bool CountsAsSummonOffense(string? absenceReason) =>
+        absenceReason is null
+        || absenceReason.Equals(AbsenceReasons.Truancy, StringComparison.Ordinal);
+}

src/HSchool.People/OffenseMemory.cs

@@ -12,11 +12,15 @@ public static class OffenseKinds
 
     public const string Reprimand = "reprimand";
 
+    /// <summary>Unexcused lesson absence (slice 13). Illness does not use this kind.</summary>
+    public const string Truancy = "truancy";
+
     public static string LocaleKey(string kind) => kind switch
     {
         Quarrel => "OffenseQuarrel",
         Fight => "OffenseFight",
         Reprimand => "OffenseReprimand",
+        Truancy => "OffenseTruancy",
         _ => "Offense" + char.ToUpperInvariant(kind[0]) + kind[1..],
     };
 }

src/HSchool.People/Seed.cs

@@ -27,6 +27,7 @@ public static class Seed
     public const int MeetingAttendSalt = 19;
     public const int DiseaseSalt = 20;
     public const int ContagionSalt = 21;
+    public const int GradeTrailSalt = 22;
 
     /// <summary>A stream that belongs to the school rather than to one family.</summary>
     public static int ForSchool(int schoolSeed, int salt) => Mix(schoolSeed, familyIndex: -1, salt);