Add tests that lesson-consequence promises were missing.

Teacher action must not cancel gain, a missing warmth need matches full warmth, snow on the street must reach DayPlans, and a lazy pupil still appears closer to the bell.

tests/HSchool.Simulation.Tests/WeatherTests.cs

@@ -1,5 +1,7 @@
+using HSchool.Ai;
 using HSchool.Content;
 using HSchool.People;
+using HSchool.Schedule;
 
 namespace HSchool.Simulation.Tests;
 
@@ -73,6 +75,24 @@ public class WeatherTests
         Assert.Equal(0, new OutdoorWeather(-5f, Precipitation.Snow).ExtraCommuteMinutes(null));
     }
 
+    [Fact]
+    public void SnowOnStreet_PlansAppearEarlierThanClear()
+    {
+        // Tick would SyncWeather and overwrite ForceWeather; Apply is the plan-build path.
+        using var clear = ComingOnTuesday();
+        using var snow = ComingOnTuesday();
+        clear.ForceWeather(new OutdoorWeather(8f, Precipitation.None));
+        snow.ForceWeather(new OutdoorWeather(-5f, Precipitation.Snow));
+        PresenceSystem.Apply(clear, 1);
+        PresenceSystem.Apply(snow, 1);
+
+        var pupilId = FirstComingPupil(clear);
+        var extra = clear.Catalog!.BehaviorRules!.CommuteSnowMinutes;
+        Assert.Equal(6, extra);
+        Assert.True(clear.Plans[pupilId].Comes);
+        Assert.Equal(clear.Plans[pupilId].AppearAt!.Value.AddMinutes(-extra), snow.Plans[pupilId].AppearAt);
+    }
+
     [Fact]
     public void SkipEmpty_SetsMondayMorningWeather_NotSaturdays()
     {
@@ -103,6 +123,25 @@ public class WeatherTests
         Assert.True(room < 18f, $"walls only, got {room}");
     }
 
+    private static readonly DateTime TuesdayMorning = new(2012, 4, 3, 6, 0, 0, DateTimeKind.Utc);
+
+    private static School ComingOnTuesday()
+    {
+        var school = Open(TuesdayMorning);
+        var schoolClass = school.Roster!.Classes.First();
+        school.SetTimetable(new Timetable(
+            [new LessonPlacement(schoolClass.Id, "Mathematics", "t1", schoolClass.RoomId, Day: 1, Period: 1)],
+            []));
+        return school;
+    }
+
+    private static string FirstComingPupil(School school)
+    {
+        var pupil = school.Roster!.People.First(person =>
+            person.IsStudent && person.ClassId == school.Timetable!.Lessons[0].ClassId);
+        return pupil.Id;
+    }
+
     private static School Open(DateTime start)
     {
         var (catalog, map) = VanillaMap();