Lock slice-2 filters and the staff-parent intake path later slices left untested.

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/HSchool.People.Tests/YearlyIntakeTests.cs

@@ -116,6 +116,43 @@ public class YearlyIntakeTests
             person => Assert.False(person.IsParent));
     }
 
+    /// <summary>
+    /// Slice 3 stopped generating staff, so the "unless they work here" branch of the test above
+    /// is vacuously empty. Hire still marks a parent <c>IsStaff</c>; intake must not drop them
+    /// with the graduates' civilian co-parent.
+    /// </summary>
+    [Fact]
+    public void StaffParentOfOnlyGraduates_StaysAfterIntake()
+    {
+        var map = Fixtures.Classrooms(4);
+        var catalog = Fixtures.Catalog();
+        var generated = Fixtures.Generate(map);
+        var graduating = generated.Classes
+            .Where(schoolClass => schoolClass.Year == 4)
+            .SelectMany(schoolClass => schoolClass.PupilIds)
+            .ToHashSet(StringComparer.Ordinal);
+        var family = generated.Families.First(candidate =>
+            candidate.ChildIds.Count > 0
+            && candidate.ChildIds.All(id => graduating.Contains(id)));
+        var staffId = family.ParentIds[0];
+        var civilians = family.ParentIds.Skip(1).ToArray();
+        var before = generated with
+        {
+            People = generated.People
+                .Select(person => person.Id.Equals(staffId, StringComparison.Ordinal)
+                    ? person with { IsStaff = true, Position = "Librarian" }
+                    : person)
+                .ToArray(),
+        };
+
+        var after = YearlyIntake.Apply(catalog, before, Fixtures.SchoolSeed, "Russia", September);
+        var stayed = Assert.Single(after.People, person => person.Id == staffId);
+
+        Assert.True(stayed.IsStaff);
+        Assert.False(stayed.IsParent);
+        Assert.All(civilians, id => Assert.DoesNotContain(after.People, person => person.Id == id));
+    }
+
     private static string Snapshot(Roster roster) =>
         string.Join('\n', roster.People.Select(person =>
             $"{person.Id}|{person.FamilyId}|{person.IsStudent}|{person.IsStaff}|{person.IsParent}|{person.ClassId}|{person.Name.Full}|{Skills(person)}"));