Phase 4: student views, opt-outs, and class schedule

Student page with a standing summary, a class-comparison histogram
(zero-dependency HTML/CSS) with a plain-language fewer/same/more
sentence, opt-out management with withdrawal of future dates, and a
call history that respects the per-course assessment-visibility
setting and never shows pending or skipped calls. Opt-outs validate
against a new per-course class-day schedule (range generator plus
individual add/remove for holidays), since Canvas has no structured
meeting-day data; courses without a schedule fall back to a free date
picker. Dev mode seeds a Tue/Thu pattern.

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

coldcall_lti/models.py

@@ -90,6 +90,19 @@ class Enrollment(Base):
     student: Mapped[Student] = relationship(back_populates="enrollments")
 
 
+class ClassDay(Base):
+    """A day the class actually meets. When a course has these, the
+    student opt-out form only offers real class days; without them it
+    falls back to a free date picker."""
+
+    __tablename__ = "class_days"
+    __table_args__ = (UniqueConstraint("course_id", "date"),)
+
+    id: Mapped[int] = mapped_column(primary_key=True)
+    course_id: Mapped[int] = mapped_column(ForeignKey("courses.id"))
+    date: Mapped[datetime.date] = mapped_column(Date)
+
+
 class OptOut(Base):
     __tablename__ = "optouts"
     __table_args__ = (UniqueConstraint("course_id", "student_id", "date"),)
@@ -132,6 +145,31 @@ def answered_call_counts(session, course_id):
     return dict(rows)
 
 
+def class_days(session, course_id, start=None, end=None):
+    q = select(ClassDay).where(ClassDay.course_id == course_id)
+    if start is not None:
+        q = q.where(ClassDay.date >= start)
+    if end is not None:
+        q = q.where(ClassDay.date <= end)
+    return session.execute(q.order_by(ClassDay.date)).scalars().all()
+
+
+def is_class_day(session, course_id, on_date):
+    """True if on_date is a listed class day, or if the course has no
+    class days defined at all (no schedule means no restriction)."""
+    if not session.execute(
+        select(ClassDay.id).where(ClassDay.course_id == course_id).limit(1)
+    ).first():
+        return True
+    return bool(
+        session.execute(
+            select(ClassDay.id).where(
+                ClassDay.course_id == course_id, ClassDay.date == on_date
+            )
+        ).first()
+    )
+
+
 def students_present(session, course_id, on_date):
     """Active student-role enrollees minus those opted out for the date."""
     opted_out = select(OptOut.student_id).where(