hide homework after expiry date

src/conversations/views.py

@@ -5,7 +5,7 @@
 following the testable-first architecture with typed data contracts.
 """
 
-from dataclasses import dataclass
+from dataclasses import dataclass, field
 from typing import Dict, Optional, List
 from uuid import UUID
 from datetime import datetime
@@ -108,9 +108,11 @@ class ConversationDetailData:
     messages: List[MessageViewData]
     can_submit: bool
     is_teacher_test: bool
-    paste_events: List[PasteEventViewData] = None
-    rapid_text_growth_events: List[RapidTextGrowthEventViewData] = None
-    user_id: UUID = None
+    paste_events: Optional[List[PasteEventViewData]] = field(default=None)
+    rapid_text_growth_events: Optional[List[RapidTextGrowthEventViewData]] = field(
+        default=None
+    )
+    user_id: Optional[UUID] = field(default=None)
 
 
 @dataclass
@@ -156,7 +158,7 @@ def validate_and_authorize_request(
         # Create processing request
         processing_request = MessageProcessingRequest(
             conversation_id=conversation_id,
-            user=request.user,
+            user=request.user,  # type: ignore[arg-type]
             content=content,
             message_type=message_type,
         )

src/courses/models.py

@@ -11,10 +11,10 @@ class Course(models.Model):
     code = models.CharField(max_length=256, unique=True)
 
     # Many-to-many relationships
-    teachers = models.ManyToManyField(
+    teachers: models.ManyToManyField = models.ManyToManyField(
         "accounts.Teacher", through="CourseTeacher", related_name="courses"
     )
-    students = models.ManyToManyField(
+    students: models.ManyToManyField = models.ManyToManyField(
         "accounts.Student", through="CourseEnrollment", related_name="enrolled_courses"
     )
 

src/courses/views.py

@@ -6,7 +6,7 @@
 """
 
 from dataclasses import dataclass
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, cast
 from uuid import UUID
 from django.views import View
 from django.http import HttpRequest, HttpResponse, HttpResponseForbidden
@@ -291,7 +291,7 @@ def get(self, request: HttpRequest, course_id: UUID) -> HttpResponse:
             has_access = course.is_student_enrolled(student_profile)
             user_type = "student"
 
-        if not has_access:
+        if not has_access or user_type is None:
             return HttpResponseForbidden("You do not have access to this course.")
 
         # Get the appropriate data based on user type
@@ -437,7 +437,10 @@ def _get_view_data(
         form = HomeworkCreateForm(initial={"course": course})
 
         # Create empty section form (we'll start with one)
-        SectionFormset = formset_factory(SectionForm, extra=1, formset=SectionFormSet)
+        SectionFormset = cast(
+            "type[SectionFormSet]",
+            formset_factory(SectionForm, extra=1, formset=SectionFormSet),
+        )
         section_formset = SectionFormset(prefix="sections")
 
         # Return form data
@@ -464,12 +467,15 @@ def _process_form_submission(
 
         # Create a mutable copy of POST data and inject course
         post_data = request.POST.copy()
-        post_data["course"] = course.id
+        post_data["course"] = str(course.id)
 
         # Create forms from POST data
         form = HomeworkCreateForm(post_data)
 
-        SectionFormset = formset_factory(SectionForm, extra=0, formset=SectionFormSet)
+        SectionFormset = cast(
+            "type[SectionFormSet]",
+            formset_factory(SectionForm, extra=0, formset=SectionFormSet),
+        )
         section_formset = SectionFormset(request.POST, prefix="sections")
 
         # Check form validity

src/homeworks/admin.py

@@ -1,6 +1,24 @@
 from django.contrib import admin
 from .models import Homework, Section, SectionSolution
 
-admin.site.register(Homework)
+
+@admin.register(Homework)
+class HomeworkAdmin(admin.ModelAdmin):
+    list_display = (
+        "title",
+        "course",
+        "due_date",
+        "expires_at",
+        "is_hidden",
+        "accessible_to_students",
+    )
+    list_filter = ("is_hidden", "course")
+    readonly_fields = ("accessible_to_students",)
+
+    @admin.display(boolean=True, description="Accessible to students")
+    def accessible_to_students(self, obj):
+        return obj.is_accessible_to_students
+
+
 admin.site.register(Section)
 admin.site.register(SectionSolution)

src/homeworks/forms.py

@@ -6,11 +6,28 @@
 """
 
 from django import forms
+from django.conf import settings
 from django.utils import timezone
 
 from .models import Homework
 
 
+def _to_local_str(dt) -> str:
+    """Convert a datetime to a local datetime-local input string."""
+    if settings.USE_TZ and timezone.is_naive(dt):
+        dt = timezone.make_aware(dt)
+    if settings.USE_TZ:
+        return timezone.localtime(dt).strftime("%Y-%m-%dT%H:%M")
+    return dt.strftime("%Y-%m-%dT%H:%M")
+
+
+def _make_aware_if_naive(dt):
+    """Make a naive datetime timezone-aware when USE_TZ is active."""
+    if dt is not None and settings.USE_TZ and timezone.is_naive(dt):
+        return timezone.make_aware(dt)
+    return dt
+
+
 class SectionForm(forms.Form):
     """Form for creating or editing a section."""
 
@@ -54,7 +71,15 @@ class HomeworkCreateForm(forms.ModelForm):
 
     class Meta:
         model = Homework
-        fields = ["title", "description", "course", "due_date", "llm_config"]
+        fields = [
+            "title",
+            "description",
+            "course",
+            "due_date",
+            "expires_at",
+            "is_hidden",
+            "llm_config",
+        ]
         widgets = {
             "title": forms.TextInput(
                 attrs={"class": "form-control", "placeholder": "Homework Title"}
@@ -76,6 +101,13 @@ class Meta:
                     "placeholder": "Due Date",
                 }
             ),
+            "expires_at": forms.DateTimeInput(
+                attrs={
+                    "class": "form-control",
+                    "type": "datetime-local",
+                }
+            ),
+            "is_hidden": forms.CheckboxInput(attrs={"class": "form-check-input"}),
             "llm_config": forms.Select(
                 attrs={"class": "form-select", "placeholder": "LLM Configuration"}
             ),
@@ -84,20 +116,45 @@ class Meta:
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
         self.fields["llm_config"].required = False
+        self.fields["expires_at"].required = False
+        self.expires_at_adjusted = False  # flag for view to flash a warning
 
-        # Convert datetime to format expected by datetime-local input
+        # Display stored datetimes in server local time, not raw UTC
         if self.instance and self.instance.due_date:
-            self.initial["due_date"] = self.instance.due_date.strftime("%Y-%m-%dT%H:%M")
+            self.initial["due_date"] = _to_local_str(self.instance.due_date)
+        if self.instance and self.instance.expires_at:
+            self.initial["expires_at"] = _to_local_str(self.instance.expires_at)
 
     def clean_due_date(self):
-        """Validate due date is in the future."""
-        due_date = self.cleaned_data.get("due_date")
+        """Make aware. Reject only strictly past dates — today is allowed."""
+        due_date = _make_aware_if_naive(self.cleaned_data.get("due_date"))
 
-        if due_date and due_date <= timezone.now():
-            raise forms.ValidationError("Due date must be in the future.")
+        if due_date:
+            today = (
+                timezone.now().date()
+                if not settings.USE_TZ
+                else timezone.localtime(timezone.now()).date()
+            )
+            if due_date.date() < today:
+                raise forms.ValidationError("Due date cannot be in the past.")
 
         return due_date
 
+    def clean_expires_at(self):
+        """Make aware if naive."""
+        return _make_aware_if_naive(self.cleaned_data.get("expires_at"))
+
+    def clean(self):
+        """Warn if expires_at precedes due_date, but allow it."""
+        cleaned_data = super().clean()
+        due_date = cleaned_data.get("due_date")
+        expires_at = cleaned_data.get("expires_at")
+
+        if due_date and expires_at and expires_at < due_date:
+            self.expires_at_adjusted = True  # view will warn the teacher
+
+        return cleaned_data
+
 
 class HomeworkEditForm(forms.ModelForm):
     """Form for editing an existing homework assignment."""
@@ -108,6 +165,8 @@ class Meta:
             "title",
             "description",
             "due_date",
+            "expires_at",
+            "is_hidden",
             "llm_config",
         ]  # Note: course is excluded
         widgets = {
@@ -128,6 +187,13 @@ class Meta:
                     "placeholder": "Due Date",
                 }
             ),
+            "expires_at": forms.DateTimeInput(
+                attrs={
+                    "class": "form-control",
+                    "type": "datetime-local",
+                }
+            ),
+            "is_hidden": forms.CheckboxInput(attrs={"class": "form-check-input"}),
             "llm_config": forms.Select(
                 attrs={"class": "form-select", "placeholder": "LLM Configuration"}
             ),
@@ -136,19 +202,33 @@ class Meta:
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
         self.fields["llm_config"].required = False
+        self.fields["expires_at"].required = False
+        self.expires_at_adjusted = False  # flag for view to flash a warning
 
-        # Convert datetime to format expected by datetime-local input
+        # Display stored datetimes in server local time, not raw UTC
         if self.instance and self.instance.due_date:
-            self.initial["due_date"] = self.instance.due_date.strftime("%Y-%m-%dT%H:%M")
+            self.initial["due_date"] = _to_local_str(self.instance.due_date)
+        if self.instance and self.instance.expires_at:
+            self.initial["expires_at"] = _to_local_str(self.instance.expires_at)
 
     def clean_due_date(self):
-        """Validate due date is in the future."""
-        due_date = self.cleaned_data.get("due_date")
+        """Make aware. No date restrictions on edit — teacher has full control."""
+        return _make_aware_if_naive(self.cleaned_data.get("due_date"))
 
-        if due_date and due_date <= timezone.now():
-            raise forms.ValidationError("Due date must be in the future.")
+    def clean_expires_at(self):
+        """Make aware if naive."""
+        return _make_aware_if_naive(self.cleaned_data.get("expires_at"))
 
-        return due_date
+    def clean(self):
+        """Warn if expires_at precedes due_date, but allow it."""
+        cleaned_data = super().clean()
+        due_date = cleaned_data.get("due_date")
+        expires_at = cleaned_data.get("expires_at")
+
+        if due_date and expires_at and expires_at < due_date:
+            self.expires_at_adjusted = True  # view will warn the teacher
+
+        return cleaned_data
 
 
 class SectionFormSet(forms.BaseFormSet):

src/homeworks/migrations/0005_add_homework_expiry_and_visibility.py

@@ -0,0 +1,28 @@
+# Generated by Django 5.2.7 on 2026-03-13 20:08
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("homeworks", "0004_alter_homework_course"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="homework",
+            name="expires_at",
+            field=models.DateTimeField(
+                blank=True,
+                help_text="Automatically hide from students after this date. Leave blank to never auto-hide.",
+                null=True,
+            ),
+        ),
+        migrations.AddField(
+            model_name="homework",
+            name="is_hidden",
+            field=models.BooleanField(
+                default=False, help_text="Immediately hide this homework from students."
+            ),
+        ),
+    ]

src/homeworks/models.py

@@ -17,6 +17,15 @@ class Homework(models.Model):
         "courses.Course", on_delete=models.CASCADE, related_name="homeworks"
     )
     due_date = models.DateTimeField()
+    expires_at = models.DateTimeField(
+        null=True,
+        blank=True,
+        help_text="Automatically hide from students after this date. Leave blank to never auto-hide.",
+    )
+    is_hidden = models.BooleanField(
+        default=False,
+        help_text="Immediately hide this homework from students.",
+    )
     llm_config = models.ForeignKey(
         "llm.LLMConfig", on_delete=models.SET_NULL, null=True, blank=True
     )
@@ -38,6 +47,20 @@ def section_count(self):
     def is_overdue(self):
         return timezone.now() > self.due_date
 
+    @property
+    def is_expired(self) -> bool:
+        """True if the auto-expiry date has passed."""
+        return self.expires_at is not None and timezone.now() > self.expires_at
+
+    @property
+    def is_accessible_to_students(self) -> bool:
+        """False if the teacher has hidden it or the expiry date has passed."""
+        if self.is_hidden:
+            return False
+        if self.is_expired:
+            return False
+        return True
+
 
 class Section(models.Model):
     """Individual section within a homework assignment."""

src/homeworks/services.py

@@ -890,7 +890,7 @@ def get_homework_submissions(homework_id: UUID) -> HomeworkSubmissionsData | Non
             # Create a map of conversation_id -> paste event count for quick lookup
             from collections import defaultdict
 
-            paste_event_count_map = defaultdict(int)
+            paste_event_count_map: defaultdict[UUID, int] = defaultdict(int)
             for paste_event in paste_events:
                 if paste_event.last_message_before_paste:
                     conv_id = paste_event.last_message_before_paste.conversation.id

src/homeworks/templates/homeworks/detail.html

@@ -20,7 +20,21 @@ <h1>{{ data.title }}</h1>
             <span class="badge bg-danger mb-2">Overdue</span><br>
             {% endif %}
             <span class="text-muted">Due: {{ data.due_date|date:"F d, Y" }}</span>
-
+
+            {% if data.user_type == 'teacher' %}
+            <div class="mt-2">
+                {% if data.is_hidden %}
+                <span class="badge bg-secondary fs-6"><i class="bi bi-eye-slash"></i> Hidden from students</span>
+                {% elif not data.is_accessible_to_students %}
+                <span class="badge bg-danger fs-6"><i class="bi bi-clock-history"></i> Expired — students cannot access</span>
+                {% elif data.expires_at %}
+                <span class="badge bg-primary fs-6"><i class="bi bi-calendar-x"></i> Expires {{ data.expires_at|date:"F d, Y" }}</span>
+                {% else %}
+                <span class="badge bg-success fs-6"><i class="bi bi-eye"></i> Visible to students</span>
+                {% endif %}
+            </div>
+            {% endif %}
+
             {% if data.can_edit %}
             <div class="mt-2">
                 <a href="{% url 'homeworks:edit' data.id %}" class="btn btn-outline-primary">