From bd9d685073c668c061646f1ba3117974f8161b1c Mon Sep 17 00:00:00 2001
From: Braden MacDonald <braden@opencraft.com>
Date: Fri, 6 Feb 2026 15:59:21 -0800
Subject: [PATCH 1/2] feat: depend on edx-organizations

---
 requirements/base.in     |  2 ++
 requirements/base.txt    | 20 ++++++++++++++++++--
 requirements/dev.txt     | 23 ++++++++++++++++++++++-
 requirements/doc.txt     | 23 ++++++++++++++++++++++-
 requirements/quality.txt | 23 ++++++++++++++++++++++-
 requirements/test.txt    | 23 ++++++++++++++++++++++-
 6 files changed, 108 insertions(+), 6 deletions(-)

diff --git a/requirements/base.in b/requirements/base.in
index 15bcd9748..508635e10 100644
--- a/requirements/base.in
+++ b/requirements/base.in
@@ -13,3 +13,5 @@ edx-drf-extensions        # Extensions to the Django REST Framework used by Open
 rules<4.0                 # Django extension for rules-based authorization checks
 
 tomlkit                   # Parses and writes TOML configuration files
+
+edx-organizations         # Implemented the "Organization" model that CatalogCourse/CourseRun are keyed to
diff --git a/requirements/base.txt b/requirements/base.txt
index 180b9cf26..fd3540ecb 100644
--- a/requirements/base.txt
+++ b/requirements/base.txt
@@ -42,13 +42,20 @@ django==5.2.11
     #   -c https://raw.githubusercontent.com/edx/edx-lint/master/edx_lint/files/common_constraints.txt
     #   -r requirements/base.in
     #   django-crum
+    #   django-model-utils
+    #   django-simple-history
     #   django-waffle
     #   djangorestframework
     #   drf-jwt
     #   edx-django-utils
     #   edx-drf-extensions
+    #   edx-organizations
 django-crum==0.7.9
     # via edx-django-utils
+django-model-utils==5.0.0
+    # via edx-organizations
+django-simple-history==3.11.0
+    # via edx-organizations
 django-waffle==5.0.0
     # via
     #   edx-django-utils
@@ -58,6 +65,7 @@ djangorestframework==3.16.1
     #   -r requirements/base.in
     #   drf-jwt
     #   edx-drf-extensions
+    #   edx-organizations
 dnspython==2.8.0
     # via pymongo
 drf-jwt==1.19.2
@@ -65,15 +73,23 @@ drf-jwt==1.19.2
 edx-django-utils==8.0.1
     # via edx-drf-extensions
 edx-drf-extensions==10.6.0
-    # via -r requirements/base.in
+    # via
+    #   -r requirements/base.in
+    #   edx-organizations
 edx-opaque-keys==3.0.0
-    # via edx-drf-extensions
+    # via
+    #   edx-drf-extensions
+    #   edx-organizations
+edx-organizations==7.3.0
+    # via -r requirements/base.in
 idna==3.11
     # via requests
 kombu==5.6.2
     # via celery
 packaging==26.0
     # via kombu
+pillow==12.1.0
+    # via edx-organizations
 prompt-toolkit==3.0.52
     # via click-repl
 psutil==7.2.2
diff --git a/requirements/dev.txt b/requirements/dev.txt
index 42895170e..bd7e64dca 100644
--- a/requirements/dev.txt
+++ b/requirements/dev.txt
@@ -132,6 +132,8 @@ django==5.2.11
     #   -r requirements/quality.txt
     #   django-crum
     #   django-debug-toolbar
+    #   django-model-utils
+    #   django-simple-history
     #   django-stubs
     #   django-stubs-ext
     #   django-waffle
@@ -140,6 +142,7 @@ django==5.2.11
     #   edx-django-utils
     #   edx-drf-extensions
     #   edx-i18n-tools
+    #   edx-organizations
 django-crum==0.7.9
     # via
     #   -r requirements/quality.txt
@@ -148,6 +151,14 @@ django-debug-toolbar==6.2.0
     # via
     #   -r requirements/dev.in
     #   -r requirements/quality.txt
+django-model-utils==5.0.0
+    # via
+    #   -r requirements/quality.txt
+    #   edx-organizations
+django-simple-history==3.11.0
+    # via
+    #   -r requirements/quality.txt
+    #   edx-organizations
 django-stubs==5.2.9
     # via
     #   -r requirements/quality.txt
@@ -166,6 +177,7 @@ djangorestframework==3.16.1
     #   -r requirements/quality.txt
     #   drf-jwt
     #   edx-drf-extensions
+    #   edx-organizations
 djangorestframework-stubs==3.16.8
     # via -r requirements/quality.txt
 dnspython==2.8.0
@@ -185,7 +197,9 @@ edx-django-utils==8.0.1
     #   -r requirements/quality.txt
     #   edx-drf-extensions
 edx-drf-extensions==10.6.0
-    # via -r requirements/quality.txt
+    # via
+    #   -r requirements/quality.txt
+    #   edx-organizations
 edx-i18n-tools==1.9.0
     # via -r requirements/dev.in
 edx-lint==5.6.0
@@ -194,6 +208,9 @@ edx-opaque-keys==3.0.0
     # via
     #   -r requirements/quality.txt
     #   edx-drf-extensions
+    #   edx-organizations
+edx-organizations==7.3.0
+    # via -r requirements/quality.txt
 fastapi==0.128.5
     # via
     #   -r requirements/quality.txt
@@ -324,6 +341,10 @@ pathspec==1.0.4
     # via
     #   -r requirements/quality.txt
     #   mypy
+pillow==12.1.0
+    # via
+    #   -r requirements/quality.txt
+    #   edx-organizations
 pip-tools==7.5.2
     # via -r requirements/pip-tools.txt
 platformdirs==4.5.1
diff --git a/requirements/doc.txt b/requirements/doc.txt
index 7b3fe0985..c7fbf9636 100644
--- a/requirements/doc.txt
+++ b/requirements/doc.txt
@@ -96,6 +96,8 @@ django==5.2.11
     #   -r requirements/test.txt
     #   django-crum
     #   django-debug-toolbar
+    #   django-model-utils
+    #   django-simple-history
     #   django-stubs
     #   django-stubs-ext
     #   django-waffle
@@ -103,6 +105,7 @@ django==5.2.11
     #   drf-jwt
     #   edx-django-utils
     #   edx-drf-extensions
+    #   edx-organizations
     #   sphinxcontrib-django
 django-crum==0.7.9
     # via
@@ -110,6 +113,14 @@ django-crum==0.7.9
     #   edx-django-utils
 django-debug-toolbar==6.2.0
     # via -r requirements/test.txt
+django-model-utils==5.0.0
+    # via
+    #   -r requirements/test.txt
+    #   edx-organizations
+django-simple-history==3.11.0
+    # via
+    #   -r requirements/test.txt
+    #   edx-organizations
 django-stubs==5.2.9
     # via
     #   -r requirements/test.txt
@@ -128,6 +139,7 @@ djangorestframework==3.16.1
     #   -r requirements/test.txt
     #   drf-jwt
     #   edx-drf-extensions
+    #   edx-organizations
 djangorestframework-stubs==3.16.8
     # via -r requirements/test.txt
 dnspython==2.8.0
@@ -152,11 +164,16 @@ edx-django-utils==8.0.1
     #   -r requirements/test.txt
     #   edx-drf-extensions
 edx-drf-extensions==10.6.0
-    # via -r requirements/test.txt
+    # via
+    #   -r requirements/test.txt
+    #   edx-organizations
 edx-opaque-keys==3.0.0
     # via
     #   -r requirements/test.txt
     #   edx-drf-extensions
+    #   edx-organizations
+edx-organizations==7.3.0
+    # via -r requirements/test.txt
 fastapi==0.128.5
     # via
     #   -r requirements/test.txt
@@ -232,6 +249,10 @@ pathspec==1.0.4
     # via
     #   -r requirements/test.txt
     #   mypy
+pillow==12.1.0
+    # via
+    #   -r requirements/test.txt
+    #   edx-organizations
 pluggy==1.6.0
     # via
     #   -r requirements/test.txt
diff --git a/requirements/quality.txt b/requirements/quality.txt
index ce7066d2f..c3a7c7898 100644
--- a/requirements/quality.txt
+++ b/requirements/quality.txt
@@ -100,6 +100,8 @@ django==5.2.11
     #   -r requirements/test.txt
     #   django-crum
     #   django-debug-toolbar
+    #   django-model-utils
+    #   django-simple-history
     #   django-stubs
     #   django-stubs-ext
     #   django-waffle
@@ -107,12 +109,21 @@ django==5.2.11
     #   drf-jwt
     #   edx-django-utils
     #   edx-drf-extensions
+    #   edx-organizations
 django-crum==0.7.9
     # via
     #   -r requirements/test.txt
     #   edx-django-utils
 django-debug-toolbar==6.2.0
     # via -r requirements/test.txt
+django-model-utils==5.0.0
+    # via
+    #   -r requirements/test.txt
+    #   edx-organizations
+django-simple-history==3.11.0
+    # via
+    #   -r requirements/test.txt
+    #   edx-organizations
 django-stubs==5.2.9
     # via
     #   -r requirements/test.txt
@@ -131,6 +142,7 @@ djangorestframework==3.16.1
     #   -r requirements/test.txt
     #   drf-jwt
     #   edx-drf-extensions
+    #   edx-organizations
 djangorestframework-stubs==3.16.8
     # via -r requirements/test.txt
 dnspython==2.8.0
@@ -148,13 +160,18 @@ edx-django-utils==8.0.1
     #   -r requirements/test.txt
     #   edx-drf-extensions
 edx-drf-extensions==10.6.0
-    # via -r requirements/test.txt
+    # via
+    #   -r requirements/test.txt
+    #   edx-organizations
 edx-lint==5.6.0
     # via -r requirements/quality.in
 edx-opaque-keys==3.0.0
     # via
     #   -r requirements/test.txt
     #   edx-drf-extensions
+    #   edx-organizations
+edx-organizations==7.3.0
+    # via -r requirements/test.txt
 fastapi==0.128.5
     # via
     #   -r requirements/test.txt
@@ -248,6 +265,10 @@ pathspec==1.0.4
     # via
     #   -r requirements/test.txt
     #   mypy
+pillow==12.1.0
+    # via
+    #   -r requirements/test.txt
+    #   edx-organizations
 platformdirs==4.5.1
     # via pylint
 pluggy==1.6.0
diff --git a/requirements/test.txt b/requirements/test.txt
index cda2ae220..214c1d373 100644
--- a/requirements/test.txt
+++ b/requirements/test.txt
@@ -79,6 +79,8 @@ ddt==1.7.2
     #   -r requirements/base.txt
     #   django-crum
     #   django-debug-toolbar
+    #   django-model-utils
+    #   django-simple-history
     #   django-stubs
     #   django-stubs-ext
     #   django-waffle
@@ -86,12 +88,21 @@ ddt==1.7.2
     #   drf-jwt
     #   edx-django-utils
     #   edx-drf-extensions
+    #   edx-organizations
 django-crum==0.7.9
     # via
     #   -r requirements/base.txt
     #   edx-django-utils
 django-debug-toolbar==6.2.0
     # via -r requirements/test.in
+django-model-utils==5.0.0
+    # via
+    #   -r requirements/base.txt
+    #   edx-organizations
+django-simple-history==3.11.0
+    # via
+    #   -r requirements/base.txt
+    #   edx-organizations
 django-stubs==5.2.9
     # via
     #   -r requirements/test.in
@@ -108,6 +119,7 @@ djangorestframework==3.16.1
     #   -r requirements/base.txt
     #   drf-jwt
     #   edx-drf-extensions
+    #   edx-organizations
 djangorestframework-stubs==3.16.8
     # via -r requirements/test.in
 dnspython==2.8.0
@@ -123,11 +135,16 @@ edx-django-utils==8.0.1
     #   -r requirements/base.txt
     #   edx-drf-extensions
 edx-drf-extensions==10.6.0
-    # via -r requirements/base.txt
+    # via
+    #   -r requirements/base.txt
+    #   edx-organizations
 edx-opaque-keys==3.0.0
     # via
     #   -r requirements/base.txt
     #   edx-drf-extensions
+    #   edx-organizations
+edx-organizations==7.3.0
+    # via -r requirements/base.txt
 fastapi==0.128.5
     # via import-linter
 freezegun==1.5.5
@@ -174,6 +191,10 @@ packaging==26.0
     #   pytest
 pathspec==1.0.4
     # via mypy
+pillow==12.1.0
+    # via
+    #   -r requirements/base.txt
+    #   edx-organizations
 pluggy==1.6.0
     # via
     #   pytest

From 8a62c9799301a7f88a965d794658ebb2fd4e7570 Mon Sep 17 00:00:00 2001
From: Braden MacDonald <braden@opencraft.com>
Date: Fri, 13 Feb 2026 11:50:34 -0800
Subject: [PATCH 2/2] feat: new catalog app to model course runs and catalog
 courses

---
 projects/dev.py                               |   3 +
 src/openedx_catalog/ARCHITECTURE.md           |  35 +++
 src/openedx_catalog/README.rst                |  22 ++
 src/openedx_catalog/__init__.py               |   0
 src/openedx_catalog/admin.py                  |  64 ++++++
 src/openedx_catalog/apps.py                   |  19 ++
 .../migrations/0001_initial.py                | 165 +++++++++++++++
 src/openedx_catalog/migrations/__init__.py    |   0
 src/openedx_catalog/models/__init__.py        |   6 +
 src/openedx_catalog/models/catalog_course.py  | 143 +++++++++++++
 src/openedx_catalog/models/course_run.py      | 193 +++++++++++++++++
 src/openedx_catalog/py.typed                  |   2 +
 test_settings.py                              |   3 +
 tests/openedx_catalog/__init__.py             |   0
 tests/openedx_catalog/test_models.py          | 199 ++++++++++++++++++
 15 files changed, 854 insertions(+)
 create mode 100644 src/openedx_catalog/ARCHITECTURE.md
 create mode 100644 src/openedx_catalog/README.rst
 create mode 100644 src/openedx_catalog/__init__.py
 create mode 100644 src/openedx_catalog/admin.py
 create mode 100644 src/openedx_catalog/apps.py
 create mode 100644 src/openedx_catalog/migrations/0001_initial.py
 create mode 100644 src/openedx_catalog/migrations/__init__.py
 create mode 100644 src/openedx_catalog/models/__init__.py
 create mode 100644 src/openedx_catalog/models/catalog_course.py
 create mode 100644 src/openedx_catalog/models/course_run.py
 create mode 100644 src/openedx_catalog/py.typed
 create mode 100644 tests/openedx_catalog/__init__.py
 create mode 100644 tests/openedx_catalog/test_models.py

diff --git a/projects/dev.py b/projects/dev.py
index 9f7488344..b876b2076 100644
--- a/projects/dev.py
+++ b/projects/dev.py
@@ -34,6 +34,9 @@
     "django.contrib.admin",
     "django.contrib.admindocs",
 
+    # Open edX Organizations (dependency for openedx_catalog)
+    "organizations",
+
     # Our Apps
     "openedx_tagging",
     "openedx_content",
diff --git a/src/openedx_catalog/ARCHITECTURE.md b/src/openedx_catalog/ARCHITECTURE.md
new file mode 100644
index 000000000..6feda9546
--- /dev/null
+++ b/src/openedx_catalog/ARCHITECTURE.md
@@ -0,0 +1,35 @@
+# Catalog App Architecture Diagram
+
+Here's a visual overview of how this app relates to other apps.
+
+(_Note: to see the diagram below, view this on GitHub or view in VS Code with [a Markdown-Mermaid extension](https://marketplace.visualstudio.com/items?itemName=bierner.markdown-mermaid) enabled._)
+
+```mermaid
+---
+config:
+  theme: 'forest'
+---
+flowchart TB
+    Catalog["**openedx_catalog** (CourseRun, CatalogCourse plus core metadata models, e.g. CourseSchedule. Other metadata models live in other apps but are 1:1 with CourseRun.)"]
+    Content["**openedx_content**<br>The content of the course. (publishing, containers, components, media)"]
+    Organizations["**edx-organizations** (Organization)"]
+    Enrollments["**platform: enrollments** (CourseEnrollment, CourseEnrollmentAllowed)"]
+    Modes["**platform: course_modes** (CourseMode)"]
+    Catalog <-. "Direction of this relationship TBD." .-> Content
+    Catalog -- References --> Organizations
+    Enrollments -- References --> Modes
+    Enrollments -- References --> Catalog
+
+    style Enrollments fill:#ccc
+    style Modes fill:#ccc
+    style Organizations fill:#ccc
+
+    Pathways["<a href='https://openedx.atlassian.net/wiki/spaces/OEPM/pages/5148147732/Brief+Modular+Content+Delivery+-+Platform+Strategy'>**openedx_pathways**</a> (Pathway, PathwaySchedule, PathwayEnrollment, PathwayCertificate, etc.)"]
+    Pathways -- References --> Catalog
+
+    style Pathways fill:#c0ffee,stroke-dasharray: 5 5
+
+    FutureCatalog["Future discovery service - learner-oriented, pluggable, browse/search courses and programs"] -- References --> Catalog
+    FutureCatalog <-- Plugin API --> Pathways
+    style FutureCatalog fill:#ffc0ee,stroke-dasharray: 5 5
+```
\ No newline at end of file
diff --git a/src/openedx_catalog/README.rst b/src/openedx_catalog/README.rst
new file mode 100644
index 000000000..f7ca28a0c
--- /dev/null
+++ b/src/openedx_catalog/README.rst
@@ -0,0 +1,22 @@
+Learning Core: Catalog App
+==========================
+
+Overview
+--------
+
+The ``openedx_catalog`` Django apps provides core models to represent all courses in the Open edX platform. Higher-level apps can build on these models to implement features like enrollment, grading, scheduling, exams, and much more.
+
+Motivation
+----------
+
+The existing ``CourseOverview`` model in ``openedx-platform`` is derived from various places, but mostly from the metadata fields of the root ``Course`` object stored in modulestore (MongoDB) for each course. As we slowly transition toward storing course content fully in Learning Core (in ``openedx_content``), we want to move to storing all course data and metadata in these sort of MySQL models. We're creating this new ``CourseRun`` model in ``openedx_catalog`` to support these goals:
+
+1. Provide a core model to represent each course, for foreign key purposes.
+2. To allow provisioning placeholder courses before any content even exists.
+3. To be much simpler and more performant than ``CourseOverview`` was (far fewer fields generally, fewer legacy fields, integer primary key).
+4. Perhaps to provide a transition mechanism, a pointer than can point either to modulestore content or learning core content, as we transition content storage.
+
+Architecture
+------------
+
+See `the architecture diagram <./ARCHITECTURE.md>`__. (Because we use RST for all Python READMEs, it cannot be embedded here directly.)
diff --git a/src/openedx_catalog/__init__.py b/src/openedx_catalog/__init__.py
new file mode 100644
index 000000000..e69de29bb
diff --git a/src/openedx_catalog/admin.py b/src/openedx_catalog/admin.py
new file mode 100644
index 000000000..9696399c6
--- /dev/null
+++ b/src/openedx_catalog/admin.py
@@ -0,0 +1,64 @@
+"""
+Django Admin pages for openedx_catalog.
+"""
+
+from django.contrib import admin
+from django.db.models import Count
+from django.urls import reverse
+from django.utils.html import format_html
+from django.utils.translation import gettext_lazy as _
+
+from .models import CatalogCourse, CourseRun
+
+
+class CatalogCourseAdmin(admin.ModelAdmin):
+    """
+    The CatalogCourse model admin.
+    """
+
+    list_filter = ["org_id", "language"]
+    list_display = ["display_name", "org", "course_code", "runs_summary", "language"]
+
+    def get_readonly_fields(self, request, obj: CatalogCourse | None = None):
+        if obj:  # editing an existing object
+            return self.readonly_fields + ("org", "course_code")
+        return self.readonly_fields
+
+    def get_queryset(self, request):
+        """Add the 'run_count' to the list_display queryset"""
+        qs = super().get_queryset(request)
+        qs = qs.annotate(run_count=Count("runs"))
+        return qs
+
+    def runs_summary(self, obj: CatalogCourse) -> str:
+        """Summarize the runs"""
+        if obj.run_count == 0:
+            return "-"
+        url = reverse("admin:openedx_catalog_courserun_changelist") + f"?catalog_course={obj.pk}"
+        first_few_runs = obj.runs.order_by("-run")[:3]
+        runs_summary = ", ".join(run.run for run in first_few_runs)
+        if obj.run_count > 4:
+            runs_summary += f", ... ({obj.runs_count})"
+        return format_html('<a href="{}">{}</a>', url, runs_summary)
+
+
+admin.site.register(CatalogCourse, CatalogCourseAdmin)
+
+
+class CourseRunAdmin(admin.ModelAdmin):
+    """
+    The CourseRun model admin.
+    """
+
+    list_display = ["display_name", "catalog_course", "run", "org_id"]
+    readonly_fields = ("course_id",)
+    # There may be thousands of catalog courses, so don't use <select>
+    raw_id_fields = ["catalog_course"]
+
+    def get_readonly_fields(self, request, obj: CourseRun | None = None):
+        if obj:  # editing an existing object
+            return self.readonly_fields + ("run",)
+        return self.readonly_fields
+
+
+admin.site.register(CourseRun, CourseRunAdmin)
diff --git a/src/openedx_catalog/apps.py b/src/openedx_catalog/apps.py
new file mode 100644
index 000000000..11aebd554
--- /dev/null
+++ b/src/openedx_catalog/apps.py
@@ -0,0 +1,19 @@
+"""
+App Config for the openedx_catalog app.
+"""
+
+from django.apps import AppConfig
+
+
+class CatalogAppConfig(AppConfig):
+    """
+    Initialize and configure the Catalog app
+    """
+
+    name = "openedx_catalog"
+    verbose_name = "Open edX Core > Catalog"
+    default_auto_field = "django.db.models.BigAutoField"
+    label = "openedx_catalog"
+
+    def ready(self) -> None:
+        pass
diff --git a/src/openedx_catalog/migrations/0001_initial.py b/src/openedx_catalog/migrations/0001_initial.py
new file mode 100644
index 000000000..bdf7c0825
--- /dev/null
+++ b/src/openedx_catalog/migrations/0001_initial.py
@@ -0,0 +1,165 @@
+# Generated by Django 5.2.11 on 2026-02-10 03:08
+
+import django.db.models.deletion
+import opaque_keys.edx.django.models
+import openedx_catalog.models.catalog_course
+import openedx_django_lib.fields
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    initial = True
+
+    dependencies = [
+        ("organizations", "0004_auto_20230727_2054"),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name="CatalogCourse",
+            fields=[
+                (
+                    "id",
+                    models.BigAutoField(
+                        editable=False,
+                        help_text="The internal database ID for this catalog course. Should not be exposed to users nor in APIs.",
+                        primary_key=True,
+                        serialize=False,
+                        verbose_name="Primary Key",
+                    ),
+                ),
+                (
+                    "course_code",
+                    openedx_django_lib.fields.MultiCollationCharField(
+                        db_collations={"mysql": "utf8mb4_bin", "sqlite": "BINARY"},
+                        help_text='The course ID, e.g. "Math100".',
+                        max_length=255,
+                    ),
+                ),
+                (
+                    "display_name",
+                    models.CharField(
+                        help_text='The full name of this catalog course. e.g. "Introduction to Calculus". Individual course runs may override this, e.g. "Into to Calc (Fall 2026 with Dr. Newton)".',
+                        max_length=255,
+                    ),
+                ),
+                (
+                    "language",
+                    models.CharField(
+                        default=openedx_catalog.models.catalog_course.get_default_language_code,
+                        help_text='The code representing the language of this catalog course\'s content. The first two digits must be the lowercase ISO 639-1 language code. e.g. "en", "es", "en-us", "pt-br". ',
+                        max_length=64,
+                    ),
+                ),
+                (
+                    "org",
+                    models.ForeignKey(
+                        on_delete=django.db.models.deletion.PROTECT,
+                        to="organizations.organization",
+                        to_field="short_name",
+                    ),
+                ),
+            ],
+            options={
+                "verbose_name": "Catalog Course",
+                "verbose_name_plural": "Catalog Courses",
+            },
+        ),
+        migrations.CreateModel(
+            name="CourseRun",
+            fields=[
+                (
+                    "id",
+                    models.BigAutoField(
+                        editable=False,
+                        help_text="The internal database ID for this course. Should not be exposed to users nor in APIs.",
+                        primary_key=True,
+                        serialize=False,
+                        verbose_name="Primary Key",
+                    ),
+                ),
+                (
+                    "course_id",
+                    opaque_keys.edx.django.models.CourseKeyField(
+                        editable=False,
+                        help_text="The main identifier for this course. Includes the org, course code, and run.",
+                        max_length=255,
+                        unique=True,
+                        verbose_name="Course ID",
+                    ),
+                ),
+                (
+                    "run",
+                    openedx_django_lib.fields.MultiCollationCharField(
+                        db_collations={"mysql": "utf8mb4_bin", "sqlite": "BINARY"},
+                        help_text='The code that identifies this particular run of the course, e.g. "2026", "2026Fall" or "2T2026"',
+                        max_length=128,
+                    ),
+                ),
+                (
+                    "display_name",
+                    models.CharField(
+                        blank=True,
+                        help_text='The full name of this course. e.g. "Introduction to Calculus". This is required and will override the name of the catalog course. Leave blank to use the same name as the catalog course. ',
+                        max_length=255,
+                    ),
+                ),
+                (
+                    "catalog_course",
+                    models.ForeignKey(
+                        on_delete=django.db.models.deletion.PROTECT,
+                        related_name="runs",
+                        to="openedx_catalog.catalogcourse",
+                    ),
+                ),
+            ],
+            options={
+                "verbose_name": "Course Run",
+                "verbose_name_plural": "Course Runs",
+            },
+        ),
+        migrations.AddConstraint(
+            model_name="catalogcourse",
+            constraint=models.UniqueConstraint(
+                fields=("org", "course_code"), name="oex_catalog_catalog_course_org_code_pair_uniq"
+            ),
+        ),
+        migrations.AddConstraint(
+            model_name="catalogcourse",
+            constraint=models.CheckConstraint(
+                condition=models.Q(("course_code__length__gt", 0)),
+                name="oex_catalog_catalogcourse_course_code_not_blank",
+            ),
+        ),
+        migrations.AddConstraint(
+            model_name="catalogcourse",
+            constraint=models.CheckConstraint(
+                condition=models.Q(("language__length__gt", 0)), name="oex_catalog_catalogcourse_language_not_blank"
+            ),
+        ),
+        migrations.AddConstraint(
+            model_name="catalogcourse",
+            constraint=models.CheckConstraint(
+                condition=models.Q(("display_name__length__gt", 0)),
+                name="oex_catalog_catalogcourse_display_name_not_blank",
+            ),
+        ),
+        migrations.AddConstraint(
+            model_name="courserun",
+            constraint=models.UniqueConstraint(
+                fields=("catalog_course", "run"), name="oex_catalog_courserun_catalog_course_run_uniq"
+            ),
+        ),
+        migrations.AddConstraint(
+            model_name="courserun",
+            constraint=models.CheckConstraint(
+                condition=models.Q(("run__length__gt", 0)), name="oex_catalog_courserun_run_not_blank"
+            ),
+        ),
+        migrations.AddConstraint(
+            model_name="courserun",
+            constraint=models.CheckConstraint(
+                condition=models.Q(("display_name__length__gt", 0)), name="oex_catalog_courserun_display_name_not_blank"
+            ),
+        ),
+    ]
diff --git a/src/openedx_catalog/migrations/__init__.py b/src/openedx_catalog/migrations/__init__.py
new file mode 100644
index 000000000..e69de29bb
diff --git a/src/openedx_catalog/models/__init__.py b/src/openedx_catalog/models/__init__.py
new file mode 100644
index 000000000..31da59962
--- /dev/null
+++ b/src/openedx_catalog/models/__init__.py
@@ -0,0 +1,6 @@
+"""
+Models that commprise openedx_catalog
+"""
+
+from .catalog_course import CatalogCourse
+from .course_run import CourseRun
diff --git a/src/openedx_catalog/models/catalog_course.py b/src/openedx_catalog/models/catalog_course.py
new file mode 100644
index 000000000..52f9368d0
--- /dev/null
+++ b/src/openedx_catalog/models/catalog_course.py
@@ -0,0 +1,143 @@
+"""
+CourseRun model
+"""
+
+from django.conf import settings
+from django.core.exceptions import ValidationError
+from django.db import models
+from django.db.models.functions import Length
+from django.utils.translation import gettext_lazy as _
+
+from organizations.models import Organization
+from openedx_django_lib.fields import case_sensitive_char_field
+
+
+def get_default_language_code() -> str:
+    return settings.LANGUAGE_CODE
+
+
+# Make 'length' available for CHECK constraints. OK if this is called multiple times.
+models.CharField.register_lookup(Length)
+
+
+class CatalogCourse(models.Model):
+    """
+    A **catalog course** is a set of course runs.
+
+    For example, the "Math 100" catalog course is comprised of one or more
+    "course runs" (e.g. "Math 100 2025Fall", "Math 100 2026Spring").
+
+    Note that most parts of the Open edX system only need to know/care about
+    course runs, not catalog courses, but this package nevertheless provides the
+    CatalogCourse model as a foundation for the few use cases that require it.
+
+    ⚠️ `CatalogCourse`s and `CourseRun`s may exist as marketing/enrollment
+    placeholders for courses that do not yet otherwise exist (do not yet have
+    content). So in general, you should not assume that any related models /
+    content exist just because the `CatalogCourse` or `CourseRun` exists.
+
+    A `CatalogCourse` may exist without any `CourseRun`s, but a `CourseRun`
+    cannot exist without a `CatalogCourse`, and this is enforced by the
+    database.
+
+    🔍 This model is intentionally as minimal as possible. For anything else you
+    may want to do that involves new fields, please add them via a related model
+    in your own app, and make a `ForeignKey` or `OneToOneField` relationship to
+    this model. (Unless you really think it's something core that all catalog
+    courses in all instances of Open edX will need.)
+    """
+
+    id = models.BigAutoField(
+        primary_key=True,
+        verbose_name=_("Primary Key"),
+        help_text=_("The internal database ID for this catalog course. Should not be exposed to users nor in APIs."),
+        editable=False,
+    )
+    org = models.ForeignKey(
+        Organization,
+        to_field="short_name",  # The org string like "MITx" _is_ the foreign key, to save you a join most of the time.
+        on_delete=models.PROTECT,
+        null=False,
+    )
+    course_code = case_sensitive_char_field(
+        max_length=255,
+        blank=False,
+        null=False,
+        help_text=_('The course ID, e.g. "Math100".'),
+    )
+    # Note: display_name should never be blank. But we previously didn't store a name for catalog courses in the core.
+    # For backfilling, if there is only one run, we use that run's name as the catalog course name. Otherwise, we can
+    # use the org + course code as the display name.
+    display_name = models.CharField(
+        max_length=255,
+        blank=False,
+        help_text=_(
+            'The full name of this catalog course. e.g. "Introduction to Calculus". '
+            'Individual course runs may override this, e.g. "Into to Calc (Fall 2026 with Dr. Newton)".'
+        ),
+    )
+    language = models.CharField(
+        max_length=64,
+        blank=False,
+        null=False,
+        default=get_default_language_code,
+        help_text=_(
+            "The code representing the language of this catalog course's content. "
+            "The first two digits must be the lowercase ISO 639-1 language code. "
+            'e.g. "en", "es", "en-us", "pt-br". '
+        ),
+    )
+
+    # 🛑 Avoid adding additional fields here. The core Open edX platform doesn't do much with catalog courses, so
+    #    we don't need "description", "visibility", "prereqs", or anything else. If you want to use such fields and
+    #    expose them to users, you'll need to supplement this with additional data/models as mentioned in the docstring.
+
+    def clean(self):
+        """
+        Validation.
+
+        This function is only used by the Django admin, or if manually called.
+        """
+        super().clean()
+
+        if self.language.lower() != self.language:
+            raise ValidationError("The language code must be lowercase, e.g. 'en'")
+        if len(self.language) < 2:
+            raise ValidationError("The language code must be two characters or more")
+        if len(self.language) > 2 and self.language[2] not in ("-", "@"):
+            raise ValidationError(
+                "If the 'language' code is more than two characers it must be separated with a hyphen or @ symbol, "
+                "e.g. 'zh-hk', not 'zh_hk' nor 'Chinese'."
+            )
+        # We could also validate that language is one of settings.LANGUAGES, but that setting can change over time.
+
+    def save(self, *args, **kwargs):
+        """Save the model, with defaults and validation."""
+        # Set a default value for display_name:
+        if not self.display_name:
+            self.display_name = self.course_code
+        self.full_clean()
+        super().save(*args, **kwargs)
+
+    def __str__(self):
+        return f"{self.display_name} ({self.org_id} {self.course_code})"
+
+    class Meta:
+        verbose_name = _("Catalog Course")
+        verbose_name_plural = _("Catalog Courses")
+        constraints = [
+            models.UniqueConstraint(
+                fields=["org", "course_code"],
+                name="oex_catalog_catalog_course_org_code_pair_uniq",
+            ),
+            # Enforce at the DB level that these required fields are not blank:
+            models.CheckConstraint(
+                condition=models.Q(course_code__length__gt=0), name="oex_catalog_catalogcourse_course_code_not_blank"
+            ),
+            models.CheckConstraint(
+                condition=models.Q(language__length__gt=0), name="oex_catalog_catalogcourse_language_not_blank"
+            ),
+            models.CheckConstraint(
+                condition=models.Q(display_name__length__gt=0), name="oex_catalog_catalogcourse_display_name_not_blank"
+            ),
+        ]
diff --git a/src/openedx_catalog/models/course_run.py b/src/openedx_catalog/models/course_run.py
new file mode 100644
index 000000000..12472d62e
--- /dev/null
+++ b/src/openedx_catalog/models/course_run.py
@@ -0,0 +1,193 @@
+"""
+CourseRun model
+"""
+
+from django.core.exceptions import ValidationError
+from django.contrib import admin
+from django.db import models
+from django.db.models.functions import Length
+from django.utils.translation import gettext_lazy as _
+from opaque_keys import InvalidKeyError
+from opaque_keys.edx.locator import CourseLocator
+from opaque_keys.edx.django.models import CourseKeyField
+
+from openedx_django_lib.fields import case_sensitive_char_field
+
+from .catalog_course import CatalogCourse
+
+# Make 'length' available for CHECK constraints. OK if this is called multiple times.
+models.CharField.register_lookup(Length)
+
+
+class CourseRun(models.Model):
+    """
+    The principal canonical model for courses (course runs).
+
+    This is a NEW model (as of 2026). Going forward:
+    Anytime you need to reference a course [run] in a django model, you should
+    do so by creating a foreign key to this model. However, any APIs or events
+    should always identify courses by their full string course ID
+    ("course-v1:...") and never expose the integer primary key of this model.
+
+    Note: throughout the system, we often abbreviate "course run" as just
+    "course", so the two concepts are usually interchangeable. The _set_ of runs
+    of a given course should always be called a "catalog course" in the code to
+    avoid ambiguity. That is, a "catalog course" (e.g. "Math 100") is comprised
+    of one or more "course runs" (e.g. "Math 100 2025Fall", "Math 100
+    2026Spring"), and we generally refer to those course runs as "courses". Most
+    parts of the Open edX system only need to know/care about course runs, not
+    catalog courses.
+
+    ⚠️ `CourseRun`s (this model) may exist as marketing/enrollment placeholders
+    for courses that do not yet otherwise exist (do not yet have content). So
+    in general, you should not assume that any related models/content exist just
+    because the `CourseRun` exists.
+
+    `CourseRun` is NOT a generic model for a learning context; this model only
+    represents courses and never represents content libraries, pathways, etc.
+
+    Existing related models:
+    - This `CourseRun` model should generally be 1:1 with `CourseOverview`;
+      however, `CourseOverview` has a number of design issues so we intend to
+      slowly transition all use cases to this new model. (In particular,
+      `CourseOverview` uses very large string primary keys; has way too many
+      fields; and has weird magic behavior when some fields are accessed).
+        * Do not assume that `CourseOverview` exists just because `CourseRun`
+          exists, nor that `CourseOverview` can be created from a `CourseRun`
+          alone.
+    - For modulestore courses (in MongoDB), there is a 1:1 relationship to
+      `SplitModulestoreCourseIndex`, if content exists, but this relationship
+      should only be used for very low-level code, and we intend to delete it in
+      the future as content is migrated to Learning Core.
+
+    Future related models:
+    - In the future, course metadata should be attached via a series of models,
+      like `CourseSchedule`, `CourseGradingPolicy`, `CourseEnrollmentOptions`,
+      `CourseMode`, `CoursePricing`, etc. Each of these models may be part of
+      this catalog app or other apps. They should not be versioned, but should
+      use the `HistoricalRecords()` history from `django-simple-history` to
+      preserve a record of all changes.
+    - In the future, there will be a relationship to Learning Package. Several
+      course runs from the same catalog course may be stored in the same
+      learning package.
+    """
+
+    # Use this field for relationships within the database:
+    id = models.BigAutoField(
+        primary_key=True,
+        verbose_name=_("Primary Key"),
+        help_text=_("The internal database ID for this course. Should not be exposed to users nor in APIs."),
+        editable=False,
+    )
+    # TODO: write tests to verify that this is case sensitive.
+    course_id = CourseKeyField(
+        max_length=255,  # CourseKeyField should specify this, not us. But Django complains if it's missing.
+        unique=True,
+        verbose_name=_("Course ID"),
+        help_text=_("The main identifier for this course. Includes the org, course code, and run."),
+        editable=False,
+    )
+    # The catalog course stores the 'org' and 'run' fields, which must match the ones in the course ID.
+    # Note: there is no need to load this relationship to get 'org' or 'run'; get them from `course_id` instead.
+    catalog_course = models.ForeignKey(
+        CatalogCourse,
+        on_delete=models.PROTECT,
+        null=False,
+        related_name="runs",
+    )
+    run = case_sensitive_char_field(
+        max_length=128,
+        blank=False,
+        null=False,
+        help_text=_('The code that identifies this particular run of the course, e.g. "2026", "2026Fall" or "2T2026"'),
+    )
+    display_name = models.CharField(
+        max_length=255,
+        blank=True,  # Only allowed to be blank temporarily when creating a new instance in the Django admin form
+        help_text=_(
+            'The full name of this course. e.g. "Introduction to Calculus". '
+            "This is required and will override the name of the catalog course. "
+            "Leave blank to use the same name as the catalog course. "
+        ),
+    )
+
+    # 🛑 Avoid adding additional fields here. This model will likely be loaded a lot, so we want to keep it small. Most
+    #    course-level configuration should be stored on dedicated models like CourseSchedule with a relationship to
+    #    this one.
+
+    @property
+    @admin.display(ordering=("catalog_course__org"))
+    def org_id(self) -> str:
+        """Get the org code (Organization short_name) of this course, e.g. "MITx" """
+        # This is not just called 'org' to distinguish it from loading the whole Organization model.
+        # Note: 'self.catalog_course.org_id' may require a JOIN/query, but self.course_id.org does not.
+        return self.course_id.org
+
+    @property
+    def course_code(self) -> str:
+        """Get the course code of this course, e.g. "Math100" """
+        # Note: 'self.catalog_course.course_code' may require a JOIN/query, but self.course_id.course does not.
+        return self.course_id.course
+
+    # Do we want a "deleted" flag to mark courses as deleted?
+    # Do we want a "created" timestamp? Probably don't need "modified" as this model is almost immutable other than
+    # display_name.
+
+    # In the future, either this model or CatalogCourse will have:
+    # learning_package = models.ForeignKey(LearningPackage)
+
+    # In the future, this model will likely have a relationship to the
+    # OutlineRoot which would be an `openedx_content` `Container` instance that
+    # holds the conten tree (Sections, Subsections, Units, etc.). For now, if
+    # the content exists, it will be in modulestore instead (you can get the
+    # `SplitModulestoreCourseIndex` using TODO: define API method).
+
+    def clean(self):
+        """Defaults and validation of model fields"""
+        if self.catalog_course and not self.display_name:
+            # For convenience, when creating a CourseRun, if the display_name is blank, copy it from the catalog course
+            self.display_name = self.catalog_course.display_name
+        if not self.course_id:
+            # For now we can assume that the course ID is going to be a CourseLocator, so generate it if missing.
+            try:
+                self.course_id = CourseLocator(
+                    org=self.catalog_course.org_id,
+                    course=self.catalog_course.course_code,
+                    run=self.run,
+                )
+            except InvalidKeyError:
+                raise ValidationError("Could not generate a valid course_id.")
+
+        if self.org_id != self.course_id.org:
+            raise ValidationError("The CatalogCourse 'org' field should match the org in the course_id key.")
+
+        if self.course_code != self.course_id.course:
+            raise ValidationError("The CatalogCourse 'course_code' field should match the org in the course_id key.")
+
+        if self.run != self.course_id.run:
+            raise ValidationError("The CourseRun 'run' field should match the run in the course_id key.")
+
+        super().clean()
+
+    def save(self, *args, **kwargs):
+        """Save the model, with defaults and validation."""
+        self.full_clean()
+        super().save(*args, **kwargs)
+
+    def __str__(self):
+        return f"{self.display_name} ({self.org_id} {self.course_code} {self.run})"
+
+    class Meta:
+        verbose_name = _("Course Run")
+        verbose_name_plural = _("Course Runs")
+        constraints = [
+            models.UniqueConstraint(
+                fields=["catalog_course", "run"],
+                name="oex_catalog_courserun_catalog_course_run_uniq",
+            ),
+            # Enforce at the DB level that these required fields are not blank:
+            models.CheckConstraint(condition=models.Q(run__length__gt=0), name="oex_catalog_courserun_run_not_blank"),
+            models.CheckConstraint(
+                condition=models.Q(display_name__length__gt=0), name="oex_catalog_courserun_display_name_not_blank"
+            ),
+        ]
diff --git a/src/openedx_catalog/py.typed b/src/openedx_catalog/py.typed
new file mode 100644
index 000000000..d1c77febe
--- /dev/null
+++ b/src/openedx_catalog/py.typed
@@ -0,0 +1,2 @@
+# The presence of this file tells Python that this entire package includes type
+# information. Without it, imports of `openedx_catalog` will be missing types.
diff --git a/test_settings.py b/test_settings.py
index b1df13adf..8b0a970ac 100644
--- a/test_settings.py
+++ b/test_settings.py
@@ -50,11 +50,14 @@ def root(*args):
     'django.contrib.admindocs',
     # Debugging
     "debug_toolbar",
+    # Open edX Organizations (dependency for openedx_catalog)
+    "organizations",
     # django-rules based authorization
     'rules.apps.AutodiscoverRulesConfig',
     # Our own apps
     "openedx_tagging",
     "openedx_content",
+    "openedx_catalog",
     *openedx_content_backcompat_apps_to_install(),
 ]
 
diff --git a/tests/openedx_catalog/__init__.py b/tests/openedx_catalog/__init__.py
new file mode 100644
index 000000000..e69de29bb
diff --git a/tests/openedx_catalog/test_models.py b/tests/openedx_catalog/test_models.py
new file mode 100644
index 000000000..84482451f
--- /dev/null
+++ b/tests/openedx_catalog/test_models.py
@@ -0,0 +1,199 @@
+"""
+Tests related to the Component models
+"""
+
+import ddt  # type: ignore[import]
+from django.core.exceptions import ValidationError
+from django.db.utils import IntegrityError
+from django.test import TestCase, override_settings
+from organizations.api import ensure_organization  # type: ignore[import]
+import pytest
+
+from openedx_catalog.models import CatalogCourse, CourseRun
+
+
+@ddt.ddt
+class TestCatalogCourseModel(TestCase):
+    """
+    Low-level tests of the CatalogCourse model.
+    """
+
+    @classmethod
+    def setUpClass(cls):
+        ensure_organization("Org1")
+        return super().setUpClass()
+
+    # org field tests:
+
+    def test_invalid_org(self) -> None:
+        """Organization must exist in the DB before CatalogCourse can be created"""
+
+        def create():
+            CatalogCourse.objects.create(org_id="NewOrg", course_code="Python100")
+
+        with pytest.raises(ValidationError):  # Or it would be IntegrityError if we didn't call full_clean() via save()
+            create()
+        ensure_organization("NewOrg")
+        create()
+
+    def test_org_case_sensitive(self) -> None:
+        """
+        Test that we can have two different catalog courses whose orgs differ
+        only by case.
+        """
+        course_code = "Python100"
+        org1 = ensure_organization("caseORG")
+        org2 = ensure_organization("CASEorg")
+        assert org1["id"] != org2["id"]
+        cc1 = CatalogCourse.objects.create(org_id="caseORG", course_code=course_code)
+        cc2 = CatalogCourse.objects.create(org_id="CASEorg", course_code=course_code)
+        cc1.refresh_from_db()
+        cc2.refresh_from_db()
+        assert cc1.org_id == "caseORG"
+        assert cc2.org_id == "CASEorg"
+
+    # course_code field tests:
+
+    def test_course_code_unique(self) -> None:
+        """
+        Test that course code is unique per org.
+        """
+        course_code = "Python100"
+        ensure_organization("Org2")
+        CatalogCourse.objects.create(org_id="Org1", course_code=course_code)
+        with pytest.raises(ValidationError):
+            CatalogCourse.objects.create(org_id="Org1", course_code=course_code)
+        # But different org is fine:
+        CatalogCourse.objects.create(org_id="Org2", course_code=course_code)
+
+    def test_course_code_case_sensitive(self) -> None:
+        """
+        Test that we can have two different catalog courses whose course code
+        differs only by case. i.e. that the "course code" field is case
+        sensitive.
+        """
+        org_id = "Org1"
+        cc1 = CatalogCourse.objects.create(org_id=org_id, course_code="Python100")
+        cc2 = CatalogCourse.objects.create(org_id=org_id, course_code="pYTHon100")
+        cc1.refresh_from_db()
+        cc2.refresh_from_db()
+        assert cc1.course_code == "Python100"
+        assert cc2.course_code == "pYTHon100"
+
+    def test_course_code_required(self) -> None:
+        """Test that course_code cannot be blank"""
+        cc = CatalogCourse.objects.create(org_id="Org1", course_code="Python100", display_name="Python 100")
+        with pytest.raises(IntegrityError):
+            # Using .update() will bypass all checks and defaults in save()/clean(), to see if the DB enforces this:
+            CatalogCourse.objects.filter(pk=cc.pk).update(course_code="")
+
+    # display_name field tests:
+
+    def test_display_name_default(self) -> None:
+        """Test that display_name has a default"""
+        cc = CatalogCourse.objects.create(org_id="Org1", course_code="Python100")
+        assert cc.display_name == "Python100"
+
+    def test_display_name_required(self) -> None:
+        """Test that display_name cannot be blank"""
+        cc = CatalogCourse.objects.create(org_id="Org1", course_code="Python100", display_name="Python 100")
+        with pytest.raises(IntegrityError):
+            # Using .update() will bypass all checks and defaults in save()/clean(), to see if the DB enforces this:
+            CatalogCourse.objects.filter(pk=cc.pk).update(display_name="")
+
+    def test_display_name_unicode(self) -> None:
+        """Test that display_name can handle any valid unicode value"""
+        # If it works with emojis, it should work with any human language characters.
+        display_name = "Happy 😊"
+        cc = CatalogCourse.objects.create(org_id="Org1", course_code="HAPPY", display_name=display_name)
+        cc.refresh_from_db()
+        assert cc.display_name == display_name
+
+    # language code field tests:
+
+    def test_language_code_default(self) -> None:
+        """Test that 'language' has a default"""
+        cc = CatalogCourse.objects.create(org_id="Org1", course_code="Python100")
+        # Our test settings don't specify a LANGUAGE_CODE, so this should be the Django default of "en-us"
+        # https://docs.djangoproject.com/en/6.0/ref/settings/#language-code
+        assert cc.language == "en-us"
+
+    @override_settings(LANGUAGE_CODE="fr")
+    def test_language_code_default2(self) -> None:
+        """Test that 'language' gets its default from settings"""
+        cc = CatalogCourse.objects.create(org_id="Org1", course_code="Python100")
+        assert cc.language == "fr"
+
+    @ddt.data(
+        # ✅ Valid language codes:
+        ("en", True),
+        ("en-us", True),
+        ("fr", True),
+        ("pt-br", True),
+        ("ca@valencia", True),  # This is one of the valid values in openedx-platform's default LANGUAGES setting
+        # ❌ Invalid language codes:
+        ("", False),
+        ("x", False),
+        ("en-US", False),  # must be lowercase
+        ("en_us", False),  # hyphen, not underscore, for consistency
+        ("English", False),
+        ("english", False),
+    )
+    @ddt.unpack
+    def test_language_code_validation(self, language_code: str, valid: bool) -> None:
+        """Test that language codes must follow the prescribed format"""
+
+        def create():
+            CatalogCourse.objects.create(org_id="Org1", course_code="Python100", language=language_code)
+
+        if valid:
+            create()
+        else:
+            with pytest.raises(ValidationError):
+                create()
+
+
+@ddt.ddt
+class TestCourseRunModel(TestCase):
+    """
+    Low-level tests of the CourseRun model.
+    """
+
+    @classmethod
+    def setUpClass(cls):
+        ensure_organization("Org1")
+        cls.catalog_course = CatalogCourse.objects.create(org_id="Org1", course_code="Python100")
+        return super().setUpClass()
+
+    # run field tests:
+
+    def test_run_unique(self) -> None:
+        """
+        Test that run is unique per catalog course.
+        """
+        run = "Fall2026"
+        catalog_course2 = CatalogCourse.objects.create(org_id="Org1", course_code="Systems300")
+        CourseRun.objects.create(catalog_course=self.catalog_course, run=run)
+        with pytest.raises(ValidationError):
+            CourseRun.objects.create(catalog_course=self.catalog_course, run=run)
+        # But different catalog course with the same run name is fine:
+        CourseRun.objects.create(catalog_course=catalog_course2, run=run)
+
+    def test_run_case_sensitive(self) -> None:
+        """
+        Test that we can have two different course runs whose run code differs
+        only by case.
+        """
+        course1 = CourseRun.objects.create(catalog_course=self.catalog_course, run="fall2026")
+        course2 = CourseRun.objects.create(catalog_course=self.catalog_course, run="FALL2026")
+        course1.refresh_from_db()
+        course2.refresh_from_db()
+        assert course1.run == "fall2026"
+        assert course2.run == "FALL2026"
+
+    def test_run_required(self) -> None:
+        """Test that run cannot be blank"""
+        course = CourseRun.objects.create(catalog_course=self.catalog_course, run="fall2026")
+        with pytest.raises(IntegrityError):
+            # Using .update() will bypass all checks and defaults in save()/clean(), to see if the DB enforces this:
+            CourseRun.objects.filter(pk=course.pk).update(run="")