diff --git a/src/openedx_content/applets/backup_restore/serializers.py b/src/openedx_content/applets/backup_restore/serializers.py
index d8f7a5c15..69abbdfe2 100644
--- a/src/openedx_content/applets/backup_restore/serializers.py
+++ b/src/openedx_content/applets/backup_restore/serializers.py
@@ -156,10 +156,24 @@ class CollectionSerializer(serializers.Serializer):  # pylint: disable=abstract-
     Serializer for collections.
     """
     title = serializers.CharField(required=True)
-    key = serializers.CharField(required=True)
+    # 'collection_code' is the current field name; 'key' is the old name kept for
+    # back-compat with archives written before the rename.  At least one must be present.
+    collection_code = serializers.CharField(required=False)
+    key = serializers.CharField(required=False)
     description = serializers.CharField(required=True, allow_blank=True)
     entities = serializers.ListField(
         child=serializers.CharField(),
         required=True,
         allow_empty=True,
     )
+
+    def validate(self, attrs):
+        # Prefer 'collection_code'; fall back to legacy 'key'.  Always remove
+        # both so only the normalised 'collection_code' key reaches the caller.
+        code = attrs.pop("collection_code", None)
+        legacy_key = attrs.pop("key", None)
+        code = code or legacy_key
+        if not code:
+            raise serializers.ValidationError("Either 'collection_code' or 'key' is required.")
+        attrs["collection_code"] = code
+        return attrs
diff --git a/src/openedx_content/applets/backup_restore/toml.py b/src/openedx_content/applets/backup_restore/toml.py
index d39861803..4470834c6 100644
--- a/src/openedx_content/applets/backup_restore/toml.py
+++ b/src/openedx_content/applets/backup_restore/toml.py
@@ -220,7 +220,10 @@ def toml_collection(collection: Collection, entity_keys: list[str]) -> str:
 
     collection_table = tomlkit.table()
     collection_table.add("title", collection.title)
-    collection_table.add("key", collection.key)
+    # Write both names so that older software (which reads 'key') stays compatible
+    # with archives produced after the Collection.key -> Collection.collection_code rename.
+    collection_table.add("key", collection.collection_code)
+    collection_table.add("collection_code", collection.collection_code)
     collection_table.add("description", collection.description)
     collection_table.add("created", collection.created)
     collection_table.add("entities", entities_array)
diff --git a/src/openedx_content/applets/backup_restore/zipper.py b/src/openedx_content/applets/backup_restore/zipper.py
index 29b9638e9..7cda1e14f 100644
--- a/src/openedx_content/applets/backup_restore/zipper.py
+++ b/src/openedx_content/applets/backup_restore/zipper.py
@@ -401,7 +401,7 @@ def create_zip(self, path: str) -> None:
             collections = self.get_collections()
 
             for collection in collections:
-                collection_hash_slug = self.get_entity_toml_filename(collection.key)
+                collection_hash_slug = self.get_entity_toml_filename(collection.collection_code)
                 collection_toml_file_path = collections_folder / f"{collection_hash_slug}.toml"
                 entity_keys_related = collection.entities.order_by("key").values_list("key", flat=True)
                 self.add_file_to_zip(
@@ -779,7 +779,7 @@ def _save_collections(self, learning_package, collections):
             )
             collection = collections_api.add_to_collection(
                 learning_package_id=learning_package.id,
-                key=collection.key,
+                collection_code=collection.collection_code,
                 entities_qset=publishing_api.get_publishable_entities(learning_package.id).filter(key__in=entities)
             )
 
diff --git a/src/openedx_content/applets/collections/admin.py b/src/openedx_content/applets/collections/admin.py
index eb0685a27..41db9e082 100644
--- a/src/openedx_content/applets/collections/admin.py
+++ b/src/openedx_content/applets/collections/admin.py
@@ -13,14 +13,14 @@ class CollectionAdmin(admin.ModelAdmin):
 
     Allows users to easily disable/enable (aka soft delete and restore) or bulk delete Collections.
     """
-    readonly_fields = ["key", "learning_package"]
+    readonly_fields = ["collection_code", "learning_package"]
     list_filter = ["enabled"]
-    list_display = ["key", "title", "enabled", "modified"]
+    list_display = ["collection_code", "title", "enabled", "modified"]
     fieldsets = [
         (
             "",
             {
-                "fields": ["key", "learning_package"],
+                "fields": ["collection_code", "learning_package"],
             }
         ),
         (
diff --git a/src/openedx_content/applets/collections/api.py b/src/openedx_content/applets/collections/api.py
index 8ab8d9cbf..b436033b8 100644
--- a/src/openedx_content/applets/collections/api.py
+++ b/src/openedx_content/applets/collections/api.py
@@ -34,7 +34,7 @@
 
 def create_collection(
     learning_package_id: int,
-    key: str,
+    collection_code: str,
     *,
     title: str,
     created_by: int | None,
@@ -44,35 +44,37 @@ def create_collection(
     """
     Create a new Collection
     """
-    collection = Collection.objects.create(
+    collection = Collection(
         learning_package_id=learning_package_id,
-        key=key,
+        collection_code=collection_code,
         title=title,
         created_by_id=created_by,
         description=description,
         enabled=enabled,
     )
+    collection.full_clean()
+    collection.save()
     return collection
 
 
-def get_collection(learning_package_id: int, collection_key: str) -> Collection:
+def get_collection(learning_package_id: int, collection_code: str) -> Collection:
     """
     Get a Collection by ID
     """
-    return Collection.objects.get_by_key(learning_package_id, collection_key)
+    return Collection.objects.get_by_code(learning_package_id, collection_code)
 
 
 def update_collection(
     learning_package_id: int,
-    key: str,
+    collection_code: str,
     *,
     title: str | None = None,
     description: str | None = None,
 ) -> Collection:
     """
-    Update a Collection identified by the learning_package_id + key.
+    Update a Collection identified by the learning_package_id + collection_code.
     """
-    collection = get_collection(learning_package_id, key)
+    collection = get_collection(learning_package_id, collection_code)
 
     # If no changes were requested, there's nothing to update, so just return
     # the Collection as-is
@@ -90,17 +92,17 @@ def update_collection(
 
 def delete_collection(
     learning_package_id: int,
-    key: str,
+    collection_code: str,
     *,
     hard_delete=False,
 ) -> Collection:
     """
-    Disables or deletes a collection identified by the given learning_package + key.
+    Disables or deletes a collection identified by the given learning_package + collection_code.
 
     By default (hard_delete=False), the collection is "soft deleted", i.e disabled.
     Soft-deleted collections can be re-enabled using restore_collection.
     """
-    collection = get_collection(learning_package_id, key)
+    collection = get_collection(learning_package_id, collection_code)
 
     if hard_delete:
         collection.delete()
@@ -112,12 +114,12 @@ def delete_collection(
 
 def restore_collection(
     learning_package_id: int,
-    key: str,
+    collection_code: str,
 ) -> Collection:
     """
     Undo a "soft delete" by re-enabling a Collection.
     """
-    collection = get_collection(learning_package_id, key)
+    collection = get_collection(learning_package_id, collection_code)
 
     collection.enabled = True
     collection.save()
@@ -126,7 +128,7 @@ def restore_collection(
 
 def add_to_collection(
     learning_package_id: int,
-    key: str,
+    collection_code: str,
     entities_qset: QuerySet[PublishableEntity],
     created_by: int | None = None,
 ) -> Collection:
@@ -146,10 +148,10 @@ def add_to_collection(
     if invalid_entity:
         raise ValidationError(
             f"Cannot add entity {invalid_entity.pk} in learning package {invalid_entity.learning_package_id} "
-            f"to collection {key} in learning package {learning_package_id}."
+            f"to collection {collection_code} in learning package {learning_package_id}."
         )
 
-    collection = get_collection(learning_package_id, key)
+    collection = get_collection(learning_package_id, collection_code)
     collection.entities.add(
         *entities_qset.all(),
         through_defaults={"created_by_id": created_by},
@@ -162,7 +164,7 @@ def add_to_collection(
 
 def remove_from_collection(
     learning_package_id: int,
-    key: str,
+    collection_code: str,
     entities_qset: QuerySet[PublishableEntity],
 ) -> Collection:
     """
@@ -174,7 +176,7 @@ def remove_from_collection(
 
     Returns the updated Collection.
     """
-    collection = get_collection(learning_package_id, key)
+    collection = get_collection(learning_package_id, collection_code)
 
     collection.entities.remove(*entities_qset.all())
     collection.modified = datetime.now(tz=timezone.utc)
@@ -196,7 +198,7 @@ def get_entity_collections(learning_package_id: int, entity_key: str) -> QuerySe
     return entity.collections.filter(enabled=True).order_by("pk")
 
 
-def get_collection_entities(learning_package_id: int, collection_key: str) -> QuerySet[PublishableEntity]:
+def get_collection_entities(learning_package_id: int, collection_code: str) -> QuerySet[PublishableEntity]:
     """
     Returns a QuerySet of PublishableEntities in a Collection.
 
@@ -204,7 +206,7 @@ def get_collection_entities(learning_package_id: int, collection_key: str) -> Qu
     """
     return PublishableEntity.objects.filter(
         learning_package_id=learning_package_id,
-        collections__key=collection_key,
+        collections__collection_code=collection_code,
     ).order_by("pk")
 
 
diff --git a/src/openedx_content/applets/collections/models.py b/src/openedx_content/applets/collections/models.py
index 2f315b247..3258ccc9c 100644
--- a/src/openedx_content/applets/collections/models.py
+++ b/src/openedx_content/applets/collections/models.py
@@ -70,7 +70,7 @@
 from django.db import models
 from django.utils.translation import gettext_lazy as _
 
-from openedx_django_lib.fields import MultiCollationTextField, case_insensitive_char_field, key_field
+from openedx_django_lib.fields import MultiCollationTextField, case_insensitive_char_field, code_field
 from openedx_django_lib.validators import validate_utc_datetime
 
 from ..publishing.models import LearningPackage, PublishableEntity
@@ -85,12 +85,12 @@ class CollectionManager(models.Manager):
     """
     Custom manager for Collection class.
     """
-    def get_by_key(self, learning_package_id: int, key: str):
+    def get_by_code(self, learning_package_id: int, collection_code: str):
         """
-        Get the Collection for the given Learning Package + key.
+        Get the Collection for the given Learning Package + collection code.
         """
         return self.select_related('learning_package') \
-                   .get(learning_package_id=learning_package_id, key=key)
+                   .get(learning_package_id=learning_package_id, collection_code=collection_code)
 
 
 class Collection(models.Model):
@@ -105,10 +105,11 @@ class Collection(models.Model):
     learning_package = models.ForeignKey(LearningPackage, on_delete=models.CASCADE)
 
     # Every collection is uniquely and permanently identified within its learning package
-    # by a 'key' that is set during creation. Both will appear in the
+    # by a 'code' that is set during creation. Both will appear in the
     # collection's opaque key:
-    # e.g. "lib-collection:lib:key" is the opaque key for a library collection.
-    key = key_field(db_column='_key')
+    # e.g. "lib-collection:{org_code}:{library_code}:{collection_code}"
+    #       is the opaque key for a library collection.
+    collection_code = code_field()
 
     title = case_insensitive_char_field(
         null=False,
@@ -170,11 +171,11 @@ class Collection(models.Model):
     class Meta:
         verbose_name_plural = "Collections"
         constraints = [
-            # Keys are unique within a given LearningPackage.
+            # Collection codes are unique within a given LearningPackage.
             models.UniqueConstraint(
                 fields=[
                     "learning_package",
-                    "key",
+                    "collection_code",
                 ],
                 name="oel_coll_uniq_lp_key",
             ),
@@ -196,7 +197,7 @@ def __str__(self) -> str:
         """
         User-facing string representation of a Collection.
         """
-        return f"<{self.__class__.__name__}> (lp:{self.learning_package_id} {self.key}:{self.title})"
+        return f"<{self.__class__.__name__}> (lp:{self.learning_package_id} {self.collection_code}:{self.title})"
 
 
 class CollectionPublishableEntity(models.Model):
diff --git a/src/openedx_content/applets/components/api.py b/src/openedx_content/applets/components/api.py
index 46de5356e..e7c4bf8c8 100644
--- a/src/openedx_content/applets/components/api.py
+++ b/src/openedx_content/applets/components/api.py
@@ -436,7 +436,7 @@ def get_components(  # pylint: disable=too-many-positional-arguments
 
 def get_collection_components(
     learning_package_id: int,
-    collection_key: str,
+    collection_code: str,
 ) -> QuerySet[Component]:
     """
     Returns a QuerySet of Components relating to the PublishableEntities in a Collection.
@@ -445,7 +445,7 @@ def get_collection_components(
     """
     return Component.objects.filter(
         learning_package_id=learning_package_id,
-        publishable_entity__collections__key=collection_key,
+        publishable_entity__collections__collection_code=collection_code,
     ).order_by('pk')
 
 
diff --git a/src/openedx_content/applets/components/models.py b/src/openedx_content/applets/components/models.py
index de93680fd..3ec181fa2 100644
--- a/src/openedx_content/applets/components/models.py
+++ b/src/openedx_content/applets/components/models.py
@@ -1,5 +1,5 @@
 """
-The model hierarchy is Component -> ComponentVersion -> Media.
+The model hierarchy is Component -> ComponentVersion -> Content.
 
 A Component is an entity like a Problem or Video. It has enough information to
 identify the Component and determine what the handler should be (e.g. XBlock
@@ -10,7 +10,7 @@
 publishing app. Component maps 1:1 to PublishableEntity and ComponentVersion
 maps 1:1 to PublishableEntityVersion.
 
-Multiple pieces of Media may be associated with a ComponentVersion, through
+Multiple pieces of Content may be associated with a ComponentVersion, through
 the ComponentVersionMedia model. ComponentVersionMedia allows to specify a
 ComponentVersion-local identifier. We're using this like a file path by
 convention, but it's possible we might want to have special identifiers later.
@@ -91,7 +91,7 @@ class Component(PublishableEntityMixin):
     Problem), but little beyond that.
 
     A Component will have many ComponentVersions over time, and most metadata is
-    associated with the ComponentVersion model and the Media that
+    associated with the ComponentVersion model and the Content that
     ComponentVersions are associated with.
 
     A Component belongs to exactly one LearningPackage.
@@ -199,7 +199,7 @@ class ComponentVersion(PublishableEntityVersionMixin):
     """
     A particular version of a Component.
 
-    This holds the media using a M:M relationship with Media via
+    This holds the media using a M:M relationship with Content via
     ComponentVersionMedia.
     """
 
@@ -225,18 +225,18 @@ class Meta:
 
 class ComponentVersionMedia(models.Model):
     """
-    Determines the Media for a given ComponentVersion.
+    Determines the Content for a given ComponentVersion.
 
     An ComponentVersion may be associated with multiple pieces of binary data.
     For instance, a Video ComponentVersion might be associated with multiple
     transcripts in different languages.
 
-    When Media is associated with an ComponentVersion, it has some local
+    When Content is associated with an ComponentVersion, it has some local
     key that is unique within the the context of that ComponentVersion. This
     allows the ComponentVersion to do things like store an image file and
     reference it by a "path" key.
 
-    Media is immutable and sharable across multiple ComponentVersions.
+    Content is immutable and sharable across multiple ComponentVersions.
     """
 
     component_version = models.ForeignKey(ComponentVersion, on_delete=models.CASCADE)
diff --git a/src/openedx_content/applets/components/readme.rst b/src/openedx_content/applets/components/readme.rst
index eb97d22f2..b79134bc6 100644
--- a/src/openedx_content/applets/components/readme.rst
+++ b/src/openedx_content/applets/components/readme.rst
@@ -1,7 +1,7 @@
 Components App
 ==============
 
-The ``components`` app holds the versioned data models for the lowest-level pieces of content that can be stored in Open edX: Components (e.g. XBlocks), as well as the individual pieces of raw data Media that they reference.
+The ``components`` app holds the versioned data models for the lowest-level pieces of content that can be stored in Open edX: Components (e.g. XBlocks), as well as the individual pieces of raw data content that they reference.
 
 Motivation
 ----------
@@ -18,6 +18,6 @@ Architecture Guidelines
 
 * We're keeping nearly unlimited history, so per-version metadata (i.e. the space/time cost of making a new version) must be kept low.
 * Do not assume that all Components will be XBlocks.
-* Encourage other apps to make models that join to (and add their own metadata to) Component, ComponentVersion, Media, etc. But it should be done in such a way that this app is not aware of them.
+* Encourage other apps to make models that join to (and add their own metadata to) Component, ComponentVersion, Content, etc. But it should be done in such a way that this app is not aware of them.
 * Always preserve the most raw version of the data possible, e.g. OLX, even if XBlocks then extend that with more sophisticated data models. At some point those XBlocks will get deprecated/removed, and we will still want to be able to export the raw data.
 * Exports should be fast and *not* require the invocation of plugin code.
\ No newline at end of file
diff --git a/src/openedx_content/applets/units/models.py b/src/openedx_content/applets/units/models.py
index 3594acb7b..acf5041fb 100644
--- a/src/openedx_content/applets/units/models.py
+++ b/src/openedx_content/applets/units/models.py
@@ -1,6 +1,7 @@
 """
 Models that implement units
 """
+from __future__ import annotations
 
 from typing import override
 
diff --git a/src/openedx_content/migrations/0004_rename_collection_key_to_code_in_python.py b/src/openedx_content/migrations/0004_rename_collection_key_to_code_in_python.py
new file mode 100644
index 000000000..dd40e17fd
--- /dev/null
+++ b/src/openedx_content/migrations/0004_rename_collection_key_to_code_in_python.py
@@ -0,0 +1,28 @@
+# Generated by Django 5.2.12 on 2026-03-24 20:33
+
+from django.conf import settings
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('openedx_content', '0003_rename_content_to_media'),
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+    ]
+
+    operations = [
+        migrations.RemoveConstraint(
+            model_name='collection',
+            name='oel_coll_uniq_lp_key',
+        ),
+        migrations.RenameField(
+            model_name='collection',
+            old_name='key',
+            new_name='collection_code',
+        ),
+        migrations.AddConstraint(
+            model_name='collection',
+            constraint=models.UniqueConstraint(fields=('learning_package', 'collection_code'), name='oel_coll_uniq_lp_key'),
+        ),
+    ]
diff --git a/src/openedx_content/migrations/0005_rename_collection_key_to_code_in_db.py b/src/openedx_content/migrations/0005_rename_collection_key_to_code_in_db.py
new file mode 100644
index 000000000..209851c58
--- /dev/null
+++ b/src/openedx_content/migrations/0005_rename_collection_key_to_code_in_db.py
@@ -0,0 +1,20 @@
+# Generated by Django 5.2.12 on 2026-03-24 20:33
+
+from django.db import migrations
+
+import openedx_django_lib.fields
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('openedx_content', '0004_rename_collection_key_to_code_in_python'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='collection',
+            name='collection_code',
+            field=openedx_django_lib.fields.MultiCollationCharField(db_collations={'mysql': 'utf8mb4_bin', 'sqlite': 'BINARY'}, max_length=500),
+        ),
+    ]
diff --git a/src/openedx_content/migrations/0006_add_collection_code_regex_validation.py b/src/openedx_content/migrations/0006_add_collection_code_regex_validation.py
new file mode 100644
index 000000000..9e92fbc56
--- /dev/null
+++ b/src/openedx_content/migrations/0006_add_collection_code_regex_validation.py
@@ -0,0 +1,23 @@
+# Generated by Django 5.2.12 on 2026-03-24 20:33
+
+import re
+
+import django.core.validators
+from django.db import migrations
+
+import openedx_django_lib.fields
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('openedx_content', '0005_rename_collection_key_to_code_in_db'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='collection',
+            name='collection_code',
+            field=openedx_django_lib.fields.MultiCollationCharField(db_collations={'mysql': 'utf8mb4_bin', 'sqlite': 'BINARY'}, max_length=255, validators=[django.core.validators.RegexValidator(re.compile('^[a-zA-Z0-9\\-\\_\\.]+\\Z'), 'Enter a valid "code name" consisting of letters, numbers, underscores, hyphens, or periods.', 'invalid')]),
+        ),
+    ]
diff --git a/src/openedx_content/migrations/0007_merge_collection_container_changes.py b/src/openedx_content/migrations/0007_merge_collection_container_changes.py
new file mode 100644
index 000000000..1c306bbb3
--- /dev/null
+++ b/src/openedx_content/migrations/0007_merge_collection_container_changes.py
@@ -0,0 +1,14 @@
+# Generated by Django 5.2.12 on 2026-03-30 14:33
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('openedx_content', '0005_containertypes'),
+        ('openedx_content', '0006_add_collection_code_regex_validation'),
+    ]
+
+    operations = [
+    ]
diff --git a/src/openedx_django_lib/fields.py b/src/openedx_django_lib/fields.py
index c41678993..13c57fe7a 100644
--- a/src/openedx_django_lib/fields.py
+++ b/src/openedx_django_lib/fields.py
@@ -11,9 +11,12 @@
 from __future__ import annotations
 
 import hashlib
+import re
 import uuid
 
+from django.core.validators import RegexValidator
 from django.db import models
+from django.utils.translation import gettext_lazy as _
 
 from .collations import MultiCollationMixin
 from .validators import validate_utc_datetime
@@ -110,6 +113,29 @@ def immutable_uuid_field() -> models.UUIDField:
     )
 
 
+# Alphanumeric, hyphens, underscores, periods
+CODE_REGEX = re.compile(r"^[a-zA-Z0-9\-\_\.]+\Z")
+
+
+def code_field(**kwargs) -> MultiCollationCharField:
+    """
+    Field to hold a 'code', i.e. a slug-like local identifier.
+    """
+    return case_sensitive_char_field(
+        max_length=255,
+        blank=False,
+        validators=[
+            RegexValidator(
+                CODE_REGEX,
+                # Translators: "letters" means latin letters: a-z and A-Z.
+                _('Enter a valid "code name" consisting of letters, numbers, underscores, hyphens, or periods.'),
+                "invalid",
+            ),
+        ],
+        **kwargs,
+    )
+
+
 def key_field(**kwargs) -> MultiCollationCharField:
     """
     Externally created Identifier fields.
diff --git a/tests/openedx_content/applets/backup_restore/test_backup.py b/tests/openedx_content/applets/backup_restore/test_backup.py
index e7a69cff7..e3b2b4d52 100644
--- a/tests/openedx_content/applets/backup_restore/test_backup.py
+++ b/tests/openedx_content/applets/backup_restore/test_backup.py
@@ -146,7 +146,7 @@ def setUpTestData(cls):
 
         cls.collection = api.create_collection(
             cls.learning_package.id,
-            key="COL1",
+            collection_code="COL1",
             created_by=cls.user.id,
             title="Collection 1",
             description="Description of Collection 1",
@@ -154,7 +154,7 @@ def setUpTestData(cls):
 
         api.add_to_collection(
             cls.learning_package.id,
-            cls.collection.key,
+            cls.collection.collection_code,
             components
         )
 
@@ -277,6 +277,17 @@ def test_lp_dump_command(self):
             for file_path, expected_content in expected_files.items():
                 self.check_toml_file(zip_path, Path(file_path), expected_content)
 
+            # Verify that collection TOMLs include both 'key' (legacy) and 'collection_code'
+            # (new name), so older software can still read archives produced after the rename.
+            self.check_toml_file(
+                zip_path,
+                Path("collections/col1.toml"),
+                [
+                    'key = "COL1"',
+                    'collection_code = "COL1"',
+                ]
+            )
+
             # Check the output message
             message = f'{lp_key} written to {file_name}'
             self.assertIn(message, out.getvalue())
diff --git a/tests/openedx_content/applets/backup_restore/test_restore.py b/tests/openedx_content/applets/backup_restore/test_restore.py
index 0116731c4..372d04939 100644
--- a/tests/openedx_content/applets/backup_restore/test_restore.py
+++ b/tests/openedx_content/applets/backup_restore/test_restore.py
@@ -8,6 +8,7 @@
 from django.core.management import call_command
 from django.test import TestCase
 
+from openedx_content.applets.backup_restore.serializers import CollectionSerializer
 from openedx_content.applets.backup_restore.zipper import LearningPackageUnzipper, generate_staged_lp_key
 from openedx_content.applets.collections import api as collections_api
 from openedx_content.applets.components import api as components_api
@@ -183,7 +184,7 @@ def verify_collections(self, lp):
         assert collections.count() == 1
         collection = collections.first()
         assert collection.title == "Collection test1"
-        assert collection.key == "collection-test"
+        assert collection.collection_code == "collection-test"
         assert collection.description == ""
         assert collection.created_by is not None
         assert collection.created_by.username == "lp_user"
@@ -354,6 +355,52 @@ def test_success_metadata_using_user_context(self):
         assert metadata == expected_metadata
 
 
+class CollectionSerializerTest(TestCase):
+    """
+    Unit tests for CollectionSerializer's back-compat handling of 'key' vs 'collection_code'.
+    """
+
+    BASE_DATA = {
+        "title": "My Collection",
+        "description": "",
+        "entities": [],
+    }
+
+    def _serialize(self, extra):
+        data = {**self.BASE_DATA, **extra}
+        s = CollectionSerializer(data=data)
+        s.is_valid()
+        return s
+
+    def test_legacy_key_field(self):
+        """Archives written before the rename use 'key'; restore must accept it."""
+        s = self._serialize({"key": "my-col"})
+        assert s.is_valid(), s.errors
+        assert s.validated_data["collection_code"] == "my-col"
+        assert "key" not in s.validated_data
+
+    def test_new_collection_code_field(self):
+        """Archives written after the rename use 'collection_code'."""
+        s = self._serialize({"collection_code": "my-col"})
+        assert s.is_valid(), s.errors
+        assert s.validated_data["collection_code"] == "my-col"
+        assert "key" not in s.validated_data
+
+    def test_both_fields_collection_code_wins(self):
+        """When both fields are present (new archives include both for back-compat),
+        'collection_code' takes precedence over 'key'."""
+        s = self._serialize({"key": "old-value", "collection_code": "new-value"})
+        assert s.is_valid(), s.errors
+        assert s.validated_data["collection_code"] == "new-value"
+        assert "key" not in s.validated_data
+
+    def test_neither_field_is_an_error(self):
+        """Missing both 'key' and 'collection_code' must fail validation."""
+        s = self._serialize({})
+        assert not s.is_valid()
+        assert "non_field_errors" in s.errors
+
+
 class RestoreUtilitiesTest(TestCase):
     """Tests for utility functions used in the restore process."""
 
diff --git a/tests/openedx_content/applets/collections/test_api.py b/tests/openedx_content/applets/collections/test_api.py
index c8d638eb8..5f5bef2b2 100644
--- a/tests/openedx_content/applets/collections/test_api.py
+++ b/tests/openedx_content/applets/collections/test_api.py
@@ -64,35 +64,35 @@ def setUpTestData(cls) -> None:
         super().setUpTestData()
         cls.collection1 = api.create_collection(
             cls.learning_package.id,
-            key="COL1",
+            collection_code="COL1",
             created_by=None,
             title="Collection 1",
             description="Description of Collection 1",
         )
         cls.collection2 = api.create_collection(
             cls.learning_package.id,
-            key="COL2",
+            collection_code="COL2",
             created_by=None,
             title="Collection 2",
             description="Description of Collection 2",
         )
         cls.collection3 = api.create_collection(
             cls.learning_package.id,
-            key="COL3",
+            collection_code="COL3",
             created_by=None,
             title="Collection 3",
             description="Description of Collection 3",
         )
         cls.another_library_collection = api.create_collection(
             cls.learning_package_2.id,
-            key="another_library",
+            collection_code="another_library",
             created_by=None,
             title="Collection 4",
             description="Description of Collection 4",
         )
         cls.disabled_collection = api.create_collection(
             cls.learning_package.id,
-            key="disabled_collection",
+            collection_code="disabled_collection",
             created_by=None,
             title="Disabled Collection",
             description="Description of Disabled Collection",
@@ -123,7 +123,7 @@ def test_get_collection_wrong_learning_package(self):
         Test getting a collection that doesn't exist in the requested learning package.
         """
         with self.assertRaises(ObjectDoesNotExist):
-            api.get_collection(self.learning_package.pk, self.another_library_collection.key)
+            api.get_collection(self.learning_package.pk, self.another_library_collection.collection_code)
 
     def test_get_collections(self):
         """
@@ -191,14 +191,14 @@ def test_create_collection(self):
         with freeze_time(created_time):
             collection = api.create_collection(
                 self.learning_package.id,
-                key='MYCOL',
+                collection_code='MYCOL',
                 title="My Collection",
                 created_by=user.id,
                 description="This is my collection",
             )
 
         assert collection.title == "My Collection"
-        assert collection.key == "MYCOL"
+        assert collection.collection_code == "MYCOL"
         assert collection.description == "This is my collection"
         assert collection.enabled
         assert collection.created == created_time
@@ -211,15 +211,35 @@ def test_create_collection_without_description(self):
         """
         collection = api.create_collection(
             self.learning_package.id,
-            key='MYCOL',
+            collection_code='MYCOL',
             created_by=None,
             title="My Collection",
         )
         assert collection.title == "My Collection"
-        assert collection.key == "MYCOL"
+        assert collection.collection_code == "MYCOL"
         assert collection.description == ""
         assert collection.enabled
 
+    def test_create_collection_invalid_code(self):
+        """
+        collection_code must only contain alphanumerics, hyphens, underscores, and periods.
+        """
+        invalid_codes = [
+            "has space",
+            "has@symbol",
+            "has/slash",
+            "has#hash",
+        ]
+        for code in invalid_codes:
+            with self.subTest(code=code):
+                with self.assertRaises(ValidationError):
+                    api.create_collection(
+                        self.learning_package.id,
+                        collection_code=code,
+                        title="Test",
+                        created_by=None,
+                    )
+
 
 class CollectionEntitiesTestCase(CollectionsTestCase):
     """
@@ -283,7 +303,7 @@ def setUpTestData(cls) -> None:
         # Add some shared components to the collections
         cls.collection1 = api.add_to_collection(
             cls.learning_package.id,
-            key=cls.collection1.key,
+            collection_code=cls.collection1.collection_code,
             entities_qset=PublishableEntity.objects.filter(id__in=[
                 cls.published_component.pk,
             ]),
@@ -291,7 +311,7 @@ def setUpTestData(cls) -> None:
         )
         cls.collection2 = api.add_to_collection(
             cls.learning_package.id,
-            key=cls.collection2.key,
+            collection_code=cls.collection2.collection_code,
             entities_qset=PublishableEntity.objects.filter(id__in=[
                 cls.published_component.pk,
                 cls.draft_component.pk,
@@ -300,7 +320,7 @@ def setUpTestData(cls) -> None:
         )
         cls.disabled_collection = api.add_to_collection(
             cls.learning_package.id,
-            key=cls.disabled_collection.key,
+            collection_code=cls.disabled_collection.collection_code,
             entities_qset=PublishableEntity.objects.filter(id__in=[
                 cls.published_component.pk,
             ]),
@@ -335,7 +355,7 @@ def test_add_to_collection(self):
         with freeze_time(modified_time):
             self.collection1 = api.add_to_collection(
                 self.learning_package.id,
-                self.collection1.key,
+                self.collection1.collection_code,
                 PublishableEntity.objects.filter(id__in=[
                     self.draft_component.pk,
                     self.draft_unit.pk,
@@ -360,7 +380,7 @@ def test_add_to_collection_again(self):
         with freeze_time(modified_time):
             self.collection2 = api.add_to_collection(
                 self.learning_package.id,
-                self.collection2.key,
+                self.collection2.collection_code,
                 PublishableEntity.objects.filter(id__in=[
                     self.published_component.pk,
                 ]),
@@ -380,7 +400,7 @@ def test_add_to_collection_wrong_learning_package(self):
         with self.assertRaises(ValidationError):
             api.add_to_collection(
                 self.learning_package_2.id,
-                self.another_library_collection.key,
+                self.another_library_collection.collection_code,
                 PublishableEntity.objects.filter(id__in=[
                     self.published_component.pk,
                 ]),
@@ -396,7 +416,7 @@ def test_remove_from_collection(self):
         with freeze_time(modified_time):
             self.collection2 = api.remove_from_collection(
                 self.learning_package.id,
-                self.collection2.key,
+                self.collection2.collection_code,
                 PublishableEntity.objects.filter(id__in=[
                     self.published_component.pk,
                     self.draft_unit.pk,
@@ -424,46 +444,46 @@ def test_get_entity_collections(self):
     def test_get_collection_components(self):
         assert list(api.get_collection_components(
             self.learning_package.id,
-            self.collection1.key,
+            self.collection1.collection_code,
         )) == [self.published_component]
         assert list(api.get_collection_components(
             self.learning_package.id,
-            self.collection2.key,
+            self.collection2.collection_code,
         )) == [self.published_component, self.draft_component]
         assert not list(api.get_collection_components(
             self.learning_package.id,
-            self.collection3.key,
+            self.collection3.collection_code,
         ))
         assert not list(api.get_collection_components(
             self.learning_package.id,
-            self.another_library_collection.key,
+            self.another_library_collection.collection_code,
         ))
 
     def test_get_collection_containers(self):
         """
         Test using `get_collection_entities()` to get containers
         """
-        def get_collection_containers(learning_package_id: int, collection_key: str):
+        def get_collection_containers(learning_package_id: int, collection_code: str):
             return (
                 pe.container for pe in
-                api.get_collection_entities(learning_package_id, collection_key).exclude(container=None)
+                api.get_collection_entities(learning_package_id, collection_code).exclude(container=None)
             )
 
         assert not list(get_collection_containers(
             self.learning_package.id,
-            self.collection1.key,
+            self.collection1.collection_code,
         ))
         assert list(get_collection_containers(
             self.learning_package.id,
-            self.collection2.key,
+            self.collection2.collection_code,
         )) == [self.draft_unit.container]
         assert not list(get_collection_containers(
             self.learning_package.id,
-            self.collection3.key,
+            self.collection3.collection_code,
         ))
         assert not list(get_collection_containers(
             self.learning_package.id,
-            self.another_library_collection.key,
+            self.another_library_collection.collection_code,
         ))
 
 
@@ -481,7 +501,7 @@ def setUpTestData(cls) -> None:
         super().setUpTestData()
         cls.collection = api.create_collection(
             cls.learning_package.id,
-            key="MYCOL",
+            collection_code="MYCOL",
             title="Collection",
             created_by=None,
             description="Description of Collection",
@@ -495,7 +515,7 @@ def test_update_collection(self):
         with freeze_time(modified_time):
             collection = api.update_collection(
                 self.learning_package.id,
-                key=self.collection.key,
+                collection_code=self.collection.collection_code,
                 title="New Title",
                 description="",
             )
@@ -511,17 +531,19 @@ def test_update_collection_partial(self):
         """
         collection = api.update_collection(
             self.learning_package.id,
-            key=self.collection.key,
+            collection_code=self.collection.collection_code,
             title="New Title",
         )
 
         assert collection.title == "New Title"
         assert collection.description == self.collection.description  # unchanged
-        assert f"{collection}" == f"<Collection> (lp:{self.learning_package.id} {self.collection.key}:New Title)"
+        assert f"{collection}" == (
+            f"<Collection> (lp:{self.learning_package.id} {self.collection.collection_code}:New Title)"
+        )
 
         collection = api.update_collection(
             self.learning_package.id,
-            key=self.collection.key,
+            collection_code=self.collection.collection_code,
             description="New description",
         )
 
@@ -536,7 +558,7 @@ def test_update_collection_empty(self):
         with freeze_time(modified_time):
             collection = api.update_collection(
                 self.learning_package.id,
-                key=self.collection.key,
+                collection_code=self.collection.collection_code,
             )
 
         assert collection.title == self.collection.title  # unchanged
@@ -550,7 +572,7 @@ def test_update_collection_not_found(self):
         with self.assertRaises(ObjectDoesNotExist):
             api.update_collection(
                 self.learning_package.id,
-                key="12345",
+                collection_code="12345",
                 title="New Title",
             )
 
@@ -568,13 +590,13 @@ def test_soft_delete(self):
         with freeze_time(modified_time):
             collection = api.delete_collection(
                 self.learning_package.id,
-                key=self.collection2.key,
+                collection_code=self.collection2.collection_code,
             )
 
         # Collection was disabled and still exists in the database
         assert not collection.enabled
         assert collection.modified == modified_time
-        assert collection == api.get_collection(self.learning_package.id, collection.key)
+        assert collection == api.get_collection(self.learning_package.id, collection.collection_code)
         # ...and the collection's entities remain intact.
         assert list(collection.entities.all()) == [
             self.draft_unit.publishable_entity,
@@ -590,7 +612,7 @@ def test_delete(self):
         with freeze_time(modified_time):
             collection = api.delete_collection(
                 self.learning_package.id,
-                key=self.collection2.key,
+                collection_code=self.collection2.collection_code,
                 hard_delete=True,
             )
 
@@ -598,7 +620,7 @@ def test_delete(self):
         assert collection.enabled
         assert not collection.id
         with self.assertRaises(ObjectDoesNotExist):
-            api.get_collection(self.learning_package.id, collection.key)
+            api.get_collection(self.learning_package.id, collection.collection_code)
         # ...and the entities have been removed from this collection
         assert list(api.get_entity_collections(
             self.learning_package.id,
@@ -615,20 +637,20 @@ def test_restore(self):
         """
         collection = api.delete_collection(
             self.learning_package.id,
-            key=self.collection2.key,
+            collection_code=self.collection2.collection_code,
         )
 
         modified_time = datetime(2024, 8, 8, tzinfo=timezone.utc)
         with freeze_time(modified_time):
             collection = api.restore_collection(
                 self.learning_package.id,
-                key=self.collection2.key,
+                collection_code=self.collection2.collection_code,
             )
 
         # Collection was enabled and still exists in the database
         assert collection.enabled
         assert collection.modified == modified_time
-        assert collection == api.get_collection(self.learning_package.id, collection.key)
+        assert collection == api.get_collection(self.learning_package.id, collection.collection_code)
         # ...and the collection's entities remain intact.
         assert list(collection.entities.all()) == [
             self.draft_unit.publishable_entity,
@@ -719,7 +741,7 @@ def test_set_collection_wrong_learning_package(self):
         )
         collection = api.create_collection(
             learning_package_3.id,
-            key="MYCOL",
+            collection_code="MYCOL",
             title="My Collection",
             created_by=None,
             description="Description of Collection",
diff --git a/tests/openedx_content/applets/components/test_api.py b/tests/openedx_content/applets/components/test_api.py
index a9af5f65d..d4f9327a6 100644
--- a/tests/openedx_content/applets/components/test_api.py
+++ b/tests/openedx_content/applets/components/test_api.py
@@ -666,21 +666,21 @@ def setUpTestData(cls) -> None:
         )
         cls.collection1 = collection_api.create_collection(
             cls.learning_package.id,
-            key="MYCOL1",
+            collection_code="MYCOL1",
             title="Collection1",
             created_by=None,
             description="Description of Collection 1",
         )
         cls.collection2 = collection_api.create_collection(
             cls.learning_package.id,
-            key="MYCOL2",
+            collection_code="MYCOL2",
             title="Collection2",
             created_by=None,
             description="Description of Collection 2",
         )
         cls.collection3 = collection_api.create_collection(
             cls.learning_package.id,
-            key="MYCOL3",
+            collection_code="MYCOL3",
             title="Collection3",
             created_by=None,
             description="Description of Collection 3",