diff --git a/cms/djangoapps/contentstore/xblock_storage_handlers/view_handlers.py b/cms/djangoapps/contentstore/xblock_storage_handlers/view_handlers.py
index f7c96d588a2e..f0650f9fab79 100644
--- a/cms/djangoapps/contentstore/xblock_storage_handlers/view_handlers.py
+++ b/cms/djangoapps/contentstore/xblock_storage_handlers/view_handlers.py
@@ -20,7 +20,8 @@
 from django.http import HttpResponse, HttpResponseBadRequest
 from django.utils.translation import gettext as _
 from edx_django_utils.plugins import pluggable_override
-from openedx.core.djangoapps.content_libraries.api import ContainerMetadata, ContainerType, LibraryXBlockMetadata
+from openedx_content import api as content_api
+from openedx.core.djangoapps.content_libraries.api import ContainerMetadata, LibraryXBlockMetadata
 from openedx.core.djangoapps.content_tagging.api import get_object_tag_counts
 from edx_proctoring.api import (
     does_backend_support_onboarding,
@@ -572,18 +573,15 @@ def sync_library_content(
                     block_type = upstream_child.usage_key.block_type
                 elif isinstance(upstream_child, ContainerMetadata):
                     upstream_key = str(upstream_child.container_key)
-                    match upstream_child.container_type:
-                        case ContainerType.Unit:
-                            block_type = "vertical"
-                        case ContainerType.Subsection:
-                            block_type = "sequential"
-                        case _:
-                            # We don't support other container types for now.
-                            log.error(
-                                "Unexpected upstream child container type: %s",
-                                upstream_child.container_type,
-                            )
-                            continue
+                    # convert "unit" -> "vertical", "subsection" -> "sequential"
+                    block_type = content_api.get_container_type(upstream_child.container_type_code).olx_tag_name
+                    if not block_type or block_type not in ("vertical", "sequential"):
+                        # We don't support other container types for now.
+                        log.error(
+                            "Unexpected upstream child container type: %s",
+                            upstream_child.container_type,
+                        )
+                        continue
                 else:
                     log.error(
                         "Unexpected type of upstream child: %s",
diff --git a/cms/djangoapps/modulestore_migrator/data.py b/cms/djangoapps/modulestore_migrator/data.py
index f2a9d725656c..a410ea01133f 100644
--- a/cms/djangoapps/modulestore_migrator/data.py
+++ b/cms/djangoapps/modulestore_migrator/data.py
@@ -18,8 +18,7 @@
     LibraryLocatorV2,
     LibraryUsageLocatorV2,
 )
-
-from openedx.core.djangoapps.content_libraries.api import ContainerType
+from openedx_content.models_api import Unit, Subsection, Section
 
 
 class CompositionLevel(Enum):
@@ -32,9 +31,9 @@ class CompositionLevel(Enum):
     Component = 'component'
 
     # Container types currently supported by Content Libraries
-    Unit = ContainerType.Unit.value
-    Subsection = ContainerType.Subsection.value
-    Section = ContainerType.Section.value
+    Unit = Unit.type_code  # "unit"
+    Subsection = Subsection.type_code  # "subsection"
+    Section = Section.type_code  # "section"
 
     @property
     def is_container(self) -> bool:
diff --git a/cms/djangoapps/modulestore_migrator/tasks.py b/cms/djangoapps/modulestore_migrator/tasks.py
index cbcbc6db52c8..47729069602b 100644
--- a/cms/djangoapps/modulestore_migrator/tasks.py
+++ b/cms/djangoapps/modulestore_migrator/tasks.py
@@ -46,7 +46,7 @@
 from common.djangoapps.split_modulestore_django.models import SplitModulestoreCourseIndex
 from common.djangoapps.util.date_utils import DEFAULT_DATE_TIME_FORMAT, strftime_localized
 from openedx.core.djangoapps.content_libraries import api as libraries_api
-from openedx.core.djangoapps.content_libraries.api import ContainerType, get_library
+from openedx.core.djangoapps.content_libraries.api import get_library
 from openedx.core.djangoapps.content_staging import api as staging_api
 from xmodule.modulestore import exceptions as modulestore_exceptions
 from xmodule.modulestore.django import modulestore
@@ -766,11 +766,11 @@ def _migrate_node(
     #                                     do not support in libraries as of Ulmo.
     should_migrate_node: bool
     should_migrate_children: bool
-    container_type: ContainerType | None  # if None, it's a Component
+    container_type: content_api.ContainerType | None  # if None, it's a Component
     if source_node.tag == "wiki":
         return _MigratedNode(None, [])
     try:
-        container_type = ContainerType.from_source_olx_tag(source_node.tag)
+        container_type = libraries_api.container_type_for_olx_tag(source_node.tag)
     except ValueError:
         container_type = None
         if source_node.tag in {"course", "library"}:
@@ -780,7 +780,7 @@ def _migrate_node(
             should_migrate_node = True
             should_migrate_children = False
     else:
-        node_level = CompositionLevel(container_type.value)
+        node_level = CompositionLevel(container_type.type_code)
         should_migrate_node = not node_level.is_higher_than(context.composition_level)
         should_migrate_children = True
     migrated_children: list[_MigratedNode] = []
@@ -842,7 +842,7 @@ def _migrate_container(
     *,
     context: _MigrationContext,
     source_key: UsageKey,
-    container_type: ContainerType,
+    container_type: content_api.ContainerType,
     title: str,
     children: list[PublishableEntityVersion],
 ) -> tuple[PublishableEntityVersion, str | None]:
@@ -889,13 +889,9 @@ def _migrate_container(
     container_publishable_entity_version = content_api.create_next_container_version(
         container.container_pk,
         title=title,
-        entity_rows=[
-            content_api.ContainerEntityRow(entity_pk=child.entity_id, version_pk=None)
-            for child in children
-        ],
+        entities=[child.entity for child in children],
         created=context.created_at,
         created_by=context.created_by,
-        container_version_cls=container_type.container_model_classes[1],
     ).publishable_entity_version
 
     # Publish the container
@@ -990,7 +986,7 @@ def _migrate_component(
 def _get_distinct_target_container_key(
     context: _MigrationContext,
     source_key: UsageKey,
-    container_type: ContainerType,
+    container_type: content_api.ContainerType,
     title: str,
 ) -> LibraryContainerLocator:
     """
@@ -1012,14 +1008,14 @@ def _get_distinct_target_container_key(
     # Use base base slug if available
     if base_slug not in context.used_container_slugs:
         return LibraryContainerLocator(
-            context.target_library_key, container_type.value, base_slug
+            context.target_library_key, container_type.type_code, base_slug
         )
     # Try numbered variations until we find one that doesn't exist
     for i in range(1, _MAX_UNIQUE_SLUG_ATTEMPTS + 1):
         candidate_slug = f"{base_slug}_{i}"
         if candidate_slug not in context.used_container_slugs:
             return LibraryContainerLocator(
-                context.target_library_key, container_type.value, candidate_slug
+                context.target_library_key, container_type.type_code, candidate_slug
             )
     # It would be extremely unlikely for us to run out of attempts
     raise RuntimeError(
diff --git a/openedx/core/djangoapps/content/search/api.py b/openedx/core/djangoapps/content/search/api.py
index b36beeba4710..5bc7780723f6 100644
--- a/openedx/core/djangoapps/content/search/api.py
+++ b/openedx/core/djangoapps/content/search/api.py
@@ -827,19 +827,19 @@ def update_library_containers_collections(
     """
     library_key = collection_key.lib_key
     library = lib_api.get_library(library_key)
-    containers = content_api.get_collection_containers(
+    container_entities = content_api.get_collection_entities(
         library.learning_package_id,
         collection_key.collection_id,
-    )
+    ).exclude(container=None).select_related("container")
 
-    paginator = Paginator(containers, batch_size)
+    paginator = Paginator(container_entities, batch_size)
     for page in paginator.page_range:
         docs = []
 
-        for container in paginator.page(page).object_list:
+        for container_entity in paginator.page(page).object_list:
             container_key = lib_api.library_container_locator(
                 library_key,
-                container,
+                container_entity.container,
             )
             doc = searchable_doc_for_key(container_key)
             doc.update(searchable_doc_collections(container_key))
diff --git a/openedx/core/djangoapps/content/search/tests/test_api.py b/openedx/core/djangoapps/content/search/tests/test_api.py
index 4ac9abe3008d..00c0e28fcb4c 100644
--- a/openedx/core/djangoapps/content/search/tests/test_api.py
+++ b/openedx/core/djangoapps/content/search/tests/test_api.py
@@ -9,6 +9,7 @@
 from unittest.mock import MagicMock, Mock, call, patch
 from opaque_keys.edx.keys import UsageKey
 from opaque_keys.edx.locator import LibraryCollectionLocator, LibraryContainerLocator
+from openedx_content import models_api as content_models
 
 import ddt
 import pytest
@@ -224,7 +225,7 @@ def setUp(self) -> None:
         with freeze_time(self.created_date):
             self.unit = library_api.create_container(
                 library_key=self.library.key,
-                container_type=library_api.ContainerType.Unit,
+                container_type=content_models.Unit,
                 slug="unit-1",
                 title="Unit 1",
                 user_id=None,
@@ -232,7 +233,7 @@ def setUp(self) -> None:
             self.unit_key = "lct:org1:lib:unit:unit-1"
             self.subsection = library_api.create_container(
                 self.library.key,
-                container_type=library_api.ContainerType.Subsection,
+                container_type=content_models.Subsection,
                 slug="subsection-1",
                 title="Subsection 1",
                 user_id=None,
@@ -245,7 +246,7 @@ def setUp(self) -> None:
             self.subsection_key = "lct:org1:lib:subsection:subsection-1"
             self.section = library_api.create_container(
                 self.library.key,
-                container_type=library_api.ContainerType.Section,
+                container_type=content_models.Section,
                 slug="section-1",
                 title="Section 1",
                 user_id=None,
diff --git a/openedx/core/djangoapps/content/search/tests/test_documents.py b/openedx/core/djangoapps/content/search/tests/test_documents.py
index a2bc09052b50..b074730d3c45 100644
--- a/openedx/core/djangoapps/content/search/tests/test_documents.py
+++ b/openedx/core/djangoapps/content/search/tests/test_documents.py
@@ -8,6 +8,7 @@
 from freezegun import freeze_time
 from opaque_keys.edx.locator import LibraryCollectionLocator, LibraryContainerLocator
 from openedx_content import api as content_api
+from openedx_content import models_api as content_models
 from organizations.models import Organization
 
 from openedx.core.djangoapps.content_libraries import api as library_api
@@ -92,7 +93,7 @@ def setUpClass(cls):
             )
             cls.container = library_api.create_container(
                 cls.library.key,
-                container_type=library_api.ContainerType.Unit,
+                container_type=content_models.Unit,
                 slug="unit1",
                 title="A Unit in the Search Index",
                 user_id=None,
@@ -102,7 +103,7 @@ def setUpClass(cls):
             )
             cls.subsection = library_api.create_container(
                 cls.library.key,
-                container_type=library_api.ContainerType.Subsection,
+                container_type=content_models.Subsection,
                 slug="subsection1",
                 title="A Subsection in the Search Index",
                 user_id=None,
@@ -112,7 +113,7 @@ def setUpClass(cls):
             )
             cls.section = library_api.create_container(
                 cls.library.key,
-                container_type=library_api.ContainerType.Section,
+                container_type=content_models.Section,
                 slug="section1",
                 title="A Section in the Search Index",
                 user_id=None,
diff --git a/openedx/core/djangoapps/content_libraries/api/blocks.py b/openedx/core/djangoapps/content_libraries/api/blocks.py
index dc0913d0fdc7..46ec16eb515b 100644
--- a/openedx/core/djangoapps/content_libraries/api/blocks.py
+++ b/openedx/core/djangoapps/content_libraries/api/blocks.py
@@ -65,8 +65,8 @@
     get_containers_contains_item,
     update_container_children,
     ContainerMetadata,
-    ContainerType,
 )
+from .container_metadata import container_type_for_olx_tag
 from .collections import library_collection_locator
 from .libraries import PublishableItem
 from .. import tasks
@@ -547,7 +547,7 @@ def _import_staged_block_as_container(
 
     container = create_container(
         library_key=library_key,
-        container_type=ContainerType.from_source_olx_tag(olx_node.tag),
+        container_type=container_type_for_olx_tag(olx_node.tag),
         slug=None,  # auto-generate slug from title
         title=title,
         user_id=user.id,
diff --git a/openedx/core/djangoapps/content_libraries/api/container_metadata.py b/openedx/core/djangoapps/content_libraries/api/container_metadata.py
index 0e6ed1ea6173..9caf3d405dbf 100644
--- a/openedx/core/djangoapps/content_libraries/api/container_metadata.py
+++ b/openedx/core/djangoapps/content_libraries/api/container_metadata.py
@@ -1,8 +1,11 @@
 """
 Content libraries data classes related to Containers.
 """
+
 from __future__ import annotations
 
+from typing import Self
+
 from dataclasses import dataclass, field as dataclass_field
 from enum import Enum
 from django.db.models import QuerySet
@@ -33,73 +36,31 @@
 __all__ = [
     # Models
     "ContainerMetadata",
-    "ContainerType",
     # Methods
+    "container_type_for_olx_tag",
     "library_container_locator",
 ]
 
+# For now, we only allow the following types of containers in content libraries, and their hierarchy is hard-coded.
+LIBRARY_ALLOWED_CONTAINER_TYPES = ["unit", "subsection", "section"]
 
-class ContainerType(Enum):
-    """
-    The container types supported by content_libraries, and logic to map them to OLX.
-    """
-    Unit = "unit"
-    Subsection = "subsection"
-    Section = "section"
-
-    @property
-    def container_model_classes(self) -> tuple[type[Container], type[ContainerVersion]]:
-        """
-        Get the container, containerversion subclasses associated with this type.
-        @@TODO Is this what we want, a hard mapping between container_types and Container classes?
-          * If so, then expand on this pattern, so that all ContainerType logic is contained within
-            this class, and get rid of the match-case statements that are all over the content_libraries
-            app.
-          * If not, then figure out what to do instead.
-        """
-        match self:
-            case self.Unit:
-                return (Unit, UnitVersion)
-            case self.Subsection:
-                return (Subsection, SubsectionVersion)
-            case self.Section:
-                return (Section, SectionVersion)
-        raise TypeError(f"unexpected ContainerType: {self!r}")
 
-    @property
-    def olx_tag(self) -> str:
-        """
-        Canonical XML tag to use when representing this container as OLX.
-
-        For example, Units are encoded as <vertical>...</vertical>.
-
-        These tag names are historical. We keep them around for the backwards compatibility of OLX
-        and for easier interaction with legacy modulestore-powered structural XBlocks
-        (e.g., copy-paste of Units between courses and V2 libraries).
-        """
-        match self:
-            case self.Unit:
-                return "vertical"
-            case self.Subsection:
-                return "sequential"
-            case self.Section:
-                return "chapter"
-        raise TypeError(f"unexpected ContainerType: {self!r}")
+def container_type_for_olx_tag(olx_tag: str) -> content_api.ContainerType:
+    """
+    Given an OLX tag code (e.g. `"vertical"` for `<vertical>`), get the
+    corresponding `ContainerType`, e.g. `Unit`.
 
-    @classmethod
-    def from_source_olx_tag(cls, olx_tag: str) -> 'ContainerType':
-        """
-        Get the ContainerType that this OLX tag maps to.
-        """
-        if olx_tag == "unit":
-            # There is an alternative implementation to VerticalBlock called UnitBlock whose
-            # OLX tag is <unit>. When converting from OLX, we want to handle both <vertical>
-            # and <unit> as Unit containers, although the canonical serialization is still <vertical>.
-            return cls.Unit
-        try:
-            return next(ct for ct in cls if olx_tag == ct.olx_tag)
-        except StopIteration:
-            raise ValueError(f"no container_type for XML tag: <{olx_tag}>") from None
+    This method is specific to content libraries.
+    """
+    try:
+        ct = next(ct for ct in content_api.get_all_container_types() if olx_tag == ct.olx_tag_name)
+    except StopIteration:
+        raise ValueError(f"Content libraries does not support containers with XML tag: <{olx_tag}>") from None
+    if ct.type_code not in LIBRARY_ALLOWED_CONTAINER_TYPES:
+        raise ValueError(
+            f'Content libraries does not support "{ct.type_code}" containers (with XML tag <{olx_tag}>)'
+        ) from None
+    return ct
 
 
 @dataclass(frozen=True, kw_only=True)
@@ -107,8 +68,9 @@ class ContainerMetadata(PublishableItem):
     """
     Class that represents the metadata about a Container (e.g. Unit) in a content library.
     """
+
     container_key: LibraryContainerLocator
-    container_type: ContainerType
+    container_type_code: str
     container_pk: int
 
     @classmethod
@@ -121,7 +83,7 @@ def from_container(cls, library_key, container: Container, associated_collection
             library_key,
             container=container,
         )
-        container_type = ContainerType(container_key.container_type)
+        type_code = content_api.get_container_type_code_of(container)
         published_by = None
         if last_publish_log and last_publish_log.published_by:
             published_by = last_publish_log.published_by.username
@@ -137,7 +99,7 @@ def from_container(cls, library_key, container: Container, associated_collection
 
         return cls(
             container_key=container_key,
-            container_type=container_type,
+            container_type_code=type_code,
             container_pk=container.pk,
             display_name=draft.title,
             created=container.created,
@@ -164,6 +126,7 @@ class ContainerHierarchy:
     database queries in the future. More details being discussed in
     https://github.com/openedx/edx-platform/pull/36813#issuecomment-3136631767
     """
+
     sections: list[ContainerHierarchyMember] = dataclass_field(default_factory=list)
     subsections: list[ContainerHierarchyMember] = dataclass_field(default_factory=list)
     units: list[ContainerHierarchyMember] = dataclass_field(default_factory=list)
@@ -174,6 +137,7 @@ class Level(Enum):
         """
         Enumeratable levels contained by the ContainerHierarchy.
         """
+
         none = 0
         components = 1
         units = 2
@@ -295,10 +259,12 @@ def _get_containers_with_entities(
     """
     qs = Container.objects.none()
     for member in members:
-        qs = qs.union(content_api.get_containers_with_entity(
-            member.entity.pk,
-            ignore_pinned=ignore_pinned,
-        ))
+        qs = qs.union(
+            content_api.get_containers_with_entity(
+                member.entity.pk,
+                ignore_pinned=ignore_pinned,
+            )
+        )
     return qs
 
 
@@ -338,6 +304,7 @@ class ContainerHierarchyMember:
     """
     Represents an individual member of ContainerHierarchy which is ready to be serialized.
     """
+
     id: LibraryContainerLocator | LibraryUsageLocatorV2
     display_name: str
     has_unpublished_changes: bool
@@ -396,23 +363,10 @@ def library_container_locator(
     """
     Returns a LibraryContainerLocator for the given library + container.
     """
-    container_type = None
-    if hasattr(container, 'unit'):
-        container_type = ContainerType.Unit
-    elif hasattr(container, 'subsection'):
-        container_type = ContainerType.Subsection
-    elif hasattr(container, 'section'):
-        container_type = ContainerType.Section
-    else:
-        # This should never happen, but we assert to ensure that we handle all cases.
-        # If this fails, it means that a new Container type was added without updating this code.
-        raise ValueError(f"Unexpected container type: {container!r}")
+    if container.type_code not in LIBRARY_ALLOWED_CONTAINER_TYPES:
+        raise ValueError(f"Unsupported container type for content libraries: {container!r}")
 
-    return LibraryContainerLocator(
-        library_key,
-        container_type=container_type.value,
-        container_id=container.publishable_entity.key,
-    )
+    return LibraryContainerLocator(library_key, container_type=container.type_code, container_id=container.key)
 
 
 def get_container_from_key(container_key: LibraryContainerLocator, include_deleted=False) -> Container:
@@ -425,13 +379,27 @@ def get_container_from_key(container_key: LibraryContainerLocator, include_delet
     content_library = ContentLibrary.objects.get_by_key(container_key.lib_key)
     learning_package = content_library.learning_package
     assert learning_package is not None
-    container = content_api.get_container_by_key(
-        learning_package.id,
-        key=container_key.container_id,
-    )
+    container = content_api.get_container_by_key(learning_package.id, key=container_key.container_id)
+    assert container.type_code in LIBRARY_ALLOWED_CONTAINER_TYPES
     # We only return the container if it exists and either:
     # 1. the container has a draft version (which means it is not soft-deleted) OR
     # 2. the container was soft-deleted but the `include_deleted` flag is set to True
     if container and (include_deleted or container.versioning.draft):
         return container
     raise ContentLibraryContainerNotFound
+
+
+def get_entity_from_key(
+    key: LibraryContainerLocator | LibraryUsageLocatorV2, /, *, include_deleted=False
+) -> PublishableEntity:
+    """
+    Given a key for an item in a library, load it as a `Component` or a `Container` subclass.
+    """
+    if isinstance(key, LibraryContainerLocator):
+        return get_container_from_key(key, include_deleted=False)
+    else:
+        assert isinstance(key, LibraryUsageLocatorV2)
+        component = get_component_from_usage_key(key)
+        if not include_deleted and not component.versioning.draft:
+            raise ContentLibraryContainerNotFound("Component has been deleted.")
+        return component
diff --git a/openedx/core/djangoapps/content_libraries/api/containers.py b/openedx/core/djangoapps/content_libraries/api/containers.py
index 54740d130321..14ea88a648f8 100644
--- a/openedx/core/djangoapps/content_libraries/api/containers.py
+++ b/openedx/core/djangoapps/content_libraries/api/containers.py
@@ -1,6 +1,7 @@
 """
 API for containers (Sections, Subsections, Units) in Content Libraries
 """
+
 from __future__ import annotations
 
 from datetime import datetime, timezone
@@ -23,20 +24,19 @@
     LIBRARY_CONTAINER_UPDATED,
 )
 from openedx_content import api as content_api
-from openedx_content.models_api import Container, ContainerVersion, Component
+from openedx_content.models_api import Container, Component, Unit
 from openedx.core.djangoapps.content_libraries.api.collections import library_collection_locator
 
-from openedx.core.djangoapps.xblock.api import get_component_from_usage_key
-
 from .. import tasks
 from ..models import ContentLibrary
 from .block_metadata import LibraryXBlockMetadata
 from .container_metadata import (
     ContainerHierarchy,
     ContainerMetadata,
-    ContainerType,
     library_container_locator,
     get_container_from_key,
+    get_entity_from_key,
+    LIBRARY_ALLOWED_CONTAINER_TYPES,
 )
 from .serializers import ContainerSerializer
 
@@ -79,7 +79,7 @@ def get_container(
         associated_collections = content_api.get_entity_collections(
             container.publishable_entity.learning_package_id,
             container_key.container_id,
-        ).values('key', 'title')
+        ).values("key", "title")
     else:
         associated_collections = None
     container_meta = ContainerMetadata.from_container(
@@ -93,7 +93,7 @@ def get_container(
 
 def create_container(
     library_key: LibraryLocatorV2,
-    container_type: ContainerType,
+    container_type: content_api.ContainerType,
     slug: str | None,
     title: str,
     user_id: int | None,
@@ -104,61 +104,37 @@ def create_container(
 
     It will initially be empty.
     """
+    assert container_type.type_code in LIBRARY_ALLOWED_CONTAINER_TYPES
     assert isinstance(library_key, LibraryLocatorV2)
     content_library = ContentLibrary.objects.get_by_key(library_key)
     assert content_library.learning_package_id  # Should never happen but we made this a nullable field so need to check
     if slug is None:
         # Automatically generate a slug. Append a random suffix so it should be unique.
-        slug = slugify(title, allow_unicode=True) + '-' + uuid4().hex[-6:]
+        slug = slugify(title, allow_unicode=True) + "-" + uuid4().hex[-6:]
     # Make sure the slug is valid by first creating a key for the new container:
     container_key = LibraryContainerLocator(
         library_key,
-        container_type=container_type.value,
+        container_type=container_type.type_code,
         container_id=slug,
     )
 
     if not created:
         created = datetime.now(tz=timezone.utc)
 
-    container: Container
-    _initial_version: ContainerVersion
-
     # Then try creating the actual container:
-    match container_type:
-        case ContainerType.Unit:
-            container, _initial_version = content_api.create_unit_and_version(
-                content_library.learning_package_id,
-                key=slug,
-                title=title,
-                created=created,
-                created_by=user_id,
-            )
-        case ContainerType.Subsection:
-            container, _initial_version = content_api.create_subsection_and_version(
-                content_library.learning_package_id,
-                key=slug,
-                title=title,
-                created=created,
-                created_by=user_id,
-            )
-        case ContainerType.Section:
-            container, _initial_version = content_api.create_section_and_version(
-                content_library.learning_package_id,
-                key=slug,
-                title=title,
-                created=created,
-                created_by=user_id,
-            )
-        case _:
-            raise NotImplementedError(f"Library does not support {container_type} yet")
+    container, _initial_version = content_api.create_container_and_version(
+        content_library.learning_package_id,
+        key=slug,
+        title=title,
+        container_type=container_type,
+        entities=[],
+        created=created,
+        created_by=user_id,
+    )
 
     # .. event_implemented_name: LIBRARY_CONTAINER_CREATED
     # .. event_type: org.openedx.content_authoring.content_library.container.created.v1
-    LIBRARY_CONTAINER_CREATED.send_event(
-        library_container=LibraryContainerData(
-            container_key=container_key,
-        )
-    )
+    LIBRARY_CONTAINER_CREATED.send_event(library_container=LibraryContainerData(container_key=container_key))
 
     return ContainerMetadata.from_container(library_key, container)
 
@@ -175,57 +151,22 @@ def update_container(
     library_key = container_key.lib_key
     created = datetime.now(tz=timezone.utc)
 
-    container_type = ContainerType(container_key.container_type)
-
-    version: ContainerVersion
     affected_containers: list[ContainerMetadata] = []
     # Get children containers or components to update their index data
-    children = get_container_children(
-        container_key,
-        published=False,
-    )
-    child_key_name = 'container_key'
-
-    match container_type:
-        case ContainerType.Unit:
-            version = content_api.create_next_unit_version(
-                container.unit,
-                title=display_name,
-                created=created,
-                created_by=user_id,
-            )
-            affected_containers = get_containers_contains_item(container_key)
-            # Components have usage_key instead of container_key
-            child_key_name = 'usage_key'
-        case ContainerType.Subsection:
-            version = content_api.create_next_subsection_version(
-                container.subsection,
-                title=display_name,
-                created=created,
-                created_by=user_id,
-            )
-            affected_containers = get_containers_contains_item(container_key)
-        case ContainerType.Section:
-            version = content_api.create_next_section_version(
-                container.section,
-                title=display_name,
-                created=created,
-                created_by=user_id,
-            )
+    children = get_container_children(container_key, published=False)
+    child_key_name = "usage_key" if isinstance(container, Unit) else "container_key"
 
-            # The `affected_containers` are not obtained, because the sections are
-            # not contained in any container.
-        case _:
-            raise NotImplementedError(f"Library does not support {container_type} yet")
+    version = content_api.create_next_container_version(
+        container,
+        title=display_name,
+        created=created,
+        created_by=user_id,
+    )
 
     # Send event related to the updated container
     # .. event_implemented_name: LIBRARY_CONTAINER_UPDATED
     # .. event_type: org.openedx.content_authoring.content_library.container.updated.v1
-    LIBRARY_CONTAINER_UPDATED.send_event(
-        library_container=LibraryContainerData(
-            container_key=container_key,
-        )
-    )
+    LIBRARY_CONTAINER_UPDATED.send_event(library_container=LibraryContainerData(container_key=container_key))
 
     # Send events related to the containers that contains the updated container.
     # This is to update the children display names used in the section/subsection previews.
@@ -233,9 +174,7 @@ def update_container(
         # .. event_implemented_name: LIBRARY_CONTAINER_UPDATED
         # .. event_type: org.openedx.content_authoring.content_library.container.updated.v1
         LIBRARY_CONTAINER_UPDATED.send_event(
-            library_container=LibraryContainerData(
-                container_key=affected_container.container_key,
-            )
+            library_container=LibraryContainerData(container_key=affected_container.container_key)
         )
     # Update children components and containers index data, for example,
     # All subsections under a section have section key in index that needs to be updated.
@@ -311,11 +250,10 @@ def delete_container(
                 container_key=affected_container.container_key,
             )
         )
-    container_type = ContainerType(container_key.container_type)
-    key_name = 'container_key'
-    if container_type == ContainerType.Unit:
+    key_name = "container_key"
+    if isinstance(container, Unit):
         # Components have usage_key instead of container_key
-        key_name = 'usage_key'
+        key_name = "usage_key"
     # Update children components and containers index data, for example,
     # All subsections under a section have section key in index that needs to be updated.
     # So if parent section is deleted, it needs to be removed from sections key of children
@@ -346,10 +284,7 @@ def restore_container(container_key: LibraryContainerLocator) -> None:
     # Fetch related containers after restore
     affected_containers = get_containers_contains_item(container_key)
     # Get children containers or components to update their index data
-    children = get_container_children(
-        container_key,
-        published=False,
-    )
+    children = get_container_children(container_key, published=False)
 
     # .. event_implemented_name: LIBRARY_CONTAINER_CREATED
     # .. event_type: org.openedx.content_authoring.content_library.container.created.v1
@@ -398,10 +333,9 @@ def restore_container(container_key: LibraryContainerLocator) -> None:
                 container_key=affected_container.container_key,
             )
         )
-    container_type = ContainerType(container_key.container_type)
-    key_name = 'container_key'
-    if container_type == ContainerType.Unit:
-        key_name = 'usage_key'
+    key_name = "container_key"
+    if content_api.get_container_type(container_key.container_type) is Unit:
+        key_name = "usage_key"
     # Update children components and containers index data, for example,
     # All subsections under a section have section key in index that needs to be updated.
     # Should restore removed parent section in sections key of children subsections
@@ -426,33 +360,16 @@ def get_container_children(
     (e.g. the components/xblocks in a unit, units in a subsection, subsections in a section)
     """
     container = get_container_from_key(container_key)
-    container_type = ContainerType(container_key.container_type)
-
-    match container_type:
-        case ContainerType.Unit:
-            child_components = content_api.get_components_in_unit(container.unit, published=published)
-            return [LibraryXBlockMetadata.from_component(
-                container_key.lib_key,
-                entry.component
-            ) for entry in child_components]
-        case ContainerType.Subsection:
-            child_units = content_api.get_units_in_subsection(container.subsection, published=published)
-            return [ContainerMetadata.from_container(
-                container_key.lib_key,
-                entry.unit
-            ) for entry in child_units]
-        case ContainerType.Section:
-            child_subsections = content_api.get_subsections_in_section(container.section, published=published)
-            return [ContainerMetadata.from_container(
-                container_key.lib_key,
-                entry.subsection,
-            ) for entry in child_subsections]
-        case _:
-            child_entities = content_api.get_entities_in_container(container, published=published)
-            return [ContainerMetadata.from_container(
-                container_key.lib_key,
-                entry.entity
-            ) for entry in child_entities]
+
+    child_entities = content_api.get_entities_in_container(container, published=published)
+    result: list[LibraryXBlockMetadata | ContainerMetadata] = []
+    for entry in child_entities:
+        if isinstance(entry.entity, Component):
+            result.append(LibraryXBlockMetadata.from_component(container_key.lib_key, entry.component))
+        else:
+            assert isinstance(entry.entity.container, Container)
+            result.append(ContainerMetadata.from_container(container_key.lib_key, entry.entity.container))
+    return result
 
 
 def get_container_children_count(
@@ -468,78 +385,32 @@ def get_container_children_count(
 
 def update_container_children(
     container_key: LibraryContainerLocator,
-    children_ids: list[LibraryUsageLocatorV2] | list[LibraryContainerLocator],
+    children_keys: list[LibraryUsageLocatorV2] | list[LibraryContainerLocator],
     user_id: int | None,
     entities_action: content_api.ChildrenEntitiesAction = content_api.ChildrenEntitiesAction.REPLACE,
 ):
     """
     [ 🛑 UNSTABLE ] Adds children components or containers to given container.
     """
-    library_key = container_key.lib_key
-    container_type = ContainerType(container_key.container_type)
     container = get_container_from_key(container_key)
     created = datetime.now(tz=timezone.utc)
-    new_version: ContainerVersion
-    match container_type:
-        case ContainerType.Unit:
-            components = [get_component_from_usage_key(key) for key in children_ids]  # type: ignore[arg-type]
-            new_version = content_api.create_next_unit_version(
-                container.unit,
-                components=components,  # type: ignore[arg-type]
-                created=created,
-                created_by=user_id,
-                entities_action=entities_action,
-            )
-
-            for key in children_ids:
-                # .. event_implemented_name: CONTENT_OBJECT_ASSOCIATIONS_CHANGED
-                # .. event_type: org.openedx.content_authoring.content.object.associations.changed.v1
-                CONTENT_OBJECT_ASSOCIATIONS_CHANGED.send_event(
-                    content_object=ContentObjectChangedData(
-                        object_id=str(key),
-                        changes=["units"],
-                    ),
-                )
-        case ContainerType.Subsection:
-            units = [get_container_from_key(key).unit for key in children_ids]  # type: ignore[arg-type]
-            new_version = content_api.create_next_subsection_version(
-                container.subsection,
-                units=units,  # type: ignore[arg-type]
-                created=created,
-                created_by=user_id,
-                entities_action=entities_action,
-            )
-
-            for key in children_ids:
-                # .. event_implemented_name: CONTENT_OBJECT_ASSOCIATIONS_CHANGED
-                # .. event_type: org.openedx.content_authoring.content.object.associations.changed.v1
-                CONTENT_OBJECT_ASSOCIATIONS_CHANGED.send_event(
-                    content_object=ContentObjectChangedData(
-                        object_id=str(key),
-                        changes=["subsections"],
-                    ),
-                )
-        case ContainerType.Section:
-            subsections = [get_container_from_key(key).subsection for key in children_ids]  # type: ignore[arg-type]
-            new_version = content_api.create_next_section_version(
-                container.section,
-                subsections=subsections,  # type: ignore[arg-type]
-                created=created,
-                created_by=user_id,
-                entities_action=entities_action,
-            )
 
-            for key in children_ids:
-                # .. event_implemented_name: CONTENT_OBJECT_ASSOCIATIONS_CHANGED
-                # .. event_type: org.openedx.content_authoring.content.object.associations.changed.v1
-                CONTENT_OBJECT_ASSOCIATIONS_CHANGED.send_event(
-                    content_object=ContentObjectChangedData(
-                        object_id=str(key),
-                        changes=["sections"],
-                    ),
-                )
-        case _:
-            raise ValueError(f"Invalid container type: {container_type}")
+    new_version = content_api.create_next_container_version(
+        container,
+        created=created,
+        created_by=user_id,
+        entities=[get_entity_from_key(key) for key in children_keys],
+        entities_action=entities_action,
+    )
+    for key in children_keys:
+        # .. event_implemented_name: CONTENT_OBJECT_ASSOCIATIONS_CHANGED
+        # .. event_type: org.openedx.content_authoring.content.object.associations.changed.v1
+        CONTENT_OBJECT_ASSOCIATIONS_CHANGED.send_event(
+            content_object=ContentObjectChangedData(
+                object_id=str(key),
+                changes=[f"{container.type_code}s"],  # "units", "subsections", "sections"
+            ),
+        )
 
     # .. event_implemented_name: LIBRARY_CONTAINER_UPDATED
     # .. event_type: org.openedx.content_authoring.content_library.container.updated.v1
@@ -549,30 +420,16 @@ def update_container_children(
         )
     )
 
-    return ContainerMetadata.from_container(library_key, new_version.container)
+    return ContainerMetadata.from_container(container_key.lib_key, new_version.container)
 
 
-def get_containers_contains_item(
-    key: LibraryUsageLocatorV2 | LibraryContainerLocator
-) -> list[ContainerMetadata]:
+def get_containers_contains_item(key: LibraryUsageLocatorV2 | LibraryContainerLocator) -> list[ContainerMetadata]:
     """
     [ 🛑 UNSTABLE ] Get containers that contains the item, that can be a component or another container.
     """
-    item: Component | Container
-
-    if isinstance(key, LibraryUsageLocatorV2):
-        item = get_component_from_usage_key(key)
-
-    elif isinstance(key, LibraryContainerLocator):
-        item = get_container_from_key(key)
-
-    containers = content_api.get_containers_with_entity(
-        item.publishable_entity.pk,
-    )
-    return [
-        ContainerMetadata.from_container(key.lib_key, container)
-        for container in containers
-    ]
+    entity = get_entity_from_key(key)
+    containers = content_api.get_containers_with_entity(entity.pk)
+    return [ContainerMetadata.from_container(key.lib_key, container) for container in containers]
 
 
 def publish_container_changes(
@@ -611,7 +468,7 @@ def copy_container(container_key: LibraryContainerLocator, user_id: int) -> User
     """
     container_metadata = get_container(container_key)
     container_serializer = ContainerSerializer(container_metadata)
-    block_type = ContainerType(container_key.container_type).olx_tag
+    block_type = content_api.get_container_type(container_key.container_type).olx_tag_name
 
     from openedx.core.djangoapps.content_staging import api as content_staging_api
 
diff --git a/openedx/core/djangoapps/content_libraries/rest_api/serializers.py b/openedx/core/djangoapps/content_libraries/rest_api/serializers.py
index 87a5dd3e3b6f..4e326b90c49a 100644
--- a/openedx/core/djangoapps/content_libraries/rest_api/serializers.py
+++ b/openedx/core/djangoapps/content_libraries/rest_api/serializers.py
@@ -15,7 +15,6 @@
 
 from openedx.core.djangoapps.content_libraries.tasks import LibraryRestoreTask
 from openedx.core.djangoapps.content_libraries import api
-from openedx.core.djangoapps.content_libraries.api.containers import ContainerType
 from openedx.core.djangoapps.content_libraries.constants import ALL_RIGHTS_RESERVED, LICENSE_OPTIONS
 from openedx.core.djangoapps.content_libraries.models import (
     ContentLibrary,
@@ -252,7 +251,8 @@ class LibraryContainerMetadataSerializer(PublishableItemSerializer):
 
     Converts from ContainerMetadata to JSON-compatible data
     """
-    # Use 'source' to get this as a string, not an enum value instance which the container_type field has.
+    container_type_code = serializers.CharField(source="container_key.container_type")
+    # Deprecated - ambiguous type
     container_type = serializers.CharField(source="container_key.container_type")
 
     # When creating a new container in a library, the slug becomes the ID part of
@@ -265,7 +265,7 @@ def to_internal_value(self, data):
         Returns a dictionary, not a ContainerMetadata instance.
         """
         result = super().to_internal_value(data)
-        result["container_type"] = ContainerType(data["container_type"])
+        del result["container_type"]  # Use container_type_code instead
         return result