diff --git a/dandiapi/api/models/version.py b/dandiapi/api/models/version.py
index bfe3a4528..17585c06f 100644
--- a/dandiapi/api/models/version.py
+++ b/dandiapi/api/models/version.py
@@ -2,9 +2,7 @@
 
 import datetime
 import logging
-from typing import TYPE_CHECKING
 
-from dandischema.metadata import aggregate_assets_summary
 from django.conf import settings
 from django.contrib.postgres.indexes import HashIndex
 from django.core.validators import RegexValidator
@@ -16,9 +14,6 @@
 
 from .dandiset import Dandiset
 
-if TYPE_CHECKING:
-    from .asset import Asset
-
 logger = logging.getLogger(__name__)
 
 
@@ -145,32 +140,6 @@ def next_published_version(cls, dandiset: Dandiset) -> str:
 
         return version
 
-    @property
-    def publish_version(self):
-        """
-        Generate a published version + metadata without saving it.
-
-        This is useful to validate version metadata without saving it.
-        """
-        # Create the published model
-        published_version = Version(
-            dandiset=self.dandiset,
-            name=self.name,
-            metadata=self.metadata,
-            status=Version.Status.VALID,
-            version=Version.next_published_version(self.dandiset),
-        )
-
-        now = datetime.datetime.now(datetime.timezone.utc)
-        # Recompute the metadata and inject the publishedBy and datePublished fields
-        published_version.metadata = {
-            **published_version._populate_metadata(version_with_assets=self),
-            'publishedBy': self.published_by(now),
-            'datePublished': now.isoformat(),
-        }
-
-        return published_version
-
     @classmethod
     def citation(cls, metadata):
         year = datetime.datetime.now().year
@@ -215,41 +184,15 @@ def strip_metadata(cls, metadata):
         ]
         return {key: metadata[key] for key in metadata if key not in computed_fields}
 
-    def _populate_metadata(self, version_with_assets: Version | None = None):
-
-        # When validating a draft version, we create a published version without saving it,
-        # calculate it's metadata, and validate that metadata. However, assetsSummary is computed
-        # based on the assets that belong to the dummy published version, which has not had assets
-        # copied to it yet. To get around this, version_with_assets is the draft version that
-        # should be used to look up the assets for the assetsSummary.
-        if version_with_assets is None:
-            version_with_assets = self
-
-        # When running _populate_metadata on an unsaved Version, self.assets is not available.
-        # Only compute the asset-based properties if this Version has an id, which means it's saved.
-        summary = {
-            'numberOfBytes': 0,
-            'numberOfFiles': 0,
-        }
-        if version_with_assets.id:
-            try:
-                assets: models.QuerySet[Asset] = version_with_assets.assets
-                summary = aggregate_assets_summary(
-                    # There is no limit to how many assets a dandiset can have, so use
-                    # `values_list` and `iterator` here to keep the memory footprint
-                    # of this list low.
-                    assets.values_list('metadata', flat=True).iterator()
-                )
-            except Exception:
-                # The assets summary aggregation may fail if any asset metadata is invalid.
-                # If so, just use the placeholder summary.
-                logger.info('Error calculating assetsSummary', exc_info=True)
-
-        # Import here to avoid dependency cycle
+    def _populate_metadata(self):
         from dandiapi.api.manifests import manifest_location
 
         metadata = {
             **self.metadata,
+            '@context': (
+                'https://raw.githubusercontent.com/dandi/schema/master/releases/'
+                f'{self.metadata["schemaVersion"]}/context.json'
+            ),
             'manifestLocation': manifest_location(self),
             'name': self.name,
             'identifier': f'DANDI:{self.dandiset.identifier}',
@@ -257,16 +200,20 @@ def _populate_metadata(self, version_with_assets: Version | None = None):
             'id': f'DANDI:{self.dandiset.identifier}/{self.version}',
             'repository': settings.DANDI_WEB_APP_URL,
             'url': f'{settings.DANDI_WEB_APP_URL}/dandiset/{self.dandiset.identifier}/{self.version}',  # noqa
-            'assetsSummary': summary,
             'dateCreated': self.dandiset.created.isoformat(),
         }
+
+        if 'assetsSummary' not in metadata:
+            metadata['assetsSummary'] = {
+                'schemaKey': 'AssetsSummary',
+                'numberOfBytes': 0,
+                'numberOfFiles': 0,
+            }
+
         if self.doi:
             metadata['doi'] = self.doi
         metadata['citation'] = self.citation(metadata)
-        metadata['@context'] = (
-            'https://raw.githubusercontent.com/dandi/schema/master/releases/'
-            f'{metadata["schemaVersion"]}/context.json'
-        )
+
         return metadata
 
     def save(self, *args, **kwargs):
diff --git a/dandiapi/api/services/metadata/__init__.py b/dandiapi/api/services/metadata/__init__.py
index 9db7c17c5..dccea925d 100644
--- a/dandiapi/api/services/metadata/__init__.py
+++ b/dandiapi/api/services/metadata/__init__.py
@@ -1,6 +1,6 @@
 from celery.utils.log import get_task_logger
 import dandischema.exceptions
-from dandischema.metadata import validate
+from dandischema.metadata import aggregate_assets_summary, validate
 from django.db import transaction
 from django.utils import timezone
 import jsonschema.exceptions
@@ -67,6 +67,21 @@ def validate_asset_metadata(*, asset: Asset) -> None:
         asset.versions.filter(version='draft').update(modified=timezone.now())
 
 
+def version_aggregate_assets_summary(version: Version):
+    if version.version != 'draft':
+        raise VersionHasBeenPublished()
+
+    version.metadata['assetsSummary'] = aggregate_assets_summary(
+        version.assets.values_list('metadata', flat=True).iterator()
+    )
+
+    Version.objects.filter(id=version.id, version='draft').update(
+        modified=timezone.now(), metadata=version.metadata
+    )
+    version.refresh_from_db()
+    return version
+
+
 def validate_version_metadata(*, version: Version) -> None:
     logger.info('Validating dandiset metadata for version %s', version.id)
 
@@ -75,17 +90,18 @@ def validate_version_metadata(*, version: Version) -> None:
         raise VersionHasBeenPublished()
 
     with transaction.atomic():
+        # validating version metadata needs to lock the version to avoid racing with
+        # other modifications e.g. aggregate_assets_summary.
+        version = (
+            Version.objects.filter(id=version.id, status=Version.Status.PENDING)
+            .select_for_update()
+            .first()
+        )
         version.status = Version.Status.VALIDATING
         version.save()
 
         try:
-            publish_version = version.publish_version
-            metadata = publish_version.metadata
-
-            # Inject a dummy DOI so the metadata is valid
-            metadata['doi'] = '10.80507/dandi.123456/0.123456.1234'
-
-            validate(metadata, schema_key='PublishedDandiset', json_validation=True)
+            validate(version.metadata, schema_key='Dandiset', json_validation=True)
         except dandischema.exceptions.ValidationError as e:
             logger.info('Error while validating version %s', version.id)
             version.status = Version.Status.INVALID
diff --git a/dandiapi/api/services/publish/__init__.py b/dandiapi/api/services/publish/__init__.py
index 121e91476..76ae0a93f 100644
--- a/dandiapi/api/services/publish/__init__.py
+++ b/dandiapi/api/services/publish/__init__.py
@@ -1,3 +1,6 @@
+import datetime
+
+from dandischema.metadata import aggregate_assets_summary, validate
 from django.contrib.auth.models import User
 from django.db import transaction
 from django.db.models import QuerySet
@@ -76,6 +79,27 @@ def _lock_dandiset_for_publishing(*, user: User, dandiset: Dandiset) -> None:
         draft_version.save()
 
 
+def _build_publishable_version_from_draft(draft_version: Version) -> Version:
+    publishable_version = Version(
+        dandiset=draft_version.dandiset,
+        name=draft_version.name,
+        metadata=draft_version.metadata,
+        status=Version.Status.VALID,
+        version=Version.next_published_version(draft_version.dandiset),
+    )
+
+    now = datetime.datetime.now(datetime.timezone.utc)
+    # inject the publishedBy and datePublished fields
+    publishable_version.metadata.update(
+        {
+            'publishedBy': draft_version.published_by(now),
+            'datePublished': now.isoformat(),
+        }
+    )
+
+    return publishable_version
+
+
 def _publish_dandiset(dandiset_id: int) -> None:
     """
     Publish a dandiset.
@@ -93,7 +117,7 @@ def _publish_dandiset(dandiset_id: int) -> None:
                 'before this function.'
             )
 
-        new_version: Version = old_version.publish_version
+        new_version: Version = _build_publishable_version_from_draft(old_version)
         new_version.save()
 
         # Bulk create the join table rows to optimize linking assets to new_version
@@ -130,7 +154,9 @@ def _publish_dandiset(dandiset_id: int) -> None:
         for draft_asset in draft_assets.iterator():
             publish_asset(asset=draft_asset)
 
-        # Save again to recompute metadata, specifically assetsSummary
+        new_version.metadata['assetsSummary'] = aggregate_assets_summary(
+            new_version.assets.values_list('metadata', flat=True).iterator()
+        )
         new_version.save()
 
         # Add asset paths with new version
@@ -141,6 +167,11 @@ def _publish_dandiset(dandiset_id: int) -> None:
         old_version.status = Version.Status.PUBLISHED
         old_version.save()
 
+        # Inject a dummy DOI so the metadata is valid
+        new_version.metadata['doi'] = '10.80507/dandi.123456/0.123456.1234'
+
+        validate(new_version.metadata, schema_key='PublishedDandiset', json_validation=True)
+
         # Write updated manifest files and create DOI after
         # published version has been committed to DB.
         transaction.on_commit(lambda: write_manifest_files.delay(new_version.id))
diff --git a/dandiapi/api/tasks/scheduled.py b/dandiapi/api/tasks/scheduled.py
index 2510dbd66..92acbbbc4 100644
--- a/dandiapi/api/tasks/scheduled.py
+++ b/dandiapi/api/tasks/scheduled.py
@@ -11,17 +11,22 @@
 from celery.utils.log import get_task_logger
 from django.conf import settings
 from django.contrib.auth.models import User
-from django.db.transaction import atomic
 
 from dandiapi.api.mail import send_pending_users_message
 from dandiapi.api.models import UserMetadata, Version
+from dandiapi.api.services.metadata import version_aggregate_assets_summary
 from dandiapi.api.tasks import validate_version_metadata_task, write_manifest_files
 
 logger = get_task_logger(__name__)
 
 
+@shared_task(soft_time_limit=10)
+def aggregate_assets_summary_task(version_id: int):
+    version = Version.objects.get(id=version_id)
+    version_aggregate_assets_summary(version)
+
+
 @shared_task(soft_time_limit=20)
-@atomic
 def validate_draft_version_metadata():
     # Select only the id of draft versions that have status PENDING
     pending_draft_versions = (
@@ -34,6 +39,7 @@ def validate_draft_version_metadata():
         logger.info('Found %s versions to validate', pending_draft_versions_count)
         for draft_version_id in pending_draft_versions.iterator():
             validate_version_metadata_task.delay(draft_version_id)
+            aggregate_assets_summary_task.delay(draft_version_id)
 
             # Revalidation should be triggered every time a version is modified,
             # so now is a good time to write out the manifests as well.
diff --git a/dandiapi/api/tests/test_dandiset.py b/dandiapi/api/tests/test_dandiset.py
index e13156177..bb72f0eb9 100644
--- a/dandiapi/api/tests/test_dandiset.py
+++ b/dandiapi/api/tests/test_dandiset.py
@@ -388,6 +388,7 @@ def test_dandiset_rest_create(api_client, user):
             }
         ],
         'assetsSummary': {
+            'schemaKey': 'AssetsSummary',
             'numberOfBytes': 0,
             'numberOfFiles': 0,
         },
@@ -480,6 +481,7 @@ def test_dandiset_rest_create_with_identifier(api_client, admin_user):
             }
         ],
         'assetsSummary': {
+            'schemaKey': 'AssetsSummary',
             'numberOfBytes': 0,
             'numberOfFiles': 0,
         },
@@ -585,6 +587,7 @@ def test_dandiset_rest_create_with_contributor(api_client, admin_user):
             }
         ],
         'assetsSummary': {
+            'schemaKey': 'AssetsSummary',
             'numberOfBytes': 0,
             'numberOfFiles': 0,
         },
@@ -675,6 +678,7 @@ def test_dandiset_rest_create_embargoed(api_client, user):
             }
         ],
         'assetsSummary': {
+            'schemaKey': 'AssetsSummary',
             'numberOfBytes': 0,
             'numberOfFiles': 0,
         },
diff --git a/dandiapi/api/tests/test_version.py b/dandiapi/api/tests/test_version.py
index 7ff104ccc..372c9f632 100644
--- a/dandiapi/api/tests/test_version.py
+++ b/dandiapi/api/tests/test_version.py
@@ -14,6 +14,7 @@
 
 from dandiapi.api import tasks
 from dandiapi.api.models import Asset, Version
+from dandiapi.api.services.publish import _build_publishable_version_from_draft
 from dandiapi.zarr.tasks import ingest_zarr_archive
 
 from .fuzzy import TIMESTAMP_RE, URN_RE, UTC_ISO_TIMESTAMP_RE, VERSION_ID_RE
@@ -279,7 +280,7 @@ def test_version_publish_version(draft_version, asset):
     draft_version.assets.add(asset)
     draft_version.save()
 
-    publish_version = draft_version.publish_version
+    publish_version = _build_publishable_version_from_draft(draft_version)
     publish_version.doi = fake_doi
     publish_version.save()
 
@@ -320,6 +321,7 @@ def test_version_publish_version(draft_version, asset):
         # The published_version cannot have a properly defined assetsSummary yet, since that would
         # require having created rows the Asset-to-Version join table, which is a side affect.
         'assetsSummary': {
+            'schemaKey': 'AssetsSummary',
             'numberOfBytes': 0,
             'numberOfFiles': 0,
         },