Letting Drupal know about new/updated/deleted external entities

Here's my experience on a project we're working on.

We have an external system that notifies us (through a custom API endpoint) about changes on our external content. Once we receive a message (operation, type, ID), after some trial and error we ended up with the following code to invoke entity lifecycle hooks:

if ($action === 'delete') {
  $entity::preDelete($entity_storage, [$entity]);
  $this->moduleHandler->invokeAll($entity->getEntityTypeId() . '_predelete', [$entity]);
  $this->moduleHandler->invokeAll('entity_predelete', [$entity]);
  $entity::postDelete($entity_storage, [$entity]);
}
else {
  $entity->original = clone $entity;
  $entity->preSave($entity_storage);
  $this->moduleHandler->invokeAll($entity->getEntityTypeId() . '_presave', [$entity]);
  $this->moduleHandler->invokeAll('entity_presave', [$entity]);
  $entity->postSave($entity_storage);
}

$hook = $action === 'create' ? 'insert' : $action;
$this->moduleHandler->invokeAll($entity->getEntityTypeId() . '_' . $hook, [$entity]);
$this->moduleHandler->invokeAll('entity_' . $hook, [$entity]);

This has worked more or less OK for quite a while. It does have some gaps, however. Thinking about the entity translation-specific hooks, for example.

After some thinking, I think the most proper way is to be able to call $external_entity->save() or $external_entity->delete(). This comes very close (if not completely) to Drupal's default way of working with entities - but doing this could (if your external entities are not marked as read-only) send a write to the external API - which is undesired in this scenario (since we only want to call it to make Drupal do its thing on the new/updated/deleted entity).

I was wondering if it's a good idea to introduce something so that we can (temporarily) mark external entities on which save/delete operations are performed, to not push through to the external API. See patch attached. It's based on a similar functionality Drupal core (setSyncing and isSyncing).

With this patch, the code above could be changed to:

$entity->skipExternalStorageMutation();
$entity->save();
$entity->skipExternalStorageMutation(FALSE);

and

$entity->skipExternalStorageMutation();
$entity->delete();
$entity->skipExternalStorageMutation(FALSE);

Any thoughts? How is everyone else tackling this problem space?

I'm not there yet but I'll keep an eye on this issue. ;)