Modifying categories via smart folder not over REST API not working

[AlgoJerViA]

Using the REST API it is not possible to modify the categories of a node when referred to with a smart folder node ref. This problem is apparent when using Digital Workspace UI (ACA) that depends on the API calls.

This behavior of the API can be observed since the introduction at Alfresco 7.4.

Step to replicate:
Download a new SDK and enable smart folders in the global properties.
Build and start the SDK.
Use Share interface to create a new folder and make it a smart folder.
Find a document's smart folder reference.
Make the API call:

curl -X POST "http://localhost:8080/alfresco/api/-default-/public/alfresco/versions/1/nodes/ { the smart noderef} /category-links" -H "accept: application/json" -H "authorization: Basic YWRtaW46YWRtaW4=" -H "Content-Type: application/json" -d "{ "categoryId": "79c8cf75-a4a2-48b4-b2da-67e4dbf51d15"}"

Observe the result:

{
"error": {
"errorKey": "Current user does not have change permission to content",
"statusCode": 403,
"briefSummary": "01020004 Current user does not have change permission to content",
"stackTrace": "For security reasons the stack trace is no longer displayed, but the property is kept for previous versions",
"descriptionURL": "https://api-explorer.alfresco.com"
}
}

[AFaust]

The reason for this is that changes to nodes exposed via smart folders have always had additional restrictions / checks applied to them. In essence, most update permissions are intrinsically denied for "smart nodes". You can see that in

alfresco-community-repo/repository/src/main/java/org/alfresco/repo/virtual/store/HasPermissionMethod.java

Line 60 in d4883af

public AccessStatus execute(VirtualProtocol virtualProtocol, Reference reference) throws ProtocolMethodException

and the configuration of

alfresco-community-repo/repository/src/main/resources/alfresco/smartfolder-context.xml

Line 129 in 945fe52

<property name="userPermissions">