Version resiliency for a host application and custom code

A method and architecture for increasing version resiliency between a host application that is unmanaged code and custom code that is managed code is provided. A host application exposes an application-level object and a document-level object. A custom code runtime provides a wrapper for the document-level object within the application domain of the custom code runtime. The custom code runtime also provides a mechanism within the application domain of the custom code runtime for providing to custom code a reference to the application-level object directly, rather than through a wrapper. Custom code can then access functionality of the application-level object directly using the reference without having to use a wrapper provided by the custom code runtime.