There is no Extension support for Gemini seemingly in any google python library

We currently use the gemini-pro models frequently to perform various tasks. I have built and tested the creation of an Extension to the LLM is able to call our service to get supporting information. My Extension works through the GCP UI without issue.

I am able to find load and run my extension using this part of the vertexai codebase from google-cloud-aiplatform

from vertexai.preview import extensions
extension_id = "<id>"
extension = extensions.Extension(extension_id)

However there is no way to pass this to generative_models.GenerativeModel to get gemini to interact with it.

I have also installed and tried google-genai and there is also no documentation to support using Extensions.

Am I missing something? Is this currently in development?