I'm trying to create a Firebase extension with a beforeUserSignedIn eventType trigger. the extension should add claims to the user on sign-in event. So far, I haven't found a way to do this. I've encountered many errors.

The documentation indicates that Firebase Extensions currently only support triggering on Authentication's onCreate and onDelete event types. Is there any workaround for this?

I tried to deploy an extension using beforeUserSignedIn as the eventType trigger, but I received an "invalid argument" error for the event type.

properties extension.yaml i tried:

resources:
  - name: beforeSignInUpdate
    type: firebaseextensions.v1beta.function
    description: before-sign-in update
    properties:
      runtime: nodejs18
      location: ${LOCATION}
      eventTrigger:
        eventType: providers/firebase.auth/eventTypes/user.beforeSignIn
        resource: projects/${PROJECT_ID}