How are you dealing with creating your own Custom Provider Types?

[denik1981]

  export type BuiltInProviders = Record<OAuthProviderType, OAuthProvider> &
  Record<CredentialsProviderType, CredentialsProvider> &
  Record<EmailProviderType, EmailProvider>
  
  export type AppProviders = Array<Provider | ReturnType<BuiltInProviders[keyof BuiltInProviders]>>

The problem I see with the above code (from providers.d.ts in next-auth@latest) is that for something as simple as to extend the Union type inside OAuthProviderType with my custom provider name then I have to retype everything if I want to rebase my new provider type from the builtin types (which I suspected is was the majority wants to do).

Probably a suggestion here is to use some generics there so we can build our custom provider types more easily.
So I would like to do type CustomOAuthProvider = OAuthProviders<OAuthProviderType | 'MyProvider'> and let;s say OAuthProviders is a type util that comes from next-auth to help us build custom types for custom providers. This is just with one generic but a second one could be added to help us extend options as well. This could be extended to different parts of the app, like adapters and so on. Just an idea

How are you managing this currently on TS?