A service declares its provider's consent-query quirks

[czpython]

Google grants a refresh token only when the consent URL carries access_type=offline and prompt=consent. Until now the only door was subclassing OauthClient and overriding get_oauth_client(), duplicating the whole base construction just to swap the class.

OauthClient takes extra_authorize_params and lands them in every consent query it begins; begin_connect's own argument layers over them on a shared key. Service declares them as a ClassVar and get_oauth_client() passes them through, so an extension states the quirk in one line next to its endpoints:

class Acme(Service):
    authorization_endpoint = "https://acme.example/oauth/authorize"
    token_endpoint = "https://acme.example/oauth/token"
    extra_authorize_params = {"access_type": "offline", "prompt": "consent"}

Connection also exposes identity — the provider's facts for the sign-in — so extensions read it off the handle, not the row.

The identity column the handle reads landed in #298.