Function should_serve_native 

fn should_serve_native(
    native_enabled: bool,
    has_default_idp: bool,
    wants_create: bool,
) -> bool

Decide whether an authorization request with no explicitly-selected provider is served the native login/register page rather than an upstream-IdP SSO redirect. Native applies when enabled and either no default IdP is configured or the client asked to create an account.