Function rotate_and_upload_key_package 

pub async fn rotate_and_upload_key_package<ApiClient, S>(
    identity: &Identity,
    api_client: &ApiClientWrapper<ApiClient>,
    mls_storage: &S,
    include_post_quantum: bool,
) -> Result<(), IdentityError>
where
    ApiClient: XmtpApi,
    S: XmtpMlsStorageProvider,

Store fresh key material before upload, then record its publication receipt. Receipt order controls retirement. A read settles unknown publications first. Receipt bookkeeping and the next rotation deadline commit together.