Even without refresh tokens, clients need to check lifetime. If the token is opaque and the lifetime is unknown, it is no different from a session cookie.

> Does that actually improve OAuth as a whole?

Like I said, this is an improvement for whoever is validating tokens and only them. Refresh tokens are not hard to use, not sure what's the confusion here:

`token = token.is_expired ? refresh_token() : token`

That's all. Even in wordy rust, it doesn't take much:

https://docs.rs/yup-oauth2/6.5.1/src/yup_oauth2/authenticato...

Are you mad that, unlike with opaque token, you know ahead of time when it's expired for sure rather than when you got 401?