Radim Vansa which timestamp are you looking to pass in for (a)?

I am not exactly sure what you mean with (b). The StandardQueryCache already does store the timestamps into the payload on put, and checks it on get.

For (c) the Session timestamp is the timestamp that the Session was opened. It could render a new query older, but that's because we'd not be using the correct timestamp. Well, it could be the correct timestamp if the QueryCache stored the timestamp.

I almost think that rather than the timestamp that the Session was opened, I think it ought to reset after each successful transaction. Then it (I think) actually work for (c).