To be clear about current French rules, the pass sanitaire is valid for 7 months after the 2nd shot. because it is 6 months + 1 month grace period.. If somebody gets their 2nd shot on December 1st, for example, they are good to go until July 2022. No decision has been made about if or when booster shots will expire.
And tests (either type) are only valid for 24 hours in France now to annoy the anti-vaxxers.