It looks like the synthesis of those two seemingly contradictory things is: If Congress is still in session after the 10 day grace period for the president to sign it has passed, the bill is treated as signed and becomes law. However if the 10 day grace period goes by and Congress is no longer in session at the end of that period, the bill is treated as vetoed.
Another approach: Does nibbling on it count as a signature?
A lot of the eggs I get are fertilized (US, California), but maybe that’s because I tend to get “free range”. Can see the tiny embryo (~1mm) in a lot of them.