Does swallowing saliva that has left the mouth during prayer invalidate it, and does swallowing mucus during prayer not invalidate it?

Swallowing saliva does not invalidate prayer or fasting, by consensus, because it is difficult to guard against it. As for intentionally swallowing mucus after it was possible to expel it, this invalidates both prayer and fasting. However, if it was not intentional or it was not possible to expel it, then it invalidates neither.