What is the ruling on constantly swallowing mucus during fasting, given that it is not drawn up or given attention?

Unintentional swallowing of mucus does not invalidate the fast. However, intentionally swallowing it is a matter of scholarly disagreement, and it is permissible to follow those who say that the fast is not invalidated in this case. Dealing with saliva in a normal way does not invalidate the fast, as swallowing saliva does not invalidate the fast.