What is the expiation for someone who intended to break their fast in Ramadan due to overwhelming intrusive thoughts about the intention or breaking the fast?

If you are afflicted by waswasa (obsessive whispering), continue to disregard these whispers, as this is their most effective cure. Do not surrender to them, do not pay attention to them, do not indulge in them, and do not yield to the devil's deception, for he only seeks to harm you. The intention (niyyah) resides in the heart; it is not prescribed to utter it aloud or to repeatedly re-establish it. As soon as it crosses your mind, even for a moment during the night, that you will fast tomorrow, you have already formed the intention. Do not pay attention to the devil's subsequent whispers that you have not intended to fast. The fundamental principle for a fasting person, once they have intended to fast and abstained from invalidators, is that their fast is valid. This principle is not removed except by certainty. As long as you are afflicted by waswasa, it is imperative for you to disregard these whispers and not pay any attention to them. You should proceed with your acts of worship without caring about what afflicts you, for waswasa does not carry any legal ruling, nor is it given any consideration.