Is someone who swallows phlegm after the Fajr call to prayer, having experienced a light sleep, considered to have broken their fast, and what should they do?

If a fasting person sleeps with food in their mouth and does not realize it until after the time of imsak (cessation of eating), if they do not swallow it, their fast is valid, even if this occurs at or after dawn. However, if they swallow it, then if the time of swallowing was before dawn, their fast is valid. But if it was after dawn, their fast is invalidated, and they must make up the day, while still refraining from food and drink for the remainder of that day. If it becomes clear that the swallowing coincided exactly with the break of dawn, then there is nothing upon them. And if they do not know whether they swallowed it before or after dawn, then they must make up the day.