What is the ruling on ritual purity (ṭahārah) and prayer (ṣalāh) upon seeing a red, viscous substance after the cessation of menstrual bleeding?

A woman determines the end of her menstruation by two signs: the white discharge (al-qassah al-bayḍāʾ) or complete dryness (al-jufūf al-tāmm). If she sees purity by one of these two signs, ritual bathing (ghusl) becomes obligatory for her. If, after purity, she experiences secretions (yellowish or brownish discharge), these are not considered menstruation but rather take the ruling of vaginal secretions, which only invalidate ablution (wuḍūʾ). However, if she sees blood again, she must consider herself menstruating as long as it is within the fifteen-day period. There is no evidence to suggest re-performing a day's prayers as a precaution.