Does one's fasting become invalid and require making up for it if one masturbates by merely external touching during a Ramadan day and discharges madhy (pre-seminal fluid)?

Masturbation is forbidden due to the harms it entails, and its sinfulness increases in Ramadan, especially during the day. It does not affect the validity of the fast unless semen is discharged. As for the discharge of pre-seminal fluid (madhy), it does not invalidate the fast according to the most preponderant opinion. One must repent to Allah and abstain from it.