E-commerce Transactions in Islam: Fiqh Muamalah on The Validity of Buying and Selling on Digital Platforms. - Wisnu Uriawan; Muhammad Farhan Tarigan; Herdin Kristianjani Zebua; Muhamad Nopid Andriansyah; Marleni Sukarya; Muhammad Rafli Haikal (CoRR, 2026)