What is the ruling on the contract session when one of the contracting parties is absent, such as selling a commodity online in the absence of the seller from the contract session?

The Shari'ah establishes for each of the two parties to a sale the right to annul the contract as long as they are in the session of the contract. However, once they part ways, the sale becomes binding and cannot be annulled except by mutual consent or a reason that permits annulment. If one of the contracting parties is absent, for example, if the seller sends a message to the buyer and the buyer accepts the sale, the sale is valid, and the buyer has the option [to annul] as long as they are in the session where the message was received and the sale was accepted. Some scholars have opined that there is no khiyar al-majlis (option of the session) if the sale is concluded in such a manner and the seller and buyer are not together in one session. If a purchase made via the internet cannot be reversed after acceptance, or if the seller stipulates this, then the khiyar al-majlis is waived, and the sale becomes binding immediately upon the buyer's acceptance.