What is the ruling on laughing as a courtesy to someone speaking directly, or sending laughing emojis on social media? Is that considered lying or deception?

This is neither lying nor cheating. In fact, it may be commendable in some cases, such as to be polite to the speaker, to show kindness to them, or to ward off their evil. Al-Bukhari titled a chapter: "Chapter: Being Conciliatory with People." And from Aisha, may Allah be pleased with her, that the Prophet, peace and blessings be upon him, said concerning a man who sought permission to enter upon him and whom the Prophet had previously disparaged: "O Aisha, the worst of people in station before Allah is he whom people leave or abandon for fear of his indecency." Qadi Iyad said: "This is from the permissible and commendable conciliation (mudaraah), which is giving of worldly things for the betterment of worldly life and religion. It is not the forbidden flattery (mudahana) which is sacrificing religion for the sake of worldly gain."