Staying Safe If Your Car Breaks Down in the Heat

Hi all, with temperatures getting higher lately, I have been thinking about what I would actually do if my car broke down on a busy road in extreme heat. Last year I saw someone stranded with their hood up and it looked stressful, especially with traffic rushing past. It made me realize I have not really planned for that situation beyond having a spare tire. I started reading more about roadside safety precautions, like pulling over safely, turning on hazard lights immediately, staying inside the vehicle if it is safer, and keeping emergency supplies on hand. I am curious what you personally keep in your car for emergencies and what steps you follow to stay calm and safe while waiting for assistance.