AWS IoT events track ESP32 connectivity, enabling app status updates

AWS IoT Core automatically publishes events when an MQTT client, like an ESP32 device, connects or disconnects. These events are sent to reserved MQTT topics and include a disconnect reason, which is valuable for debugging connection issues. To ensure a mobile app reliably displays a device's online status, the article recommends using an IoT Rule to forward these events to a named Device Shadow. Storing the state in the Shadow allows the app to read it at any time, solving the problem of missing real-time events if the app opens after a disconnection.