You are tasked with designing a smart home management system. This system allows users to control various aspects of their home $($e$.$g$.,$ lighting, heating, security cameras$)$ via a mobile app. The system should also integrate with third$-$party services like Google Home and Amazon Alexa, providing a seamless experience. The smart home system should ensure high security and privacy of user data.

Questions:

$1.$ Apply availability and security tactics to ensure the smart home system is reliable and secure$.$ Provide an example of a tactic for both availability and security in the context of the system. Draw a diagram to illustrate the application of these tactics.

$2.$ The current system needs to support third$-$party integrations without compromising security. Explain the role of modifiability tactics to ensure that the system can evolve with future integrations $($e$.$g$.,$ additional smart devices or services$).$

$3.$ Provide three design decisions for performance that you would take to ensure that the system remains responsive even when multiple devices and third$-$party services are in use simultaneously. Use the given case study to explain your answer.