Let's refine the design of a simplified LinkedIn. This isn't about building a full-fledged social network, but rather focusing on the core interaction: the connection network and the feed. We'll model users, their connections, and how they consume and publish content in their feed. The key is to design this with a focus on scalability, extensibility (imagine adding new content types or feed filtering options), and thread safety (many users interacting concurrently).

Think about the core actions a user performs: connecting with other users, posting different types of content (text, image, video), and viewing a personalized feed. The system needs to efficiently manage these connections and generate feeds based on user preferences and network activity. We aim for a design that minimizes coupling between components and promotes code reusability.

Requirements