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You’ve joined Ping, a messaging app with one-to-one chats and groups. The difficulty is not the messages — it is the unread badge. “Unread” is not a property of a message: the same message is unread for one member, read for another, and invisible to a third who joined the group afterwards. Store that naively and one message in a two-hundred-person group becomes two hundred rows.
out of scopeEncryption and key exchange · media storage · delivery and retries · push notifications · typing indicators · calls
pnpm dev:api and reload.The canvas below still works, so you can model now and run the review once the service is up.Practice studio
Start with the data model, then layer system context
Use entities and relationships for the real ERD. Add notes, containers, or curated cloud shapes only when they sharpen the story you are architecting.
This scenario runs a full workspace — editor, canvas and results side by side. It needs a laptop or desktop to be usable. Open this page on a bigger screen to start building.