Your question is Send Message with Tagging in Slack-Style UI. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
Design a "Send message" functionality on Slack: tagging people in messages, UI component design, and communication protocols to use.
Asked in the Hiring manager stage.
Focus on the end-to-end client and backend flow, including how mention suggestions are generated, how the composer UI stays responsive, and how message delivery is coordinated across devices. Keep assumptions explicit and discuss tradeoffs in protocol choice, offline handling, and failure recovery.
