Design Slack-like chat system

## System design: Slack/Discord-like chat Design the **chat subsystem** for an app like Slack/Discord. ### Product requirements - The product has **workspaces**. Each workspace contains **channels**. - Users can **join workspaces** and view all channels in that workspace. - Users can send **plain-text messages** in any channel they have access to. - Users can also have **1:1 private chats (DMs)**. - Users can **scroll back and read the full message history** (assume no expiration). - Users should **see new messages without refreshing** (real-time updates). - Anticipated top feedback: support **editing and deleting messages**. ### What to cover - Core APIs (send message, fetch history, subscribe for real-time, edit/delete) - Data model and storage - Real-time delivery approach - Ordering/consistency expectations - Scaling considerations and key trade-offs You may assume typical Slack-like scale (many workspaces, many channels, high fanout).