TL;DR Building real-time collaboration from scratch takes significant effort. You need sync logic, presence, comments, and infrastructure before you even ship the feature. In this guide, we generate a pixel perfect HackMD style editor UI using Antigravity, connect live markdown preview in React, and then use Velt to add presence, live sync, and comments in just a few steps. What We’re Building We are building a HackMD style markdown editor with a clean two pane layout. On the left, users can write markdown. On the right, they see a live rendered preview. The interface follows a dark theme and mirrors the structure and layout of HackMD closely. This is not just a static clone. The final result will support real time collaboration, allowing multiple users to edit, comment, and stay aware of each other inside the same document. Tech Stack We use a focused, minimal stack: React with Vite and TypeScript: Provides a fast development setup and a clean component-based architecture.…