What’s changed from Replit Agent 3 to Agent 4

Replit Agent 4 introduces significant changes to the building experience, focusing on design, collaboration, and workflow. The new Design Canvas replaces the old Design Mode, offering an infinite board for mockups and live previews compatible with all artifact types. Collaboration has shifted from a fork-and-merge model to a shared project environment where an AI agent assists with merging tasks from multiple contributors. The development process is now parallel, allowing users to plan while building, as tasks are executed in isolated environments and managed on a shared Kanban board.