What’s changed from Replit Agent 3 to Agent 4

Summary Replit Agent 4 meaningfully evolves four core pillars of the building experience: design, collaboration, what you can build, and how you plan and build. Design Mode has been replaced by the Design Canvas—an infinite board that supports all artifact types, live previews, and direct manipulation tools. The old fork-and-merge collaboration model is gone; teammates now work together in a single shared project with agent-assisted merging.