Replit Agent 4 overhauls design, collaboration, and build workflows for product teams

Replit has released Agent 4, a significant product update that restructures four core pillars of its building platform: design workflows, team collaboration, artifact scope, and development planning.

Design Canvas Replaces Standalone Design Mode

The most visible change is the replacement of Design Mode—a separate editor tab in Agent 3—with an always-available Design Canvas. The new canvas is an infinite board that displays two types of content side-by-side: interactive artifact previews (running versions of actual applications) and design mockups (lightweight visual prototypes for rapid exploration).

Unlike the previous Design Mode, which only supported web apps, the Design Canvas works with all artifact types: web apps, mobile apps, slide decks, and data visualizations. Users can resize frames, edit inline, change colors, and preview across mobile, tablet, and desktop sizes without triggering a full agent execution loop. When ready to move from exploration to implementation, users select a frame and ask the Agent to convert it into a working artifact.

Collaboration: From Fork-Merge to Shared Projects

Agent 4 eliminates the fork-and-merge collaboration model from Agent 3. Previously, each team member would fork the project into an isolated environment, work independently, and manually resolve merge conflicts when integrating changes.

The new system places all collaborators in a single shared project. Each team member creates their own chat thread as a personal planning space with the Agent, then dispatches tasks simultaneously with teammates. All tasks appear on a shared Kanban board with four columns: Drafts, Active, Ready, and Done. The Agent handles merge operations automatically—no manual conflict resolution required. Git tracking remains under the hood but is abstracted from the user experience.

Plan-While-Building Workflow

Agent 3 enforced sequential planning and execution: teams had to plan first, confirm the plan, then build. Agent 4 enables concurrent planning and building. Users can open a new chat to plan with the Agent while their main build continues running. New plans create tasks that execute in isolated environments (exact copies of the current project) and move through the Kanban board independently, never touching the main project until explicitly approved.

This concurrent execution is safe because tasks run in isolation. If two tasks modify the same files, the system flags the conflict and handles resolution through the Agent without manual intervention.

Expanded Artifact Support

Agent 3 required users to pre-select an artifact type before starting. Agent 4 removes this constraint. Users can describe what they need—slides, a website, a web app, or mobile app—and the Agent handles artifact creation. Multiple artifacts can be built in parallel within a single project. The platform also supports connecting external services (Linear, Slack, Notion, Google Sheets) and using the Agent to pull data across them.

Backward Compatibility

Existing Agent 3 projects remain fully functional. All Agent 4 features—Design Canvas, shared collaboration, and parallel task execution—are available in new projects. The multi-artifact-per-project feature is not yet compatible with legacy projects but is in development.

What This Means

Agent 4 shifts Replit's positioning from a solo-builder tool toward a team-based development platform. The elimination of fork-merge friction and introduction of real-time collaboration directly addresses a core pain point for distributed teams. The plan-while-building workflow reduces idle time and enables continuous progress on complex projects. However, the complexity of multi-threaded planning and concurrent task execution introduces new surface area for conflicts—though Replit claims the Agent handles these automatically. Whether this reduces or merely redistributes cognitive load for teams remains to be seen in practice.