# What Replit Agent 3 promised at launch

> Agent 3 added browser testing and longer autonomous runs, with progress available for human review.

Source: https://fullbytedeveloper.com/blog/replit-agent-three-autonomous-runtime
Originally posted: 2025-09-15
Published here: 2026-11-06

Replit introduced Agent 3 with automated application testing and autonomous runs of up to 200 minutes. The announcement described building, testing and fixing an app while users monitored progress. The duration was a product claim, not a guarantee that every task would finish correctly. [1]

## Give the agent an observable target

Describe a small result that you can check, such as submitting a form and seeing the saved record. Include expected error cases and the screens that should remain unchanged.

Replit said Agent 3 could use a browser to test applications, including login flows built with Replit Auth. That can expose failures in a visible workflow, but it does not replace a review of permissions or data handling. [1]

## Review before release

Read the changes, repeat the important user journey and check what the agent actually tested. Keep a recoverable version before a long run. Runtime is useful context for planning a task; acceptance still depends on the result.

## Sources

1. [Replit Agent 3 announcement](https://replit.com/blog/introducing-agent-3-our-most-autonomous-agent-yet)

## Original posts

- [Instagram post](https://www.instagram.com/fullbytedeveloper/p/DOoWz3bjIfb/)