---
title: 'Rebuilding Devin for Claude Sonnet 4.5: Lessons and Challenges'
link: https://cognition.com/blog/devin-sonnet-4-5-lessons-and-challenges
source: cognition
published: 2025-09-29T00:00:00Z
first_seen: 2026-09-02T14:07:29.769486161Z
summary: We rebuilt Devin for Claude Sonnet 4.5. The new version is 2x faster, 12% better on our Junior Developer Evals, and it's available now in Agent Preview. For users who prefer the old Devin, that remains available.
---

We rebuilt Devin for Claude Sonnet 4.5. The new version is 2x faster, 12% better on our Junior Developer Evals, and it's available now in Agent Preview. For users who prefer the old Devin, that remains available.