Ruby on Rails creator David Heinemeier Hansson declares 'pencils down' on handwritten code at 37signals; admits AI agents struggled on Basecamp even as they built all of Omarchy

David Heinemeier Hansson, the creator of Ruby on Rails, has declared a 'pencils down' policy at 37signals, marking a significant shift in software development practices. During his keynote at Rails World 2026, he stated, "We are going, and have gone, pencils down," emphasizing the transition away from handwritten code.²

At 37signals, AI agents like Claude Opus and Gemini Flash are now responsible for most coding tasks. However, Hansson acknowledged that while these agents successfully generated code for the Omarchy Quattro release, they faced challenges with the legacy code of Basecamp and HEY. He explained, "An agent can be told to build a feature. It's a different task entirely to ask it to understand why a decade-old billing module was built the way it was before touching it."¹³⁴

Hansson noted that the economic benefits of manually refining code are diminishing as AI takes over more coding responsibilities. He remarked, "This is a recognition of what is already happening," and highlighted the need to adapt to the evolving landscape of software development. Despite the advancements, he pointed out that the transition is not without its difficulties, particularly when dealing with complex, accumulated codebases.

The audience's response was telling; when Hansson asked how many were still writing significant amounts of code by hand, only a handful raised their hands. "That's about five," he quipped, underscoring the shift in the industry.