Ruby on Rails creator says the industry is realizing how important senior developers are

Ruby on Rails creator David Heinemeier Hansson says it’s senior developers who are thriving in the AI agentic era.

“The most successful and applicable agent acceleration that I’ve seen at 37 Signal has been from the most senior people, the people who are able to validate whether what the agent produces is suitable to be deployed to millions of people,” Hansson said told “The Pragmatic Engineer” podcast/newsletter in an interview posted on Thursday.

Hansson, who co-owns 37signals, a software company, said junior employees don’t yet have the knowledge base to be able to discern whether AI-created code can be trusted.

“Whenever it’s mission critical for something of that nature, we cannot yet rely on the agents to have vetted it all, and junior programmers are not capable of figuring it out,” he said.

At 37signals, Hansson said senior engineers are much better at working alongside agents, particularly many at once.

“They’re able to, first of all, work in parallel with lots of agents, but critically examine the quality of the agent output and have a high degree of confidence of whether this is going to work or not, or redirect them if not, because this is what made them senior in the first place,” he said.

As an example of what can go wrong, Hansson mentioned the difficulties Amazon has encountered with its internal coding tool, Kiro. Business Insider previously reported in March that Amazon was instituting a 90-day, temporary safety guideline to ensure engineers have two people review their work before implementing changes to services that can directly impact consumers.

In January, Hansson said that AI hadn’t yet reached the level of a junior engineer, though it showed promise.

Now, the veteran programmer said, “My daily work is agent first on everything.”