AI-Powered Rails Upgrades with Ernesto Tagwerker: NextRails and the Future of Framework Modernization

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When AI Refused to Listen and Then Became the Best Developer on the Team

Rarely does a story about an AI tool actively resisting instructions end up being the most compelling argument for using that tool. When Claude initially pushed back against adding conditionals for dual booting large legacy Rails applications, the team at FastRuby had to essentially teach it their own hard-won expertise rather than letting it default to general Stack Overflow consensus.

Ernesto Tagwerker from OmbuLabs and FastRuby joins Valentino Stoll and Joe Leo to unpack what that process actually looks like in practice. The conversation covers dual booting (running test suites against multiple Rails versions simultaneously), encoding human experience into AI-usable skills, and the shift toward outcome-based value rather than hourly billing. After more than 60,000 development hours across eight years of Rails upgrades, FastRuby has started consistently beating their project estimates with one human and one AI agent matching two humans' output.

What does it actually mean to keep humans in the loop when AI handles ninety percent of implementation work? Ernesto argues that Ruby's readability makes it especially valuable precisely when humans need to oversee and debug AI-generated code. Genuinely, the point lands well and stays with you.

Tune in for a grounded, honest look at where AI genuinely helps and where it still falls short.

Mentioned in the show:

• Ernesto Tagwerker
• Ernesto Tagwerker on GitHub
• OmbuLabs.ai
• OmbuLabs.ai Open Source AI Projects & Claude Code Skills
• FastRuby.io
• FastRuby.io Team
• FastRuby.io Blog: Articles by Ernesto Tagwerker
• next_rails GitHub Repo
• The Next Rails Gem
• How to Dual Boot Rails
• FastRuby.io Rails Upgrade Methodology as Claude Code Skills
• Claude Code Rails Upgrade Skill
• Claude Code Dual Boot Skill
• Claude Code Rails Load Defaults Skill
• Automated Roadmap to Upgrade Rails
• Ruby Critic
• Skunk
• MetricFu
• RailsBump
• Ruby LLM
• GitHub Scientist
• The Well-Grounded Rubyist
• Minerva's New Journal