For more than 8 years, we have been publishing detailed guides on how to upgrade Rails applications.
We have documented every minor version from Rails 2.3 through 8.1 in our Rails Upgrade Series and distilled our methodology into an ebook: The Complete Guide to Upgrade Rails

All of that knowledge comes from more than 60,000 developer-hours of hands-on upgrade work for companies of all sizes, from solo-founded SaaS products to huge Rails monoliths running at Fortune 500 public companies.
Today, we are making that methodology available to everyone as an open source Claude Code Skill: claude-code_rails-upgrade-skill.
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