#168 🚀 Can your CI/CD survive 200 deploys a day?

Happy Wednesday!

Here is issue #168 of our newsletter, bringing you news and the best tools for your current or future Rails projects…

1. 🤖 Rails World 2026: Can an AI agent approve your pull requests? Ernesto recaps Ryan Sherlock's talk on Shrek, Fin's five-stage review agent that approves about 40% of pull requests with only one human in the loop. Want to try this yourself? Start with the test selection, heartbeat metrics, and automatic rollbacks that make auto-approval safe, then see what each of Shrek's five stages checks.

2. 🤔 Rails World 2026: Who understands your app when production breaks? Ernesto recaps DHH's keynote and his panel with Matz. See where he disagrees on Rust and black-box code, and why humans still need to read and understand what agents write.

3. 💎 Curious what's coming in Ruby 4.1? The first preview is out, with a garbage collector that runs per Ractor (the Ruby team says allocation-heavy Ractor programs now scale like forked processes), YJIT on Windows (mswin, x64 only), and autoload_relative. Before you try it, check the compatibility changes in the Ruby 4.1.0-preview1 announcement, such as only a class's owner Ractor being able to modify it.

Upcoming Events & Learning

⚡Philly.rb's Lightning Talks at Indy Hall: October 20th, 5:30–8:00 PM. Space
is limited, so RSVP here. Don't forget to submit a talk if you've got one to share.

🎟️ Is your team using AI safely? Join OmbuLabs.ai on October 22nd, 11:00 AM ET for a free 45-minute webinar on rolling out Claude at a small business: data privacy, team ground rules, and three first steps. Register here​

🌉 SF Ruby 2026 is approaching. Join us Nov 10-12 at the SF Jazz Center for year # two of the event. Two days of Ruby talks for small teams and big teams: Day 1 AI-heavy and Day 2 AI-light, then a community day.

4. 🚀 RubyGems and Bundler 4.0.23 are out. RubyGems now drops setuid, setgid and sticky bits when extracting gems, and Bundler stops retrying a 416 response to a request without Range. Check the 4.0.23 release notes for the full list and update commands.

5. 🛠️ Want your own bin/rails commands in your app? Thor commands in lib/commands are auto-discovered in gems and engines, but not in a Rails app. Ben Sheldon's post shows the one-line config/boot.rb fix, a sample Rails::Command::Base command, and why the patch is needed: Rails looks up commands before lib is on the load path. Try it today, then see his upstream Rails PR that aims to make it unnecessary.

6. 🌸 Why is every Hanami action its own class? Aaron Allen's answer to that common complaint is scoping: with one class per endpoint, there are no filter lists to cross-reference. See how before_action filters double refund a customer in a Rails controller, then why the same @adjustments ||= [] pattern raises a FrozenError in a Hanami action instead.

7. 🚨 Two new CVEs in Mechanize: upgrade to 2.14.1. Earlier versions can leak headers set through request_headers= to another host after a redirect or a meta refresh. Check the advisories for the redirect leak and the meta refresh leak to confirm you are not exposed.

Check out our other articles on: ​​​​Ruby | Rails | Compatibility | ​​Upgrades​​​​ | ​​​​Tech Debt​​​ | AI​

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Best,

The ​​​​​​FastRuby.io​​​​​​ Team