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Over in the OmbuLabs.ai blog, our post on the ReAct pattern in Ruby opens a new window walked through building an agent that reasons about a task, calls tools, and acts on the results, all inside a single Ruby script. That’s fine for a command-line experiment. It’s a different story once that same agent needs to run inside a Rails app, triggered by a web request, where a multi-step reasoning loop can easily take longer than any request should stay open.

The obvious fix is to move the agent into a background job. Sidekiq already handles work that takes a while, so an agent’s loop of thinking, searching, and acting should fit right in. It does, mostly, but a job’s retry semantics were built around retrying a database write, not a chain of API calls that has real, sometimes irreversible, side effects.

In this article, you’ll learn why an agent’s reasoning loop doesn’t survive a naive move into a background job, how to make its side effects idempotent against Sidekiq retries, and how to stream its progress to the user while it runs.

You’ve decided your Ruby on Rails app needs to move from Bootstrap 4 to Bootstrap 5. Bootstrap 4 is end of life opens a new window and no longer receives bug fixes or security updates. Maybe you also want to get jQuery out of your front end, or maybe a component you need only exists in version 5. The catch is that Bootstrap 5 renames classes and data attributes, and that touches many of the views in the app. In a large application, changing all of them in a single pull request is hard to review, hard to test, and hard to roll back.

We recently borrowed the idea behind the Dual-Boot technique opens a new window , running two versions of a dependency side by side, for something other than Rails: Bootstrap itself. Instead of upgrading everything at once, we kept both versions in the app and moved one controller at a time, for many of the same reasons that you might upgrade Rails in increments opens a new window . In this article, you will learn how to run Bootstrap 4 and 5 side by side in one Rails app, how to pick the version per controller with a layout, and how to sequence the migration into small pull requests.

DatabaseCleaner was a very popular gem that helped you keep a clean database between tests. However, newer versions of Rails removed the need for this tool for most cases. Even so, many applications that always used it still use it to this day. Let’s talk about what it does, why it was needed, and why you probably don’t need it anymore, and when you still might.

I was in the audience at Rails World 2026 for Ryan Sherlock’s talk, “Shipping is your heartbeat: Rails in the agentic era.” Ryan is Senior Director of Engineering at Fin opens a new window , the company formerly known as Intercom, and he shared how a very large Rails monolith gets code from a pull request into production.

And it is large. The app is 15 years old, has about 5 million lines of code, and gets deployed more than 200 times a day, with roughly 5 minutes between merging a pull request and seeing it live. In a post on X after the talk opens a new window , Ryan added that they run about 230,000 tests (25,000 of them added in August alone) and ship a new backend every two to three minutes.

I was in the audience in Austin when DHH opened Rails World 2026. The conference tagline was “Shaping the future of Ruby on Rails,” so I walked in expecting to hear about the future of Rails.

That’s not quite what happened.

The opening keynote opens a new window was almost entirely about AI agents. DHH told the room that 37signals has gone “pencils down” on writing code by hand, that HEY is moving to native apps with a Rust backend, and that he has retired as a professional programmer.

The next day, he sat down with Matz and Jeremy Daer for Ruby, Rails, and the future of programming opens a new window , which went even further down the same path.

I’ll recap both sessions, share where I disagree with them, and explain why I’m still excited about where Rails is going. There is a lot going on behind the scenes to make Rails faster and more secure, and to give the view layer some much-needed attention.

I was in the audience at Rails World 2026 when Mike Dalessio, a Rails Core team member who joined earlier this year, put up a slide that said “You are not worried enough (probably).”

He had good reasons to say it.

This summer, Mike handled CVE-2026-66066 opens a new window , an Active Storage vulnerability that let a crafted image upload read files from the server, including your application’s secrets.

His talk, Hot Cell: Securing Active Storage in the age of AI opens a new window , was half post-mortem and half proposal: if we can’t stop image libraries from being vulnerable, maybe we can stop their vulnerabilities from reaching our secrets.

In this article, you will learn what that CVE actually meant, why patching image libraries is no longer enough, how Hot Cell sandboxes Active Storage, and whether you can use it in your Rails application today.

I was in the audience at Rails World 2026 when Aaron Patterson (tenderlove) kicked off the closing keynote. Aaron opened with a well-worn line: “the purpose of a system is what it does.” He wasn’t satisfied with it. The purpose of a system, he argued, is what it does for whoever is observing it.

Hand an old Nokia 3310 to someone who has never seen a cell phone before, and they might use it as a hammer. In that moment, to that person, it is a hammer. What a system does depends on who’s watching.

That distinction has a name in compiler design: The as-if rule.

In this post, we’ll walk through what the as-if rule means for Ruby’s compiler, where Ractors push it right up to its edges, and how the same idea explains a real RubyGems.org security incident that played out earlier this year.

I was in the audience at Rails World 2026 for Jenny Shen’s talk on the RubyGems Compact Index, the last technical talk before the closing keynote. Jenny is a Senior Developer at Shopify and a RubyGems.org opens a new window maintainer, and she opened by asking the room who had heard of the compact index before. Not many hands went up, which was kind of the point: it’s a piece of infrastructure that handles tens of millions of requests a day, and most Rubyists never think about it.

I watched Marco Roth’s talk at Rails World 2026, and it left me excited about where the Rails view layer is headed.

Marco has spent the last couple of years building Herb, an HTML-aware ERB parser that is on its way into Rails 8.2 core, and at Rails World he showed what he is building on top of it: A project called ReActionView opens a new window .

Last month the Rails Foundation published something the Ruby on Rails community had not seen before: a leaderboard of coding agents scored on real Rails work. The first Agents on Rails report opens a new window topped out at 92% in the Accuracy column for the best model tested, which is roughly what you would expect from a field of frontier models. The Rails API recall opens a new window column tells a different story: it shows the share of runs where the model reached for the Rails API that a task was built around, instead of hand-rolling its own version. In that first report it ran from 8% to 35%, and a follow-up published on September 2 opens a new window moved the top of the range to 41%.

Those results describe Writebook opens a new window , the application the benchmark runs against. They do not describe your application. On August 24 the Rails team open sourced lemans opens a new window , the harness behind every number they have published, which means you no longer have to take the leaderboard’s word for anything.

In this article, you will learn what lemans measures, how to build a small bench you can run on your own machine, and how to prove that bench is worth trusting before you spend anything on it.

I was in the audience at Rails World 2026 for Jorge Manrubia’s talk on Lexxy, a new rich text editor for Action Text. Jorge is a Principal Programmer at 37signals, and if you’ve used Active Record Encryption, you’ve used something he built.

Jorge explained why 37signals built a new editor, what Lexxy adds, and how the work opens Action Text to other editors beyond Trix, the editor that’s shipped with Action Text since day one.

In this post, we’ll walk through why Trix became a maintenance burden, why 37signals picked Meta’s Lexical framework over the more obvious open source contenders, and what Lexxy actually does differently inside Action Text.

When we talk about building with AI, most of the attention goes to what’s new. Models, agent frameworks, protocols, and tools seem to appear every week, making it easy to assume that adopting AI means introducing an entirely new technology stack.

But Rails developers already have many of the building blocks needed to create useful AI-assisted workflows. Generators, Rake tasks, command-line interfaces, schemas, tests, and APIs were designed to make software easier to work with by providing structure and predictable behavior. Those same qualities make them well suited for AI coding tools.

In this context, an AI-assisted workflow doesn’t mean building an agent into a Rails application. It can be as simple as a developer using an AI coding tool to complete a task in an existing codebase, whether that’s adding a feature, running tests, analyzing technical debt, or helping with a Rails upgrade. As these tools become capable of taking more actions on a developer’s behalf, they need reliable ways to interact with the codebase and the tooling around it.

This article explores how existing Ruby and Rails tooling can become part of AI-assisted development, and why introducing AI doesn’t require starting from scratch.

ERB does not know that it is generating HTML. It finds the <% %> tags, evaluates the Ruby inside them, and concatenates everything else as plain text. Whether the result is valid markup has never been its problem.

Herb changes that. On August 25, 2026, the Ruby on Rails core team merged Add Herb as an HTML-aware ERB implementation opens a new window , which brings in Herb opens a new window , an ERB implementation that parses HTML and ERB into a single syntax tree and uses Prism opens a new window for the Ruby inside the tags. Broken markup can now fail while the template compiles, instead of reaching a browser.

In this article, you will learn what Herb is, how to audit your own views with it today, what it can fix for you, what it cannot, and what it costs to run. We used the FastRuby.io views as the test subject.

RFC 10008, published in June 2026, defines the QUERY method as safe and idempotent like GET, and it carries its query in the request body like POST. Ruby on Rails merged support for QUERY on August 14, 2026, under the 8.2.0 milestone.

I set up a small application on edge Rails to check it working. The routing and the request object are ready, but the parts of the specification that make QUERY more than a POST with better manners are not quite there yet, since Rails parses only JSON bodies and does not enforce the content type rule RFC 10008 requires. In this article, we will check how the QUERY method works in Rails, how to route and test it, how Puma is handling it, and which pieces of the specification are still missing. Everything below reflects the state of things at the beginning of September 2026, and since Rails, Rack, and Puma all have the interesting parts sitting on unreleased branches, it is worth checking the versions yourself before trusting any of it.

Founded in 1912, the Irish Chess Union (ICU) is the governing body for chess across the island of Ireland. It has about 2,500 members and run entirely by volunteers.

Its website, icu.ie opens a new window , has been maintained by webmaster Jonathan O’Connor since 2015. Earlier this year, Jonathan reached out to us. He wanted help taking the ICU’s Rails application from 7.0 to 8.1.

We used Claude Code and our open source Claude Code Rails Upgrade Skill opens a new window to get it done. We also recorded the sessions as a video series, so other teams could see the methodology in practice.

In this article, we’ll walk through the upgrade, one version at a time, and share what Jonathan thought of the process.