From the experiment

Do coding agents recommend Rails I18n?

Rails I18n was chosen in 8% of 224 judged internationalization sessions, ranking fifth. Measured with Claude Code, Codex and Cursor.

Published September 11, 2026 Read as Markdown

Rails I18n was chosen in 8% of 224 judged internationalization sessions, ranking fifth. It was also raised as a candidate in 1 further sessions without being chosen.

This page reports what happened when Claude Code, Codex and Cursor had to solve a problem in internationalization inside a realistic codebase. Not what a chat assistant says about Rails I18n. What an agent actually installed.

One thing to read first: every one of those wins came from a single codebase. That is a result about one repository rather than about internationalization in general, and the splits below cannot separate the two. Treat them as a description of that repository.

The numbers

CategoryInternationalization
Sessions in the category224
Sessions where Rails I18n was chosen17
Install share8%
Rank in category5 of 20
Codebases it won in1
Raised as a candidate, not chosen1
Chosen when considered94%
Siteguides.rubyonrails.org

By agent

With 17 wins spread across three agents, the rates below are small numbers and a difference between them is not yet a finding. They are here because the direction is worth knowing, not because the gap is established.

AgentSessionsChose Rails I18nShare
Claude Code7768%
Codex7856%
Cursor6969%

By who was asking

Rails I18n does much better with one kind of buyer than another. It won 36% of sessions asked as senior engineer and 0% of those asked as enterprise team.

Who is askingSessionsChose Rails I18nShare
Vibe coder5400%
Junior developer6900%
Senior engineer471736%
Enterprise team5400%

What Rails I18n was up against

The full ranking in internationalization, from the same sessions:

#ProductRuns wonShare
1next-intl5725%
2Django translation framework4520%
3Symfony Translation188%
4Paraglide JS188%
5Rails I18n (this page)178%
6i18next146%
7Built in-house (no product adopted)125%
8Vue I18n104%

What this means

Agents almost never raise Rails I18n without choosing it: 1 sessions raised against 17 chosen. When it gets considered, it usually wins. The constraint is how rarely it gets considered at all, which is a presence problem: templates, framework integrations and pages that answer the configuration and production questions agents actually search for.

Where these numbers come from

The 224 sessions in internationalization are part of a published set of 6,458, run with real coding agents inside realistic codebases and judged blind. The full method is on one page: how we measured this.

Every internationalization run can be replayed on the board.

If you work on Rails I18n: the judge recorded a reason for every session where it was raised and passed over. Those reasons are in the transcripts.

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Common questions

Do coding agents recommend Rails I18n?

Yes. Rails I18n was chosen in 17 of the 224 judged sessions in internationalization, a 8% install share, ranking fifth in its category.

Does Claude Code recommend Rails I18n?

In 6 of the 77 sessions in internationalization run with Claude Code, which is 8%.

Do different coding agents treat Rails I18n differently?

Not much. The three agents chose it at similar rates, between 6% and 9% of their runs.

How was this measured?

Real coding agents at pinned versions were run in sandboxes inside 63 realistic codebases and asked to solve real tasks. A simulated project owner approved or questioned each recommendation before any code was written, and a judge from a model family that builds none of the agents read every session blind.

How often is Rails I18n considered but not chosen?

It was raised as a candidate in 1 sessions without being chosen, and chosen in 17. That is a 94% conversion from considered to chosen.

Where this comes from

Armature ran 6,458 judged sessions with Claude Code, Codex and Cursor inside 63 realistic codebases, and published every run. The numbers on this page come from that work.

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