rigor-rails-i18n

Validates t('key.path') / I18n.t(...) / I18n.translate(...) calls against config/locales/*.yml: missing keys (with did-you-mean suggestions), per-locale coverage gaps, and interpolation-variable mismatches. No Rails runtime dependency — locale files are read through Prism and YAML.safe_load only.

It ships bundled in rigortype. Activate it under plugins::

plugins:
  - rigor-rails-i18n

What it checks

Against a locale catalogue, every statically-resolvable call site is validated:

demo.rb:14:1: info:    `t('users.welcome')` resolves in en, ja
errors_demo.rb:12:1: error:   missing translation key `users.welcom` in any locale (did you mean `users.welcome`?)
errors_demo.rb:16:1: error:   `t('users.welcome')` expects interpolation `name`, got (none)
errors_demo.rb:20:1: warning: `t('users.welcome')` does not use interpolation `extra` (known placeholders: `name`)
errors_demo.rb:25:1: warning: `t('errors.messages.blank')` is missing from locale(s) ja

1. Key existence — a key absent from every locale is flagged, with DidYouMean near-matches.
2. Per-locale coverage — a key present in some configured_locales but not others emits a missing-locale warning (suppressed when the call passes default:).
3. Interpolation variables — the leaf string’s %{var} placeholders must match the call’s keyword arguments. Missing required placeholders are errors; extras are warnings. Reserved I18n option keys (default: / scope: / locale: / count: / raise: / …) are excluded.

Recognised call shapes

t(...) (implicit self), I18n.t(...), and I18n.translate(...) with a literal first argument. Lazy keys — t('.title') in a controller — are expanded to <controller_scope>.<action>.<key> from the file path and the innermost enclosing def, matching Rails’ convention; lazy keys in non-controller files are skipped (the scope can’t be determined statically). Calls with a non-literal key (t(some_variable)) pass through unchecked.

Keys under the prefixes Rails and the rails-i18n gem ship themselves (date. / time. / datetime. / number. / errors.messages. / errors.format / support.array. / helpers.{select,submit,label}. / i18n.transliterate. / activerecord.errors.{messages,models}.) are not flagged as unknown, since the framework provides them.

Configuration

plugins:
  - gem: rigor-rails-i18n
    config:
      locale_search_paths: ["config/locales"]   # default
      configured_locales: ["en"]                # default

configured_locales is the set of locales the project ships; setting it to ["en", "ja"] turns on missing-locale warnings whenever a key resolves in one but not the other.

Limitations

• Literal-string keys only — a variable key passes through.
• Lazy keys outside controllers are skipped — the controller/action scope t('.x') depends on isn’t derivable in a model / helper / mailer.
• Pluralization is recognised but not validated — count: is treated as a reserved option; whether the locale defines :zero / :one / :other is not checked.
• Per-locale interpolation differences are merged into one placeholder set (if en uses %{name} and ja uses %{user_name}, both are treated as required).
• safe_load only — YAML aliases / merges are accepted; custom Ruby classes in the YAML are not.

Plugin internals

The locale loader / index, the cached :locale_index producer, the demo, and the contract surfaces this plugin exercises are in the plugin’s README. To write a plugin, see examples/ and the rigor-plugin-author skill.