fix(types): type the i18n config key with the augmentable ModuleOptions interface

[lazerg]

🔗 Linked issue

• Resolves NuxtConfig['i18n'] is typed via a type alias, so it cannot be augmented by other modules #4138

📚 Description

ModuleOptions is an interface, so companion modules can extend it through declaration merging. The i18n key on NuxtConfig and NuxtOptions is typed with the UserNuxtI18nOptions alias instead, which an augmentation never reaches, so adding a custom key under i18n fails with TS2353 even though the value survives at runtime.

Both keys now point at ModuleOptions. It extends UserNuxtI18nOptions and adds no members, so the exposed type stays the same and only augmentability changes.

Summary by CodeRabbit

• Bug Fixes
  • Improved TypeScript support for internationalization configuration in Nuxt projects.
  • Configuration options now provide more accurate and consistent type checking across Nuxt configuration contexts.
  • Helps surface invalid settings earlier and improves editor autocomplete when configuring internationalization.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro Plus

Run ID: ff6c48fa-7a4e-4cef-824f-24a15efe0463

📥 Commits

Reviewing files that changed from the base of the PR and between 6a72568 and be80662.

📒 Files selected for processing (1)

• src/module.ts

---

Walkthrough

The Nuxt module augmentation now types NuxtConfig['i18n'] as Partial<ModuleOptions> and NuxtOptions['i18n'] as ModuleOptions. Both declarations previously used UserNuxtI18nOptions.

Estimated code review effort: 1 (Trivial) | ~2 minutes

Merge Risk: ⚪ Minimal · up to be806

This localized type-only change makes the i18n configuration keys augmentable without changing runtime behavior, and no actionable merge-blocking risk remains.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly describes the type change that enables augmentation of the i18n configuration key.
Linked Issues check	✅ Passed	The changes address issue #4138 by typing NuxtConfig and NuxtOptions i18n keys with the augmentable ModuleOptions interface.
Out of Scope Changes check	✅ Passed	The pull request changes only the i18n type declarations required to support ModuleOptions augmentation.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}