Nextjs I18n

What the source does

• FilesystemNone observedNo reads or writes in the source
• NetworkNone observedNo outbound calls in the source
• ShellNone observedNo commands run in the source
• DependenciesPinnedNothing floats
• SecretsNone foundNo keys in source

Five audit layers

Gates applied: no behavioural pass.

Audit 0.4.1 · source sha 6f5be687a268 · 14 Oct 2026Report an issue or request a re-scan

• PublisherHoangNguyen0403 GitHub userOwner of the repository this skill is read from
• Source folderHoangNguyen0403/agent-skills-standard/skills/nextjs/nextjs-i18nThe exact folder we audited
• LicenceMITAs the repository states it
• Commit pinned for this verdict6f5be687a268A new audit runs when the source changes
• Repository statusNot archivedPushed today
• Sandboxed runNot runSkills are read, not executed; layer L4 is skipped

Its description: Best practices for multi-language handling, locale routing, and detection strategies across App and Pages Router. Use when adding i18n, locale routing, or language detection in Next.js.

---
name: nextjs-i18n
description: Best practices for multi-language handling, locale routing, and detection strategies across App and Pages Router. Use when adding i18n, locale routing, or language detection in Next.js.
metadata:
  triggers:
    files:
    - 'middleware.ts'
    - 'app/[lang]/**'
    - 'pages/[locale]/**'
    - 'messages/*.json'
    - 'next.config.js'
    keywords:
    - i18n
    - locale
    - translation
    - next-intl
    - react-intl
    - next-translate
---
# Internationalization (i18n)

## **Priority: P2 (MEDIUM)**

Maintain single source of truth for locales and ensure SEO-friendly sub-path routing.

## Workflow: Add i18n to Next.js App Router Project

1. Install `next-intl` and create `messages/en.json`, `messages/fr.json`, etc.
2. Add locale detection middleware in `middleware.ts`
3. Create `app/[lang]/layout.tsx` with locale param
4. Load translations server-side via `getMessages()`
5. Add `hreflang` tags in `generateMetadata`
6. Pre-render locales with `generateStaticParams`
7. Verify: run `next build` and confirm all locale paths render

## Middleware Example

See [implementation examples](references/implementation.md)

## Implementation Guidelines

- **Locale Routing**: Follow URL-first approach for SEO. Use dynamic segments in App Router (`app/[lang]/page.tsx`) and `i18n` configuration in `next.config.js` for Pages Router.
- **Library Selection**: Use `next-intl` for App Router (modern) or `react-intl` / `next-translate` for legacy apps.
- **Detection**: Implement middleware localization in `middleware.ts` to detect user language from `Accept-Language` headers or cookies and perform redirects.
- **Server-Side**: Load translation `messages/*.json` dictionaries in Server Components to keep client bundle small.
- **SEO**: Ensure `hreflang` tags generated correctly in `metadata` API for all translated routes.
- **Static Generation**: Use `generateStaticParams` to pre-render localized versions of static pages at build time.

### Library Specifics

For detailed setup with common libraries, refer to:

- [references/react-intl.md](references/react-intl.md)
- [references/next-intl.md](references/next-intl.md)

## Anti-Patterns

- **No hardcoded strings in JSX**: Use translation keys; never commit raw text.
- **No client-side translation bundles**: Load dictionaries server-side with `getMessages()`.
- **No mixed URL locale patterns**: Use sub-paths or domains consistently.

## Canonical response anchors

When this skill applies, preserve the following domain terminology or equivalent concrete examples in the answer when relevant:
- consistent

Excerpt, first 2,610 characters of SKILL.md, verbatim from the audited commit. It is text from someone else’s repository, quoted so you can judge it before your agent reads it.

git clone https://github.com/HoangNguyen0403/agent-skills-standard
git -C agent-skills-standard checkout 6f5be687a268

Works in

1. 2026-10-14
   ✓SAFE B 89 / 100

   first audit · source 6f5be687a268

Questions about Nextjs I18n

• github.com/HoangNguyen0403/agent-skills-standard/tree/develop/sk — the audited source at commit 6f5be687a268 and every finding aboveObserved · 14 Oct 2026

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