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vindreshsinghvindreshsingh/engineering-skills/skills/i18n-l10n/SKILL.md

i18n-l10n

Skill0 starsChanged 5 months agoMITView on GitHub

Internationalizes and localizes products — strings, locales, formats, RTL, and translation workflow. Use when adding languages, fixing locale bugs, or expanding to non-English markets.

1 other project uses a version of this.

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The file

We split this skill into the rules it gives an agent

4 rules. About 0 are common, 2 are distinctive, and 2 are very specific to this project.

  • ≈0

    Common · estimate

    Many files like this have a rule of this kind.

  • ≈2

    Distinctive · estimate

    This author's own choices. Worth a look.

  • 2

    Very specific

    Tied to their project's names, files or tools. Probably skip.

  • Common
  • Distinctive
  • Very specific
  1. Very specific:

    Test with de-DE, ja-JP, ar-SA at minimum.

    line 58
  2. Distinctive:

    Don't mirror logos or media with text

    line 64
  3. Distinctive:

    Test [[accessibility]] with screen reader in target language

    line 65
  4. Very specific:

    Import and verify in UI (pseudo-locale for overflow: [[!!]])

    line 71

≈ “Common” is an estimate: at least 1 in 5 of the 350,495 skill files we read have a rule of the same kind, not the same words. “Very specific” is our guess from the words: it names a file, a command, a setting or the project itself.

Keep what fits and drop the rest. Your version, ready for your agents.
Files
SKILL.md

i18n / l10n

English-only caps your market. i18n (internationalization) makes the app locale-ready; l10n (localization) delivers each language correctly — including dates, numbers, currency, and layout direction.

Pairs with [[ui-craft]] for UI implementation, [[accessibility]] for RTL and language attributes, [[technical-writing]] for translated docs, and [[test-first]] for locale-specific tests.

When to Use

  • Adding a second language
  • Hard-coded strings in UI or API errors
  • Date/number/currency shown wrong in non-US locales
  • RTL language support (Arabic, Hebrew)
  • Translation workflow for releases

Skip for internal English-only tools with documented scope.

Process

1. Choose i18n architecture

ApproachBest for
Key-based JSON/PO filesWeb (react-i18next, next-intl)
Platform native (Android strings.xml, iOS Localizable.strings)Mobile
DB-backed stringsCMS-heavy, frequent copy changes

Rule: no user-facing string literals in components after i18n pass.

2. Extract and namespace strings

namespace.feature.element
auth.login.title
auth.login.submit
errors.network.timeout
  • Complete sentences in one key — don't split for grammar across keys
  • Interpolation for variables: "Hello, {{name}}"
  • Pluralization keys per ICU/plural rules

3. Locale formatting

Centralize:

  • Dates and times (timezone-aware)
  • Numbers and decimals
  • Currency (ISO 4217)
  • Relative time ("2 hours ago")

Test with de-DE, ja-JP, ar-SA at minimum.

4. RTL and layout

  • dir="rtl" on <html> or root when locale is RTL
  • Mirror icons that imply direction (arrows, back)
  • Don't mirror logos or media with text
  • Test [[accessibility]] with screen reader in target language

5. Translation workflow

  1. Export strings (JSON/XLIFF)
  2. Translate — human for marketing copy, MT+review for UI chrome OK
  3. Import and verify in UI (pseudo-locale for overflow: [[!!]])
  4. Lock strings before release; changelog for copy changes

6. Test per locale

  • All screens render without truncation/overflow
  • Plural forms correct (1 item vs 5 items)
  • Error messages translated
  • SEO: hreflang tags if public web ([[seo-growth]])

Common Rationalizations

  • "We'll translate when we have users there" — Retrofit i18n costs 3–5x vs building in.
  • "Google Translate in the UI" — Quality breaks trust; use proper workflow.
  • "English URLs are fine" — hreflang and locale paths matter for SEO.

Red Flags

  • Concatenated strings: "Hello " + name
  • Dates hard-coded as MM/DD/YYYY
  • Icons not mirrored in RTL
  • Missing translations fall back to empty string
  • Legal/compliance text machine-translated only

Verification

  • No hard-coded user-facing strings in changed files
  • Keys namespaced; plurals and interpolation correct
  • Formatting uses locale APIs
  • RTL tested if applicable
  • Translation export/import process documented
  • At least one non-English locale verified in browser

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