I18n Date Patterns

What it does

When your agent uses it

• Building multilingual UIs
• Formatting dates/currency

Example prompts

• “Use the i18n-date-patterns skill to implement internationalization (i18n) in React applications”
• “/i18n-date-patterns”

Requirements

• Compatibility (from SKILL.md): Claude Code 2.1.277+.
• Pre-approved tools (allowed-tools): Read, Glob, Grep, WebFetch, WebSearch

Workflow steps

5 steps, taken from the step headings in SKILL.md.

1. 1useTranslation Hook (All UI Strings)
2. 2useFormatting Hook (Locale-Aware Data)
3. 3Date Formatting
4. 4ICU MessageFormat (Complex Plurals)
5. 5Trans Component (Rich Text)

What it can do on your machine

Read from SKILL.md and the folder at commit 02bbf9a. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves these tools, so the agent can use them without asking each time:

  • Read
  • Glob
  • Grep
  • WebFetch
  • WebSearch

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  No scripts in the folder and no shell commands in SKILL.md (its code samples are typescript and json).

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  Links to these hosts (documentation or services it may open):

  • unicode-org.github.io
  • developer.mozilla.org
  • formatjs.github.io
  • cldr.unicode.org
  • react.i18next.com
  • github.com

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

• Compatibility

  Claude Code 2.1.277+.

  From compatibility in the SKILL.md frontmatter.

Context cost

I18n Date Patterns loads about 2.6k tokens when it runs, and up to ~4.8k if it reads all its reference files. Until then it costs about 64 tokens; SKILL.md has 716 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~64

When it runs · the whole SKILL.md, loaded when a task matches

~2.6k

With references · SKILL.md plus every file in references/, read only if the agent opens them

~4.8k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from yonatangross/orchestkit at commit 02bbf9a, republished under its MIT licence (© yonatangross). 716 words, ~2,596 tokens.

name

i18n-date-patterns

description

Implements internationalization (i18n) in React applications. Covers user-facing strings, date/time handling, locale-aware formatting, ICU MessageFormat, and RTL support. Use when building multilingual UIs or formatting dates/currency.

allowed-tools

Read, Glob, Grep, WebFetch, WebSearch

compatibility

Claude Code 2.1.277+.

license

MIT

context

inherit

user-invocable

false

disable-model-invocation

true

effort

low

model

haiku

metadata.category

document-asset-creation

metadata.version

1.2.0

metadata.author

Yonatan Gross

metadata.complexity

low

import { useTranslation } from 'react-i18next';

function MyComponent() {
  const { t } = useTranslation(['patients', 'common']);
  
  return (
    <div>
      <h1>{t('patients:title')}</h1>
      <button>{t('common:actions.save')}</button>
    </div>
  );
}

import { useFormatting } from '@/hooks';

function PriceDisplay({ amount, items }) {
  const { formatILS, formatList, formatOrdinal } = useFormatting();
  
  return (
    <div>
      <p>Price: {formatILS(amount)}</p>        {/* ₪1,500.00 */}
      <p>Items: {formatList(items)}</p>        {/* "a, b, and c" */}
      <p>Position: {formatOrdinal(3)}</p>      {/* "3rd" */}
    </div>
  );
}

import { formatDate, formatDateShort, calculateWaitTime } from '@/lib/dates';

const date = formatDate(appointment.date);    // "Jan 6, 2026"
const waitTime = calculateWaitTime('09:30');  // "15 min"

{
  "patients": "{count, plural, =0 {No patients} one {# patient} other {# patients}}"
}

t('patients', { count: 5 })  // → "5 patients"

import { Trans } from 'react-i18next';

<Trans
  i18nKey="richText.welcome"
  values={{ name: userName }}
  components={{ strong: <strong /> }}
/>

frontend/src/i18n/locales/
├── en/
│   ├── common.json      # Shared: actions, status, time
│   ├── patients.json    # Patient-related strings
│   ├── dashboard.json   # Dashboard strings
│   ├── owner.json       # Owner portal strings
│   └── invoices.json    # Invoice strings
└── he/
    └── (same structure)

// ❌ NEVER hardcode strings
<h1>מטופלים</h1>                    // Use t('patients:title')
<button>Save</button>               // Use t('common:actions.save')

// ❌ NEVER use .join() for lists
items.join(', ')                    // Use formatList(items)

// ❌ NEVER hardcode currency
"₪" + price                         // Use formatILS(price)

// ❌ NEVER use new Date() for formatting
new Date().toLocaleDateString()     // Use formatDate() from @/lib/dates

// ❌ NEVER use inline plural logic
count === 1 ? 'item' : 'items'      // Use ICU MessageFormat

// ❌ NEVER leave console.log in production
console.log('debug')                // Remove before commit

// ❌ NEVER use dangerouslySetInnerHTML for i18n
dangerouslySetInnerHTML             // Use <Trans> component

© yonatangross, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 10 other files (references) in src/skills/i18n-date-patterns of yonatangross/orchestkit.

• SKILL.md
• checklists/i18n-checklist.md
• examples/component-i18n-example.md
• references/formatting-utilities.md
• references/ork-delta.md
• rules/_sections.md
• rules/_template.md
• rules/i18n-formatting-antipatterns.md
• rules/i18n-icu-plurals.md
• rules/i18n-trans-component.md
• test-cases.json

Open the folder on GitHubat commit 02bbf9a