loom-i18n

# Internationalization (i18n) ## Overview Designing software to adapt to languages/regions without code changes (i18n), then adapting it per-locale (l10n). Covers translation architecture, ICU pluralization, `Intl`-based formatting, RTL/bidi, and libraries (i18next, react-intl/FormatJS, gettext). ## The Rules That Prevent Rework 1. **Never concatenate translated fragments.** Word order, gender agreement, and grammar differ per language. Use one full-sentence key with named placeholders; the translator controls order. ```javascript // Wrong — impossible to translate; order is baked into code t("You have") + " " + count + " " + t("new messages"); // Right — one message, interpolation + plural inside it t("inbox.newMessages", { count }); // "{count, plural, one {# new message} other {# new messages}}" ``` 2. **Pluralize with CLDR categories, never `if (count === 1)`.** English has 2 forms; Russian/Polish 3–4; Arabic 6 (`zero one two few many other`). Which categories a language uses is defined by CLDR — use ICU MessageFormat / `Intl.PluralRules`, not hand-rolled logic. 3. **Format with `Intl`, never by hand.** Decimal/grouping separators, currency placement, date order, and calendars are locale data you will get wrong manually (`1,234.56` en-US vs `1.234,56` de-DE vs `1 234,56` fr-FR). 4. **A locale is language + region.** `en-US` vs `en-GB`: `12/25/2024` vs `25/12/2024`, `color` vs `colour`, different currency. Store and resolve full BCP-47 tags; fall ba...