# @wrnexus/i18n

Recursive locale loading, fallback resolution, SSR/browser translations, locale formatting, and language UI blocks for WRNexusJS.

## Locale files

Both layouts can be used together:

```text
app/locales/en.json
app/locales/en/common.json
app/locales/en/auth.json
app/locales/mr/common.json
```

Namespaced files become keys such as `common.save` and `auth.signIn`.

```ts
import { loadLocales, makeT, resolveI18n, resolveLang } from "@wrnexus/i18n";

const i18n = resolveI18n(loadLocales("app/locales", { strict: true }), {
  default: "en",
  locales: ["en", "mr", "hi"],
  fallbacks: { "mr-IN": ["mr", "en"] },
  cookie: { name: "wire-lang", sameSite: "Lax", secure: true },
});

const lang = resolveLang(i18n, cookieValue, request.headers.get("accept-language"));
const t = makeT(i18n, lang);
t("common.hello", { name: "Ajay" });
```

## Resolution behavior

- normalized BCP-47-style locale names
- cookie preference
- weighted `Accept-Language`
- wildcard language ranges
- regional base fallback
- explicit fallback chains
- configured default language
- automatic RTL for Arabic, Hebrew, Persian, Urdu, and related languages

Locale JSON is size-limited and rejects prototype-pollution keys. Recursive namespace collisions are resolved safely.

## Views and runtime

```html
<h1 data-t="dashboard.title">Dashboard</h1>
<input t:placeholder="search.placeholder" />
```

Text and translated attributes are resolved during SSR. Active/fallback messages are serialized safely for the language runtime, which rebinds `data-t` markers after client navigation.

Enable `i18nPlugin()` to use:

- `<LanguageSwitcher />`
- `<LocaleStatus />`

`LanguageSwitcher` renders a native `select[data-wire-lang]`. The packaged runtime validates the
selection against the configured locales, writes the configured language cookie, updates the
document `lang`/`dir` attributes, emits `wrnexus:language-change`, and reloads so the next SSR
request uses the same cookie. No application-owned browser script is required.

## Formatting

- `formatNumber`
- `formatCurrency`
- `formatDate`
- `formatRelativeTime`
- `plural`
- `createLocaleFormatter`
- `translationCoverage`
  Localization tooling can extract statically discoverable `t("key")`,
  `i18n.t("key")`, and `data-i18n="key"` usage, compare every locale with a
  reference, and create layout-stressing pseudo-locales:

```ts
import {
  auditLocaleKeys,
  createPseudoLocale,
  extractTranslationKeysFromFiles,
} from "@wrnexus/i18n";

const used = extractTranslationKeysFromFiles(sourceFiles);
const coverage = auditLocaleKeys(messages, "en");
const enXA = createPseudoLocale(messages.en);
const arXB = createPseudoLocale(messages.en, { rtl: true });
```

Pseudo-localization preserves interpolation placeholders and markup tags. RTL
pseudo output uses Unicode direction controls, while runtime direction detection
continues to derive `rtl` from Arabic and other RTL language subtags.
