@dcsv-io/d2-i18n

ITranslator interface + SupportedLocales registry + default Translator implementation. Mirrors DcsvIo.D2.I18n (.NET) so cross-language wire stays consistent. The TS-side TK constants catalog itself is provided by Paraglide in the SvelteKit BFF; this package is the SHARED interface that any TS consumer (Paraglide-backed or hand-rolled) implements against.

Install

pnpm add @dcsv-io/d2-i18n

Public API

| Export | Purpose | | ----------------------------------------- | ----------------------------------------------------------------------------------------- | | ITranslator (interface) | t(locale, message): string. Resolves a TK message to its rendered string. NEVER throws. | | SupportedLocales (class) | BCP 47 supported-locale registry with canonical casing + language fallback. | | SupportedLocalesConfig | Constructor input — enabled list + optional default. | | loadSupportedLocalesConfig(prefix, env) | Reads indexed env-var array (PREFIX__0=en-US, PREFIX__1=fr-FR). | | Translator (class) | Default ITranslator impl with locale fallback + {name} parameter substitution. | | LocaleCatalogs | Map of locale → key → template-string consumed by Translator. | | TKMessage / tk() | Re-exported from @dcsv-io/d2-i18n-abstractions for caller convenience. |

Dependencies

• @dcsv-io/d2-utilities — boundary helpers, env parsing
• @dcsv-io/d2-i18n-abstractions — TKMessage type + tk() factory

Usage example

import { SupportedLocales, Translator, tk } from "@dcsv-io/d2-i18n";

const locales = new SupportedLocales({ enabled: ["en-US", "fr-FR"] });
const catalogs = {
  "en-US": { "TK.greet": "Hello, {name}" },
  "fr-FR": { "TK.greet": "Bonjour, {name}" },
};
const t = new Translator(locales, catalogs);

t.t("fr-CH", tk("TK.greet", { name: "Alice" })); // "Bonjour, Alice"

Parity with .NET

Mirrors DcsvIo.D2.I18n:

• ITranslator ↔ DcsvIo.D2.I18n.ITranslator
• SupportedLocales ↔ DcsvIo.D2.I18n.SupportedLocales — same canonical-casing + language-fallback semantics.
• Translator ↔ DcsvIo.D2.I18n.Translator — same fallback chain (requested → default → key-verbatim) + same {name} placeholder syntax.

Edge cases

• SupportedLocales.resolve(null/undefined/empty) returns the default locale (never throws).
• Translator.t returns the key verbatim when no catalog entry matches — discoverable in output, never raises.
• Unmatched placeholders are left literal ({name} stays in output) so the operator notices missing bindings.
• loadSupportedLocalesConfig returns enabled: [] when no env entries — the constructor then throws on construct, surfacing the misconfiguration immediately rather than silently using a default.