add Vietnamese language

docs/I18N.md

@@ -1,6 +1,6 @@
 # Translations
 
-Liner ships in 11 languages: en, ru, uk, es, de, it, fr, pl, tr, pt, id. English is the
+Liner ships in 12 languages: en, ru, uk, es, de, it, fr, pl, tr, pt, id, vi. English is the
 source and the fallback for every other language.
 
 ## How it works
@@ -41,7 +41,7 @@ When `count` is a number, the translator first looks for a plural form chosen by
 | en, de, tr     | `_one`, `_other`                                        |
 | es, it, fr, pt | `_one`, `_other`, and `_many` (used for round millions) |
 | ru, uk, pl     | `_one`, `_few`, `_many`, `_other`                       |
-| id             | `_other`                                                |
+| id, vi         | `_other`                                                |
 
 A missing form does not fall back to `_other`: it goes to `<key>_plural` and then the
 plain key. Provide every form in the table, or add a `<key>_plural` as a catch-all.

src/languages/data.ts

@@ -9,6 +9,7 @@ import pl from "./locales/pl.json";
 import tr from "./locales/tr.json";
 import pt from "./locales/pt.json";
 import id from "./locales/id.json";
+import vi from "./locales/vi.json";
 import type { Locale } from "./locale";
 
 export const translations: Record<Locale, Record<string, unknown>> = {
@@ -23,4 +24,5 @@ export const translations: Record<Locale, Record<string, unknown>> = {
   tr,
   pt,
   id,
+  vi,
 };

src/languages/locale.test.ts

@@ -75,6 +75,7 @@ describe("getBrowserLocale", () => {
     ["pt-BR", "pt"],
     ["pt-PT", "pt"],
     ["en-GB", "en"],
+    ["vi-VN", "vi"],
   ])(
     "returns the matching locale when navigator.language is %s",
     (language, expected) => {

src/languages/locale.ts

@@ -10,6 +10,7 @@ export const SUPPORTED_LOCALES = [
   "tr",
   "pt",
   "id",
+  "vi",
 ] as const;
 
 export type Locale = (typeof SUPPORTED_LOCALES)[number];

src/languages/options.tsx

@@ -59,4 +59,9 @@ export const LOCALE_OPTIONS: SelectOption<Locale>[] = [
     label: "Bahasa Indonesia",
     icon: <Emoji name="flag-indonesia" width={16} />,
   },
+  {
+    value: "vi",
+    label: "Tiếng Việt",
+    icon: <Emoji name="flag-vietnam" width={16} />,
+  },
 ];

src/languages/translator.test.ts

@@ -107,6 +107,12 @@ describe("createTranslatorSync with plurals", () => {
     expect(tUk("common.tracks", { count: 10 })).toBe("10 треків");
   });
 
+  it("translates correctly in Vietnamese", () => {
+    const tVi = createTranslatorSync("vi");
+    expect(tVi("common.sidebar.library")).toBe("Thư viện");
+    expect(tVi("common.tracks", { count: 3 })).toBe("3 bài hát");
+  });
+
   it("falls back to English when key is missing in target locale", () => {
     const tRu = createTranslatorSync("ru");
     expect(tRu("common.app.name")).toBe("Liner");