refactor progress

packages/locale/package.json

@@ -0,0 +1,23 @@
+{
+	"name": "@fluxer/locale",
+	"version": "0.0.0",
+	"private": true,
+	"type": "module",
+	"exports": {
+		"./*": "./*"
+	},
+	"scripts": {
+		"test": "vitest run",
+		"test:watch": "vitest",
+		"typecheck": "tsgo --noEmit"
+	},
+	"dependencies": {
+		"@fluxer/constants": "workspace:*"
+	},
+	"devDependencies": {
+		"@types/node": "catalog:",
+		"@typescript/native-preview": "catalog:",
+		"vite-tsconfig-paths": "catalog:",
+		"vitest": "catalog:"
+	}
+}

packages/locale/src/LocaleService.tsx

@@ -0,0 +1,63 @@
+/*
+ * Copyright (C) 2026 Fluxer Contributors
+ *
+ * This file is part of Fluxer.
+ *
+ * Fluxer is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Fluxer is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with Fluxer. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+import type {LocaleCode} from '@fluxer/constants/src/Locales';
+import {
+	getLocaleByCode,
+	getLocaleDisplayName,
+	getLocaleFlagCode,
+	getLocaleLanguageCode,
+} from '@fluxer/locale/src/catalog/LocaleCatalog';
+import {resolveLocaleFromAcceptLanguageHeader} from '@fluxer/locale/src/resolution/AcceptLanguageNegotiation';
+
+export interface LocaleMetadata {
+	code: LocaleCode;
+	languageCode: string;
+	name: string;
+	flagCode: string;
+}
+
+export function getLocaleMetadata(locale: LocaleCode): LocaleMetadata {
+	return {
+		code: locale,
+		languageCode: getLocaleLanguageCode(locale),
+		name: getLocaleDisplayName(locale),
+		flagCode: getLocaleFlagCode(locale),
+	};
+}
+
+export function getLocaleName(locale: LocaleCode): string {
+	return getLocaleDisplayName(locale);
+}
+
+export function getFlagCode(locale: LocaleCode): string {
+	return getLocaleFlagCode(locale);
+}
+
+export function getLocaleFromCode(code: string): LocaleCode | null {
+	return getLocaleByCode(code);
+}
+
+export function getLocaleCode(locale: LocaleCode): string {
+	return getLocaleLanguageCode(locale);
+}
+
+export function parseAcceptLanguage(acceptLanguageHeader: string | null | undefined): LocaleCode {
+	return resolveLocaleFromAcceptLanguageHeader(acceptLanguageHeader);
+}

packages/locale/src/catalog/LocaleCatalog.tsx

@@ -0,0 +1,263 @@
+/*
+ * Copyright (C) 2026 Fluxer Contributors
+ *
+ * This file is part of Fluxer.
+ *
+ * Fluxer is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Fluxer is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with Fluxer. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+import {AllLocales, type LocaleCode, Locales} from '@fluxer/constants/src/Locales';
+
+interface LocaleMetadata {
+	displayName: string;
+	flagCode: string;
+	aliases?: ReadonlyArray<string>;
+}
+
+export const DEFAULT_LOCALE: LocaleCode = Locales.EN_US;
+export const SUPPORTED_LOCALES: ReadonlyArray<LocaleCode> = AllLocales;
+
+const SUPPORTED_LOCALE_SET: ReadonlySet<LocaleCode> = new Set<LocaleCode>(SUPPORTED_LOCALES);
+
+const LANGUAGE_FALLBACK_BY_LANGUAGE_CODE: Record<string, LocaleCode> = {
+	en: Locales.EN_US,
+	es: Locales.ES_ES,
+	pt: Locales.PT_BR,
+	zh: Locales.ZH_CN,
+	sv: Locales.SV_SE,
+};
+
+const LOCALE_METADATA_BY_CODE: Record<LocaleCode, LocaleMetadata> = {
+	[Locales.AR]: {
+		displayName: 'العربية',
+		flagCode: '1f1f8-1f1e6',
+	},
+	[Locales.BG]: {
+		displayName: 'Български',
+		flagCode: '1f1e7-1f1ec',
+	},
+	[Locales.CS]: {
+		displayName: 'Čeština',
+		flagCode: '1f1e8-1f1ff',
+	},
+	[Locales.DA]: {
+		displayName: 'Dansk',
+		flagCode: '1f1e9-1f1f0',
+	},
+	[Locales.DE]: {
+		displayName: 'Deutsch',
+		flagCode: '1f1e9-1f1ea',
+	},
+	[Locales.EL]: {
+		displayName: 'Ελληνικά',
+		flagCode: '1f1ec-1f1f7',
+	},
+	[Locales.EN_GB]: {
+		displayName: 'English',
+		flagCode: '1f1ec-1f1e7',
+	},
+	[Locales.EN_US]: {
+		displayName: 'English (US)',
+		flagCode: '1f1fa-1f1f8',
+		aliases: ['en'],
+	},
+	[Locales.ES_ES]: {
+		displayName: 'Español (España)',
+		flagCode: '1f1ea-1f1f8',
+	},
+	[Locales.ES_419]: {
+		displayName: 'Español (Latinoamérica)',
+		flagCode: '1f30e',
+	},
+	[Locales.FI]: {
+		displayName: 'Suomi',
+		flagCode: '1f1eb-1f1ee',
+	},
+	[Locales.FR]: {
+		displayName: 'Français',
+		flagCode: '1f1eb-1f1f7',
+	},
+	[Locales.HE]: {
+		displayName: 'עברית',
+		flagCode: '1f1ee-1f1f1',
+	},
+	[Locales.HI]: {
+		displayName: 'हिन्दी',
+		flagCode: '1f1ee-1f1f3',
+	},
+	[Locales.HR]: {
+		displayName: 'Hrvatski',
+		flagCode: '1f1ed-1f1f7',
+	},
+	[Locales.HU]: {
+		displayName: 'Magyar',
+		flagCode: '1f1ed-1f1fa',
+	},
+	[Locales.ID]: {
+		displayName: 'Bahasa Indonesia',
+		flagCode: '1f1ee-1f1e9',
+	},
+	[Locales.IT]: {
+		displayName: 'Italiano',
+		flagCode: '1f1ee-1f1f9',
+	},
+	[Locales.JA]: {
+		displayName: '日本語',
+		flagCode: '1f1ef-1f1f5',
+	},
+	[Locales.KO]: {
+		displayName: '한국어',
+		flagCode: '1f1f0-1f1f7',
+	},
+	[Locales.LT]: {
+		displayName: 'Lietuvių',
+		flagCode: '1f1f1-1f1f9',
+	},
+	[Locales.NL]: {
+		displayName: 'Nederlands',
+		flagCode: '1f1f3-1f1f1',
+	},
+	[Locales.NO]: {
+		displayName: 'Norsk',
+		flagCode: '1f1f3-1f1f4',
+	},
+	[Locales.PL]: {
+		displayName: 'Polski',
+		flagCode: '1f1f5-1f1f1',
+	},
+	[Locales.PT_BR]: {
+		displayName: 'Português (Brasil)',
+		flagCode: '1f1e7-1f1f7',
+	},
+	[Locales.RO]: {
+		displayName: 'Română',
+		flagCode: '1f1f7-1f1f4',
+	},
+	[Locales.RU]: {
+		displayName: 'Русский',
+		flagCode: '1f1f7-1f1fa',
+	},
+	[Locales.SV_SE]: {
+		displayName: 'Svenska',
+		flagCode: '1f1f8-1f1ea',
+		aliases: ['sv'],
+	},
+	[Locales.TH]: {
+		displayName: 'ไทย',
+		flagCode: '1f1f9-1f1ed',
+	},
+	[Locales.TR]: {
+		displayName: 'Türkçe',
+		flagCode: '1f1f9-1f1f7',
+	},
+	[Locales.UK]: {
+		displayName: 'Українська',
+		flagCode: '1f1fa-1f1e6',
+	},
+	[Locales.VI]: {
+		displayName: 'Tiếng Việt',
+		flagCode: '1f1fb-1f1f3',
+	},
+	[Locales.ZH_CN]: {
+		displayName: '简体中文',
+		flagCode: '1f1e8-1f1f3',
+	},
+	[Locales.ZH_TW]: {
+		displayName: '繁體中文',
+		flagCode: '1f1f9-1f1fc',
+	},
+};
+
+const NORMALIZED_LOCALE_TO_CODE = createNormalizedLocaleLookup();
+
+export function normalizeLocaleCode(code: string): string {
+	return code.trim().replace(/_/g, '-').toLowerCase();
+}
+
+export function isSupportedLocale(locale: LocaleCode): boolean {
+	return SUPPORTED_LOCALE_SET.has(locale);
+}
+
+export function getLocaleDisplayName(locale: LocaleCode): string {
+	return LOCALE_METADATA_BY_CODE[locale].displayName;
+}
+
+export function getLocaleFlagCode(locale: LocaleCode): string {
+	return LOCALE_METADATA_BY_CODE[locale].flagCode;
+}
+
+export function getLocaleByCode(code: string): LocaleCode | null {
+	const normalizedCode = normalizeLocaleCode(code);
+	if (!normalizedCode) {
+		return null;
+	}
+
+	const locale = NORMALIZED_LOCALE_TO_CODE.get(normalizedCode);
+	return locale ?? null;
+}
+
+export function getLocaleLanguageCode(locale: LocaleCode): string {
+	return locale.split('-')[0];
+}
+
+export function getPreferredLocaleForLanguageCode(languageCode: string): LocaleCode | null {
+	const normalizedLanguageCode = normalizeLocaleCode(languageCode);
+	if (!normalizedLanguageCode) {
+		return null;
+	}
+
+	const preferredLocale = LANGUAGE_FALLBACK_BY_LANGUAGE_CODE[normalizedLanguageCode];
+	if (!preferredLocale) {
+		return null;
+	}
+
+	if (!isSupportedLocale(preferredLocale)) {
+		return null;
+	}
+
+	return preferredLocale;
+}
+
+export function findLocaleByLanguagePrefix(languageCode: string): LocaleCode | null {
+	const normalizedLanguageCode = normalizeLocaleCode(languageCode);
+	if (!normalizedLanguageCode) {
+		return null;
+	}
+
+	const languagePrefix = `${normalizedLanguageCode}-`;
+	for (const locale of SUPPORTED_LOCALES) {
+		if (locale.toLowerCase().startsWith(languagePrefix)) {
+			return locale;
+		}
+	}
+
+	return null;
+}
+
+function createNormalizedLocaleLookup(): ReadonlyMap<string, LocaleCode> {
+	const lookup = new Map<string, LocaleCode>();
+
+	for (const locale of SUPPORTED_LOCALES) {
+		lookup.set(normalizeLocaleCode(locale), locale);
+	}
+
+	for (const locale of SUPPORTED_LOCALES) {
+		const aliases = LOCALE_METADATA_BY_CODE[locale].aliases ?? [];
+		for (const alias of aliases) {
+			lookup.set(normalizeLocaleCode(alias), locale);
+		}
+	}
+
+	return lookup;
+}

packages/locale/src/resolution/AcceptLanguageNegotiation.tsx

@@ -0,0 +1,120 @@
+/*
+ * Copyright (C) 2026 Fluxer Contributors
+ *
+ * This file is part of Fluxer.
+ *
+ * Fluxer is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Fluxer is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with Fluxer. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+import type {LocaleCode} from '@fluxer/constants/src/Locales';
+import {
+	DEFAULT_LOCALE,
+	findLocaleByLanguagePrefix,
+	getLocaleByCode,
+	getPreferredLocaleForLanguageCode,
+	normalizeLocaleCode,
+} from '@fluxer/locale/src/catalog/LocaleCatalog';
+
+interface AcceptLanguagePreference {
+	locale: string;
+	quality: number;
+}
+
+export function resolveLocaleFromAcceptLanguageHeader(acceptLanguageHeader: string | null | undefined): LocaleCode {
+	if (!acceptLanguageHeader) {
+		return DEFAULT_LOCALE;
+	}
+
+	try {
+		const preferences = parseAcceptLanguagePreferences(acceptLanguageHeader);
+		const exactLocaleMatch = findExactLocaleMatch(preferences);
+		if (exactLocaleMatch) {
+			return exactLocaleMatch;
+		}
+
+		const languageFallbackMatch = findLanguageFallbackMatch(preferences);
+		if (languageFallbackMatch) {
+			return languageFallbackMatch;
+		}
+
+		return DEFAULT_LOCALE;
+	} catch {
+		return DEFAULT_LOCALE;
+	}
+}
+
+function parseAcceptLanguagePreferences(acceptLanguageHeader: string): Array<AcceptLanguagePreference> {
+	return acceptLanguageHeader
+		.split(',')
+		.map((languageToken) => parseLanguagePreference(languageToken))
+		.sort((a, b) => b.quality - a.quality);
+}
+
+function parseLanguagePreference(languageToken: string): AcceptLanguagePreference {
+	const parts = languageToken.trim().split(';');
+	const locale = parts[0].trim();
+	const quality = parseQualityValue(parts[1]);
+	return {
+		locale,
+		quality,
+	};
+}
+
+function parseQualityValue(rawQuality: string | undefined): number {
+	const qualityMatch = rawQuality?.match(/q=([\d.]+)/);
+	if (!qualityMatch) {
+		return 1.0;
+	}
+
+	const parsedQuality = Number.parseFloat(qualityMatch[1]);
+	if (!Number.isFinite(parsedQuality)) {
+		return 1.0;
+	}
+
+	return parsedQuality;
+}
+
+function findExactLocaleMatch(preferences: ReadonlyArray<AcceptLanguagePreference>): LocaleCode | null {
+	for (const {locale} of preferences) {
+		const exactMatch = getLocaleByCode(locale);
+		if (exactMatch) {
+			return exactMatch;
+		}
+	}
+
+	return null;
+}
+
+function findLanguageFallbackMatch(preferences: ReadonlyArray<AcceptLanguagePreference>): LocaleCode | null {
+	for (const {locale} of preferences) {
+		const languageCode = getLanguageCode(locale);
+		const preferredFallbackLocale = getPreferredLocaleForLanguageCode(languageCode);
+		if (preferredFallbackLocale) {
+			return preferredFallbackLocale;
+		}
+
+		const prefixMatchLocale = findLocaleByLanguagePrefix(languageCode);
+		if (prefixMatchLocale) {
+			return prefixMatchLocale;
+		}
+	}
+
+	return null;
+}
+
+function getLanguageCode(locale: string): string {
+	const normalizedLocale = normalizeLocaleCode(locale);
+	const [languageCode] = normalizedLocale.split('-');
+	return languageCode ?? '';
+}

packages/locale/src/tests/LocaleService.test.tsx

@@ -0,0 +1,193 @@
+/*
+ * Copyright (C) 2026 Fluxer Contributors
+ *
+ * This file is part of Fluxer.
+ *
+ * Fluxer is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Fluxer is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with Fluxer. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+import {AllLocales, type LocaleCode, Locales} from '@fluxer/constants/src/Locales';
+import {
+	getFlagCode,
+	getLocaleCode,
+	getLocaleFromCode,
+	getLocaleMetadata,
+	getLocaleName,
+	parseAcceptLanguage,
+} from '@fluxer/locale/src/LocaleService';
+import {describe, expect, it} from 'vitest';
+
+interface LocaleLookupCase {
+	input: string;
+	expected: LocaleCode | null;
+}
+
+interface AcceptLanguageCase {
+	header: string | null | undefined;
+	expected: LocaleCode;
+}
+
+const localeNameCases: Array<{locale: LocaleCode; expected: string}> = [
+	{locale: Locales.EN_US, expected: 'English (US)'},
+	{locale: Locales.EN_GB, expected: 'English'},
+	{locale: Locales.DE, expected: 'Deutsch'},
+	{locale: Locales.JA, expected: '日本語'},
+	{locale: Locales.ZH_CN, expected: '简体中文'},
+	{locale: Locales.ZH_TW, expected: '繁體中文'},
+	{locale: Locales.ES_419, expected: 'Español (Latinoamérica)'},
+	{locale: Locales.PT_BR, expected: 'Português (Brasil)'},
+];
+
+const flagCodeCases: Array<{locale: LocaleCode; expected: string}> = [
+	{locale: Locales.EN_US, expected: '1f1fa-1f1f8'},
+	{locale: Locales.EN_GB, expected: '1f1ec-1f1e7'},
+	{locale: Locales.DE, expected: '1f1e9-1f1ea'},
+	{locale: Locales.JA, expected: '1f1ef-1f1f5'},
+	{locale: Locales.ZH_CN, expected: '1f1e8-1f1f3'},
+	{locale: Locales.ES_419, expected: '1f30e'},
+	{locale: Locales.PT_BR, expected: '1f1e7-1f1f7'},
+];
+
+const localeLookupCases: Array<LocaleLookupCase> = [
+	{input: 'en', expected: Locales.EN_US},
+	{input: 'en-US', expected: Locales.EN_US},
+	{input: 'en-us', expected: Locales.EN_US},
+	{input: 'en_GB', expected: Locales.EN_GB},
+	{input: 'en-gb', expected: Locales.EN_GB},
+	{input: 'de', expected: Locales.DE},
+	{input: 'ja', expected: Locales.JA},
+	{input: 'zh-CN', expected: Locales.ZH_CN},
+	{input: 'zh-cn', expected: Locales.ZH_CN},
+	{input: 'zh-TW', expected: Locales.ZH_TW},
+	{input: 'zh-tw', expected: Locales.ZH_TW},
+	{input: 'es-419', expected: Locales.ES_419},
+	{input: 'pt-br', expected: Locales.PT_BR},
+	{input: 'sv', expected: Locales.SV_SE},
+	{input: 'sv-se', expected: Locales.SV_SE},
+	{input: 'xx', expected: null},
+	{input: '', expected: null},
+	{input: 'en-AU', expected: null},
+];
+
+const localeCodeCases: Array<{locale: LocaleCode; expected: string}> = [
+	{locale: Locales.EN_US, expected: 'en'},
+	{locale: Locales.EN_GB, expected: 'en'},
+	{locale: Locales.DE, expected: 'de'},
+	{locale: Locales.ZH_CN, expected: 'zh'},
+	{locale: Locales.ZH_TW, expected: 'zh'},
+	{locale: Locales.ES_ES, expected: 'es'},
+	{locale: Locales.ES_419, expected: 'es'},
+	{locale: Locales.PT_BR, expected: 'pt'},
+	{locale: Locales.SV_SE, expected: 'sv'},
+	{locale: Locales.JA, expected: 'ja'},
+];
+
+const acceptLanguageCases: Array<AcceptLanguageCase> = [
+	{header: null, expected: Locales.EN_US},
+	{header: undefined, expected: Locales.EN_US},
+	{header: '', expected: Locales.EN_US},
+	{header: 'de', expected: Locales.DE},
+	{header: 'en-GB', expected: Locales.EN_GB},
+	{header: 'en-gb', expected: Locales.EN_GB},
+	{header: 'de;q=0.9, fr;q=1.0', expected: Locales.FR},
+	{header: 'en-US,en;q=0.9,de;q=0.8', expected: Locales.EN_US},
+	{header: 'en-AU', expected: Locales.EN_US},
+	{header: 'es', expected: Locales.ES_ES},
+	{header: 'pt', expected: Locales.PT_BR},
+	{header: 'zh', expected: Locales.ZH_CN},
+	{header: 'sv', expected: Locales.SV_SE},
+	{header: 'de;q=0.5, ja;q=0.9, fr;q=0.7', expected: Locales.JA},
+	{header: 'de, fr;q=0.5', expected: Locales.DE},
+	{header: 'xx-YY', expected: Locales.EN_US},
+	{header: 'fr-CA', expected: Locales.EN_US},
+	{header: '  de  ,  fr  ', expected: Locales.DE},
+	{header: 'zh-TW', expected: Locales.ZH_TW},
+	{header: 'zh-CN', expected: Locales.ZH_CN},
+	{header: 'es-419', expected: Locales.ES_419},
+	{header: 'pt-BR', expected: Locales.PT_BR},
+	{header: 'sv-SE', expected: Locales.SV_SE},
+	{header: 'xx-YY, zz-AA, qq-BB', expected: Locales.EN_US},
+	{header: 'zh-TW, zh;q=0.9', expected: Locales.ZH_TW},
+	{header: 'en-US,en;q=0.9,ja;q=0.8,de;q=0.7,fr;q=0.6', expected: Locales.EN_US},
+	{header: 'de;q=0.999, fr;q=0.998', expected: Locales.DE},
+	{header: 'de;q=0, fr;q=1', expected: Locales.FR},
+];
+
+describe('LocaleService', () => {
+	describe('getLocaleMetadata', () => {
+		it('returns consolidated metadata for a locale', () => {
+			expect(getLocaleMetadata(Locales.EN_US)).toEqual({
+				code: Locales.EN_US,
+				languageCode: 'en',
+				name: 'English (US)',
+				flagCode: '1f1fa-1f1f8',
+			});
+		});
+
+		it('returns metadata for every supported locale', () => {
+			for (const locale of AllLocales) {
+				const metadata = getLocaleMetadata(locale);
+				expect(metadata.code).toBe(locale);
+				expect(metadata.name.length).toBeGreaterThan(0);
+				expect(metadata.flagCode.length).toBeGreaterThan(0);
+			}
+		});
+	});
+
+	describe('getLocaleName', () => {
+		for (const {locale, expected} of localeNameCases) {
+			it(`returns ${expected} for ${locale}`, () => {
+				expect(getLocaleName(locale)).toBe(expected);
+			});
+		}
+	});
+
+	describe('getFlagCode', () => {
+		for (const {locale, expected} of flagCodeCases) {
+			it(`returns ${expected} for ${locale}`, () => {
+				expect(getFlagCode(locale)).toBe(expected);
+			});
+		}
+	});
+
+	describe('getLocaleFromCode', () => {
+		for (const {input, expected} of localeLookupCases) {
+			it(`resolves ${input || 'empty'} to ${expected ?? 'null'}`, () => {
+				expect(getLocaleFromCode(input)).toBe(expected);
+			});
+		}
+
+		it('resolves canonical locale codes for all supported locales', () => {
+			for (const locale of AllLocales) {
+				expect(getLocaleFromCode(locale)).toBe(locale);
+			}
+		});
+	});
+
+	describe('getLocaleCode', () => {
+		for (const {locale, expected} of localeCodeCases) {
+			it(`returns ${expected} for ${locale}`, () => {
+				expect(getLocaleCode(locale)).toBe(expected);
+			});
+		}
+	});
+
+	describe('parseAcceptLanguage', () => {
+		for (const {header, expected} of acceptLanguageCases) {
+			it(`selects ${expected} for ${header ?? 'nullish header'}`, () => {
+				expect(parseAcceptLanguage(header)).toBe(expected);
+			});
+		}
+	});
+});

packages/locale/tsconfig.json

@@ -0,0 +1,5 @@
+{
+	"extends": "../../tsconfigs/package.json",
+	"compilerOptions": {},
+	"include": ["src/**/*"]
+}

packages/locale/vitest.config.ts

@@ -0,0 +1,44 @@
+/*
+ * Copyright (C) 2026 Fluxer Contributors
+ *
+ * This file is part of Fluxer.
+ *
+ * Fluxer is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Fluxer is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with Fluxer. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+import path from 'node:path';
+import {fileURLToPath} from 'node:url';
+import tsconfigPaths from 'vite-tsconfig-paths';
+import {defineConfig} from 'vitest/config';
+
+const __dirname = path.dirname(fileURLToPath(import.meta.url));
+
+export default defineConfig({
+	plugins: [
+		tsconfigPaths({
+			root: path.resolve(__dirname, '../..'),
+		}),
+	],
+	test: {
+		globals: true,
+		environment: 'node',
+		include: ['**/*.{test,spec}.{ts,tsx}'],
+		exclude: ['node_modules', 'dist'],
+		coverage: {
+			provider: 'v8',
+			reporter: ['text', 'json', 'html'],
+			exclude: ['**/*.test.tsx', '**/*.spec.tsx', 'node_modules/'],
+		},
+	},
+});