refactor: localesをworkspace管理下のパッケージに (#16895)

* refactor: localesをworkspace管理下のパッケージに

* fix copilot review

* move

* move

* rename

* fix ci

* revert unwanted indent changes

* fix

* fix

* fix

* fix

* 間違えてコミットしていたのを戻す

* 不要

* 追加漏れ

* ymlの場所だけ戻す

* localesの位置を戻したのでこの差分は不要

* 内容的にlocalesにある方が正しい

* i18nパッケージ用のREADME.mdを用意

* fix locale.yml

* fix locale.yml

---------

Co-authored-by: kakkokari-gtyih <67428053+kakkokari-gtyih@users.noreply.github.com>

packages/backend/src/core/NotificationService.ts

@@ -202,7 +202,7 @@ export class NotificationService implements OnApplicationShutdown {
 	}
 
 	// TODO
-	//const locales = await import('../../../../locales/index.js');
+	//const locales = await import('i18n');
 
 	// TODO: locale ファイルをクライアント用とサーバー用で分けたい
 
@@ -271,7 +271,7 @@ export class NotificationService implements OnApplicationShutdown {
 		let untilTime = untilId ? this.toXListId(untilId) : null;
 
 		let notifications: MiNotification[];
-		for (;;) {
+		for (; ;) {
 			let notificationsRes: [id: string, fields: string[]][];
 
 			// sinceidのみの場合は古い順、そうでない場合は新しい順。 QueryService.makePaginationQueryも参照

packages/frontend-builder/locale-inliner.ts

@@ -10,7 +10,7 @@ import { collectModifications } from './locale-inliner/collect-modifications.js'
 import { applyWithLocale } from './locale-inliner/apply-with-locale.js';
 import { blankLogger } from './logger.js';
 import type { Logger } from './logger.js';
-import type { Locale } from '../../locales/index.js';
+import type { Locale } from 'i18n';
 import type { Manifest as ViteManifest } from 'vite';
 
 export class LocaleInliner {

packages/frontend-builder/locale-inliner/apply-with-locale.ts

@@ -5,7 +5,7 @@
 
 import MagicString from 'magic-string';
 import { assertNever } from '../utils.js';
-import type { Locale, ILocale } from '../../../locales/index.js';
+import type { ILocale, Locale } from 'i18n';
 import type { TextModification } from '../locale-inliner.js';
 import type { Logger } from '../logger.js';
 

packages/frontend-builder/package.json

@@ -18,6 +18,7 @@
 		"typescript": "5.9.3"
 	},
 	"dependencies": {
+		"i18n": "workspace:*",
 		"estree-walker": "3.0.3",
 		"magic-string": "0.30.21",
 		"vite": "7.2.4"

packages/frontend-embed/build.ts

@@ -2,7 +2,7 @@ import * as fs from 'fs/promises';
 import url from 'node:url';
 import path from 'node:path';
 import { execa } from 'execa';
-import locales from '../../locales/index.js';
+import locales from 'i18n';
 import { LocaleInliner } from '../frontend-builder/locale-inliner.js'
 import { createLogger } from '../frontend-builder/logger';
 

packages/frontend-embed/package.json

@@ -11,6 +11,7 @@
 	},
 	"dependencies": {
 		"@discordapp/twemoji": "16.0.1",
+		"i18n": "workspace:*",
 		"@rollup/plugin-json": "6.1.0",
 		"@rollup/plugin-replace": "6.0.3",
 		"@rollup/pluginutils": "5.3.0",

packages/frontend-embed/src/components/I18n.vue

@@ -9,7 +9,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 
 <script setup lang="ts" generic="T extends string | ParameterizedString">
 import { computed, h } from 'vue';
-import type { ParameterizedString } from '../../../../locales/index.js';
+import type { ParameterizedString } from 'i18n';
 
 const props = withDefaults(defineProps<{
 	src: T;
@@ -25,7 +25,7 @@ const slots = defineSlots<T extends ParameterizedString<infer R> ? { [K in R]: (
 const parsed = computed(() => {
 	let str = props.src as string;
 	const value: (string | { arg: string; })[] = [];
-	for (;;) {
+	for (; ;) {
 		const nextBracketOpen = str.indexOf('{');
 		const nextBracketClose = str.indexOf('}');
 

packages/frontend-embed/src/i18n.ts

@@ -6,7 +6,7 @@
 import { markRaw } from 'vue';
 import { I18n } from '@@/js/i18n.js';
 import { locale } from '@@/js/locale.js';
-import type { Locale } from '../../../locales/index.js';
+import type { Locale } from 'i18n';
 
 export const i18n = markRaw(new I18n<Locale>(locale, _DEV_));
 

packages/frontend-embed/vite.config.ts

@@ -1,10 +1,10 @@
 import path from 'path';
 import pluginVue from '@vitejs/plugin-vue';
-import { type UserConfig, defineConfig } from 'vite';
+import { defineConfig, type UserConfig } from 'vite';
 import * as yaml from 'js-yaml';
 import { promises as fsp } from 'fs';
 
-import locales from '../../locales/index.js';
+import locales from 'i18n';
 import meta from '../../package.json';
 import packageInfo from './package.json' with { type: 'json' };
 import pluginJson5 from './vite.json5.js';

packages/frontend-shared/js/i18n.ts

@@ -3,7 +3,7 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import type { ILocale, ParameterizedString } from '../../../locales/index.js';
+import type { ILocale, ParameterizedString } from 'i18n';
 
 // eslint-disable-next-line @typescript-eslint/no-explicit-any
 type TODO = any;

packages/frontend-shared/js/locale.ts

@@ -4,7 +4,7 @@
  */
 
 import { lang, version } from '@@/js/config.js';
-import type { Locale } from '../../../locales/index.js';
+import type { Locale } from 'i18n';
 
 // ここはビルド時に const locale = JSON.parse("...") みたいな感じで置き換えられるので top-level await は消える
 export let locale: Locale = await window.fetch(`/assets/locales/${lang}.${version}.json`).then(r => r.json(), () => null);

packages/frontend-shared/js/store-boot-errors.ts

@@ -3,7 +3,7 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import type { Locale } from '../../../locales/index.js';
+import type { Locale } from 'i18n';
 
 type BootLoaderLocaleBody = Locale['_bootErrors'] & { reload: Locale['reload'] };
 

packages/frontend-shared/package.json

@@ -34,6 +34,7 @@
 		"js-built"
 	],
 	"dependencies": {
+		"i18n": "workspace:*",
 		"misskey-js": "workspace:*",
 		"vue": "3.5.24"
 	}

packages/frontend/.storybook/preload-locale.ts

@@ -4,7 +4,7 @@
  */
 
 import { writeFile } from 'node:fs/promises';
-import locales from '../../../locales/index.js';
+import locales from 'i18n';
 
 await writeFile(
 	new URL('locale.ts', import.meta.url),

packages/frontend/build.ts

@@ -2,7 +2,7 @@ import * as fs from 'fs/promises';
 import url from 'node:url';
 import path from 'node:path';
 import { execa } from 'execa';
-import locales from '../../locales/index.js';
+import locales from 'i18n';
 import { LocaleInliner } from '../frontend-builder/locale-inliner.js'
 import { createLogger } from '../frontend-builder/logger';
 

packages/frontend/lib/vite-plugin-watch-locales.ts

@@ -4,7 +4,7 @@
  */
 
 import path from 'node:path'
-import locales from '../../../locales/index.js';
+import locales from 'i18n';
 
 const localesDir = path.resolve(__dirname, '../../../locales')
 
@@ -13,14 +13,14 @@ const localesDir = path.resolve(__dirname, '../../../locales')
  * @returns {import('vite').Plugin}
  */
 export default function pluginWatchLocales() {
-  return {
-    name: 'watch-locales',
+	return {
+		name: 'watch-locales',
 
-    configureServer(server) {
-      const localeYmlPaths = Object.keys(locales).map(locale => path.join(localesDir, `${locale}.yml`));
+		configureServer(server) {
+			const localeYmlPaths = Object.keys(locales).map(locale => path.join(localesDir, `${locale}.yml`));
 
-      // watcherにパスを追加
-      server.watcher.add(localeYmlPaths);
+			// watcherにパスを追加
+			server.watcher.add(localeYmlPaths);
 
 			server.watcher.on('change', (filePath) => {
 				if (localeYmlPaths.includes(filePath)) {
@@ -31,6 +31,6 @@ export default function pluginWatchLocales() {
 					})
 				}
 			});
-    },
-  };
+		},
+	};
 }

packages/frontend/package.json

@@ -20,6 +20,7 @@
 		"@discordapp/twemoji": "16.0.1",
 		"@github/webauthn-json": "2.1.1",
 		"@mcaptcha/vanilla-glue": "0.1.0-alpha-3",
+		"i18n": "workspace:*",
 		"@misskey-dev/browser-image-resizer": "2024.1.0",
 		"@rollup/plugin-json": "6.1.0",
 		"@rollup/plugin-replace": "6.0.3",

packages/frontend/src/components/global/I18n.vue

@@ -9,7 +9,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 
 <script setup lang="ts" generic="T extends string | ParameterizedString">
 import { computed, h } from 'vue';
-import type { ParameterizedString } from '../../../../../locales/index.js';
+import type { ParameterizedString } from 'i18n';
 
 const props = withDefaults(defineProps<{
 	src: T;
@@ -25,7 +25,7 @@ const slots = defineSlots<T extends ParameterizedString<infer R> ? { [K in R]: (
 const parsed = computed(() => {
 	let str = props.src as string;
 	const value: (string | { arg: string; })[] = [];
-	for (;;) {
+	for (; ;) {
 		const nextBracketOpen = str.indexOf('{');
 		const nextBracketClose = str.indexOf('}');
 

packages/frontend/src/i18n.ts

@@ -6,7 +6,7 @@
 import { markRaw } from 'vue';
 import { I18n } from '@@/js/i18n.js';
 import { locale } from '@@/js/locale.js';
-import type { Locale } from '../../../locales/index.js';
+import type { Locale } from 'i18n';
 
 export const i18n = markRaw(new I18n<Locale>(locale, _DEV_));
 

packages/frontend/test/i18n.test.ts

@@ -5,7 +5,7 @@
 
 import { describe, expect, it } from 'vitest';
 import { I18n } from '../../frontend-shared/js/i18n.js'; // @@で参照できなかったので
-import type { ParameterizedString } from '../../../locales/index.js';
+import type { ParameterizedString } from 'i18n';
 
 // TODO: このテストはfrontend-sharedに移動する
 

packages/frontend/test/init.ts

@@ -7,13 +7,13 @@ import { vi } from 'vitest';
 import createFetchMock from 'vitest-fetch-mock';
 import type { Ref } from 'vue';
 import { ref } from 'vue';
+// Set i18n
+import locales from 'i18n';
+import { updateI18n } from '@/i18n.js';
 
 const fetchMocker = createFetchMock(vi);
 fetchMocker.enableMocks();
 
-// Set i18n
-import locales from '../../../locales/index.js';
-import { updateI18n } from '@/i18n.js';
 updateI18n(locales['en-US']);
 
 // XXX: misskey-js panics if WebSocket is not defined

packages/frontend/vite.config.ts

@@ -2,18 +2,18 @@ import path from 'path';
 import pluginReplace from '@rollup/plugin-replace';
 import pluginVue from '@vitejs/plugin-vue';
 import pluginGlsl from 'vite-plugin-glsl';
-import { defineConfig } from 'vite';
 import type { UserConfig } from 'vite';
+import { defineConfig } from 'vite';
 import * as yaml from 'js-yaml';
 import { promises as fsp } from 'fs';
 
-import locales from '../../locales/index.js';
+import locales from 'i18n';
 import meta from '../../package.json';
 import packageInfo from './package.json' with { type: 'json' };
 import pluginUnwindCssModuleClassName from './lib/rollup-plugin-unwind-css-module-class-name.js';
 import pluginJson5 from './vite.json5.js';
-import pluginCreateSearchIndex from './lib/vite-plugin-create-search-index.js';
 import type { Options as SearchIndexOptions } from './lib/vite-plugin-create-search-index.js';
+import pluginCreateSearchIndex from './lib/vite-plugin-create-search-index.js';
 import pluginWatchLocales from './lib/vite-plugin-watch-locales.js';
 import { pluginRemoveUnrefI18n } from '../frontend-builder/rollup-plugin-remove-unref-i18n.js';
 

packages/i18n/README.md

@@ -0,0 +1,5 @@
+# Misskey i18n
+
+Misskey の言語ファイル本体 (ja-JP.yml など) はリポジトリ直下の `/locales` に置かれており、そこから Crowdin 連携やビルド資産が生成されます。
+
+このパッケージは Misskey モノレポ内で、これらの言語ファイルを共通で扱うためのヘルパー群や型情報をまとめる位置づけです。バックエンド / フロントエンド / Service Worker など各パッケージが同じ翻訳データと型定義を利用できるようにすることを目的としており、npm での外部配布は想定していません。

packages/i18n/build.ts

@@ -0,0 +1,163 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import fs from 'node:fs';
+import { fileURLToPath } from 'node:url';
+import { dirname, resolve } from 'node:path';
+import { watch as chokidarWatch } from 'chokidar';
+import * as esbuild from 'esbuild';
+import { build } from 'esbuild';
+import { execa } from 'execa';
+import { globSync } from 'glob';
+import { generateLocaleInterface } from './scripts/generateLocaleInterface.js';
+import type { BuildOptions, BuildResult, Plugin, PluginBuild } from 'esbuild';
+
+const _filename = fileURLToPath(import.meta.url);
+const _dirname = dirname(_filename);
+const _package = JSON.parse(fs.readFileSync(_dirname + '/package.json', 'utf-8'));
+const _rootPackageDir = resolve(_dirname, '../../');
+const _rootPackage = JSON.parse(fs.readFileSync(resolve(_rootPackageDir, 'package.json'), 'utf-8'));
+const _frontendLocalesDir = resolve(_dirname, '../../built/_frontend_dist_/locales');
+const _localesDir = resolve(_rootPackageDir, 'locales');
+
+const entryPoints = globSync('./src/**/**.{ts,tsx}');
+
+const options: BuildOptions = {
+	entryPoints,
+	minify: process.env.NODE_ENV === 'production',
+	sourceRoot: 'src',
+	outdir: './built',
+	target: 'es2022',
+	platform: 'node',
+	format: 'esm',
+	sourcemap: 'linked',
+};
+
+// コマンドライン引数を取得
+const args = process.argv.slice(2).map(arg => arg.toLowerCase());
+
+// built配下をすべて削除する
+if (!args.includes('--no-clean')) {
+	fs.rmSync('./built', { recursive: true, force: true });
+}
+
+if (args.includes('--watch')) {
+	await watchSrc();
+} else {
+	await buildSrc();
+}
+
+function copyLocales(): void {
+	const srcDir = _localesDir;
+	const destDir = resolve(_dirname, 'built/locales');
+
+	fs.mkdirSync(destDir, { recursive: true });
+
+	const files = fs.readdirSync(srcDir).filter(f => f.endsWith('.yml'));
+	for (const file of files) {
+		fs.copyFileSync(resolve(srcDir, file), resolve(destDir, file));
+	}
+	console.log(`[${_package.name}] locales copied (${files.length} files).`);
+}
+
+/**
+ * フロントエンド用の locale JSON を書き出す
+ * Service Worker が HTTP 経由で取得するために必要
+ */
+async function writeFrontendLocalesJson(): Promise<void> {
+	// 動的 import でビルド済みモジュールから読み込み（循環参照回避）
+	const { writeFrontendLocalesJson: write } = await import('./built/index.js');
+	await write(_frontendLocalesDir, _rootPackage.version);
+	console.log(`[${_package.name}] frontend locales JSON written to ${_frontendLocalesDir}`);
+}
+
+async function buildSrc(): Promise<void> {
+	console.log(`[${_package.name}] start building...`);
+
+	await generateLocaleInterface(_localesDir);
+
+	await build(options)
+		.then(() => {
+			console.log(`[${_package.name}] build succeeded.`);
+		})
+		.catch((err) => {
+			process.stderr.write(err.stderr);
+			process.exit(1);
+		});
+
+	copyLocales();
+	await writeFrontendLocalesJson();
+
+	if (process.env.NODE_ENV === 'production') {
+		console.log(`[${_package.name}] skip building d.ts because NODE_ENV is production.`);
+	} else {
+		await buildDts();
+	}
+
+	console.log(`[${_package.name}] finish building.`);
+}
+
+function buildDts(): Promise<unknown> {
+	return execa(
+		'tsc',
+		[
+			'--project', 'tsconfig.json',
+			'--rootDir', 'src',
+			'--outDir', 'built',
+			'--declaration', 'true',
+			'--emitDeclarationOnly', 'true',
+		],
+		{
+			stdout: process.stdout,
+			stderr: process.stderr,
+		},
+	);
+}
+
+async function watchSrc(): Promise<void> {
+	const localesWatcher = chokidarWatch(_localesDir, {
+		ignoreInitial: true,
+	});
+	localesWatcher.on('all', async (event, path) => {
+		if (!path.endsWith('.yml')) return;
+		console.log(`[${_package.name}] locales changed: ${event} ${path}`);
+		copyLocales();
+		await writeFrontendLocalesJson();
+		await generateLocaleInterface(_localesDir);
+	});
+
+	const plugins: Plugin[] = [{
+		name: 'gen-dts',
+		setup(build: PluginBuild) {
+			build.onStart(() => {
+				console.log(`[${_package.name}] detect changed...`);
+			});
+			build.onEnd(async (result: BuildResult) => {
+				if (result.errors.length > 0) {
+					console.error(`[${_package.name}] watch build failed:`, result);
+					return;
+				}
+				await buildDts();
+			});
+		},
+	}];
+
+	console.log(`[${_package.name}] start watching...`);
+
+	const context = await esbuild.context({ ...options, plugins });
+	await context.watch();
+
+	await new Promise((resolve, reject) => {
+		process.on('SIGHUP', resolve);
+		process.on('SIGINT', resolve);
+		process.on('SIGTERM', resolve);
+		process.on('uncaughtException', reject);
+		process.on('exit', resolve);
+	}).finally(async () => {
+		await context.dispose();
+		await localesWatcher.close();
+		console.log(`[${_package.name}] finish watching.`);
+	});
+}

packages/i18n/eslint.config.js

@@ -0,0 +1,35 @@
+import tsParser from '@typescript-eslint/parser';
+import sharedConfig from '../shared/eslint.config.js';
+
+// eslint-disable-next-line import/no-default-export
+export default [
+	...sharedConfig,
+	{
+		ignores: [
+			'**/node_modules',
+			'built',
+			'coverage',
+			'vitest.config.ts',
+			'test',
+			'test-d',
+			'generator',
+		],
+	},
+	{
+		files: ['**/*.ts', '**/*.tsx'],
+		languageOptions: {
+			parserOptions: {
+				parser: tsParser,
+				project: ['./tsconfig.eslint.json'],
+				sourceType: 'module',
+				tsconfigRootDir: import.meta.dirname,
+			},
+		},
+	},
+	{
+		files: ['src/autogen/**/*.ts', 'src/autogen/**/*.tsx'],
+		rules: {
+			'@stylistic/indent': 'off',
+		},
+	},
+];

packages/i18n/package.json

@@ -0,0 +1,42 @@
+{
+	"name": "i18n",
+	"type": "module",
+	"private": true,
+	"main": "./built/index.js",
+	"types": "./built/index.d.ts",
+	"exports": {
+		".": {
+			"types": "./built/index.d.ts",
+			"import": "./built/index.js"
+		}
+	},
+	"scripts": {
+		"generate": "tsx scripts/generateLocaleInterface.ts",
+		"verify": "tsx scripts/verify.ts",
+		"build": "tsx ./build.ts",
+		"watch": "nodemon -w package.json -e json --exec \"tsx ./build.ts --watch\"",
+		"tsd": "tsd",
+		"typecheck": "tsc --noEmit",
+		"lint": "pnpm typecheck && pnpm eslint",
+		"lint:fix": "pnpm eslint --fix"
+	},
+	"files": [
+		"built"
+	],
+	"devDependencies": {
+		"@types/js-yaml": "4.0.9",
+		"@types/node": "24.10.1",
+		"@typescript-eslint/eslint-plugin": "8.47.0",
+		"@typescript-eslint/parser": "8.47.0",
+		"chokidar": "4.0.3",
+		"esbuild": "0.27.0",
+		"execa": "9.6.0",
+		"glob": "11.1.0",
+		"nodemon": "3.1.11",
+		"tsx": "4.20.6",
+		"typescript": "5.9.3"
+	},
+	"dependencies": {
+		"js-yaml": "4.1.1"
+	}
+}

packages/i18n/scripts/generateLocaleInterface.ts

@@ -0,0 +1,153 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import * as fs from 'node:fs';
+import { fileURLToPath } from 'node:url';
+import { dirname, resolve } from 'node:path';
+import * as yaml from 'js-yaml';
+import ts from 'typescript';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = dirname(__filename);
+const parameterRegExp = /\{(\w+)\}/g;
+
+interface LocaleRecord {
+	[key: string]: string | LocaleRecord;
+}
+
+function createMemberType(item: string | LocaleRecord): ts.TypeNode {
+	if (typeof item !== 'string') {
+		return ts.factory.createTypeLiteralNode(createMembers(item));
+	}
+	const parameters = Array.from(
+		item.matchAll(parameterRegExp),
+		([, parameter]) => parameter,
+	);
+	return parameters.length
+		? ts.factory.createTypeReferenceNode(
+			ts.factory.createIdentifier('ParameterizedString'),
+			[
+				ts.factory.createUnionTypeNode(
+					parameters.map((parameter) =>
+						ts.factory.createLiteralTypeNode(ts.factory.createStringLiteral(parameter)),
+					),
+				),
+			],
+		)
+		: ts.factory.createKeywordTypeNode(ts.SyntaxKind.StringKeyword);
+}
+
+function createMembers(record: LocaleRecord): ts.TypeElement[] {
+	return Object.entries(record).map(([k, v]) => {
+		const node = ts.factory.createPropertySignature(
+			undefined,
+			ts.factory.createStringLiteral(k),
+			undefined,
+			createMemberType(v),
+		);
+		if (typeof v === 'string') {
+			ts.addSyntheticLeadingComment(
+				node,
+				ts.SyntaxKind.MultiLineCommentTrivia,
+				`*
+ * ${v.replace(/\n/g, '\n * ')}
+ `,
+				true,
+			);
+		}
+		return node;
+	});
+}
+
+export async function generateLocaleInterface(localesDir: string): Promise<void> {
+	const locale = yaml.load(fs.readFileSync(`${localesDir}/ja-JP.yml`, 'utf-8').toString()) as LocaleRecord;
+	const members = createMembers(locale);
+
+	const elements: ts.Statement[] = [
+		ts.factory.createImportDeclaration(
+			undefined,
+			ts.factory.createImportClause(
+				false,
+				undefined,
+				ts.factory.createNamedImports([
+					ts.factory.createImportSpecifier(
+						true,
+						undefined,
+						ts.factory.createIdentifier('ILocale'),
+					),
+					ts.factory.createImportSpecifier(
+						true,
+						undefined,
+						ts.factory.createIdentifier('ParameterizedString'),
+					),
+				]),
+			),
+			ts.factory.createStringLiteral('../types.js'),
+			undefined,
+		),
+		ts.factory.createInterfaceDeclaration(
+			[ts.factory.createToken(ts.SyntaxKind.ExportKeyword)],
+			ts.factory.createIdentifier('Locale'),
+			undefined,
+			[
+				ts.factory.createHeritageClause(ts.SyntaxKind.ExtendsKeyword, [
+					ts.factory.createExpressionWithTypeArguments(
+						ts.factory.createIdentifier('ILocale'),
+						undefined,
+					),
+				]),
+			],
+			members,
+		),
+	];
+
+	ts.addSyntheticLeadingComment(
+		elements[0],
+		ts.SyntaxKind.MultiLineCommentTrivia,
+		' eslint-disable ',
+		true,
+	);
+	ts.addSyntheticLeadingComment(
+		elements[0],
+		ts.SyntaxKind.SingleLineCommentTrivia,
+		' This file is generated by scripts/generateLocaleInterface.ts',
+		true,
+	);
+	ts.addSyntheticLeadingComment(
+		elements[0],
+		ts.SyntaxKind.SingleLineCommentTrivia,
+		' Do not edit this file directly.',
+		true,
+	);
+
+	const printed = ts
+		.createPrinter({
+			newLine: ts.NewLineKind.LineFeed,
+		})
+		.printList(
+			ts.ListFormat.MultiLine,
+			ts.factory.createNodeArray(elements),
+			ts.createSourceFile(
+				'locale.ts',
+				'',
+				ts.ScriptTarget.ESNext,
+				true,
+				ts.ScriptKind.TS,
+			),
+		);
+
+	const autogenDir = `${__dirname}/../src/autogen`;
+	fs.mkdirSync(autogenDir, { recursive: true });
+
+	// 一瞬ファイルが存在しなくなって途切れる→不安定になるらしいので、リネームで対処
+	fs.writeFileSync(`${autogenDir}/_locale.ts`, printed, 'utf-8');
+	fs.renameSync(`${autogenDir}/_locale.ts`, `${autogenDir}/locale.ts`);
+}
+
+// スクリプトとして直接実行された場合
+const isMain = import.meta.url === `file://${process.argv[1]}`;
+if (isMain) {
+	await generateLocaleInterface(resolve(__dirname, '../../../locales'));
+}

packages/i18n/scripts/verify.ts

@@ -0,0 +1,70 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+let valid = true;
+
+interface LocaleRecord {
+	[key: string]: string | LocaleRecord;
+}
+
+interface ErrorData {
+	expected?: string;
+	actual?: string;
+	parameter?: string;
+}
+
+function writeError(type: string, lang: string, tree: string, data: ErrorData): void {
+	process.stderr.write(JSON.stringify({ type, lang, tree, data }));
+	process.stderr.write('\n');
+	valid = false;
+}
+
+function verify(expected: LocaleRecord, actual: LocaleRecord, lang: string, trace?: string): void {
+	for (const key in expected) {
+		if (!Object.prototype.hasOwnProperty.call(actual, key)) {
+			continue;
+		}
+		if (typeof expected[key] === 'object') {
+			if (typeof actual[key] !== 'object') {
+				writeError('mismatched_type', lang, trace ? `${trace}.${key}` : key, { expected: 'object', actual: typeof actual[key] });
+				continue;
+			}
+			verify(expected[key] as LocaleRecord, actual[key] as LocaleRecord, lang, trace ? `${trace}.${key}` : key);
+		} else if (typeof expected[key] === 'string') {
+			switch (typeof actual[key]) {
+				case 'object':
+					writeError('mismatched_type', lang, trace ? `${trace}.${key}` : key, { expected: 'string', actual: 'object' });
+					break;
+				case 'undefined':
+					continue;
+				case 'string': {
+					const expectedParameters = new Set((expected[key] as string).match(/\{[^}]+\}/g)?.map((s) => s.slice(1, -1)));
+					const actualParameters = new Set((actual[key] as string).match(/\{[^}]+\}/g)?.map((s) => s.slice(1, -1)));
+					for (const parameter of expectedParameters) {
+						if (!actualParameters.has(parameter)) {
+							writeError('missing_parameter', lang, trace ? `${trace}.${key}` : key, { parameter });
+						}
+					}
+				}
+			}
+		}
+	}
+}
+
+// index.tsはtsのまま動かすことを想定していない（ビルド成果物を外部に公開する）.
+// よってビルド後のものを検証する
+const locales = await import('../built/index.js');
+const { 'ja-JP': original, ...verifiees } = locales as unknown as Record<string, LocaleRecord>;
+
+for (const lang in verifiees) {
+	if (!Object.prototype.hasOwnProperty.call(locales, lang)) {
+		continue;
+	}
+	verify(original, verifiees[lang], lang);
+}
+
+if (!valid) {
+	process.exit(1);
+}

packages/i18n/src/index.ts

@@ -0,0 +1,166 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+/**
+ * Languages Loader
+ */
+
+import * as fs from 'node:fs';
+import * as yaml from 'js-yaml';
+import type { Locale } from './autogen/locale.js';
+import type { ILocale, ParameterizedString } from './types.js';
+
+const languages = [
+	'ar-SA',
+	'ca-ES',
+	'cs-CZ',
+	'da-DK',
+	'de-DE',
+	'en-US',
+	'es-ES',
+	'fr-FR',
+	'id-ID',
+	'it-IT',
+	'ja-JP',
+	'ja-KS',
+	'kab-KAB',
+	'kn-IN',
+	'ko-KR',
+	'nl-NL',
+	'no-NO',
+	'pl-PL',
+	'pt-PT',
+	'ru-RU',
+	'sk-SK',
+	'th-TH',
+	'tr-TR',
+	'ug-CN',
+	'uk-UA',
+	'vi-VN',
+	'zh-CN',
+	'zh-TW',
+] as const;
+
+type Language = typeof languages[number];
+
+const primaries = {
+	'en': 'US',
+	'ja': 'JP',
+	'zh': 'CN',
+} as const satisfies Record<string, string>;
+
+type PrimaryLang = keyof typeof primaries;
+
+type Locales = Record<Language, ILocale>;
+
+/**
+ * オブジェクトを再帰的にマージする
+ */
+function merge<T extends ILocale>(...args: (T | ILocale | undefined)[]): T {
+	return args.reduce<ILocale>((a, c) => ({
+		...a,
+		...c,
+		...Object.entries(a)
+			.filter(([k]) => c && typeof c[k] === 'object')
+			.reduce<Record<string, ILocale[string]>>((acc, [k, v]) => {
+				acc[k] = merge(v as ILocale, (c as ILocale)[k] as ILocale);
+				return acc;
+			}, {}),
+	}), {} as ILocale) as T;
+}
+
+/**
+ * 何故か文字列にバックスペース文字が混入することがあり、YAMLが壊れるので取り除く
+ */
+function clean (text: string) {
+	return text.replace(new RegExp(String.fromCodePoint(0x08), 'g'), '');
+}
+
+/**
+ * 空文字列が入ることがあり、フォールバックが動作しなくなるのでプロパティごと消す
+ */
+function removeEmpty<T extends ILocale>(obj: T): T {
+	for (const [k, v] of Object.entries(obj)) {
+		if (v === '') {
+			delete obj[k];
+		} else if (typeof v === 'object') {
+			removeEmpty(v as ILocale);
+		}
+	}
+	return obj;
+}
+
+function build(): Record<Language, Locale> {
+	// vitestの挙動を調整するため、一度ローカル変数化する必要がある
+	// https://github.com/vitest-dev/vitest/issues/3988#issuecomment-1686599577
+	// https://github.com/misskey-dev/misskey/pull/14057#issuecomment-2192833785
+	const metaUrl = import.meta.url;
+	const locales = languages.reduce<Locales>((a, lang) => {
+		a[lang] = (yaml.load(clean(fs.readFileSync(new URL(`./locales/${lang}.yml`, metaUrl), 'utf-8'))) ?? {}) as ILocale;
+		return a;
+	}, {} as Locales);
+
+	removeEmpty(locales);
+
+	return Object.entries(locales).reduce<Record<Language, Locale>>((a, [k, v]) => {
+		const lang = k.split('-')[0];
+		const key = k as Language;
+
+		switch (key) {
+			case 'ja-JP':
+				a[key] = v as Locale;
+				break;
+			case 'ja-KS':
+			case 'en-US':
+				a[key] = merge<Locale>(locales['ja-JP'] as Locale, v);
+				break;
+			default: {
+				const primaryLang = lang as PrimaryLang;
+				const primaryKey = (lang in primaries ? `${lang}-${primaries[primaryLang]}` : undefined) as Language | undefined;
+				a[key] = merge<Locale>(
+					locales['ja-JP'] as Locale,
+					locales['en-US'],
+					primaryKey ? locales[primaryKey] : {},
+					v,
+				);
+				break;
+			}
+		}
+
+		return a;
+	}, {} as Record<Language, Locale>);
+}
+
+const locales = build() as {
+	[lang: string]: Locale;
+};
+
+/**
+ * フロントエンド用の locale JSON を書き出す
+ * Service Worker が HTTP 経由で取得するために必要
+ * @param destDir 出力先ディレクトリ（例: built/_frontend_dist_/locales）
+ * @param version バージョン文字列（ファイル名とJSON内に埋め込まれる）
+ */
+async function writeFrontendLocalesJson(destDir: string, version: string): Promise<void> {
+	const { mkdir, writeFile } = await import('node:fs/promises');
+	const { resolve } = await import('node:path');
+
+	await mkdir(destDir, { recursive: true });
+
+	const builtLocales = build();
+	const v = { '_version_': version };
+
+	for (const [lang, locale] of Object.entries(builtLocales)) {
+		await writeFile(
+			resolve(destDir, `${lang}.${version}.json`),
+			JSON.stringify({ ...locale, ...v }),
+			'utf-8',
+		);
+	}
+}
+
+export { locales, build, writeFrontendLocalesJson };
+export type { Language, Locale, ILocale, ParameterizedString };
+export default locales;

packages/i18n/src/types.ts

@@ -0,0 +1,14 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+declare const kParameters: unique symbol;
+
+export type ParameterizedString<T extends string = string> = string & {
+	[kParameters]: T;
+};
+
+export interface ILocale {
+	[_: string]: string | ParameterizedString | ILocale;
+}

packages/i18n/tsconfig.eslint.json

@@ -0,0 +1,8 @@
+{
+    "extends": "./tsconfig.json",
+    "include": [
+        "src/**/*.ts",
+        "scripts/**/*.ts",
+        "build.ts"
+    ]
+}

packages/i18n/tsconfig.json

@@ -0,0 +1,14 @@
+{
+	"compilerOptions": {
+		"target": "ESNext",
+		"module": "NodeNext",
+		"moduleResolution": "NodeNext",
+		"esModuleInterop": true,
+		"forceConsistentCasingInFileNames": true,
+		"strict": true,
+		"skipLibCheck": true
+	},
+	"include": [
+		"src/**/*.ts"
+	]
+}

packages/sw/build.js

@@ -7,8 +7,9 @@
 
 import { fileURLToPath } from 'node:url';
 import * as esbuild from 'esbuild';
-import locales from '../../locales/index.js';
+import locales from 'i18n';
 import meta from '../../package.json' with { type: 'json' };
+
 const watch = process.argv[2]?.includes('watch');
 
 const __dirname = fileURLToPath(new URL('.', import.meta.url));

packages/sw/package.json

@@ -9,6 +9,7 @@
 		"lint": "pnpm typecheck && pnpm eslint"
 	},
 	"dependencies": {
+		"i18n": "workspace:*",
 		"esbuild": "0.27.0",
 		"idb-keyval": "6.2.2",
 		"misskey-js": "workspace:*"

packages/sw/src/scripts/lang.ts

@@ -8,7 +8,7 @@
  */
 import { get, set } from 'idb-keyval';
 import { I18n } from '@@/js/i18n.js';
-import type { Locale } from '../../../../locales/index.js';
+import type { Locale } from 'i18n';
 
 class SwLang {
 	public cacheName = `mk-cache-${_VERSION_}`;

packages/sw/src/sw.ts

@@ -7,7 +7,7 @@ import { get } from 'idb-keyval';
 import * as Misskey from 'misskey-js';
 import type { PushNotificationDataMap } from '@/types.js';
 import type { I18n } from '@@/js/i18n.js';
-import type { Locale } from '../../../locales/index.js';
+import type { Locale } from 'i18n';
 import { createEmptyNotification, createNotification } from '@/scripts/create-notification.js';
 import { swLang } from '@/scripts/lang.js';
 import * as swos from '@/scripts/operations.js';