per-locale bundle & inline locale (#16369)

* feat: split entry file by locale name

* chore: とりあえず transform hook で雑に分割

* chore: とりあえず transform 結果をいい感じに

* chore: concurrent buildで高速化

* chore: vite ではローケルのないものをビルドして後処理でどうにかするように

* chore: 後処理のためにi18n.jを単体になるように切り出す

* chore: use typescript

* chore: remove unref(i18n) in vite build process

* chore: inline variable

* fix: build error

* fix: i18n.ts.something.replaceAll() become error

* chore: ignore export specifier from error

* chore: support i18n.tsx as object

* chore: process literal for all files

* chore: split config and locale

* chore: inline locale name

* chore: remove updating locale in boot common

* chore: use top-level await to load locales

* chore: inline locale

* chore: remove loading locale from boot.js

* chore: remove loading locale from boot.js

* コメント追加

* fix test; fetchに失敗する

* import削除ログをdebugレベルに

* fix: watch pug

* chore: use hash for entry files

* chore: remove es-module-lexer from dependencies

* chore: move to frontend-builder

* chore: use inline locale in embed

* chore: refetch json on hot reload

* feat: store localization related to boot.js in backend in bootloaderLocales localstorage

* 応急処置を戻す

* fix spex

* fix `Using i18n identifier "e" directly. Skipping inlining.` warning

* refactor: use scriptsDir parameter

* chore: remove i18n from depmap

* chore: make build crash if errors

* error -> warn few conditions

* use inline object

* update localstorage keys

* remove accessing locale localstorage

* fix: failed to process i18n.tsx.aaa({x:i18n.bbb})

12 files changed, 77 insertions, 37 deletions

diff --git a/packages/frontend/.gitignore b/packages/frontend/.gitignore
index 1aa0ac14e8..4f8684c18e 100644
--- a/packages/frontend/.gitignore
+++ b/packages/frontend/.gitignore
@@ -1 +1,2 @@
 /storybook-static
+/build/
diff --git a/packages/frontend/.storybook/preview.ts b/packages/frontend/.storybook/preview.ts
index fb855c1410..2aac8af400 100644
--- a/packages/frontend/.storybook/preview.ts
+++ b/packages/frontend/.storybook/preview.ts
@@ -9,7 +9,6 @@ import { type Preview, setup } from '@storybook/vue3';
 import isChromatic from 'chromatic/isChromatic';
 import { initialize, mswLoader } from 'msw-storybook-addon';
 import { userDetailed } from './fakes.js';
-import locale from './locale.js';
 import { commonHandlers, onUnhandledRequest } from './mocks.js';
 import themes from './themes.js';
 import '../src/style.scss';
@@ -55,7 +54,6 @@ function initLocalStorage() {
 		...userDetailed(),
 		policies: {},
 	}));
-	localStorage.setItem('locale', JSON.stringify(locale));
 }
 
 initialize({
diff --git a/packages/frontend/build.ts b/packages/frontend/build.ts
new file mode 100644
index 0000000000..0401c2b9ba
--- /dev/null
+++ b/packages/frontend/build.ts
@@ -0,0 +1,51 @@
+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 { LocaleInliner } from '../frontend-builder/locale-inliner.js'
+import { createLogger } from '../frontend-builder/logger';
+
+// requires node 21 or later
+const __dirname = path.dirname(url.fileURLToPath(import.meta.url));
+const outputDir = __dirname + '/../../built/_frontend_vite_';
+
+/**
+ * @return {Promise<void>}
+ */
+async function viteBuild() {
+	await execa('vite', ['build'], {
+		cwd: __dirname,
+		stdout: process.stdout,
+		stderr: process.stderr,
+	});
+}
+
+
+async function buildAllLocale() {
+	const logger = createLogger()
+	const inliner = await LocaleInliner.create({
+		outputDir,
+		logger,
+		scriptsDir: 'scripts',
+		i18nFile: 'src/i18n.ts',
+	})
+
+	await inliner.loadFiles();
+
+	inliner.collectsModifications();
+
+	await inliner.saveAllLocales(locales);
+
+	if (logger.errorCount > 0) {
+		throw new Error(`Build failed with ${logger.errorCount} errors and ${logger.warningCount} warnings.`);
+	}
+}
+
+async function build() {
+	await fs.rm(outputDir, { recursive: true, force: true });
+	await viteBuild();
+	await buildAllLocale();
+}
+
+await build();
diff --git a/packages/frontend/package.json b/packages/frontend/package.json
index f4f72d944a..eaefe92612 100644
--- a/packages/frontend/package.json
+++ b/packages/frontend/package.json
@@ -4,7 +4,7 @@
 	"type": "module",
 	"scripts": {
 		"watch": "vite",
-		"build": "vite build",
+		"build": "tsx build.ts",
 		"storybook-dev": "nodemon --verbose --watch src --ext \"mdx,ts,vue\" --ignore \"*.stories.ts\" --exec \"pnpm build-storybook-pre && pnpm exec storybook dev -p 6006 --ci\"",
 		"build-storybook-pre": "(tsc -p .storybook || echo done.) && node .storybook/generate.js && node .storybook/preload-locale.js && node .storybook/preload-theme.js",
 		"build-storybook": "pnpm build-storybook-pre && storybook build --webpack-stats-json storybook-static",
@@ -47,6 +47,7 @@
 		"date-fns": "4.1.0",
 		"estree-walker": "3.0.3",
 		"eventemitter3": "5.0.1",
+		"execa": "9.6.0",
 		"frontend-shared": "workspace:*",
 		"icons-subsetter": "workspace:*",
 		"idb-keyval": "6.2.2",
@@ -137,6 +138,7 @@
 		"start-server-and-test": "2.0.12",
 		"storybook": "9.1.0",
 		"storybook-addon-misskey-theme": "github:misskey-dev/storybook-addon-misskey-theme",
+		"tsx": "4.20.3",
 		"vite-plugin-turbosnap": "1.0.3",
 		"vitest": "3.2.4",
 		"vitest-fetch-mock": "0.4.5",
diff --git a/packages/frontend/src/boot/common.ts b/packages/frontend/src/boot/common.ts
index ea41155ab0..395d1e5e7e 100644
--- a/packages/frontend/src/boot/common.ts
+++ b/packages/frontend/src/boot/common.ts
@@ -5,9 +5,10 @@
 
 import { computed, watch, version as vueVersion } from 'vue';
 import { compareVersions } from 'compare-versions';
-import { version, lang, updateLocale, locale, apiUrl, isSafeMode } from '@@/js/config.js';
+import { version, lang, apiUrl, isSafeMode } from '@@/js/config.js';
 import defaultLightTheme from '@@/themes/l-light.json5';
 import defaultDarkTheme from '@@/themes/d-green-lime.json5';
+import { storeBootloaderErrors } from '@@/js/store-boot-errors';
 import type { App } from 'vue';
 import widgets from '@/widgets/index.js';
 import directives from '@/directives/index.js';
@@ -79,25 +80,7 @@ export async function common(createVue: () => Promise<App<Element>>) {
 	//#endregion
 
 	//#region Detect language & fetch translations
-	const localeVersion = miLocalStorage.getItem('localeVersion');
-	const localeOutdated = (localeVersion == null || localeVersion !== version || locale == null);
-
-	async function fetchAndUpdateLocale({ useCache } = { useCache: true }) {
-		const fetchOptions: RequestInit | undefined = useCache ? undefined : { cache: 'no-store' };
-		const res = await window.fetch(`/assets/locales/${lang}.${version}.json`, fetchOptions);
-		if (res.status === 200) {
-			const newLocale = await res.text();
-			const parsedNewLocale = JSON.parse(newLocale);
-			miLocalStorage.setItem('locale', newLocale);
-			miLocalStorage.setItem('localeVersion', version);
-			updateLocale(parsedNewLocale);
-			updateI18n(parsedNewLocale);
-		}
-	}
-
-	if (localeOutdated) {
-		fetchAndUpdateLocale();
-	}
+	storeBootloaderErrors({ ...i18n.ts._bootErrors, reload: i18n.ts.reload });
 
 	if (import.meta.hot) {
 		import.meta.hot.on('locale-update', async (updatedLang: string) => {
@@ -106,7 +89,8 @@ export async function common(createVue: () => Promise<App<Element>>) {
 				await new Promise(resolve => {
 					window.setTimeout(resolve, 500);
 				});
-				await fetchAndUpdateLocale({ useCache: false });
+				// fetch with cache: 'no-store' to ensure the latest locale is fetched
+				await window.fetch(`/assets/locales/${lang}.${version}.json`, { cache: 'no-store' }).then(async res => res.status === 200 && await res.text());
 				window.location.reload();
 			}
 		});
diff --git a/packages/frontend/src/components/MkExtensionInstaller.vue b/packages/frontend/src/components/MkExtensionInstaller.vue
index a2247d844b..c9d18ee731 100644
--- a/packages/frontend/src/components/MkExtensionInstaller.vue
+++ b/packages/frontend/src/components/MkExtensionInstaller.vue
@@ -17,7 +17,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 
 	<MkInfo :warn="true">{{ i18n.ts._externalResourceInstaller.checkVendorBeforeInstall }}</MkInfo>
 
-	<div v-if="isPlugin" class="_gaps_s">
+	<div v-if="extension.type === 'plugin'" class="_gaps_s">
 		<MkFolder :defaultOpen="true">
 			<template #icon><i class="ti ti-info-circle"></i></template>
 			<template #label>{{ i18n.ts.metadata }}</template>
@@ -60,7 +60,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 			<MkCode :code="extension.raw"/>
 		</MkFolder>
 	</div>
-	<div v-else-if="isTheme" class="_gaps_s">
+	<div v-else-if="extension.type === 'theme'" class="_gaps_s">
 		<MkFolder :defaultOpen="true">
 			<template #icon><i class="ti ti-info-circle"></i></template>
 			<template #label>{{ i18n.ts.metadata }}</template>
@@ -78,7 +78,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 				</FormSplit>
 				<MkKeyValue>
 					<template #key>{{ i18n.ts._externalResourceInstaller._meta.base }}</template>
-					<template #value>{{ i18n.ts[extension.meta.base ?? 'none'] }}</template>
+					<template #value>{{ { light: i18n.ts.light, dark: i18n.ts.dark, none: i18n.ts.none }[extension.meta.base ?? 'none'] }}</template>
 				</MkKeyValue>
 			</div>
 		</MkFolder>
diff --git a/packages/frontend/src/i18n.ts b/packages/frontend/src/i18n.ts
index 6ad503b089..0b2b206b7e 100644
--- a/packages/frontend/src/i18n.ts
+++ b/packages/frontend/src/i18n.ts
@@ -5,11 +5,12 @@
 
 import { markRaw } from 'vue';
 import { I18n } from '@@/js/i18n.js';
+import { locale } from '@@/js/locale.js';
 import type { Locale } from '../../../locales/index.js';
-import { locale } from '@@/js/config.js';
 
 export const i18n = markRaw(new I18n<Locale>(locale, _DEV_));
 
+// test 以外では使わないこと。インライン化されてるのでだいたい意味がない
 export function updateI18n(newLocale: Locale) {
 	i18n.locale = newLocale;
 }
diff --git a/packages/frontend/src/local-storage.ts b/packages/frontend/src/local-storage.ts
index b64a8c5dd5..687983bcdb 100644
--- a/packages/frontend/src/local-storage.ts
+++ b/packages/frontend/src/local-storage.ts
@@ -22,8 +22,7 @@ export type Keys = (
 	'fontSize' |
 	'ui' |
 	'ui_temp' |
-	'locale' |
-	'localeVersion' |
+	'bootloaderLocales' |
 	'theme' |
 	'themeId' |
 	'customCss' |
diff --git a/packages/frontend/src/pages/settings/preferences.vue b/packages/frontend/src/pages/settings/preferences.vue
index ed4f36c0e5..fb1a409180 100644
--- a/packages/frontend/src/pages/settings/preferences.vue
+++ b/packages/frontend/src/pages/settings/preferences.vue
@@ -886,8 +886,6 @@ const useSystemFont = ref(miLocalStorage.getItem('useSystemFont') != null);
 
 watch(lang, () => {
 	miLocalStorage.setItem('lang', lang.value as string);
-	miLocalStorage.removeItem('locale');
-	miLocalStorage.removeItem('localeVersion');
 });
 
 watch(fontSize, () => {
diff --git a/packages/frontend/src/utility/clear-cache.ts b/packages/frontend/src/utility/clear-cache.ts
index b6ae254727..8a62265438 100644
--- a/packages/frontend/src/utility/clear-cache.ts
+++ b/packages/frontend/src/utility/clear-cache.ts
@@ -13,8 +13,6 @@ export async function clearCache() {
 	os.waiting();
 	miLocalStorage.removeItem('instance');
 	miLocalStorage.removeItem('instanceCachedAt');
-	miLocalStorage.removeItem('locale');
-	miLocalStorage.removeItem('localeVersion');
 	miLocalStorage.removeItem('theme');
 	miLocalStorage.removeItem('emojis');
 	miLocalStorage.removeItem('lastEmojisFetchedAt');
diff --git a/packages/frontend/tsconfig.json b/packages/frontend/tsconfig.json
index 9c7c611e5b..c445ada034 100644
--- a/packages/frontend/tsconfig.json
+++ b/packages/frontend/tsconfig.json
@@ -46,6 +46,7 @@
 	},
 	"compileOnSave": false,
 	"include": [
+		"./build.ts",
 		"./lib/**/*.ts",
 		"./src/**/*.ts",
 		"./src/**/*.vue",
diff --git a/packages/frontend/vite.config.ts b/packages/frontend/vite.config.ts
index 7b6bf436b1..e9707d13d1 100644
--- a/packages/frontend/vite.config.ts
+++ b/packages/frontend/vite.config.ts
@@ -14,6 +14,7 @@ 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 pluginWatchLocales from './lib/vite-plugin-watch-locales.js';
+import pluginRemoveUnrefI18n from '../frontend-builder/rollup-plugin-remove-unref-i18n.js';
 
 const url = process.env.NODE_ENV === 'development' ? yaml.load(await fsp.readFile('../../.config/default.yml', 'utf-8')).url : null;
 const host = url ? (new URL(url)).hostname : undefined;
@@ -111,6 +112,7 @@ export function getConfig(): UserConfig {
 			pluginWatchLocales(),
 			...searchIndexes.map(options => pluginCreateSearchIndex(options)),
 			pluginVue(),
+			pluginRemoveUnrefI18n(),
 			pluginUnwindCssModuleClassName(),
 			pluginJson5(),
 			...process.env.NODE_ENV === 'production'
@@ -174,16 +176,21 @@ export function getConfig(): UserConfig {
 			manifest: 'manifest.json',
 			rollupOptions: {
 				input: {
-					app: './src/_boot_.ts',
+					i18n: './src/i18n.ts',
+					entry: './src/_boot_.ts',
 				},
 				external: externalPackages.map(p => p.match),
+				preserveEntrySignatures: 'allow-extension',
 				output: {
 					manualChunks: {
 						vue: ['vue'],
 						photoswipe: ['photoswipe', 'photoswipe/lightbox', 'photoswipe/style.css'],
+						// dependencies of i18n.ts
+						'config': ['@@/js/config.js'],
 					},
-					chunkFileNames: process.env.NODE_ENV === 'production' ? '[hash:8].js' : '[name]-[hash:8].js',
-					assetFileNames: process.env.NODE_ENV === 'production' ? '[hash:8][extname]' : '[name]-[hash:8][extname]',
+					entryFileNames: 'scripts/[hash:8].js',
+					chunkFileNames: 'scripts/[hash:8].js',
+					assetFileNames: 'assets/[hash:8][extname]',
 					paths(id) {
 						for (const p of externalPackages) {
 							if (p.match.test(id)) {