fix: select Firefox artifact by release version

README.md

@@ -67,6 +67,15 @@ Headers:
 
 Rotating the token in Desktop invalidates the value stored by the extension.
 
+## Language
+
+The popup settings provide a persisted `System / English / Russian` language
+selector. `System` follows the browser UI language: Russian browser locales use
+Russian, and all other locales use English.
+
+The extension and desktop application store their language choices
+independently. Changing one does not change the other.
+
 Payload:
 
 ```json

chromium/manifest.json

@@ -1,7 +1,7 @@
 {
   "manifest_version": 3,
   "name": "Verstak Bridge",
-  "version": "2.0.1",
+  "version": "2.0.2",
   "description": "Send pages, selections, links, and files to the local Verstak browser inbox.",
   "author": "Verstak",
   "homepage_url": "https://git.mirv.top/verstak/verstak-browser-extension",

docs/superpowers/plans/2026-07-11-browser-extension-localization.md

@@ -0,0 +1,328 @@
+# Browser Extension Localization Implementation Plan
+
+> **For agentic workers:** REQUIRED SUB-SKILL: Use superpowers:subagent-driven-development (recommended) or superpowers:executing-plans to implement this plan task-by-task. Steps use checkbox (`- [ ]`) syntax for tracking.
+
+**Goal:** Add persisted `System / English / Russian` language selection to the browser extension, localizing popup chrome and context menus in Chromium and Firefox.
+
+**Architecture:** A framework-independent `shared/i18n.js` resolves preferences and loads extension-owned JSON catalogs. Popup and background both consume it; background owns persistence and context-menu recreation, while popup performs immediate DOM translation and sends settings updates.
+
+**Tech Stack:** WebExtension APIs, plain ES5-compatible JavaScript, JSON catalogs, Node `assert`/`vm` tests, existing Node build script.
+
+## Global Constraints
+
+- Store only `system`, `en`, or `ru`; missing/invalid values normalize to `system`.
+- `ru` and `ru-*` browser UI locales resolve to Russian; all other system locales resolve to English.
+- Keep the extension language independent from desktop settings.
+- Add no runtime dependency and no manifest-localization scope.
+- Never translate receiver URLs, tokens, file names, user content, or raw receiver error text.
+- Preserve receiver URL/token values when language changes.
+- Both browser distributions must contain `i18n.js`, `locales/en.json`, and `locales/ru.json`.
+
+---
+
+### Task 1: Shared Locale Runtime and Catalog Contract
+
+**Files:**
+
+- Create: `shared/i18n.js`
+- Create: `shared/locales/en.json`
+- Create: `shared/locales/ru.json`
+- Create: `scripts/test-i18n.js`
+- Modify: `package.json`
+
+**Interfaces:**
+
+- Produces: `globalThis.VerstakBrowserI18n.normalizePreference(value)`.
+- Produces: `globalThis.VerstakBrowserI18n.resolveLocale(preference, systemLocale)`.
+- Produces: `globalThis.VerstakBrowserI18n.loadCatalogs(loadJSON)` returning `Promise<{en,ru}>`.
+- Produces: `globalThis.VerstakBrowserI18n.createTranslator(catalogs, locale)` returning `t(key, params, fallback)`.
+
+- [ ] **Step 1: Write the failing runtime/catalog test**
+
+Create `scripts/test-i18n.js` that loads `shared/i18n.js` in `vm`, reads both JSON catalogs, and asserts:
+
+```js
+assert.strictEqual(i18n.normalizePreference('de'), 'system');
+assert.strictEqual(i18n.resolveLocale('system', 'ru-RU'), 'ru');
+assert.strictEqual(i18n.resolveLocale('system', 'uk-UA'), 'en');
+assert.strictEqual(i18n.resolveLocale('en', 'ru-RU'), 'en');
+assert.deepStrictEqual(Object.keys(ru).sort(), Object.keys(en).sort());
+assert.ok(Object.values(en).every((value) => typeof value === 'string'));
+assert.ok(Object.values(ru).every((value) => typeof value === 'string'));
+assert.strictEqual(i18n.createTranslator({ en, ru }, 'ru')('status.queued'), 'В очереди до запуска Верстака');
+assert.strictEqual(i18n.createTranslator({ en, ru }, 'en')('error.value', { error: 'offline' }), 'Error: offline');
+```
+
+- [ ] **Step 2: Run the test and confirm RED**
+
+Run: `node scripts/test-i18n.js`
+
+Expected: FAIL because `shared/i18n.js` and catalogs do not exist.
+
+- [ ] **Step 3: Implement the minimal shared runtime**
+
+Implement an IIFE exporting the four functions. `loadCatalogs(loadJSON)` must call `loadJSON('en')` and `loadJSON('ru')`; translation lookup order is selected catalog, English catalog, explicit fallback, key. Interpolation replaces `{name}` only when `params` owns that property.
+
+Catalogs must define identical keys for:
+
+```text
+popup.subtitle
+label.receiver
+label.pending
+label.url
+label.file
+label.receiverUrl
+label.pairingToken
+label.language
+action.sendPage
+action.sendFile
+action.retryPending
+action.save
+hint.contextMenu
+receiver.online
+receiver.offline
+receiver.unknown
+language.system
+language.en
+language.ru
+status.sending
+status.queued
+status.done
+status.readingFile
+status.saved
+error.chooseFile
+error.fileTooLarge
+error.invalidReceiverUrl
+error.value
+context.sendPage
+context.sendSelection
+context.sendLink
+```
+
+- [ ] **Step 4: Add the test to `npm test` and verify GREEN**
+
+Set:
+
+```json
+"test": "node scripts/test-protocol.js && node scripts/test-i18n.js && node scripts/test-popup-settings.js"
+```
+
+Run: `node scripts/test-i18n.js`
+
+Expected: `browser extension localization runtime tests passed`.
+
+- [ ] **Step 5: Commit the shared contract**
+
+```bash
+git add shared/i18n.js shared/locales scripts/test-i18n.js package.json
+git commit -m "feat: add browser extension localization runtime"
+```
+
+---
+
+### Task 2: Persisted Language and Localized Context Menus
+
+**Files:**
+
+- Modify: `shared/background.js`
+- Modify: `chromium/manifest.json`
+- Modify: `firefox/manifest.json`
+- Create: `scripts/test-background-i18n.js`
+
+**Interfaces:**
+
+- Consumes: `VerstakBrowserI18n.loadCatalogs`, `normalizePreference`, `resolveLocale`, `createTranslator`.
+- Produces: persisted `settings.language` and context-menu recreation after `saveSettings`.
+
+- [ ] **Step 1: Write the failing background test**
+
+Load `protocol.js`, `queue.js`, `i18n.js`, and `background.js` into `vm` with fake storage/context-menu APIs. Seed `settings.language = 'ru'`, trigger `runtime.onInstalled`, and assert:
+
+```js
+assert.deepStrictEqual(menuTitles, [
+  'Отправить страницу в Верстак',
+  'Отправить выделение в Верстак',
+  'Отправить ссылку в Верстак',
+]);
+```
+
+Send a `saveSettings` message with `{ receiverUrl, receiverToken, language: 'en' }`, then assert stored receiver fields are unchanged and menu titles become English.
+
+- [ ] **Step 2: Run the test and confirm RED**
+
+Run: `node scripts/test-background-i18n.js`
+
+Expected: FAIL because background defaults contain no language and menu titles are literal English.
+
+- [ ] **Step 3: Implement background localization**
+
+Add `language: 'system'` to `DEFAULT_SETTINGS`. Normalize it in `getSettings`/`saveSettings`. Load catalogs with:
+
+```js
+function loadLocaleCatalogs() {
+  return localeCatalogs || i18n.loadCatalogs(function (locale) {
+    return fetch(ext.runtime.getURL('locales/' + locale + '.json')).then(function (response) {
+      if (!response.ok) throw new Error('catalog load failed: ' + locale);
+      return response.json();
+    });
+  });
+}
+```
+
+Make `setupContextMenus()` resolve settings plus catalogs, choose
+`ext.i18n.getUILanguage()` with English fallback, and create the three menu
+titles via `t('context.sendPage')`, `t('context.sendSelection')`, and
+`t('context.sendLink')`. Call it after language settings are saved.
+
+- [ ] **Step 4: Load `i18n.js` before background code in both manifests**
+
+- Chromium service worker remains bundled by the build concatenation order.
+- Firefox `background.scripts` becomes `protocol.js`, `api.js`, `queue.js`, `i18n.js`, `background.js`.
+
+Also append `node scripts/test-background-i18n.js` to the `test` script in
+`package.json` now that the test file exists.
+
+- [ ] **Step 5: Verify and commit**
+
+Run: `node scripts/test-background-i18n.js`
+
+Expected: `browser extension background localization tests passed`.
+
+```bash
+git add shared/background.js chromium/manifest.json firefox/manifest.json scripts/test-background-i18n.js
+git commit -m "feat: localize browser extension context menus"
+```
+
+---
+
+### Task 3: Popup Language Selector and Live Translation
+
+**Files:**
+
+- Modify: `shared/popup/popup.html`
+- Modify: `shared/popup/popup.js`
+- Modify: `shared/popup/popup.css`
+- Modify: `scripts/test-popup-settings.js`
+
+**Interfaces:**
+
+- Consumes: state `settings.language` from background and the shared translator.
+- Produces: immediate popup translation plus a `saveSettings` message containing receiver URL, token, and language.
+
+- [ ] **Step 1: Extend the popup test and confirm RED**
+
+Add fake elements for every localized ID plus `language-select`, mock catalog fetches, `browser.i18n.getUILanguage()`, and `document.documentElement.lang`. Assert initial `system` with `ru-RU` renders Russian. Change select value to `en`, dispatch `change`, flush promises, then assert:
+
+```js
+assert.strictEqual(elements['capture-page'].textContent, 'Send Page');
+assert.strictEqual(elements['receiver-state'].textContent, 'Unknown');
+assert.strictEqual(document.documentElement.lang, 'en');
+assert.strictEqual(savedSettings.language, 'en');
+assert.strictEqual(savedSettings.receiverUrl, initialState.settings.receiverUrl);
+assert.strictEqual(savedSettings.receiverToken, initialState.settings.receiverToken);
+```
+
+- [ ] **Step 2: Add popup markup**
+
+Load `../i18n.js` before `popup.js`, give all static user-visible elements stable IDs, and add:
+
+```html
+<label id="language-label" for="language-select">Language</label>
+<select id="language-select">
+  <option value="system">System</option>
+  <option value="en">English</option>
+  <option value="ru">Русский</option>
+</select>
+```
+
+- [ ] **Step 3: Implement asynchronous popup initialization and live switch**
+
+Load both catalogs through `ext.runtime.getURL`, resolve the locale from saved
+preference plus browser UI language, and apply all static text through one
+`applyLocale(preference)` function. `render(state)` localizes
+online/offline/unknown. Known statuses and validations use catalog keys; raw
+error messages are wrapped only when needed by `error.value`.
+
+The select `change` handler must call `applyLocale` before awaiting background
+storage, then send all three settings fields. The existing Save button also
+sends the selected language.
+
+- [ ] **Step 4: Style the select consistently and verify GREEN**
+
+Share the existing input box model/colors with `select` and keep the popup
+minimum width unchanged.
+
+Run: `node scripts/test-popup-settings.js`
+
+Expected: `browser extension popup localization/settings tests passed`.
+
+- [ ] **Step 5: Commit**
+
+```bash
+git add shared/popup scripts/test-popup-settings.js
+git commit -m "feat: add browser extension language selector"
+```
+
+---
+
+### Task 4: Distribution Packaging, Documentation, and Full Verification
+
+**Files:**
+
+- Modify: `scripts/build-extension.js`
+- Modify: `README.md`
+- Test: `scripts/test-i18n.js`
+- Test: `scripts/test-background-i18n.js`
+- Test: `scripts/test-popup-settings.js`
+
+**Interfaces:**
+
+- Consumes: shared runtime/catalogs and updated manifests.
+- Produces: complete `dist/chromium` and `dist/firefox` extension directories.
+
+- [ ] **Step 1: Add failing build-content assertions**
+
+Extend `scripts/test-i18n.js` to run after build when `dist` exists and assert
+both targets contain:
+
+```text
+i18n.js
+locales/en.json
+locales/ru.json
+```
+
+- [ ] **Step 2: Update the build**
+
+For Chromium, concatenate `shared/i18n.js` before `shared/background.js` and
+also copy it as `dist/chromium/i18n.js` for popup use. For Firefox, copy
+`shared/i18n.js` beside background scripts. Copy both JSON catalogs to each
+target's `locales/` directory.
+
+- [ ] **Step 3: Document the selector**
+
+Add a README section stating that popup settings provide persisted
+`System / English / Russian`, that System uses browser UI language, and that
+extension/desktop preferences are independent.
+
+- [ ] **Step 4: Run complete verification**
+
+```bash
+npm test
+npm run build
+npm test
+git diff --check
+```
+
+Expected:
+
+- protocol, runtime, popup, and background tests pass;
+- both browser distributions build;
+- post-build content assertions pass;
+- no whitespace errors.
+
+- [ ] **Step 5: Commit packaging and docs**
+
+```bash
+git add scripts/build-extension.js README.md scripts/test-i18n.js
+git commit -m "build: package browser extension locale catalogs"
+```

docs/superpowers/specs/2026-07-11-browser-extension-localization-design.md

@@ -0,0 +1,114 @@
+# Browser Extension Localization Design
+
+## Goal
+
+Add English and Russian localization to the Verstak browser extension with a
+persisted manual `System / English / Russian` language selector. The extension
+remains independent from the desktop application's language preference.
+
+## Scope
+
+The change covers:
+
+- all user-visible popup labels, hints, statuses, validation messages, and
+  receiver-state labels;
+- the three browser context-menu titles;
+- persisted language selection;
+- Chromium and Firefox build packaging;
+- automated tests for locale resolution, persistence, live popup updates, and
+  context-menu localization.
+
+Manifest name and description localization is not part of this milestone. The
+existing English manifest values remain the fallback in both browser builds.
+
+## Locale Model
+
+The stored setting is named `language` and accepts only:
+
+- `system` (default);
+- `en`;
+- `ru`.
+
+`system` resolves the browser UI language through
+`browser.i18n.getUILanguage()` / `chrome.i18n.getUILanguage()`. Popup code may
+fall back to `navigator.language` when the extension i18n API is unavailable.
+`ru` and `ru-*` resolve to Russian; every other value resolves to English.
+Invalid or missing stored preferences normalize to `system`.
+
+## Catalogs and Runtime
+
+The extension owns framework-independent JSON catalogs:
+
+```text
+shared/locales/en.json
+shared/locales/ru.json
+```
+
+A small shared runtime provides:
+
+- preference normalization;
+- system-locale resolution;
+- key lookup with English and literal fallback;
+- `{parameter}` interpolation.
+
+The runtime has no dependency on desktop, the plugin SDK, DOM APIs, or external
+packages. It is loaded by both popup and background scripts.
+
+Both catalogs must contain identical string-only keys. The build copies them
+into `dist/chromium/locales` and `dist/firefox/locales` together with the shared
+runtime.
+
+## Popup Behavior
+
+The existing settings section gains a labeled language `<select>` with
+`system`, `en`, and `ru` options. Selecting a value:
+
+1. updates all popup chrome immediately without reopening the popup;
+2. sends the full settings patch to background storage;
+3. preserves receiver URL and pairing token values;
+4. shows the localized saved/error state.
+
+The `<html lang>` attribute is updated to the resolved locale. User data,
+receiver URLs, tokens, file names, and backend-provided error text are not
+translated.
+
+## Background and Context Menus
+
+`DEFAULT_SETTINGS` gains `language: "system"`. Context-menu creation resolves
+the effective locale from stored settings and creates localized page,
+selection, and link titles.
+
+After a language setting is saved, background recreates the context menus so
+the new language applies without reinstalling or reloading the extension.
+Failure to access the i18n API falls back to English and must not block capture
+or settings operations.
+
+## Error Handling
+
+- Missing catalog keys fall back to English, then to the provided literal/key.
+- Invalid stored language values behave as `system`.
+- Catalog or browser-language detection failure falls back to English.
+- Existing receiver and capture errors continue to be shown; known extension
+  validation/status chrome around them is localized.
+
+## Verification
+
+Tests are written before production changes and cover:
+
+- `ru-*` and non-Russian system-language resolution;
+- explicit language override and invalid-preference normalization;
+- English/Russian catalog parity and interpolation;
+- popup language persistence without losing receiver settings;
+- live popup translation after selecting Russian/English;
+- localized online/offline/unknown and capture status messages;
+- localized context-menu creation and recreation after language changes;
+- build contents for both Chromium and Firefox.
+
+Final verification commands:
+
+```bash
+npm test
+npm run build
+```
+
+Manual installation or store signing is outside this milestone.

firefox/manifest.json

@@ -1,7 +1,7 @@
 {
   "manifest_version": 2,
   "name": "Verstak Bridge",
-  "version": "2.0.1",
+  "version": "2.0.2",
   "description": "Send pages, selections, links, and files to the local Verstak browser inbox.",
   "author": "Verstak",
   "homepage_url": "https://git.mirv.top/verstak/verstak-browser-extension",
@@ -17,7 +17,7 @@
   },
   "permissions": ["contextMenus", "storage", "tabs", "http://127.0.0.1/*", "http://localhost/*"],
   "background": {
-    "scripts": ["protocol.js", "api.js", "queue.js", "background.js"]
+    "scripts": ["protocol.js", "api.js", "queue.js", "i18n.js", "background.js"]
   },
   "browser_action": {
     "default_popup": "popup/popup.html",

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "verstak-browser-extension",
-  "version": "2.0.1",
+  "version": "2.0.2",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "verstak-browser-extension",
-      "version": "2.0.1",
+      "version": "2.0.2",
       "devDependencies": {
         "web-ext": "^8.3.0"
       }

package.json

@@ -1,11 +1,11 @@
 {
   "name": "verstak-browser-extension",
-  "version": "2.0.1",
+  "version": "2.0.2",
   "private": true,
   "description": "Verstak browser capture extension for Chromium and Firefox",
   "scripts": {
     "build": "node scripts/build-extension.js",
-    "test": "node scripts/test-protocol.js && node scripts/test-popup-settings.js",
+    "test": "node scripts/test-protocol.js && node scripts/test-i18n.js && node scripts/test-popup-settings.js && node scripts/test-popup-catalog-fallback.js && node scripts/test-background-i18n.js",
     "sign:firefox": "./scripts/sign-firefox-xpi.sh",
     "release:firefox": "./scripts/release-firefox-xpi.sh"
   },

scripts/build-extension.js

@@ -38,6 +38,13 @@ function copyIcons(destRoot) {
   }
 }
 
+function copyLocalization(destRoot) {
+  copy(path.join(shared, 'i18n.js'), path.join(destRoot, 'i18n.js'));
+  for (const locale of ['en', 'ru']) {
+    copy(path.join(shared, 'locales', `${locale}.json`), path.join(destRoot, 'locales', `${locale}.json`));
+  }
+}
+
 rm(dist);
 
 const chromiumDist = path.join(dist, 'chromium');
@@ -47,18 +54,21 @@ concat([
   path.join(shared, 'protocol.js'),
   path.join(shared, 'api.js'),
   path.join(shared, 'queue.js'),
+  path.join(shared, 'i18n.js'),
   path.join(shared, 'background.js'),
 ], path.join(chromiumDist, 'background.js'));
 copyPopup(chromiumDist);
 copyIcons(chromiumDist);
+copyLocalization(chromiumDist);
 
 const firefoxDist = path.join(dist, 'firefox');
 mkdir(firefoxDist);
 copy(path.join(root, 'firefox', 'manifest.json'), path.join(firefoxDist, 'manifest.json'));
-for (const name of ['protocol.js', 'api.js', 'queue.js', 'background.js']) {
+for (const name of ['protocol.js', 'api.js', 'queue.js', 'i18n.js', 'background.js']) {
   copy(path.join(shared, name), path.join(firefoxDist, name));
 }
 copyPopup(firefoxDist);
 copyIcons(firefoxDist);
+copyLocalization(firefoxDist);
 
 console.log('built dist/chromium and dist/firefox');

scripts/release-firefox-xpi.sh

@@ -44,9 +44,9 @@ if [[ -z "$VERSION" || -z "$ADDON_ID" ]]; then
   exit 1
 fi
 
-SIGNED_XPI="$(find "$ARTIFACTS_DIR" -maxdepth 1 -type f -name '*.xpi' | sort | tail -n 1 || true)"
+SIGNED_XPI="$(find "$ARTIFACTS_DIR" -maxdepth 1 -type f -name "*-${VERSION}.xpi" | sort | tail -n 1 || true)"
 if [[ -z "$SIGNED_XPI" ]]; then
-  echo "ERROR: no signed XPI found in $ARTIFACTS_DIR" >&2
+  echo "ERROR: no signed XPI for version $VERSION found in $ARTIFACTS_DIR" >&2
   exit 1
 fi
 

scripts/sign-firefox-xpi.sh

@@ -84,7 +84,7 @@ echo "Using AMO API proxy from WEB_EXT_API_PROXY"
 
 npx web-ext "${SIGN_ARGS[@]}"
 
-SIGNED_XPI="$(find "$ARTIFACTS_DIR" -maxdepth 1 -type f -name '*.xpi' | sort | tail -n 1 || true)"
+SIGNED_XPI="$(find "$ARTIFACTS_DIR" -maxdepth 1 -type f -name '*.xpi' -printf '%T@ %p\n' | sort -n | tail -n 1 | cut -d' ' -f2- || true)"
 if [[ -z "$SIGNED_XPI" ]]; then
   echo "ERROR: signed XPI was not created in $ARTIFACTS_DIR" >&2
   exit 1

scripts/test-background-i18n.js

@@ -0,0 +1,119 @@
+#!/usr/bin/env node
+const assert = require('assert');
+const fs = require('fs');
+const path = require('path');
+const vm = require('vm');
+
+const root = path.resolve(__dirname, '..');
+const catalogs = {
+  en: JSON.parse(fs.readFileSync(path.join(root, 'shared', 'locales', 'en.json'), 'utf8')),
+  ru: JSON.parse(fs.readFileSync(path.join(root, 'shared', 'locales', 'ru.json'), 'utf8')),
+};
+const state = {
+  settings: {
+    receiverUrl: 'http://127.0.0.1:47731/api/browser-inbox/v1/captures',
+    receiverToken: 'paired-token',
+    language: 'ru',
+  },
+};
+let menuTitles = [];
+let installedListener;
+let messageListener;
+
+const browser = {
+  storage: {
+    local: {
+      get(key) {
+        if (typeof key === 'string') return Promise.resolve({ [key]: state[key] });
+        return Promise.resolve({ ...state });
+      },
+      set(patch) {
+        Object.assign(state, patch || {});
+        return Promise.resolve();
+      },
+    },
+  },
+  contextMenus: {
+    removeAll() {
+      menuTitles = [];
+      return Promise.resolve();
+    },
+    create(item) {
+      menuTitles.push(item.title);
+    },
+    onClicked: { addListener() {} },
+  },
+  runtime: {
+    getURL(relativePath) { return `extension://${relativePath}`; },
+    onInstalled: { addListener(listener) { installedListener = listener; } },
+    onMessage: { addListener(listener) { messageListener = listener; } },
+  },
+  i18n: { getUILanguage() { return 'en-US'; } },
+  tabs: { query() { return Promise.resolve([]); } },
+};
+
+function fetchCatalog(url) {
+  const locale = /\/ru\.json$/.test(url) ? 'ru' : 'en';
+  return Promise.resolve({ ok: true, json: () => Promise.resolve(catalogs[locale]) });
+}
+
+const context = vm.createContext({
+  browser,
+  console,
+  Date,
+  Math,
+  Promise,
+  URL,
+  fetch: fetchCatalog,
+  setTimeout,
+  clearTimeout,
+});
+context.globalThis = context;
+for (const file of ['protocol.js', 'api.js', 'queue.js', 'i18n.js', 'background.js']) {
+  vm.runInContext(fs.readFileSync(path.join(root, 'shared', file), 'utf8'), context, { filename: file });
+}
+
+async function flush() {
+  for (let i = 0; i < 8; i += 1) await Promise.resolve();
+}
+
+function sendMessage(message) {
+  return new Promise((resolve) => {
+    messageListener(message, {}, resolve);
+  });
+}
+
+(async () => {
+  installedListener();
+  await flush();
+  assert.deepStrictEqual(menuTitles, [
+    'Отправить страницу в Верстак',
+    'Отправить выделение в Верстак',
+    'Отправить ссылку в Верстак',
+  ]);
+
+  const nextState = await sendMessage({
+    type: 'verstak.capture',
+    action: 'saveSettings',
+    settings: {
+      receiverUrl: state.settings.receiverUrl,
+      receiverToken: state.settings.receiverToken,
+      language: 'en',
+    },
+  });
+  await flush();
+
+  assert.strictEqual(state.settings.receiverUrl, 'http://127.0.0.1:47731/api/browser-inbox/v1/captures');
+  assert.strictEqual(state.settings.receiverToken, 'paired-token');
+  assert.strictEqual(state.settings.language, 'en');
+  assert.strictEqual(nextState.settings.language, 'en');
+  assert.deepStrictEqual(menuTitles, [
+    'Send page to Verstak',
+    'Send selection to Verstak',
+    'Send link to Verstak',
+  ]);
+  console.log('browser extension background localization tests passed');
+})().catch((error) => {
+  console.error(error);
+  process.exit(1);
+});

scripts/test-i18n.js

@@ -0,0 +1,57 @@
+#!/usr/bin/env node
+const assert = require('assert');
+const fs = require('fs');
+const path = require('path');
+
+const root = path.resolve(__dirname, '..');
+const i18n = require(path.join(root, 'shared', 'i18n.js'));
+const en = JSON.parse(fs.readFileSync(path.join(root, 'shared', 'locales', 'en.json'), 'utf8'));
+const ru = JSON.parse(fs.readFileSync(path.join(root, 'shared', 'locales', 'ru.json'), 'utf8'));
+
+assert.strictEqual(i18n.normalizePreference(undefined), 'system');
+assert.strictEqual(i18n.normalizePreference('de'), 'system');
+assert.strictEqual(i18n.normalizePreference('system'), 'system');
+assert.strictEqual(i18n.normalizePreference('en'), 'en');
+assert.strictEqual(i18n.normalizePreference('ru'), 'ru');
+
+assert.strictEqual(i18n.resolveLocale('system', 'ru'), 'ru');
+assert.strictEqual(i18n.resolveLocale('system', 'ru-RU'), 'ru');
+assert.strictEqual(i18n.resolveLocale('system', 'RU-ru'), 'ru');
+assert.strictEqual(i18n.resolveLocale('system', 'uk-UA'), 'en');
+assert.strictEqual(i18n.resolveLocale('system', 'en-US'), 'en');
+assert.strictEqual(i18n.resolveLocale('en', 'ru-RU'), 'en');
+assert.strictEqual(i18n.resolveLocale('ru', 'en-US'), 'ru');
+
+assert.deepStrictEqual(Object.keys(ru).sort(), Object.keys(en).sort());
+assert.ok(Object.values(en).every((value) => typeof value === 'string'));
+assert.ok(Object.values(ru).every((value) => typeof value === 'string'));
+
+const tEn = i18n.createTranslator({ en, ru }, 'en');
+const tRu = i18n.createTranslator({ en, ru }, 'ru');
+assert.strictEqual(tRu('status.queued'), 'В очереди до запуска Верстака');
+assert.strictEqual(tEn('error.value', { error: 'offline' }), 'Error: offline');
+assert.strictEqual(tRu('missing', null, 'Fallback'), 'Fallback');
+assert.strictEqual(tRu('missing.key'), 'missing.key');
+
+const dist = path.join(root, 'dist');
+if (fs.existsSync(dist)) {
+  for (const target of ['chromium', 'firefox']) {
+    for (const relativePath of ['i18n.js', 'locales/en.json', 'locales/ru.json']) {
+      assert.ok(
+        fs.existsSync(path.join(dist, target, relativePath)),
+        `${target} build is missing ${relativePath}`,
+      );
+    }
+  }
+}
+
+i18n.loadCatalogs((locale) => Promise.resolve(locale === 'ru' ? ru : en))
+  .then((catalogs) => {
+    assert.strictEqual(catalogs.en, en);
+    assert.strictEqual(catalogs.ru, ru);
+    console.log('browser extension localization runtime tests passed');
+  })
+  .catch((error) => {
+    console.error(error);
+    process.exit(1);
+  });

scripts/test-popup-catalog-fallback.js

@@ -0,0 +1,71 @@
+#!/usr/bin/env node
+const assert = require('assert');
+const fs = require('fs');
+const path = require('path');
+const vm = require('vm');
+
+class Element {
+  constructor(text) {
+    this.value = '';
+    this.textContent = text || '';
+    this.className = '';
+    this.files = [];
+    this.listeners = {};
+  }
+  addEventListener(type, listener) { this.listeners[type] = listener; }
+}
+
+const ids = [
+  'status', 'receiver-state', 'receiver-url', 'receiver-input', 'receiver-token-input',
+  'language-select', 'file-input', 'pending-count', 'status-dot', 'subtitle',
+  'receiver-label', 'pending-label', 'url-label', 'file-label', 'receiver-url-label',
+  'receiver-token-label', 'language-label', 'capture-page', 'capture-file', 'retry',
+  'save-settings', 'context-menu-hint', 'language-system-option', 'language-en-option',
+  'language-ru-option',
+];
+const elements = Object.fromEntries(ids.map((id) => [id, new Element()]));
+elements['capture-page'].textContent = 'Send Page';
+
+const browser = {
+  runtime: {
+    getURL(relativePath) { return `extension://${relativePath}`; },
+    sendMessage() {
+      return Promise.resolve({
+        settings: { receiverUrl: 'http://127.0.0.1/', receiverToken: '', language: 'system' },
+        pendingCount: 0,
+        status: {},
+      });
+    },
+  },
+  i18n: { getUILanguage() { return 'en-US'; } },
+};
+const document = {
+  activeElement: null,
+  documentElement: { lang: '' },
+  getElementById(id) { return elements[id]; },
+};
+const context = vm.createContext({
+  browser,
+  document,
+  navigator: { language: 'en-US' },
+  console: { warn() {}, error: console.error },
+  Promise,
+  fetch() { return Promise.reject(new Error('catalog unavailable')); },
+});
+context.globalThis = context;
+
+const root = path.resolve(__dirname, '..');
+for (const file of ['shared/i18n.js', 'shared/popup/popup.js']) {
+  vm.runInContext(fs.readFileSync(path.join(root, file), 'utf8'), context, { filename: file });
+}
+
+(async () => {
+  for (let i = 0; i < 16; i += 1) await Promise.resolve();
+  assert.strictEqual(elements['capture-page'].textContent, 'Send Page');
+  assert.strictEqual(elements['receiver-state'].textContent, 'Unknown');
+  assert.strictEqual(document.documentElement.lang, 'en');
+  console.log('browser extension popup catalog fallback tests passed');
+})().catch((error) => {
+  console.error(error);
+  process.exit(1);
+});

scripts/test-popup-settings.js

@@ -20,6 +20,10 @@ class Element {
   click() {
     if (this.listeners.click) this.listeners.click();
   }
+
+  change() {
+    if (this.listeners.change) this.listeners.change({ target: this });
+  }
 }
 
 const elements = {};
@@ -32,10 +36,23 @@ const elements = {};
   'file-input',
   'pending-count',
   'status-dot',
+  'subtitle',
+  'receiver-label',
+  'pending-label',
+  'url-label',
   'capture-page',
   'capture-file',
   'retry',
+  'file-label',
+  'receiver-url-label',
+  'receiver-token-label',
+  'language-label',
+  'language-select',
+  'language-system-option',
+  'language-en-option',
+  'language-ru-option',
   'save-settings',
+  'context-menu-hint',
 ].forEach((id) => {
   elements[id] = new Element();
 });
@@ -45,12 +62,14 @@ const initialState = {
   settings: {
     receiverUrl: 'http://127.0.0.1:47731/api/browser-inbox/v1/captures',
     receiverToken: 'persisted-token',
+    language: 'system',
   },
   pendingCount: 0,
   status: {},
 };
 const browser = {
   runtime: {
+    getURL(relativePath) { return `extension://${relativePath}`; },
     sendMessage(message) {
       if (message.action === 'getState') return Promise.resolve(initialState);
       if (message.action === 'saveSettings') {
@@ -60,24 +79,56 @@ const browser = {
       return Promise.resolve(initialState);
     },
   },
+  i18n: { getUILanguage() { return 'ru-RU'; } },
 };
 const document = {
   activeElement: null,
+  documentElement: { lang: '' },
   getElementById(id) {
     return elements[id];
   },
 };
+const catalogs = {
+  en: JSON.parse(fs.readFileSync(path.join(__dirname, '..', 'shared', 'locales', 'en.json'), 'utf8')),
+  ru: JSON.parse(fs.readFileSync(path.join(__dirname, '..', 'shared', 'locales', 'ru.json'), 'utf8')),
+};
+function fetchCatalog(url) {
+  const locale = /\/ru\.json$/.test(url) ? 'ru' : 'en';
+  return Promise.resolve({ ok: true, json: () => Promise.resolve(catalogs[locale]) });
+}
+const i18nPath = path.join(__dirname, '..', 'shared', 'i18n.js');
 const popupPath = path.join(__dirname, '..', 'shared', 'popup', 'popup.js');
-vm.runInNewContext(fs.readFileSync(popupPath, 'utf8'), { browser, console, document, Promise, btoa });
+const context = vm.createContext({ browser, console, document, Promise, btoa, fetch: fetchCatalog, navigator: { language: 'en-US' } });
+context.globalThis = context;
+vm.runInContext(fs.readFileSync(i18nPath, 'utf8'), context, { filename: i18nPath });
+vm.runInContext(fs.readFileSync(popupPath, 'utf8'), context, { filename: popupPath });
 
 async function flush() {
-  for (let i = 0; i < 4; i += 1) await Promise.resolve();
+  for (let i = 0; i < 16; i += 1) await Promise.resolve();
 }
 
 (async () => {
   await flush();
   assert.strictEqual(elements['receiver-input'].value, initialState.settings.receiverUrl);
   assert.strictEqual(elements['receiver-token-input'].value, initialState.settings.receiverToken);
+  assert.strictEqual(elements['language-select'].value, 'system');
+  assert.strictEqual(elements['capture-page'].textContent, 'Отправить страницу');
+  assert.strictEqual(elements['receiver-state'].textContent, 'Неизвестно');
+  assert.strictEqual(document.documentElement.lang, 'ru');
+  elements['capture-file'].click();
+  assert.strictEqual(elements.status.textContent, 'Сначала выберите файл');
+
+  elements['language-select'].value = 'en';
+  elements['language-select'].change();
+  await flush();
+
+  assert.strictEqual(elements['capture-page'].textContent, 'Send Page');
+  assert.strictEqual(elements['receiver-state'].textContent, 'Unknown');
+  assert.strictEqual(document.documentElement.lang, 'en');
+  assert.ok(savedSettings);
+  assert.strictEqual(savedSettings.language, 'en');
+  assert.strictEqual(savedSettings.receiverUrl, initialState.settings.receiverUrl);
+  assert.strictEqual(savedSettings.receiverToken, initialState.settings.receiverToken);
 
   elements['receiver-input'].value = 'http://127.0.0.1:47731/api/browser-inbox/v1/captures';
   elements['receiver-token-input'].value = 'new-token';
@@ -87,7 +138,8 @@ async function flush() {
   assert.ok(savedSettings);
   assert.strictEqual(savedSettings.receiverUrl, 'http://127.0.0.1:47731/api/browser-inbox/v1/captures');
   assert.strictEqual(savedSettings.receiverToken, 'new-token');
-  console.log('browser extension popup settings tests passed');
+  assert.strictEqual(savedSettings.language, 'en');
+  console.log('browser extension popup localization/settings tests passed');
 })().catch((error) => {
   console.error(error);
   process.exit(1);

shared/background.js

@@ -4,20 +4,49 @@
   var ext = typeof browser !== 'undefined' ? browser : chrome;
   var protocol = globalThis.VerstakBrowser;
   var queue = new protocol.CaptureQueue(protocol.browserStorageAdapter(ext));
+  var i18n = globalThis.VerstakBrowserI18n;
   var DEFAULT_SETTINGS = {
     receiverUrl: protocol.DEFAULT_RECEIVER_URL,
-    receiverToken: ''
+    receiverToken: '',
+    language: 'system'
   };
   var STATUS_KEY = 'verstak.status';
+  var localeCatalogs = null;
 
   function getSettings() {
     return ext.storage.local.get('settings').then(function (result) {
-      return Object.assign({}, DEFAULT_SETTINGS, result && result.settings || {});
+      var settings = Object.assign({}, DEFAULT_SETTINGS, result && result.settings || {});
+      settings.language = i18n.normalizePreference(settings.language);
+      return settings;
     });
   }
 
   function saveSettings(settings) {
-    return ext.storage.local.set({ settings: Object.assign({}, DEFAULT_SETTINGS, settings || {}) });
+    settings = Object.assign({}, DEFAULT_SETTINGS, settings || {});
+    settings.language = i18n.normalizePreference(settings.language);
+    return ext.storage.local.set({ settings: settings });
+  }
+
+  function loadLocaleCatalogs() {
+    if (localeCatalogs) return localeCatalogs;
+    localeCatalogs = i18n.loadCatalogs(function (locale) {
+      return fetch(ext.runtime.getURL('locales/' + locale + '.json')).then(function (response) {
+        if (!response.ok) throw new Error('catalog load failed: ' + locale);
+        return response.json();
+      });
+    }).catch(function (error) {
+      console.warn('[verstak] localization catalogs unavailable:', error);
+      return { en: {}, ru: {} };
+    });
+    return localeCatalogs;
+  }
+
+  function browserLocale() {
+    try {
+      return ext.i18n && ext.i18n.getUILanguage ? ext.i18n.getUILanguage() : 'en';
+    } catch (_) {
+      return 'en';
+    }
   }
 
   function setStatus(patch) {
@@ -105,11 +134,28 @@
   }
 
   function setupContextMenus() {
-    if (!ext.contextMenus) return;
-    ext.contextMenus.removeAll(function () {
-      ext.contextMenus.create({ id: 'verstak-capture-page', title: 'Send page to Verstak', contexts: ['page'] });
-      ext.contextMenus.create({ id: 'verstak-capture-selection', title: 'Send selection to Verstak', contexts: ['selection'] });
-      ext.contextMenus.create({ id: 'verstak-capture-link', title: 'Send link to Verstak', contexts: ['link'] });
+    if (!ext.contextMenus) return Promise.resolve();
+    return Promise.all([getSettings(), loadLocaleCatalogs()]).then(function (results) {
+      var locale = i18n.resolveLocale(results[0].language, browserLocale());
+      var t = i18n.createTranslator(results[1], locale);
+      return new Promise(function (resolve) {
+        var created = false;
+        function createMenus() {
+          if (created) return;
+          created = true;
+          ext.contextMenus.create({ id: 'verstak-capture-page', title: t('context.sendPage', null, 'Send page to Verstak'), contexts: ['page'] });
+          ext.contextMenus.create({ id: 'verstak-capture-selection', title: t('context.sendSelection', null, 'Send selection to Verstak'), contexts: ['selection'] });
+          ext.contextMenus.create({ id: 'verstak-capture-link', title: t('context.sendLink', null, 'Send link to Verstak'), contexts: ['link'] });
+          resolve();
+        }
+        var removal;
+        try {
+          removal = ext.contextMenus.removeAll(createMenus);
+        } catch (_) {
+          removal = ext.contextMenus.removeAll();
+        }
+        if (removal && typeof removal.then === 'function') removal.then(createMenus, createMenus);
+      });
     });
   }
 
@@ -128,6 +174,8 @@
     if (message.action === 'getState') return getState();
     if (message.action === 'saveSettings') {
       return saveSettings(message.settings).then(function () {
+        return setupContextMenus();
+      }).then(function () {
         return setStatus({ receiverReachable: null, lastResult: 'settings-saved', lastError: '' });
       }).then(getState);
     }

shared/i18n.js

@@ -0,0 +1,54 @@
+(function (root, factory) {
+  'use strict';
+
+  var api = factory();
+  root.VerstakBrowserI18n = api;
+  if (typeof module !== 'undefined' && module.exports) module.exports = api;
+})(typeof globalThis !== 'undefined' ? globalThis : this, function () {
+  'use strict';
+
+  var PREFERENCES = { system: true, en: true, ru: true };
+
+  function normalizePreference(value) {
+    value = String(value || '').trim().toLowerCase();
+    return PREFERENCES[value] ? value : 'system';
+  }
+
+  function resolveLocale(preference, systemLocale) {
+    preference = normalizePreference(preference);
+    if (preference === 'en' || preference === 'ru') return preference;
+    systemLocale = String(systemLocale || '').trim().toLowerCase();
+    return systemLocale === 'ru' || systemLocale.indexOf('ru-') === 0 ? 'ru' : 'en';
+  }
+
+  function interpolate(message, params) {
+    if (!params) return message;
+    return message.replace(/\{([A-Za-z0-9_.-]+)\}/g, function (placeholder, name) {
+      return Object.prototype.hasOwnProperty.call(params, name) ? String(params[name]) : placeholder;
+    });
+  }
+
+  function loadCatalogs(loadJSON) {
+    return Promise.all([loadJSON('en'), loadJSON('ru')]).then(function (catalogs) {
+      return { en: catalogs[0] || {}, ru: catalogs[1] || {} };
+    });
+  }
+
+  function createTranslator(catalogs, locale) {
+    catalogs = catalogs || {};
+    locale = locale === 'ru' ? 'ru' : 'en';
+    return function translate(key, params, fallback) {
+      var message = catalogs[locale] && catalogs[locale][key];
+      if (message == null && catalogs.en) message = catalogs.en[key];
+      if (message == null) message = fallback == null ? key : fallback;
+      return interpolate(String(message), params);
+    };
+  }
+
+  return {
+    normalizePreference: normalizePreference,
+    resolveLocale: resolveLocale,
+    loadCatalogs: loadCatalogs,
+    createTranslator: createTranslator
+  };
+});

shared/locales/en.json

@@ -0,0 +1,33 @@
+{
+  "popup.subtitle": "Browser Inbox",
+  "label.receiver": "Receiver",
+  "label.pending": "Pending",
+  "label.url": "URL",
+  "label.file": "File",
+  "label.receiverUrl": "Receiver URL",
+  "label.pairingToken": "Pairing token",
+  "label.language": "Language",
+  "action.sendPage": "Send Page",
+  "action.sendFile": "Send File",
+  "action.retryPending": "Retry Pending",
+  "action.save": "Save",
+  "hint.contextMenu": "Selection and link captures are available from the page context menu.",
+  "receiver.online": "Online",
+  "receiver.offline": "Offline",
+  "receiver.unknown": "Unknown",
+  "language.system": "System",
+  "language.en": "English",
+  "language.ru": "Russian",
+  "status.sending": "Sending...",
+  "status.queued": "Queued until Verstak is available",
+  "status.done": "Done",
+  "status.readingFile": "Reading file...",
+  "status.saved": "Saved",
+  "error.chooseFile": "Choose a file first",
+  "error.fileTooLarge": "File is too large for browser capture",
+  "error.invalidReceiverUrl": "Receiver URL must start with http:// or https://",
+  "error.value": "Error: {error}",
+  "context.sendPage": "Send page to Verstak",
+  "context.sendSelection": "Send selection to Verstak",
+  "context.sendLink": "Send link to Verstak"
+}

shared/locales/ru.json

@@ -0,0 +1,33 @@
+{
+  "popup.subtitle": "Входящие из браузера",
+  "label.receiver": "Приёмник",
+  "label.pending": "В очереди",
+  "label.url": "URL",
+  "label.file": "Файл",
+  "label.receiverUrl": "URL приёмника",
+  "label.pairingToken": "Токен сопряжения",
+  "label.language": "Язык",
+  "action.sendPage": "Отправить страницу",
+  "action.sendFile": "Отправить файл",
+  "action.retryPending": "Повторить отправку",
+  "action.save": "Сохранить",
+  "hint.contextMenu": "Выделение и ссылки можно отправить через контекстное меню страницы.",
+  "receiver.online": "Доступен",
+  "receiver.offline": "Недоступен",
+  "receiver.unknown": "Неизвестно",
+  "language.system": "Системный",
+  "language.en": "Английский",
+  "language.ru": "Русский",
+  "status.sending": "Отправка...",
+  "status.queued": "В очереди до запуска Верстака",
+  "status.done": "Готово",
+  "status.readingFile": "Чтение файла...",
+  "status.saved": "Сохранено",
+  "error.chooseFile": "Сначала выберите файл",
+  "error.fileTooLarge": "Файл слишком велик для отправки из браузера",
+  "error.invalidReceiverUrl": "URL приёмника должен начинаться с http:// или https://",
+  "error.value": "Ошибка: {error}",
+  "context.sendPage": "Отправить страницу в Верстак",
+  "context.sendSelection": "Отправить выделение в Верстак",
+  "context.sendLink": "Отправить ссылку в Верстак"
+}

shared/popup/popup.css

@@ -126,6 +126,17 @@ input {
   color: #e5e7eb;
 }
 
+select {
+  box-sizing: border-box;
+  width: 100%;
+  margin-top: 5px;
+  border: 1px solid #374151;
+  border-radius: 4px;
+  padding: 7px 8px;
+  background: #0f172a;
+  color: #e5e7eb;
+}
+
 input[type="file"] {
   cursor: pointer;
   font-size: 12px;

shared/popup/popup.html

@@ -1,5 +1,5 @@
 <!doctype html>
-<html lang="ru">
+<html lang="en">
   <head>
     <meta charset="utf-8">
     <meta name="viewport" content="width=device-width, initial-scale=1">
@@ -17,15 +17,15 @@
 
       <section class="panel">
         <div class="row">
-          <span>Receiver</span>
+          <span id="receiver-label">Receiver</span>
           <strong id="receiver-state">Unknown</strong>
         </div>
         <div class="row">
-          <span>Pending</span>
+          <span id="pending-label">Pending</span>
           <strong id="pending-count">0</strong>
         </div>
         <div class="row url-row">
-          <span>URL</span>
+          <span id="url-label">URL</span>
           <code id="receiver-url"></code>
         </div>
       </section>
@@ -37,21 +37,28 @@
       </section>
 
       <section class="file-picker">
-        <label for="file-input">File</label>
+        <label id="file-label" for="file-input">File</label>
         <input id="file-input" type="file">
       </section>
 
       <section class="settings">
-        <label for="receiver-input">Receiver URL</label>
+        <label id="receiver-url-label" for="receiver-input">Receiver URL</label>
         <input id="receiver-input" type="url" spellcheck="false">
-        <label for="receiver-token-input">Pairing token</label>
+        <label id="receiver-token-label" for="receiver-token-input">Pairing token</label>
         <input id="receiver-token-input" type="password" spellcheck="false" autocomplete="off">
+        <label id="language-label" for="language-select">Language</label>
+        <select id="language-select">
+          <option id="language-system-option" value="system">System</option>
+          <option id="language-en-option" value="en">English</option>
+          <option id="language-ru-option" value="ru">Русский</option>
+        </select>
         <button id="save-settings" class="secondary">Save</button>
       </section>
 
-      <p class="hint">Selection and link captures are available from the page context menu.</p>
+      <p id="context-menu-hint" class="hint">Selection and link captures are available from the page context menu.</p>
       <p id="status"></p>
     </main>
+    <script src="../i18n.js"></script>
     <script src="popup.js"></script>
   </body>
 </html>

shared/popup/popup.js

@@ -2,16 +2,93 @@
   'use strict';
 
   var ext = typeof browser !== 'undefined' ? browser : chrome;
+  var i18n = globalThis.VerstakBrowserI18n;
   var statusEl = document.getElementById('status');
   var receiverStateEl = document.getElementById('receiver-state');
   var receiverUrlEl = document.getElementById('receiver-url');
   var receiverInputEl = document.getElementById('receiver-input');
   var receiverTokenInputEl = document.getElementById('receiver-token-input');
+  var languageSelectEl = document.getElementById('language-select');
   var fileInputEl = document.getElementById('file-input');
   var pendingCountEl = document.getElementById('pending-count');
   var statusDotEl = document.getElementById('status-dot');
   var MAX_FILE_TEXT_LENGTH = 2 * 1024 * 1024;
   var MAX_FILE_BYTES = 8 * 1024 * 1024;
+  var catalogs = { en: {}, ru: {} };
+  var currentPreference = 'system';
+  var currentState = {};
+  var t = i18n.createTranslator(catalogs, 'en');
+
+  var staticText = {
+    subtitle: 'popup.subtitle',
+    'receiver-label': 'label.receiver',
+    'pending-label': 'label.pending',
+    'url-label': 'label.url',
+    'file-label': 'label.file',
+    'receiver-url-label': 'label.receiverUrl',
+    'receiver-token-label': 'label.pairingToken',
+    'language-label': 'label.language',
+    'capture-page': 'action.sendPage',
+    'capture-file': 'action.sendFile',
+    retry: 'action.retryPending',
+    'save-settings': 'action.save',
+    'context-menu-hint': 'hint.contextMenu',
+    'language-system-option': 'language.system',
+    'language-en-option': 'language.en',
+    'language-ru-option': 'language.ru'
+  };
+
+  function browserLocale() {
+    try {
+      if (ext.i18n && ext.i18n.getUILanguage) return ext.i18n.getUILanguage();
+    } catch (_) {}
+    return typeof navigator !== 'undefined' ? navigator.language : 'en';
+  }
+
+  function loadCatalogs() {
+    return i18n.loadCatalogs(function (locale) {
+      return fetch(ext.runtime.getURL('locales/' + locale + '.json')).then(function (response) {
+        if (!response.ok) throw new Error('catalog load failed: ' + locale);
+        return response.json();
+      });
+    }).catch(function (error) {
+      console.warn('[verstak] localization catalogs unavailable:', error);
+      return { en: {}, ru: {} };
+    });
+  }
+
+  function applyReceiverState(state) {
+    var reachable = state && state.status && state.status.receiverReachable;
+    if (reachable === true) {
+      receiverStateEl.textContent = t('receiver.online', null, 'Online');
+      receiverStateEl.className = 'online';
+      statusDotEl.className = 'dot online';
+    } else if (reachable === false) {
+      receiverStateEl.textContent = t('receiver.offline', null, 'Offline');
+      receiverStateEl.className = 'offline';
+      statusDotEl.className = 'dot offline';
+    } else {
+      receiverStateEl.textContent = t('receiver.unknown', null, 'Unknown');
+      receiverStateEl.className = '';
+      statusDotEl.className = 'dot unknown';
+    }
+  }
+
+  function applyLocale(preference) {
+    currentPreference = i18n.normalizePreference(preference);
+    var locale = i18n.resolveLocale(currentPreference, browserLocale());
+    t = i18n.createTranslator(catalogs, locale);
+    document.documentElement.lang = locale;
+    languageSelectEl.value = currentPreference;
+    Object.keys(staticText).forEach(function (id) {
+      var element = document.getElementById(id);
+      if (element) {
+        if (element.__verstakI18nFallback == null) element.__verstakI18nFallback = element.textContent;
+        element.textContent = t(staticText[id], null, element.__verstakI18nFallback);
+      }
+    });
+    applyReceiverState(currentState);
+  }
 
   function arrayBufferToBase64(buffer) {
     var bytes = new Uint8Array(buffer);
@@ -42,48 +119,58 @@
   }
 
   function render(state) {
-    state = state || {};
-    var settings = state.settings || {};
-    var status = state.status || {};
-    var reachable = status.receiverReachable;
-    pendingCountEl.textContent = String(state.pendingCount || 0);
+    currentState = state || {};
+    var settings = currentState.settings || {};
+    pendingCountEl.textContent = String(currentState.pendingCount || 0);
     receiverUrlEl.textContent = settings.receiverUrl || '';
-    if (document.activeElement !== receiverInputEl) {
-      receiverInputEl.value = settings.receiverUrl || '';
-    }
-    if (document.activeElement !== receiverTokenInputEl) {
-      receiverTokenInputEl.value = settings.receiverToken || '';
-    }
-
-    if (reachable === true) {
-      receiverStateEl.textContent = 'Online';
-      receiverStateEl.className = 'online';
-      statusDotEl.className = 'dot online';
-    } else if (reachable === false) {
-      receiverStateEl.textContent = 'Offline';
-      receiverStateEl.className = 'offline';
-      statusDotEl.className = 'dot offline';
-    } else {
-      receiverStateEl.textContent = 'Unknown';
-      receiverStateEl.className = '';
-      statusDotEl.className = 'dot unknown';
-    }
+    if (document.activeElement !== receiverInputEl) receiverInputEl.value = settings.receiverUrl || '';
+    if (document.activeElement !== receiverTokenInputEl) receiverTokenInputEl.value = settings.receiverToken || '';
+    applyReceiverState(currentState);
   }
 
   function refresh() {
-    return request({ type: 'verstak.capture', action: 'getState' }).then(render).catch(function (err) {
-      setStatus(err && err.message ? err.message : String(err));
+    return request({ type: 'verstak.capture', action: 'getState' }).then(function (state) {
+      render(state);
+      applyLocale(state.settings && state.settings.language || 'system');
+      return state;
+    }).catch(function (error) {
+      setStatus(error && error.message ? error.message : String(error));
+    });
+  }
+
+  function currentSettings() {
+    return {
+      receiverUrl: receiverInputEl.value.trim(),
+      receiverToken: receiverTokenInputEl.value.trim(),
+      language: currentPreference
+    };
+  }
+
+  function saveCurrentSettings(successMessage) {
+    return request({
+      type: 'verstak.capture',
+      action: 'saveSettings',
+      settings: currentSettings()
+    }).then(function (state) {
+      render(state);
+      if (successMessage) setStatus(t('status.saved', null, 'Saved'));
+      return state;
+    }).catch(function (error) {
+      setStatus(error && error.message ? error.message : String(error));
     });
   }
 
   function send(message) {
-    setStatus('Sending...');
+    setStatus(t('status.sending', null, 'Sending...'));
     request(message).then(function (state) {
       render(state);
-      if (state.status && state.status.lastResult === 'queued') setStatus('Queued until Verstak is available');
-      else setStatus('Done');
-    }).catch(function (err) {
-      setStatus(err && err.message ? err.message : String(err));
+      if (state.status && state.status.lastResult === 'queued') {
+        setStatus(t('status.queued', null, 'Queued until Verstak is available'));
+      } else {
+        setStatus(t('status.done', null, 'Done'));
+      }
+    }).catch(function (error) {
+      setStatus(error && error.message ? error.message : String(error));
     });
   }
 
@@ -94,27 +181,26 @@
   document.getElementById('capture-file').addEventListener('click', function () {
     var file = fileInputEl.files && fileInputEl.files[0];
     if (!file) {
-      setStatus('Choose a text file first');
+      setStatus(t('error.chooseFile', null, 'Choose a file first'));
       return;
     }
     if (file.size > MAX_FILE_BYTES) {
-      setStatus('File is too large for browser capture');
+      setStatus(t('error.fileTooLarge', null, 'File is too large for browser capture'));
       return;
     }
-    setStatus('Reading file...');
+    setStatus(t('status.readingFile', null, 'Reading file...'));
     Promise.all([file.arrayBuffer(), readOptionalText(file)]).then(function (results) {
-      var content = results[1] || '';
       send({
         type: 'verstak.capture',
         kind: 'file',
         fileName: file.name,
         fileMime: file.type || '',
         fileSize: file.size,
-        fileText: content,
+        fileText: results[1] || '',
         fileDataBase64: arrayBufferToBase64(results[0])
       });
-    }).catch(function (err) {
-      setStatus(err && err.message ? err.message : String(err));
+    }).catch(function (error) {
+      setStatus(error && error.message ? error.message : String(error));
     });
   });
 
@@ -122,24 +208,22 @@
     send({ type: 'verstak.capture', action: 'retryPending' });
   });
 
-  document.getElementById('save-settings').addEventListener('click', function () {
-    var receiverUrl = receiverInputEl.value.trim();
-    var receiverToken = receiverTokenInputEl.value.trim();
-    if (!/^https?:\/\//.test(receiverUrl)) {
-      setStatus('Receiver URL must start with http:// or https://');
-      return;
-    }
-    request({
-      type: 'verstak.capture',
-      action: 'saveSettings',
-      settings: { receiverUrl: receiverUrl, receiverToken: receiverToken }
-    }).then(function (state) {
-      render(state);
-      setStatus('Saved');
-    }).catch(function (err) {
-      setStatus(err && err.message ? err.message : String(err));
-    });
+  languageSelectEl.addEventListener('change', function () {
+    applyLocale(languageSelectEl.value);
+    saveCurrentSettings(true);
   });
 
-  refresh();
+  document.getElementById('save-settings').addEventListener('click', function () {
+    if (!/^https?:\/\//.test(receiverInputEl.value.trim())) {
+      setStatus(t('error.invalidReceiverUrl', null, 'Receiver URL must start with http:// or https://'));
+      return;
+    }
+    saveCurrentSettings(true);
+  });
+
+  loadCatalogs().then(function (loadedCatalogs) {
+    catalogs = loadedCatalogs;
+    applyLocale('system');
+    return refresh();
+  });
 })();