diff --git a/.github/workflows/checks.yml b/.github/workflows/checks.yml
new file mode 100644
index 0000000..89f88a4
--- /dev/null
+++ b/.github/workflows/checks.yml
@@ -0,0 +1,36 @@
+name: Checks
+
+on:
+  pull_request:
+  push:
+    branches: [main]
+
+jobs:
+  lint-format:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: '20'
+          cache: 'npm'
+      - run: npm ci || npm install
+      - run: npm run lint
+      - run: npm run format
+
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: '20'
+      - run: npm install --no-save
+      - name: Build extension zip
+        run: npm run package
+      - name: Upload artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: tweai-extension
+          path: tweai-v*.zip
+          retention-days: 14
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
new file mode 100644
index 0000000..dbecd27
--- /dev/null
+++ b/.github/workflows/release.yml
@@ -0,0 +1,35 @@
+name: Release
+
+on:
+  push:
+    tags:
+      - 'v*'
+
+permissions:
+  contents: write
+
+jobs:
+  release:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: '20'
+      - run: npm install --no-save
+      - name: Build extension zip
+        run: npm run package
+      - name: Capture zip path
+        id: zip
+        run: |
+          ZIP=$(ls tweai-v*.zip | head -1)
+          echo "path=$ZIP" >> "$GITHUB_OUTPUT"
+          echo "name=$(basename "$ZIP")" >> "$GITHUB_OUTPUT"
+      - name: Create GitHub release
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          TAG="${GITHUB_REF#refs/tags/}"
+          gh release create "$TAG" "${{ steps.zip.outputs.path }}" \
+            --title "$TAG" \
+            --generate-notes
diff --git a/.gitignore b/.gitignore
index 29ff4b5..4b88d34 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,9 @@
 node_modules/
 env.json
+
+# Build artifacts
+dist/
+*.zip
+
+# Tooling
+.eslintcache
diff --git a/.prettierignore b/.prettierignore
new file mode 100644
index 0000000..22c4b2d
--- /dev/null
+++ b/.prettierignore
@@ -0,0 +1,8 @@
+node_modules
+dist
+*.zip
+docs
+tweai-mcp-server
+_locales
+LICENSE
+.git
diff --git a/.prettierrc.json b/.prettierrc.json
new file mode 100644
index 0000000..8fd548f
--- /dev/null
+++ b/.prettierrc.json
@@ -0,0 +1,9 @@
+{
+  "semi": true,
+  "singleQuote": true,
+  "trailingComma": "all",
+  "printWidth": 100,
+  "tabWidth": 2,
+  "arrowParens": "avoid",
+  "endOfLine": "lf"
+}
diff --git a/eslint.config.js b/eslint.config.js
new file mode 100644
index 0000000..bccea90
--- /dev/null
+++ b/eslint.config.js
@@ -0,0 +1,94 @@
+// Flat config for ESLint 9.x. WebExtensions globals + browser env.
+// Намеренно мягкие правила: цель — поймать опечатки и явные баги, не переписать
+// весь codebase. Style-issues идут через prettier.
+
+export default [
+  {
+    ignores: [
+      'node_modules/**',
+      'dist/**',
+      '*.zip',
+      'tweai-mcp-server/**',
+      'docs/**',
+      '_locales/**',
+    ],
+  },
+  {
+    files: ['**/*.js', '**/*.mjs'],
+    languageOptions: {
+      ecmaVersion: 2022,
+      sourceType: 'script',
+      globals: {
+        // WebExtensions
+        chrome: 'readonly',
+        browser: 'readonly',
+        // Browser
+        window: 'readonly',
+        document: 'readonly',
+        navigation: 'readonly',
+        location: 'readonly',
+        localStorage: 'readonly',
+        history: 'readonly',
+        console: 'readonly',
+        fetch: 'readonly',
+        URL: 'readonly',
+        URLSearchParams: 'readonly',
+        setTimeout: 'readonly',
+        clearTimeout: 'readonly',
+        setInterval: 'readonly',
+        clearInterval: 'readonly',
+        Promise: 'readonly',
+        Map: 'readonly',
+        Set: 'readonly',
+        Boolean: 'readonly',
+        Number: 'readonly',
+        String: 'readonly',
+        Object: 'readonly',
+        Array: 'readonly',
+        Math: 'readonly',
+        Date: 'readonly',
+        JSON: 'readonly',
+        RegExp: 'readonly',
+        Error: 'readonly',
+        AbortController: 'readonly',
+        AbortSignal: 'readonly',
+        MutationObserver: 'readonly',
+        IntersectionObserver: 'readonly',
+        InputEvent: 'readonly',
+        Event: 'readonly',
+        CustomEvent: 'readonly',
+        HTMLElement: 'readonly',
+        Element: 'readonly',
+        Node: 'readonly',
+        getComputedStyle: 'readonly',
+        requestAnimationFrame: 'readonly',
+        addEventListener: 'readonly',
+        // own globals (shared between content scripts in same isolated world)
+        TTASelectors: 'writable',
+        TTALogger: 'writable',
+      },
+    },
+    rules: {
+      'no-undef': 'error',
+      'no-unused-vars': ['warn', { args: 'none', varsIgnorePattern: '^_' }],
+      'no-constant-condition': ['error', { checkLoops: false }],
+      'no-empty': ['error', { allowEmptyCatch: true }],
+      'no-prototype-builtins': 'off',
+      'no-cond-assign': ['error', 'except-parens'],
+      'no-control-regex': 'off',
+      'no-useless-escape': 'warn',
+    },
+  },
+  {
+    // Build/tools — Node environment
+    files: ['tools/**/*.mjs', '*.mjs'],
+    languageOptions: {
+      sourceType: 'module',
+      globals: {
+        process: 'readonly',
+        console: 'readonly',
+        URL: 'readonly',
+      },
+    },
+  },
+];
diff --git a/package.json b/package.json
new file mode 100644
index 0000000..0154665
--- /dev/null
+++ b/package.json
@@ -0,0 +1,20 @@
+{
+  "name": "tweai",
+  "version": "1.8.1",
+  "private": true,
+  "description": "TweAI — AI Reply Assistant for X / Twitter. Chrome extension.",
+  "license": "Apache-2.0",
+  "type": "module",
+  "scripts": {
+    "lint": "eslint .",
+    "lint:fix": "eslint . --fix",
+    "format": "prettier --check .",
+    "format:fix": "prettier --write .",
+    "package": "node tools/build.mjs",
+    "check": "npm run lint && npm run format"
+  },
+  "devDependencies": {
+    "eslint": "^9.0.0",
+    "prettier": "^3.0.0"
+  }
+}
diff --git a/tools/build.mjs b/tools/build.mjs
new file mode 100644
index 0000000..696dade
--- /dev/null
+++ b/tools/build.mjs
@@ -0,0 +1,94 @@
+#!/usr/bin/env node
+// Сборка артефакта расширения для Chrome Web Store.
+//
+// Текущее состояние: vanilla content scripts без bundler — просто копируем
+// рантайм-файлы в dist/, исключая node-репку MCP-сервера, docs, dev-файлы.
+// Когда (если) перейдём на ESM-модули в options/ — этот же скрипт будет
+// запускать esbuild перед копированием.
+//
+// Использование:
+//   node tools/build.mjs           # → dist/ + tweai-v<version>.zip
+//   node tools/build.mjs --no-zip  # только dist/
+
+import { readFile, rm, mkdir, cp, readdir, stat } from 'node:fs/promises';
+import { spawn } from 'node:child_process';
+import { join, dirname } from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const __dirname = dirname(fileURLToPath(import.meta.url));
+const ROOT = join(__dirname, '..');
+const DIST = join(ROOT, 'dist');
+
+const INCLUDE = [
+  'manifest.json',
+  'background.js',
+  'content_script.js',
+  'selectors.js',
+  'dev-logger.js',
+  'ad-blocker.js',
+  'profile-scraper.js',
+  'options.html',
+  'options.js',
+  'options.css',
+  'styles.css',
+  'icons',
+  '_locales',
+  'LICENSE',
+];
+
+async function readVersion() {
+  const m = JSON.parse(await readFile(join(ROOT, 'manifest.json'), 'utf8'));
+  return m.version;
+}
+
+async function copyTree(src, dst) {
+  await cp(src, dst, { recursive: true });
+}
+
+async function zipDir(srcDir, outZip) {
+  // Используем системный `zip` — он есть на macOS/Linux и GitHub Actions
+  // runner. Без extra deps: добавлять JS-zip-библиотеку ради одной операции
+  // не стоит.
+  await new Promise((resolve, reject) => {
+    const proc = spawn('zip', ['-r', outZip, '.'], { cwd: srcDir, stdio: 'inherit' });
+    proc.on('exit', code => (code === 0 ? resolve() : reject(new Error(`zip exit ${code}`))));
+    proc.on('error', reject);
+  });
+}
+
+async function main() {
+  const version = await readVersion();
+  const wantZip = !process.argv.includes('--no-zip');
+
+  await rm(DIST, { recursive: true, force: true });
+  await mkdir(DIST, { recursive: true });
+
+  for (const name of INCLUDE) {
+    const src = join(ROOT, name);
+    const dst = join(DIST, name);
+    try {
+      await stat(src);
+    } catch {
+      console.warn(`[build] skip missing: ${name}`);
+      continue;
+    }
+    await copyTree(src, dst);
+  }
+
+  console.log(`[build] dist/ ready — version ${version}`);
+  const entries = await readdir(DIST);
+  console.log(`[build] ${entries.length} top-level entries`);
+
+  if (wantZip) {
+    const zipPath = join(ROOT, `tweai-v${version}.zip`);
+    await rm(zipPath, { force: true });
+    await zipDir(DIST, zipPath);
+    const s = await stat(zipPath);
+    console.log(`[build] wrote ${zipPath} (${(s.size / 1024).toFixed(1)} KB)`);
+  }
+}
+
+main().catch(e => {
+  console.error('[build] failed:', e);
+  process.exit(1);
+});