feat: Separate preview server from react-email

.changeset/pre.json

@@ -35,7 +35,6 @@
   },
   "changesets": [
     "crazy-seas-eat",
-    "dirty-needles-chew",
     "great-parrots-yell",
     "mighty-pigs-add",
     "stupid-ghosts-decide",

.changeset/puny-chicken-argue.md

@@ -0,0 +1,5 @@
+---
+"react-email": minor
+---
+
+use a separate package for storing the preview server (@react-email/preview-server)

apps/demo/package.json

@@ -3,7 +3,7 @@
   "version": "0.0.0",
   "private": true,
   "scripts": {
-    "build": "email build",
+    "build": "pnpm install --frozen-lockfile && email build",
     "dev": "email dev",
     "start": "email start",
     "export": "email export"
@@ -15,7 +15,8 @@
     "react-email": "workspace:*"
   },
   "devDependencies": {
-    "next": "15.3.1",
+    "@react-email/preview-server": "workspace:*",
+    "next": "^15.2.4",
     "@types/react": "^19",
     "@types/react-dom": "^19",
     "tsx": "4.19.3"

biome.json

@@ -87,7 +87,7 @@
       "!**/pnpm-lock.yaml",
       "!**/.next",
       "!**/public",
-      "!packages/react-email/src/actions/email-validation/caniemail-data.ts",
+      "!packages/preview-server/src/actions/email-validation/caniemail-data.ts",
       "!**/.react-email/**/*",
       "!**/node_modules/**/*",
       "!**/*.d.ts",

packages/preview-server/.gitignore

@@ -0,0 +1,5 @@
+node_modules
+.next
+
+# for testing
+static

packages/preview-server/.npmignore

@@ -0,0 +1,5 @@
+.react-email
+./emails
+./emails/static
+node_modules
+.turbo

packages/preview-server/_index.js

@@ -0,0 +1,4 @@
+/**
+ * this file is just a placeholder file so that import.meta.resolve and require.resolve can properly
+ * find out the path to this module. This file does not do anything nor does it need to export anything of value.
+ */

packages/preview-server/license.md

@@ -0,0 +1,7 @@
+Copyright 2024 Plus Five Five, Inc
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

packages/preview-server/package.json

@@ -0,0 +1,82 @@
+{
+  "name": "@react-email/preview-server",
+  "version": "1.0.0-canary.0",
+  "description": "A live preview of your emails right in your browser.",
+  "scripts": {
+    "caniemail:fetch": "node ./scripts/fill-caniemail-data.mjs",
+    "clean": "rm -rf dist",
+    "build": "node ./scripts/build-preview-server.mjs",
+    "test": "vitest run",
+    "test:watch": "vitest"
+  },
+  "main": "./_index.js",
+  "dependencies": {
+    "@babel/core": "7.26.10",
+    "@babel/parser": "^7.27.0",
+    "@babel/traverse": "^7.27.0",
+    "@lottiefiles/dotlottie-react": "0.13.3",
+    "@radix-ui/colors": "3.0.0",
+    "@radix-ui/react-collapsible": "1.1.7",
+    "@radix-ui/react-dropdown-menu": "2.1.10",
+    "@radix-ui/react-popover": "1.1.10",
+    "@radix-ui/react-slot": "1.2.0",
+    "@radix-ui/react-tabs": "1.1.7",
+    "@radix-ui/react-toggle-group": "1.1.6",
+    "@radix-ui/react-tooltip": "1.2.3",
+    "@types/node": "22.14.1",
+    "@types/normalize-path": "3.0.2",
+    "@types/react": "19.0.10",
+    "@types/react-dom": "19.0.4",
+    "@types/webpack": "5.28.5",
+    "autoprefixer": "10.4.21",
+    "chalk": "^4.1.2",
+    "clsx": "2.1.1",
+    "esbuild": "^0.25.0",
+    "framer-motion": "12.7.5",
+    "json5": "2.2.3",
+    "log-symbols": "^4.1.0",
+    "module-punycode": "npm:[email protected]",
+    "next": "^15.2.4",
+    "node-html-parser": "7.0.1",
+    "ora": "^5.4.1",
+    "pretty-bytes": "6.1.1",
+    "prism-react-renderer": "2.4.1",
+    "react": "19.0.0",
+    "react-dom": "19.0.0",
+    "sharp": "0.34.1",
+    "socket.io-client": "4.8.1",
+    "sonner": "2.0.3",
+    "source-map-js": "1.2.1",
+    "spamc": "0.0.5",
+    "stacktrace-parser": "0.1.11",
+    "tailwind-merge": "3.2.0",
+    "tailwindcss": "3.4.0",
+    "use-debounce": "10.0.4",
+    "zod": "3.24.3"
+  },
+  "devDependencies": {
+    "@react-email/components": "workspace:*",
+    "@types/babel__core": "7.20.5",
+    "@types/babel__traverse": "7.20.7",
+    "@types/fs-extra": "11.0.1",
+    "@types/mime-types": "2.1.4",
+    "@types/node": "22.10.2",
+    "@types/normalize-path": "3.0.2",
+    "@types/react": "19.0.10",
+    "@types/react-dom": "19.0.4",
+    "@types/webpack": "5.28.5",
+    "autoprefixer": "10.4.21",
+    "postcss": "8.5.3",
+    "tailwindcss": "3.4.0",
+    "typescript": "5.8.3"
+  },
+  "license": "MIT",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/resend/react-email.git",
+    "directory": "packages/preview-server"
+  },
+  "publishConfig": {
+    "access": "public"
+  }
+}

packages/preview-server/scripts/build-preview-server.mjs

@@ -0,0 +1,29 @@
+import { spawn } from 'node:child_process';
+import fs from 'node:fs';
+import path from 'node:path';
+import url from 'node:url';
+
+const filename = url.fileURLToPath(import.meta.url);
+const dirname = path.dirname(filename);
+
+const nextBuildProcess = spawn('pnpm', ['next', 'build'], {
+  detached: true,
+  shell: true,
+  stdio: 'inherit',
+  cwd: path.resolve(dirname, '../'),
+});
+
+process.on('SIGINT', () => {
+  nextBuildProcess.kill('SIGINT');
+});
+
+nextBuildProcess.on('exit', (code) => {
+  if (code !== 0) {
+    console.error(`next build failed with exit code ${code}`);
+    process.exit(code);
+  }
+
+  fs.rmSync(path.resolve(dirname, '../.next/cache'), {
+    recursive: true,
+  });
+});

packages/preview-server/src/utils/esbuild/escape-string-for-regex.ts

@@ -0,0 +1,3 @@
+export function escapeStringForRegex(string: string) {
+  return string.replace(/[|\\{}()[\]^$+*?.]/g, '\\$&').replace(/-/g, '\\x2d');
+}

packages/preview-server/src/utils/esbuild/renderring-utilities-exporter.ts

@@ -0,0 +1,63 @@
+import { promises as fs } from 'node:fs';
+import path from 'node:path';
+import type { Loader, PluginBuild, ResolveOptions } from 'esbuild';
+import { escapeStringForRegex } from './escape-string-for-regex';
+
+/**
+ * Made to export the `render` function out of the user's email template
+ * so that issues like https://github.com/resend/react-email/issues/649 don't
+ * happen.
+ *
+ * This also exports the `createElement` from the user's React version as well
+ * to avoid mismatches.
+ *
+ * This avoids multiple versions of React being involved, i.e., the version
+ * in the CLI vs. the version the user has on their emails.
+ */
+export const renderingUtilitiesExporter = (emailTemplates: string[]) => ({
+  name: 'rendering-utilities-exporter',
+  setup: (b: PluginBuild) => {
+    b.onLoad(
+      {
+        filter: new RegExp(
+          emailTemplates
+            .map((emailPath) => escapeStringForRegex(emailPath))
+            .join('|'),
+        ),
+      },
+      async ({ path: pathToFile }) => {
+        return {
+          contents: `${await fs.readFile(pathToFile, 'utf8')};
+          export { render } from 'react-email-module-that-will-export-render'
+          export { createElement as reactEmailCreateReactElement } from 'react';
+        `,
+          loader: path.extname(pathToFile).slice(1) as Loader,
+        };
+      },
+    );
+
+    b.onResolve(
+      { filter: /^react-email-module-that-will-export-render$/ },
+      async (args) => {
+        const options: ResolveOptions = {
+          kind: 'import-statement',
+          importer: args.importer,
+          resolveDir: args.resolveDir,
+          namespace: args.namespace,
+        };
+        let result = await b.resolve('@react-email/render', options);
+        if (result.errors.length === 0) {
+          return result;
+        }
+
+        // If @react-email/render does not exist, resolve to @react-email/components
+        result = await b.resolve('@react-email/components', options);
+        if (result.errors.length > 0 && result.errors[0]) {
+          result.errors[0].text =
+            "Failed trying to import `render` from either `@react-email/render` or `@react-email/components` to be able to render your email template.\n Maybe you don't have either of them installed?";
+        }
+        return result;
+      },
+    );
+  },
+});

packages/preview-server/src/utils/get-emails-directory-metadata.spec.ts

@@ -0,0 +1,82 @@
+import path from 'node:path';
+import { getEmailsDirectoryMetadata } from './get-emails-directory-metadata';
+
+test('getEmailsDirectoryMetadata on demo emails', async () => {
+  const emailsDirectoryPath = path.resolve(
+    __dirname,
+    '../../../../apps/demo/emails',
+  );
+  expect(await getEmailsDirectoryMetadata(emailsDirectoryPath)).toEqual({
+    absolutePath: emailsDirectoryPath,
+    directoryName: 'emails',
+    relativePath: '',
+    emailFilenames: [],
+    subDirectories: [
+      {
+        absolutePath: `${emailsDirectoryPath}/magic-links`,
+        directoryName: 'magic-links',
+        relativePath: 'magic-links',
+        emailFilenames: [
+          'aws-verify-email',
+          'linear-login-code',
+          'notion-magic-link',
+          'plaid-verify-identity',
+          'raycast-magic-link',
+          'slack-confirm',
+        ],
+        subDirectories: [],
+      },
+      {
+        absolutePath: `${emailsDirectoryPath}/newsletters`,
+        directoryName: 'newsletters',
+        relativePath: 'newsletters',
+        emailFilenames: [
+          'codepen-challengers',
+          'google-play-policy-update',
+          'stack-overflow-tips',
+        ],
+        subDirectories: [],
+      },
+      {
+        absolutePath: `${emailsDirectoryPath}/notifications`,
+        directoryName: 'notifications',
+        relativePath: 'notifications',
+        emailFilenames: [
+          'github-access-token',
+          'papermark-year-in-review',
+          'vercel-invite-user',
+          'yelp-recent-login',
+        ],
+        subDirectories: [],
+      },
+      {
+        absolutePath: `${emailsDirectoryPath}/receipts`,
+        directoryName: 'receipts',
+        relativePath: 'receipts',
+        emailFilenames: ['apple-receipt', 'nike-receipt'],
+        subDirectories: [],
+      },
+      {
+        absolutePath: `${emailsDirectoryPath}/reset-password`,
+        directoryName: 'reset-password',
+        relativePath: 'reset-password',
+        emailFilenames: ['dropbox-reset-password', 'twitch-reset-password'],
+        subDirectories: [],
+      },
+      {
+        absolutePath: `${emailsDirectoryPath}/reviews`,
+        directoryName: 'reviews',
+        relativePath: 'reviews',
+        emailFilenames: ['airbnb-review', 'amazon-review'],
+        subDirectories: [],
+      },
+      {
+        absolutePath: `${emailsDirectoryPath}/welcome`,
+        directoryName: 'welcome',
+        relativePath: 'welcome',
+        emailFilenames: ['koala-welcome', 'netlify-welcome', 'stripe-welcome'],
+        subDirectories: [],
+      },
+    ],
+  });
+});