Improve Lighthouse Scrore

.github/actions/setup_build_env/action.yml

@@ -14,6 +14,10 @@ inputs:
   python-version:
     description: "Python version setup"
     required: true
+  node-version:
+    description: "Node.js version setup"
+    required: false
+    default: "22"
   run-uv-sync:
     description: "Whether to run uv sync on current dir"
     required: false
@@ -37,7 +41,7 @@ runs:
     - name: Setup Node
       uses: actions/setup-node@v4
       with:
-        node-version: 22
+        node-version: ${{ inputs.node-version }}
     - name: Install Dependencies
       if: inputs.run-uv-sync == 'true'
       run: uv sync

.github/workflows/performance.yml

@@ -44,3 +44,37 @@ jobs:
         with:
           mode: instrumentation
           run: uv run pytest -v tests/benchmarks --codspeed
+
+  lighthouse:
+    name: Run Lighthouse benchmark
+    runs-on: ubuntu-22.04
+    timeout-minutes: 30
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-tags: true
+          fetch-depth: 0
+
+      - uses: ./.github/actions/setup_build_env
+        with:
+          python-version: "3.14"
+          node-version: "22"
+          run-uv-sync: true
+
+      - name: Install playwright
+        run: uv run playwright install chromium --only-shell
+
+      - name: Run Lighthouse benchmark
+        env:
+          REFLEX_RUN_LIGHTHOUSE: "1"
+        run: |
+          mkdir -p .pytest-tmp/lighthouse
+          uv run pytest tests/integration/test_lighthouse.py -q -s --tb=no --basetemp=.pytest-tmp/lighthouse
+
+      - name: Upload Lighthouse artifacts
+        if: always()
+        uses: actions/upload-artifact@v4
+        with:
+          name: lighthouse-report
+          path: .pytest-tmp/lighthouse
+          if-no-files-found: ignore

docs/getting_started/project-structure.md

@@ -60,6 +60,8 @@ Initializing your project creates a directory with the same name as your app. Th
 
 Reflex generates a default app within the `hello/hello.py` file. You can modify this file to customize your app.
 
+The starter page also includes explicit page metadata. As you customize the app, update the page `title` and `description` in `app.add_page(...)` or `@rx.page(...)` so your production pages describe your project clearly.
+
 ## Python Project Files
 
 `pyproject.toml` defines your Python project metadata and dependencies. `uv add reflex` records the Reflex dependency there before you initialize the app.

docs/hosting/self-hosting.md

@@ -67,6 +67,53 @@ the backend (event handlers) will be listening on port `8000`.
 Because the backend uses websockets, some reverse proxy servers, like [nginx](https://nginx.org/en/docs/http/websocket.html) or [apache](https://httpd.apache.org/docs/2.4/mod/mod_proxy.html#protoupgrade), must be configured to pass the `Upgrade` header to allow backend connectivity.
 ```
 
+## Pre-compressed Frontend Assets
+
+Production builds generate pre-compressed frontend assets so they can be served
+without compressing responses on the fly. By default Reflex emits `gzip`
+sidecars. You can also opt into Brotli and Zstandard in `rxconfig.py`:
+
+```python
+config = rx.Config(
+    app_name="your_app_name",
+    frontend_compression_formats=["gzip", "brotli", "zstd"],
+)
+```
+
+When Reflex serves the compiled frontend itself, it will negotiate
+`Accept-Encoding` and serve matching sidecar files directly. If you would rather
+have your reverse proxy handle compression itself, set
+`frontend_compression_formats=[]` to disable build-time pre-compression.
+
+If you are serving `.web/build/client` from a reverse proxy, enable its
+precompressed-file support:
+
+### Caddy
+
+```caddy
+example.com {
+    root * /srv/your-app/.web/build/client
+    try_files {path} /404.html
+    file_server {
+        precompressed zstd br gzip
+    }
+}
+```
+
+### Nginx
+
+```nginx
+location / {
+    root /srv/your-app/.web/build/client;
+    try_files $uri $uri/ /404.html;
+    gzip_static on;
+}
+```
+
+Nginx supports prebuilt `gzip` files directly. If you also want Brotli or Zstd
+at the proxy layer, use the corresponding Nginx modules or handle compression
+at a CDN/load-balancer layer instead.
+
 ## Exporting a Static Build
 
 Exporting a static build of the frontend allows the app to be served using a

docs/pages/overview.md

@@ -45,6 +45,26 @@ In this example we create three pages:
 # Video: Pages and URL Routes
 ```
 
+## Page Structure and Accessibility
+
+For better accessibility and Lighthouse scores, wrap your page content in an `rx.el.main` element. This provides the `<main>` HTML landmark that screen readers and search engines use to identify the primary content of the page.
+
+```python
+def index():
+    return rx.el.main(
+        navbar(),
+        rx.container(
+            rx.heading("Welcome"),
+            rx.text("Page content here."),
+        ),
+        footer(),
+    )
+```
+
+```md alert
+# Every page should have exactly one `<main>` landmark. Without it, accessibility tools like Lighthouse will flag the "Document does not have a main landmark" audit.
+```
+
 ## Page Decorator
 
 You can also use the `@rx.page` decorator to add a page.
@@ -200,6 +220,8 @@ meta = [
 app = rx.App()
 ```
 
+For production apps, set `title` and `description` explicitly on each public page with `@rx.page(...)` or `app.add_page(...)`. Reflex will use what you provide there, so it is best to treat page metadata as part of the page definition rather than something to fill in later.
+
 ## Getting the Current Page
 
 You can access the current page from the `router` attribute in any state. See the [router docs](/docs/utility-methods/router-attributes) for all available attributes.

packages/reflex-base/src/reflex_base/.templates/apps/blank/code/blank.py

@@ -11,26 +11,37 @@ class State(rx.State):
 
 def index() -> rx.Component:
     # Welcome Page (Index)
-    return rx.container(
-        rx.color_mode.button(position="top-right"),
-        rx.vstack(
-            rx.heading("Welcome to Reflex!", size="9"),
-            rx.text(
-                "Get started by editing ",
-                rx.code(f"{config.app_name}/{config.app_name}.py"),
-                size="5",
+    return rx.el.main(
+        rx.container(
+            rx.color_mode.button(position="top-right"),
+            rx.vstack(
+                rx.heading("Welcome to Reflex!", size="9"),
+                rx.text(
+                    "Get started by editing ",
+                    rx.code(f"{config.app_name}/{config.app_name}.py"),
+                    size="5",
+                ),
+                rx.button(
+                    rx.link(
+                        "Check out our docs!",
+                        href="https://reflex.dev/docs/getting-started/introduction/",
+                        is_external=True,
+                        underline="none",
+                    ),
+                    as_child=True,
+                    high_contrast=True,
+                ),
+                spacing="5",
+                justify="center",
+                min_height="85vh",
             ),
-            rx.link(
-                rx.button("Check out our docs!"),
-                href="https://reflex.dev/docs/getting-started/introduction/",
-                is_external=True,
-            ),
-            spacing="5",
-            justify="center",
-            min_height="85vh",
         ),
     )
 
 
 app = rx.App()
-app.add_page(index)
+app.add_page(
+    index,
+    title="Welcome to Reflex",
+    description="A starter Reflex app.",
+)

packages/reflex-base/src/reflex_base/.templates/web/compress-static.js

@@ -0,0 +1,9 @@
+import { compressDirectory } from "./vite-plugin-compress.js";
+
+const [directory, formatsArg = "[]"] = process.argv.slice(2);
+
+if (!directory) {
+  throw new Error("Missing static output directory for compression.");
+}
+
+await compressDirectory(directory, JSON.parse(formatsArg));

packages/reflex-base/src/reflex_base/.templates/web/utils/helpers/upload.js

@@ -1,4 +1,3 @@
-import JSON5 from "json5";
 import env from "$/env.json";
 
 /**
@@ -45,7 +44,7 @@ export const uploadFiles = async (
     // So only process _new_ chunks beyond resp_idx.
     chunks.slice(resp_idx).map((chunk_json) => {
       try {
-        const chunk = JSON5.parse(chunk_json);
+        const chunk = JSON.parse(chunk_json);
         event_callbacks.map((f, ix) => {
           f(chunk)
             .then(() => {

packages/reflex-base/src/reflex_base/.templates/web/vite-plugin-compress.js

@@ -0,0 +1,139 @@
+/* vite-plugin-compress.js
+ *
+ * Generate pre-compressed build assets so they can be served directly by
+ * production static file servers and reverse proxies without on-the-fly
+ * compression. The default format is gzip, with optional brotli and zstd.
+ */
+
+import * as zlib from "node:zlib";
+import { dirname } from "node:path";
+import { access, readFile, writeFile } from "node:fs/promises";
+import { promisify } from "node:util";
+import {
+  validateFormats,
+  outputDirectoryExists,
+  walkFiles,
+} from "./vite-plugin-utils.js";
+
+const gzipAsync = promisify(zlib.gzip);
+const brotliAsync =
+  typeof zlib.brotliCompress === "function"
+    ? promisify(zlib.brotliCompress)
+    : null;
+const zstdAsync =
+  typeof zlib.zstdCompress === "function" ? promisify(zlib.zstdCompress) : null;
+
+const COMPRESSIBLE_EXTENSIONS = /\.(js|css|html|json|svg|xml|txt|map|mjs)$/;
+
+// Only compress files above this size (bytes). Tiny assets rarely benefit,
+// but HTML entrypoints are always compressed so their negotiated sidecars exist.
+const MIN_SIZE = 256;
+
+const COMPRESSORS = {
+  gzip: {
+    extension: ".gz",
+    compress: (raw) => gzipAsync(raw, { level: 9 }),
+  },
+  brotli: brotliAsync && {
+    extension: ".br",
+    compress: (raw) =>
+      brotliAsync(raw, {
+        params: {
+          [zlib.constants.BROTLI_PARAM_QUALITY]:
+            zlib.constants.BROTLI_MAX_QUALITY ?? 11,
+        },
+      }),
+  },
+  zstd: zstdAsync && {
+    extension: ".zst",
+    compress: (raw) => zstdAsync(raw),
+  },
+};
+
+// Concurrency limit for parallel file compression.
+const CONCURRENCY = 16;
+
+function ensureFormatsSupported(formats) {
+  const unavailableFormats = formats.filter(
+    (format) => !COMPRESSORS[format]?.compress,
+  );
+  if (unavailableFormats.length > 0) {
+    throw new Error(
+      `The configured frontend compression formats are not supported by this Node.js runtime: ${unavailableFormats.join(", ")}`,
+    );
+  }
+}
+
+async function compressFile(filePath, formats) {
+  const pendingFormats = [];
+  for (const format of formats) {
+    const compressor = COMPRESSORS[format];
+    try {
+      await access(filePath + compressor.extension);
+    } catch {
+      pendingFormats.push([format, compressor]);
+    }
+  }
+
+  if (pendingFormats.length === 0) return;
+
+  const raw = await readFile(filePath);
+  if (raw.length < MIN_SIZE && !filePath.endsWith(".html")) return;
+
+  await Promise.all(
+    pendingFormats.map(([_format, compressor]) => {
+      return compressor
+        .compress(raw)
+        .then((compressed) =>
+          writeFile(filePath + compressor.extension, compressed),
+        );
+    }),
+  );
+}
+
+export async function compressDirectory(directory, formats = ["gzip"]) {
+  validateFormats(formats, COMPRESSORS, "frontend compression format");
+  ensureFormatsSupported(formats);
+
+  if (!(await outputDirectoryExists(directory))) {
+    return;
+  }
+
+  const pending = [];
+  for await (const filePath of walkFiles(directory)) {
+    if (!COMPRESSIBLE_EXTENSIONS.test(filePath)) continue;
+    pending.push(filePath);
+  }
+
+  for (let i = 0; i < pending.length; i += CONCURRENCY) {
+    await Promise.all(
+      pending
+        .slice(i, i + CONCURRENCY)
+        .map((file) => compressFile(file, formats)),
+    );
+  }
+}
+
+/**
+ * Vite plugin that generates pre-compressed files for eligible build assets.
+ * @param {{ formats?: string[] }} [options]
+ * @returns {import('vite').Plugin}
+ */
+export default function compressPlugin(options = {}) {
+  const formats = options.formats ?? ["gzip"];
+  validateFormats(formats, COMPRESSORS, "frontend compression format");
+
+  return {
+    name: "vite-plugin-compress",
+    apply: "build",
+    enforce: "post",
+
+    async writeBundle(outputOptions) {
+      const outputDir =
+        outputOptions.dir ??
+        (outputOptions.file ? dirname(outputOptions.file) : null);
+      if (!outputDir) return;
+      await compressDirectory(outputDir, formats);
+    },
+  };
+}