diff --git a/AGENTS.md b/AGENTS.md
index 63231a67..8ef52016 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -175,7 +175,7 @@ This project uses [Portless](https://github.com/vercel-labs/portless) for local
 
 To bypass Portless: `PORTLESS=0 yarn start`
 
-Android phone over USB (Chrome on device → dev server via `adb reverse`): `yarn start:android-usb`
+Android phone over USB (default browser opens via `adb`; `ANDROID_USB_OPEN_BROWSER=0` to skip): `yarn start:android-usb`
 
 ## Common Commands
 
diff --git a/README.md b/README.md
index ae110201..81d22bf1 100644
--- a/README.md
+++ b/README.md
@@ -108,7 +108,7 @@ The dev server runs at http://5chan.localhost:1355 via [Portless](https://port13
 
 For device testing on a USB-connected Android phone (without relying on `5chan.localhost` DNS from the device):
 
-- `yarn start:android-usb` starts Vite bound to `127.0.0.1` and runs `adb reverse`, so the phone can load the dev site at `http://localhost:1355` in Chrome (or another browser). Requires [Android platform-tools](https://developer.android.com/tools/releases/platform-tools) (`adb` on your `PATH`), USB debugging enabled, and the device showing as `device` in `adb devices`.
+- `yarn start:android-usb` starts Vite bound to `127.0.0.1` and runs `adb reverse`, so the phone can load the dev site at `http://localhost:1355`. When the server is up, it opens that URL in each connected device’s default browser via `adb`. Set `ANDROID_USB_OPEN_BROWSER=0` to skip auto-open. Requires [Android platform-tools](https://developer.android.com/tools/releases/platform-tools) (`adb` on your `PATH`), USB debugging enabled, and the device showing as `device` in `adb devices`.
 
 ### Scripts
 
diff --git a/scripts/AGENTS.md b/scripts/AGENTS.md
index e63ee26b..b929d452 100644
--- a/scripts/AGENTS.md
+++ b/scripts/AGENTS.md
@@ -4,7 +4,7 @@ These rules apply to `scripts/**`. Follow the repo-root `AGENTS.md` first, then
 
 - Keep scripts non-interactive and idempotent. Print the command, URL, branch, or path being acted on so failures are diagnosable.
 - Use repo-relative paths and environment variables instead of user-specific absolute paths.
-- For dev-server helpers, default to `http://5chan.localhost:1355` and respect the existing `PORTLESS=0` fallback instead of hard-coding alternate ports. For USB Android preview, `scripts/start-android-usb.mjs` mirrors bitsocial-web: `adb reverse` plus Vite on `127.0.0.1` so the device opens `http://localhost:<port>`.
+- For dev-server helpers, default to `http://5chan.localhost:1355` and respect the existing `PORTLESS=0` fallback instead of hard-coding alternate ports. For USB Android preview, `scripts/start-android-usb.mjs` mirrors bitsocial-web: `adb reverse` plus Vite on `127.0.0.1`, then `am start` VIEW to open the default browser when the port is listening (disable with `ANDROID_USB_OPEN_BROWSER=0`).
 - Keep shell helpers thin. When logic becomes stateful or cross-platform, prefer a Node script.
 - Git and worktree helpers must validate input and default to safe operations.
 - If a helper deletes local branches automatically, document the exact eligibility checks and keep the behavior conservative.
diff --git a/scripts/dev-server-utils.mjs b/scripts/dev-server-utils.mjs
index 4d822826..b1edc5cb 100644
--- a/scripts/dev-server-utils.mjs
+++ b/scripts/dev-server-utils.mjs
@@ -33,6 +33,30 @@ export async function resolvePort(requestedPort) {
   return port;
 }
 
+export async function waitForPort(host, port, timeoutMs = 30_000) {
+  const startedAt = Date.now();
+
+  while (Date.now() - startedAt < timeoutMs) {
+    const ready = await new Promise((resolve) => {
+      const socket = net.connect({ host, port });
+
+      socket.once('connect', () => {
+        socket.destroy();
+        resolve(true);
+      });
+      socket.once('error', () => resolve(false));
+    });
+
+    if (ready) {
+      return;
+    }
+
+    await new Promise((resolve) => setTimeout(resolve, 100));
+  }
+
+  throw new Error(`Timed out waiting for dev server on http://${host}:${port}`);
+}
+
 export function startVite(host, port) {
   const child = spawn('corepack', ['yarn', 'exec', 'vite', '--host', host, '--port', String(port), '--strictPort'], {
     cwd: repoRoot,
diff --git a/scripts/start-android-usb.mjs b/scripts/start-android-usb.mjs
index 472244f4..c62c8b82 100644
--- a/scripts/start-android-usb.mjs
+++ b/scripts/start-android-usb.mjs
@@ -2,11 +2,12 @@
 
 import { spawnSync } from 'node:child_process';
 import process from 'node:process';
-import { isWindows, repoRoot, resolvePort, startVite } from './dev-server-utils.mjs';
+import { isWindows, repoRoot, resolvePort, startVite, waitForPort } from './dev-server-utils.mjs';
 
 const adbBin = isWindows ? 'adb.exe' : 'adb';
 const host = '127.0.0.1';
 const requestedPort = Number(process.env.ANDROID_USB_PORT || 1355);
+const openBrowser = process.env.ANDROID_USB_OPEN_BROWSER !== '0' && process.env.ANDROID_USB_OPEN_BROWSER !== 'false';
 
 function fail(message) {
   console.error(message);
@@ -68,6 +69,20 @@ function reversePorts(devices, port) {
   }
 }
 
+/** Opens the preview URL in each device's default browser via VIEW intent. */
+function openPreviewOnDevices(devices, url) {
+  for (const serial of devices) {
+    const open = spawnSync(adbBin, ['-s', serial, 'shell', 'am', 'start', '-a', 'android.intent.action.VIEW', '-d', url], {
+      cwd: repoRoot,
+      encoding: 'utf8',
+    });
+
+    if (open.status !== 0) {
+      console.warn(`Could not open URL on ${serial}: ${open.stderr.trim() || open.stdout.trim() || 'unknown error'}`);
+    }
+  }
+}
+
 runPrestart();
 
 const devices = getReadyDevices();
@@ -82,7 +97,24 @@ if (port !== requestedPort) {
   console.log(`Preferred port ${requestedPort} is busy, so this run will use ${port}.`);
 }
 console.log(`ADB reverse is active for: ${devices.join(', ')}`);
-console.log(`Open http://localhost:${port} in Chrome on the Android device.`);
+const deviceUrl = `http://localhost:${port}`;
+if (openBrowser) {
+  console.log(`Opening ${deviceUrl} in the default browser on the device(s) when the dev server is ready…`);
+} else {
+  console.log(`Open ${deviceUrl} in a browser on the Android device (ANDROID_USB_OPEN_BROWSER=0).`);
+}
 console.log('');
 
 startVite(host, port);
+
+if (openBrowser) {
+  waitForPort(host, port)
+    .then(() => {
+      openPreviewOnDevices(devices, deviceUrl);
+      console.log(`Opened ${deviceUrl} on device(s): ${devices.join(', ')}`);
+      console.log('');
+    })
+    .catch((err) => {
+      console.warn(String(err.message || err));
+    });
+}