diff --git a/README.md b/README.md
index 1b2eb34..c909b05 100644
--- a/README.md
+++ b/README.md
@@ -86,10 +86,11 @@ then runs `npm install` and `npm run build`:
 ### Scripts
 
 ```bash
-npm run dev     # next dev --turbopack
-npm run build   # next build --turbopack
-npm run start   # next start (production)
-npm run lint    # eslint
+npm run dev      # node scripts/dev-server.mjs (dev + live updates)
+npm run dev:next # next dev --turbopack (raw dev server, unprotected)
+npm run build    # next build --turbopack
+npm run start    # next start (production)
+npm run lint     # eslint
 ```
 
 Handy checks before shipping: `npx tsc --noEmit`, `npx eslint <files>`, `npm run build`.
@@ -101,6 +102,14 @@ on the local network and from the `beta.dvorakmortonxd.dev` tunnel. Without it N
 rejects the dev asset requests *and* the HMR WebSocket, which leaves the page un-hydrated
 (stacked icons, dead buttons).
 
+A plain `next dev` server is meant for localhost and exposes unauthenticated debug endpoints
+(`/__nextjs*` — open-a-file-in-editor, stack frames, source maps, debugger attach, restart)
+that you don't want on a tunnel. `npm run dev` therefore runs `scripts/dev-server.mjs`, a
+custom server that keeps the app and live updates (HMR / Fast Refresh) but returns `404` for
+those endpoints and `*.map` for any request that isn't a direct localhost connection.
+Localhost keeps the full dev experience; the LAN and tunnel get a plain, live-reloading
+site. To force the raw server instead, use `npm run dev:next` (don't point a tunnel at it).
+
 ## 📡 API Routes
 
 | Route | Method | What it does |
@@ -140,6 +149,8 @@ src/app/
     Clock.tsx               → live clock
     JokerLogo.tsx           → logo with click easter egg
     SlBackground.tsx        → animated ASCII train background
+scripts/
+    dev-server.mjs          → custom dev server: live updates without the dev-only debug surface
 public/                     → fonts, wallpapers, icons, friend pages, /revival-inc game, llms.txt, robots.txt, sitemap.xml
 ```
 
diff --git a/next.config.ts b/next.config.ts
index 1d41c65..d5e2047 100644
--- a/next.config.ts
+++ b/next.config.ts
@@ -1,18 +1,25 @@
 import { NextConfig } from "next";
 
 const nextConfig: NextConfig = {
+  // Next's on-screen dev indicator is a debug affordance, not a feature of the
+  // site, so it stays hidden. Compile/runtime errors are still reported.
+  devIndicators: false,
   // Allow testing the dev server from other devices on the LAN (e.g. a phone).
   // Without this Next.js blocks cross-origin requests to /_next/* dev assets
   // with a 403, which stops the JS from loading and makes the page inert.
   // The HMR WebSocket is checked against this list too: if the tunnel/beta host
   // isn't listed, the socket is rejected and the dev client never hydrates
   // (SSR-only page: stacked icons, dead buttons).
+  //
+  // Keep this list tight — private LAN ranges plus the one exact tunnel host.
+  // A `**.dvorakmortonxd.dev` wildcard would let any subdomain drive the dev
+  // server. Note this only gates assets/HMR; the dangerous `/__nextjs_*` debug
+  // endpoints are stripped by scripts/dev-server.mjs, not by this list.
   allowedDevOrigins: [
-    "192.168.10.124",
+    "127.0.0.1",
     "192.168.*.*",
     "10.*.*.*",
     "beta.dvorakmortonxd.dev",
-    "*.dvorakmortonxd.dev",
   ],
   webpack(config) {
     config.module.rules.push({
diff --git a/opencode.md b/opencode.md
index 97a14bf..7cee25a 100644
--- a/opencode.md
+++ b/opencode.md
@@ -46,10 +46,11 @@ picks which one to show based on theme and device.
 
 ### Scripts
 ```bash
-npm run dev     # next dev --turbopack   (a server may already be running on :3000)
-npm run build   # next build --turbopack
-npm run start   # next start
-npm run lint    # eslint
+npm run dev      # node scripts/dev-server.mjs (dev + HMR; strips dev-only debug for non-local access)
+npm run dev:next # next dev --turbopack (raw, UNPROTECTED escape hatch — don't use behind the tunnel)
+npm run build    # next build --turbopack
+npm run start    # next start
+npm run lint     # eslint
 ```
 Useful checks before handing work back: `npx tsc --noEmit`, `npx eslint <files>`,
 `npm run build`.
@@ -100,6 +101,8 @@ src/app/
     Clock.tsx           → live clock (useSyncExternalStore + interval)
     JokerLogo.tsx       → site logo with a click easter egg
     SlBackground.tsx    → animated ASCII train background (terminal theme)
+scripts/
+  dev-server.mjs      → custom dev server: live updates minus the dev-only debug surface
 ```
 
 ### How UI selection works
@@ -233,12 +236,28 @@ list reordering, not free placement. Don't confuse the two.
   `59` is duplicated in `skeuo.css` (`.win-window.maximized` height,
   `.win-window.centered` bottom / max-height) — keep them in sync. Note
   `useDesktopIcons.ts` has its **own** `TASKBAR_HEIGHT = 48` for the icon grid.
-- Exposing the **dev** server over a tunnel needs the tunnel host in
-  `allowedDevOrigins` (`next.config.ts`). Without it Next dev rejects the
-  cross-origin HMR WebSocket, so the client never hydrates — the page is SSR
-  only: icons all stacked at `(0,0)`, buttons dead. Changing `next.config.ts`
-  needs a dev-server restart. For a public URL prefer a production build
-  (`npm run build && npm run start`): no HMR socket, so nothing to reject.
+- **Serving the dev server through the tunnel: read this.** `npm run dev` does
+  **not** run `next dev` directly — it runs `node scripts/dev-server.mjs`, a
+  custom server that wraps Next's request handler. It keeps the live-update
+  path (`/_next/hmr`, Fast Refresh) but returns `404` for Next's dev-only debug
+  endpoints (`/__nextjs*`: launch-editor, original stack frames, source maps,
+  node-inspector attach, server restart, …) and for `*.map` whenever the
+  request did **not** arrive over loopback without proxy headers. Those
+  endpoints are unauthenticated, and Next wires them in unconditionally, so
+  `next.config.ts` cannot disable them — that is what makes a publicly
+  tunnelled dev server unsafe. Net effect:
+  `localhost:3000` keeps the full dev experience; the LAN/tunnel get a plain,
+  live-reloading site. Use `npm run dev:next` only if you explicitly want the
+  raw, unprotected server (never point the tunnel at it).
+- `allowedDevOrigins` (`next.config.ts`) still matters: the tunnel host and any
+  LAN origin must be listed or Next rejects the HMR WebSocket with a 403 (the
+  client then never hydrates — SSR only, icons stacked at `(0,0)`, dead
+  buttons). Keep it tight (private ranges + the one exact tunnel host); a
+  `**.dvorakmortonxd.dev` wildcard would let any subdomain drive the dev
+  server. Changing `next.config.ts` needs a dev-server restart.
+- `devIndicators: false` in `next.config.ts` hides Next's on-screen dev badge.
+- For a fully public URL a production build (`npm run build && npm run start`)
+  is still the gold standard: no dev server, no debug endpoints, no HMR socket.
 - The SMP service shortcut opens `SMP_APP` (in `apps.tsx`, registered in
   `APP_BY_ID` only, like `ALACRITTY_APP`) — a Minecraft-style join menu that
   reads live data from `/api/ping?url=minecraft://…`.
@@ -257,6 +276,17 @@ list reordering, not free placement. Don't confuse the two.
 - There is **no test suite**. Verification is `tsc --noEmit`, `eslint`, and
   `next build`.
 - A dev server may already be running on port 3000; check before starting one.
+  Two dev servers on this repo collide on `.next/dev/lock`, so stop the old one
+  (and delete the stale lock) before starting the custom one.
+- Dev-server guard check: `curl -s -o /dev/null -w '%{http_code}' \
+  http://localhost:3000/__nextjs_server_status` must be `200` (localhost keeps
+  debug), while the same path through the LAN IP or `beta.dvorakmortonxd.dev`
+  must be `404`. Note a request from this host to its **own** LAN IP is routed
+  over loopback, so `localAddress` reads `127.0.0.1` — a same-host curl to the
+  LAN IP does NOT exercise the non-loopback branch. Test that branch through
+  the tunnel or from another machine. HMR is fine as long as a real
+  `/_next/hmr` WebSocket upgrade returns `101` and then sends a frame (the HMR
+  client appends `?id=self.__next_r` from the served HTML).
 - The desktop layout is geometry-heavy. When changing grid maths, a small
   standalone script mirroring `normalize()` / `posToCell()` is a fast way to
   prove one-icon-per-cell holds for edge cases (offscreen drops, tiny
diff --git a/package.json b/package.json
index 2a92539..0c02d90 100644
--- a/package.json
+++ b/package.json
@@ -3,7 +3,8 @@
   "version": "2.1.0",
   "private": true,
   "scripts": {
-    "dev": "next dev --turbopack",
+    "dev": "node scripts/dev-server.mjs",
+    "dev:next": "next dev --turbopack",
     "build": "next build --turbopack",
     "start": "next start",
     "lint": "eslint"
diff --git a/scripts/dev-server.mjs b/scripts/dev-server.mjs
new file mode 100644
index 0000000..0ca232b
--- /dev/null
+++ b/scripts/dev-server.mjs
@@ -0,0 +1,115 @@
+// Custom Next.js dev server that keeps live updates but drops the dev-only
+// debug surface for anyone who is not on localhost.
+//
+// WHY THIS EXISTS
+// `beta.dvorakmortonxd.dev` is an unauthenticated tunnel straight to the dev
+// server, and a Next.js dev server is not meant to be public. It exposes a set
+// of unauthenticated debug endpoints under `/__nextjs_*` (open-the-editor,
+// stack-frame/source-map lookups, node debugger attach, server restart, …) that
+// you really do not want on the internet. Next.js wires those endpoints in
+// unconditionally, so `next.config.ts` cannot turn them off.
+//
+// This server sits in front of Next's request handler and returns 404 for
+// `/__nextjs*` and source maps when the request did not arrive over loopback.
+// Everything the browser needs for live updates still goes through:
+//   - normal app routes
+//   - `/_next/hmr` (the HMR / Fast Refresh WebSocket)
+//
+// So `localhost:3000` keeps the full dev experience, while the LAN/tunnel get
+// a plain, live-reloading version of the site.
+//
+// Run with `npm run dev`. To bypass it entirely, use `npx next dev --turbopack`.
+
+import { createServer } from "node:http";
+import next from "next";
+
+const dev = process.env.NODE_ENV !== "production";
+const port = Number.parseInt(process.env.PORT || "3000", 10);
+const hostname = process.env.HOSTNAME || "0.0.0.0";
+
+// Next's dev-only internals all share this prefix:
+//   /__nextjs_launch-editor, /__nextjs_original-stack-frames,
+//   /__nextjs_source-map, /__nextjs_server_status,
+//   /__nextjs_attach-nodejs-inspector, /__nextjs_restart_dev, …
+const DEV_DEBUG_PREFIX = "/__nextjs";
+
+function isLoopback(socket) {
+  const address = socket.localAddress || "";
+  return (
+    address === "127.0.0.1" ||
+    address === "::1" ||
+    address === "::ffff:127.0.0.1" ||
+    address.startsWith("127.")
+  );
+}
+
+// A request that arrived through a proxy/tunnel (Cloudflare or otherwise) is
+// never a local dev request, even if the proxy itself runs on this machine and
+// therefore connects over loopback.
+function hasForwardedHeaders(req) {
+  const headers = req.headers;
+  return Boolean(
+    headers["cf-connecting-ip"] ||
+      headers["cf-ray"] ||
+      headers["x-forwarded-for"] ||
+      headers["x-forwarded-proto"] ||
+      headers["forwarded"],
+  );
+}
+
+function isLocalDebugRequest(req) {
+  return isLoopback(req.socket) && !hasForwardedHeaders(req);
+}
+
+function isDevDebugRequest(req) {
+  let pathname = req.url || "/";
+  try {
+    pathname = new URL(req.url || "/", "http://localhost").pathname;
+  } catch {
+    // Fall back to the raw URL if it is not parseable.
+  }
+  return (
+    pathname.startsWith(DEV_DEBUG_PREFIX) || pathname.endsWith(".map")
+  );
+}
+
+let handle;
+const server = createServer((req, res) => {
+  if (!isLocalDebugRequest(req) && isDevDebugRequest(req)) {
+    res.statusCode = 404;
+    res.setHeader("content-type", "text/plain; charset=utf-8");
+    res.setHeader("cache-control", "no-store");
+    res.end("Not found");
+    return;
+  }
+  // `handle` is assigned right after `getRequestHandler()` below; requests
+  // cannot arrive before `listen`, which happens after that assignment.
+  handle(req, res);
+});
+
+// Passing our HTTP server in lets Next attach its HMR upgrade handler to it.
+const app = next({ dev, turbopack: true, hostname, port, httpServer: server });
+handle = app.getRequestHandler();
+
+await app.prepare();
+
+server.listen(port, hostname, () => {
+  console.log(`> dev server ready on http://localhost:${port}`);
+  console.log(
+    "> dev debug endpoints are localhost-only (404 on the LAN/tunnel); HMR still works",
+  );
+});
+
+function shutdown() {
+  // Drop idle keep-alive sockets so Ctrl+C exits promptly instead of waiting
+  // on lingering connections.
+  server.closeAllConnections?.();
+  server.close(() => {
+    app.close().finally(() => process.exit(0));
+  });
+  // Hard exit if Next's cleanup hangs.
+  setTimeout(() => process.exit(0), 3000).unref();
+}
+
+process.on("SIGINT", shutdown);
+process.on("SIGTERM", shutdown);