antoinerousseau · August 5, 2026 21:38
diff --git a/README.md b/README.md
diff --git a/echo-server.js b/echo-server.js
 // Plain TCP echo server, unrelated to Next.js — stands in for any
 // non-fetch/non-HTTP TCP consumer (a Postgres driver, Redis client, etc).
 const net = require("node:net");
 const server = net.createServer((socket) => {
  socket.on("data", (data) => socket.write(data));
 });
 server.listen(process.env.ECHO_PORT || 3901, () => {
  console.log("echo server up on", server.address().port);
 });
diff --git a/layout.js b/layout.js
 export default function RootLayout({ children }) {
  return (
    <html>
      <body>{children}</body>
    </html>
  );
 }
diff --git a/next.config.js b/next.config.js
 /** @type {import('next').NextConfig} */
 module.exports = {
  experimental: {
    // Toggle this to reproduce: true hangs, false/omitted works.
    testProxy: process.env.ENABLE_TEST_PROXY === "true",
  },
 };
diff --git a/package.json b/package.json
 {
  "name": "next-testproxy-repro",
  "version": "0.0.0",
  "private": true,
  "scripts": {
    "build": "next build",
    "start": "next start -p 3900"
  },
  "dependencies": {
    "next": "16.3.0",
    "react": "19.2.8",
    "react-dom": "19.2.8"
  }
 }
diff --git a/page.js b/page.js
 export default function Page() {
  return <div>ok</div>;
 }
diff --git a/route.js b/route.js
 import net from "node:net";

 // Opens a raw TCP connection (no fetch/HTTP involved) to a plain TCP echo
 // server, writes a byte, and waits for the echo back.
 function probeRawSocket(port) {
  return new Promise((resolve, reject) => {
    const socket = net.createConnection({ host: "127.0.0.1", port }, () => {
      socket.write("ping");
    });
    socket.on("data", (data) => {
      socket.end();
      resolve(data.toString());
    });
    socket.on("error", reject);
  });
 }

 export async function GET() {
  const start = Date.now();
  const reply = await probeRawSocket(Number(process.env.ECHO_PORT));
  return Response.json({ reply, ms: Date.now() - start });
 }
	// Plain TCP echo server, unrelated to Next.js — stands in for any
	// non-fetch/non-HTTP TCP consumer (a Postgres driver, Redis client, etc).
	const net = require("node:net");
	const server = net.createServer((socket) => {
	socket.on("data", (data) => socket.write(data));
	});
	server.listen(process.env.ECHO_PORT \|\| 3901, () => {
	console.log("echo server up on", server.address().port);
	});
	export default function RootLayout({ children }) {
	return (
	<html>
	<body>{children}</body>
	</html>
	);
	}
	/** @type {import('next').NextConfig} */
	module.exports = {
	experimental: {
	// Toggle this to reproduce: true hangs, false/omitted works.
	testProxy: process.env.ENABLE_TEST_PROXY === "true",
	},
	};
	{
	"name": "next-testproxy-repro",
	"version": "0.0.0",
	"private": true,
	"scripts": {
	"build": "next build",
	"start": "next start -p 3900"
	},
	"dependencies": {
	"next": "16.3.0",
	"react": "19.2.8",
	"react-dom": "19.2.8"
	}
	}
	import net from "node:net";

	// Opens a raw TCP connection (no fetch/HTTP involved) to a plain TCP echo
	// server, writes a byte, and waits for the echo back.
	function probeRawSocket(port) {
	return new Promise((resolve, reject) => {
	const socket = net.createConnection({ host: "127.0.0.1", port }, () => {
	socket.write("ping");
	});
	socket.on("data", (data) => {
	socket.end();
	resolve(data.toString());
	});
	socket.on("error", reject);
	});
	}

	export async function GET() {
	const start = Date.now();
	const reply = await probeRawSocket(Number(process.env.ECHO_PORT));
	return Response.json({ reply, ms: Date.now() - start });
	}