open-design/scripts/dev-all.mjs

#!/usr/bin/env node
// Launcher for `npm run dev:all`.
//
// Probes for free ports for the daemon (OD_PORT, default 7456) and the
// Next.js dev server (NEXT_PORT, default 3000) before spawning
// `concurrently`, so a stray process holding either port doesn't kill the
// whole boot. The resolved ports are exported into the child env, which
// means:
//   * the daemon's cli.js sees the new OD_PORT and binds to it
//   * next.config.ts reads the same OD_PORT and proxies /api, /artifacts,
//     /frames to the daemon's actual port
//   * Next.js binds to NEXT_PORT (we pass `next dev -p $NEXT_PORT` so the
//     `dev` script can stay parameter-free for the common single-process
//     case where the user runs just `pnpm dev`)
//
// If a port is busy we walk forward up to PORT_SEARCH_RANGE steps and log
// the switch so the user notices.

import { spawn } from 'node:child_process';
import net from 'node:net';

const HOST = '127.0.0.1';
const PORT_SEARCH_RANGE = 50;

function isPortFree(port, host = HOST) {
  return new Promise((resolve) => {
    const server = net.createServer();
    server.unref();
    server.once('error', () => resolve(false));
    server.listen({ port, host, exclusive: true }, () => {
      server.close(() => resolve(true));
    });
  });
}

async function findFreePort(start, label) {
  for (let port = start; port < start + PORT_SEARCH_RANGE; port++) {
    if (await isPortFree(port)) return port;
  }
  throw new Error(
    `[dev:all] could not find a free ${label} port near ${start} (tried ${PORT_SEARCH_RANGE})`,
  );
}

const desiredDaemon = Number(process.env.OD_PORT) || 7456;
const desiredNext = Number(process.env.NEXT_PORT) || 3000;

const daemonPort = await findFreePort(desiredDaemon, 'daemon');
const nextPort = await findFreePort(desiredNext, 'next');

if (daemonPort !== desiredDaemon) {
  console.log(
    `[dev:all] daemon port ${desiredDaemon} is busy, switching to ${daemonPort}`,
  );
}
if (nextPort !== desiredNext) {
  console.log(
    `[dev:all] next port ${desiredNext} is busy, switching to ${nextPort}`,
  );
}

const env = {
  ...process.env,
  OD_PORT: String(daemonPort),
  NEXT_PORT: String(nextPort),
  PORT: String(nextPort),
};

// `npm:daemon` is the shorthand for the daemon script, and `next dev -p
// <port>` is invoked directly so we can pass the resolved port without
// round-tripping through npm scripts. Keep the port numeric before it reaches
// the command string, and avoid shell interpretation on POSIX; Windows needs
// shell mode so the local `.cmd` shim can resolve.
const child = spawn(
  'concurrently',
  ['-k', '-n', 'daemon,web', '-c', 'cyan,magenta', 'npm:daemon', `next dev -p ${nextPort}`],
  { env, stdio: 'inherit', shell: process.platform === 'win32' },
);

child.on('exit', (code, signal) => {
  if (signal) process.kill(process.pid, signal);
  else process.exit(code ?? 0);
});

for (const sig of ['SIGINT', 'SIGTERM']) {
  process.on(sig, () => {
    if (!child.killed) child.kill(sig);
  });
}