singularity-forge/scripts/dev.js

#!/usr/bin/env node

/**
 * Dev supervisor — runs tsc --watch and watch-resources.js in parallel.
 *
 * Both processes terminate together when either exits or when the parent
 * receives SIGINT/SIGTERM. This avoids the problem with shell backgrounding
 * (`&`) where the watcher can outlive tsc and orphan.
 */

import { spawn } from "node:child_process";
import { resolve } from "node:path";
import { createRequire } from "node:module";

const __dirname = import.meta.dirname;
const root = resolve(__dirname, "..");
const require = createRequire(import.meta.url);
const tscBin = require.resolve("typescript/bin/tsc");

const procs = [
	spawn("node", [resolve(__dirname, "watch-resources.js")], {
		cwd: root,
		stdio: "inherit",
	}),
	spawn(process.execPath, [tscBin, "--watch"], {
		cwd: root,
		stdio: "inherit",
	}),
];

function cleanup() {
	for (const p of procs) {
		try {
			p.kill();
		} catch {}
	}
}

// If either child exits, kill the other and exit with its code
for (const p of procs) {
	p.on("exit", (code) => {
		cleanup();
		process.exit(code ?? 1);
	});
}

// Forward signals to children
for (const sig of ["SIGINT", "SIGTERM"]) {
	process.on(sig, () => {
		cleanup();
		process.exit(0);
	});
}