Add project scripts and tooling

tools/dev.mjs

@@ -0,0 +1,78 @@
+import { spawn } from "node:child_process";
+import net from "node:net";
+
+const commands = [
+  {
+    name: "service",
+    command: "node",
+    args: ["service/src/server.js"],
+    port: 4317
+  },
+  {
+    name: "web",
+    command: "npm.cmd",
+    args: ["run", "web:dev"],
+    port: 5173
+  }
+];
+
+const occupied = [];
+for (const command of commands) {
+  if (await isPortInUse(command.port)) {
+    occupied.push(command);
+  }
+}
+
+if (occupied.length > 0) {
+  for (const command of occupied) {
+    console.error(`[dev] port ${command.port} is already in use; not starting ${command.name}.`);
+  }
+  console.error("[dev] stop the old process first, then run npm.cmd run dev again.");
+  process.exit(1);
+}
+
+const children = commands.map(({ name, command, args }) => {
+  const child = spawn(command, args, {
+    cwd: process.cwd(),
+    stdio: ["ignore", "pipe", "pipe"],
+    shell: false
+  });
+
+  child.stdout.on("data", (data) => writePrefixed(name, data));
+  child.stderr.on("data", (data) => writePrefixed(name, data));
+  child.on("exit", (code) => {
+    if (code !== 0 && code !== null) {
+      console.error(`[${name}] exited with code ${code}`);
+    }
+  });
+
+  return child;
+});
+
+for (const signal of ["SIGINT", "SIGTERM"]) {
+  process.on(signal, () => {
+    for (const child of children) {
+      child.kill(signal);
+    }
+    process.exit(0);
+  });
+}
+
+function writePrefixed(name, data) {
+  const lines = data.toString().split(/\r?\n/).filter(Boolean);
+  for (const line of lines) {
+    console.log(`[${name}] ${line}`);
+  }
+}
+
+function isPortInUse(port) {
+  return new Promise((resolve) => {
+    const server = net.createServer();
+
+    server.once("error", () => resolve(true));
+    server.once("listening", () => {
+      server.close(() => resolve(false));
+    });
+    server.listen(port, "127.0.0.1");
+  });
+}