fix(dev): clean up web backend lifecycle

scripts/dev-server-command.mjs

@@ -1,3 +1,5 @@
+import { spawnSync } from 'node:child_process'
+
 export function createChatlabStartCommand({ serverDir, backendPort, nodeExecutable = process.execPath }) {
   return {
     command: nodeExecutable,
@@ -16,6 +18,34 @@ export function createChatlabStartCommand({ serverDir, backendPort, nodeExecutab
       cwd: serverDir,
       stdio: ['ignore', 'pipe', 'pipe'],
       env: { ...process.env },
+      detached: true,
     },
   }
 }
+
+export function terminateChatlabStartProcess(
+  childProcess,
+  { platform = process.platform, killProcess = process.kill, spawnSyncFn = spawnSync } = {}
+) {
+  if (!childProcess) return
+  if (childProcess.exitCode !== null || childProcess.signalCode !== null) return
+
+  const pid = childProcess.pid
+  if (!pid) {
+    childProcess.kill('SIGTERM')
+    return
+  }
+
+  if (platform === 'win32') {
+    const result = spawnSyncFn('taskkill', ['/PID', String(pid), '/T', '/F'], { stdio: 'ignore' })
+    if (result.status === 0) return
+    childProcess.kill('SIGTERM')
+    return
+  }
+
+  try {
+    killProcess(-pid, 'SIGTERM')
+  } catch {
+    childProcess.kill('SIGTERM')
+  }
+}