Function spawnDetachedDaemon

src/mcp/index.ts:178–217

* Spawn the shared daemon as a fully detached background process: its own * session/process group (so a SIGHUP/SIGINT to the launcher's terminal can't * reach it) with stdio decoupled from the launcher (logs to * `.codegraph/daemon.log`). Re-invokes the *same* CLI faithfully across dev and * bun

(root: string)

 * launcher proxies through the single winner.
 */
function spawnDetachedDaemon(root: string): void {
  const scriptPath = process.argv[1];
  if (!scriptPath) {
    // No resolvable CLI entry point to re-invoke — let the caller fall back to
    // direct mode rather than spawn something broken.
    throw new Error('cannot resolve CLI script path to spawn the daemon');
  }

  let logFd: number | null = null;
  let stdio: StdioOptions = 'ignore';
  try {
    logFd = fs.openSync(path.join(getCodeGraphDir(root), 'daemon.log'), 'a');
    stdio = ['ignore', logFd, logFd];
  } catch {
    stdio = 'ignore'; // no log file — discard daemon output rather than fail
  }
  try {
    // The daemon has no host: scrub the threaded host pid so it can't leak
    // into the daemon's env (and from there into anything the daemon spawns),
    // where a long-dead session's host pid would trigger spurious shutdowns.
    const env: NodeJS.ProcessEnv = { ...process.env, [DAEMON_INTERNAL_ENV]: '1' };
    delete env[HOST_PPID_ENV];
    const child = spawn(
      process.execPath,
      [...process.execArgv, scriptPath, 'serve', '--mcp', '--path', root],
      {
        detached: true,
        stdio,
        windowsHide: true,
        env,
      },
    );
    child.unref();
  } finally {
    // The child holds its own dup of the log fd now; the launcher doesn't need it.
    if (logFd !== null) {
      try { fs.closeSync(logFd); } catch { /* ignore */ }
    }
  }
}

/**
 * MCP Server for CodeGraph