Function forceExit

src/utils/gracefulShutdown.ts:193–232

* Force process exit, handling the case where the terminal is gone. * When the terminal/PTY is closed (e.g., SIGHUP), process.exit() can throw * EIO errors because Bun tries to flush stdout to a dead file descriptor. * In that case, fall back to SIGKILL which always works.

(exitCode: number)

 * In that case, fall back to SIGKILL which always works.
 */
function forceExit(exitCode: number): never {
  // Clear failsafe timer since we're exiting now
  if (failsafeTimer !== undefined) {
    clearTimeout(failsafeTimer)
    failsafeTimer = undefined
  }
  // Drain stdin LAST, right before exit. cleanupTerminalModes() sent
  // DISABLE_MOUSE_TRACKING early, but the terminal round-trip plus any
  // events already in flight means bytes can arrive during the seconds
  // of async cleanup between then and now. Draining here catches them.
  // Use the Ink class method (not the standalone drainStdin()) so we
  // drain the instance's stdin — when process.stdin is piped,
  // getStdinOverride() opens /dev/tty as the real input stream and the
  // class method knows about it; the standalone function defaults to
  // process.stdin which would early-return on isTTY=false.
  try {
    instances.get(process.stdout)?.drainStdin()
  } catch {
    // Terminal may be gone (SIGHUP). Ignore — we are about to exit.
  }
  try {
    process.exit(exitCode)
  } catch (e) {
    // process.exit() threw. In tests, it's mocked to throw - re-throw so test sees it.
    // In production, it's likely EIO from dead terminal - use SIGKILL.
    if ((process.env.NODE_ENV as string) === 'test') {
      throw e
    }
    // Fall back to SIGKILL which doesn't try to flush anything.
    process.kill(process.pid, 'SIGKILL')
  }
  // In tests, process.exit may be mocked to return instead of exiting.
  // In production, we should never reach here.
  if ((process.env.NODE_ENV as string) !== 'test') {
    throw new Error('unreachable')
  }
  // TypeScript trick: cast to never since we know this only happens in tests
  // where the mock returns instead of exiting
  return undefined as never
}

/**
 * Set up global signal handlers for graceful shutdown