Generator-Driven Finite State Machine for Multi-Step Transactional Control Flow in Next.js Server Actions

export function* createCheckoutWorkflow(cartItems) {
  const validated = yield { step: 'VALIDATING', items: cartItems };
  if (!validated.success) return { status: 'FAILED_VALIDATION' };
 
  const charged = yield { step: 'CHARGING', amount: validated.total };
  if (!charged.success) return { status: 'FAILED_PAYMENT' };
 
  return { status: 'COMPLETED', orderId: charged.txId };
}
 
export async function processOrderAction(cartItems) {
  'use server';
  const workflow = createCheckoutWorkflow(cartItems);
  
  let next = workflow.next();
  const validRes = { success: true, total: 99.99 };
  
  next = workflow.next(validRes);
  const payRes = { success: true, txId: 'tx_9981' };
  
  const finalResult = workflow.next(payRes);
  return finalResult.value;
}