Project Detected: Node.js Express application with an existing Redis configuration --- Background Job Added: * Job name: generate-invoice-pdf * Trigger: After a new invoice is created * Job purpose: Generate the invoice PDF without blocking the API request --- Queue or Scheduler: BullMQ worker using the project's existing Redis connection --- Reliability Controls: * Maximum of 3 attempts with exponential backoff * Failed jobs are logged with invoice ID and error summary * Existing PDF files are checked before regeneration to reduce duplicate work --- Files Modified: * src/queues/invoiceQueue.js * src/workers/invoiceWorker.js * src/services/invoiceService.js * src/routes/invoices.js * tests/invoiceQueue.test.js * package.json --- Commands Executed: * npm install bullmq * npm test --- Validation Result: Queue registration and invoice job tests passed. A local worker processed the mocked invoice job successfully. --- How to Run: Start the application with `npm start` and the worker with `npm run worker:invoices`. --- Important Notes: Redis must be available before starting the worker. No production queue or external invoice was modified during validation.