Concept demo: an invoice data extraction and approval workflow for PDF invoices. It extracts vendor, date, invoice number, amounts, and line items; validates formats and duplicates; flags mismatches; requires human approval; then sends clean data to an accounting API with an audit log. Designed for implementation with OCR, OpenAI, n8n, accounting APIs, confidence thresholds, role-based approval, exception handling, acceptance tests, and clear handoff documentation.