Receipt scanning for expense reports

Design receipt scanning for a company expense tool. An employee photographs a receipt in the mobile app, and the system fills in merchant, date, total, currency and a category using a hosted model that reads images and returns structured fields. The employee confirms or corrects the fields before submitting. The company has 5,000 employees who submit about 3,000 receipts a day, with month-end spikes of about five times that. Extraction can take 10 seconds and sometimes returns fields that are wrong or missing. Receipts must be kept for seven years, and finance wants a warning when a receipt looks like one already submitted. Describe the upload and extraction flow, how the output is validated, and how corrections are used.