Use this when a question marked attachDocument, on the current application page or among carrier follow-ups, asks for a document such as a replacement cost estimate or an existing policy or application, and the customer has attached it or wants to provide it. Pass the customer's attachment as file when this chat app supports file inputs; Menlo checks it is a PDF, JPEG or PNG up to 5 MB, keeps it with that question and saves the question's upload answer, which can resume eligible carrier processing. When no file arrives, returns attached false, a website upload link for the customer and the next step. An attached existing policy or application can suggest answers, saved with answer_quote_page once the customer confirms each. Takes the current baseRevision and an eventId; a retry of the same file reuses its eventId. Do not use for a file that answers no open document question, or for protected information.