An invoice stays editable while it is a draft. The first send issues it and preserves the exact PDF, customer details, seller details, dates, items, and totals as a private record. Issued invoices cannot be edited or deleted; duplicate one to start a new draft.
Due, Overdue, Paid, and Void are separate states. Paid invoices can be sent again with their original PDF. Each recipient gets a private email, and the invoice activity shows whether each delivery was sent.
The invoice editor now keeps entered values after validation errors, starts with an item, updates contact payment terms, warns about unsaved work, and returns from adding a contact without losing the draft. Invoice search, status counts, and outstanding totals now describe the same filtered set.