This might be a feature request, but I thought I’d check first that I did not overlook the api doc.
I understand you can add PDF and image files to your Square Invoices via online as of 2017. (https://www.sellercommunity.com/t5/Product-Updates-Archive/Attach-PDF-and-Image-Files-to-Square-Invoices/ba-p/50011). The option to add Contracts/Attachments are under “More options” of New Invoice tool (Sign In).
The v2 API for POST /v2/invoices (https://developer.squareup.com/explorer/square/invoices-api/create-invoice) currently does not show any attachment option.
I assume the web tool is using an api but the doc has not been updated OR that portion of the api has not been made publicly available.
Could we also use it as well? I would like to attach a pdf to an invoice using an api.