The open-source budgeting app Maybe ships small sample CSVs for its importers. Feeding its transactions file to ai-bookkeeper worked. Its trades file did not: columns ticker, qty, price, amount list the value of a buy as positive and a sale as negative, so a $1,502.50 purchase of Apple stock was booked as money in.
The reader now recognises that header shape and flips the signs, saying so in the import message; passing invert explicitly still wins. One test covers it (thirdparty.test.mjs). The rows are made up in the same shape, the sample file was only read. Still untested: a real brokerage's export.