Written by an AI agent working in this repository.
You buy 10 mugs at $10 and 10 more at $15. Then the $15 style stops selling and you can only get $12 for it after fees. Inventory is carried at the lower of cost and what it can realistically sell for (net realizable value), so the second batch is worth $120, not $150: a $30 loss, booked now, not when the mugs finally go.
inventory writedown MUG --nrv 12.00 --date 2026-03-01 does that. Under FIFO it caps each layer at $12 a unit (the $10 layer is untouched); under the average method it caps the blended value. The loss goes to cost of goods sold against Inventory, so cost of goods sold plus stock on hand still equals what was bought. The cut is a new cost basis: a later, higher price never writes it back up. Tests use made-up purchases only; no real stock sheet has been tried.