The start screen
The problem
Big stores sell returned items by the pallet with a list of what's inside. Deciding how much to bid means pricing dozens of items by hand.
Rescoping it
The first version tried to do everything: scan auctions, scrape four marketplaces, send alerts. I cut it back to the one decision that mattered, wrote a design spec and a test-first plan, and rebuilt it: upload a manifest, and it prices every item against real eBay sales and tells you the most you can bid and still make your minimum profit.
Rules that keep it honest
Matching a listing to an item follows strict rules: the brand, product type, model and generation all have to match, so a Dyson V8 never prices a V10. If fewer than three real sales match, the item is worth $0 rather than a guess, and if eBay blocks a lookup, the run stops loudly instead of quietly pricing things at zero. An audit spreadsheet shows every comparison kept or rejected.