Every error Merchant Center throws at your feed, ranked by what it costs you and the order to fix them. The GTIN backfill and the title rewrite formula included, no developer required.
Seven rules, built by hand inside the Merchant Center UI: exact attribute, exact construction, before and after. Then how we split Shopping budget once every SKU carries a margin label.
Nothing to download here. Open the account, do the work, and write down what you found. This is the lesson people skip and it is the one that changes the number.
