BAD_REQUEST — malformed JSON body, a missing required field, or an empty items array.

Missing, malformed, unknown or revoked API token.

Valid token, but it belongs to a different organization, the plan lacks api_access, or a mutation was attempted with a read-only token.

COGS_NOT_FOUND — no cost data on file for that SKU. Distinct from a SKU priced at zero, which returns 200 with costPerUnit 0.