I got Cooked Book as Denathrius, which gives +n/+n to a minion you purchase as it’s delivered from the shop to your hand. Shipwright was the first card I bought after completing the quest, and it was buffed from 1/5 to 2/6. Given that it gained attack, it should have buffed to 2/7.
Cards in your hand don’t have an effect unless they read otherwise
Their card text is disabled if not on the field
Oh I see. The word “whenever” in “Whenever this gains Attack, gain +1 Health permanently.” misled me, but that makes sense that it follows the logic of cards in hand not triggering effects.