If the first time an engineer sees your work is the day you call it finished, you are using handoff as a review. It is not one. Handoff moves a decision that is already made, which makes it the worst place to learn the decision was expensive.
Bring them in while it is still ugly. Show the sketch, the rough flow, the two options you cannot choose between. Engineers know things you do not — that option B reuses something already built, that the data for option A does not arrive in the order you have drawn it, that a slightly different interaction costs a fraction of the work.
Leave it late and the design still gets made, just not by you. Someone hits the thing you never drew — the error state, the list that comes back in the wrong order, the field the API does not have — in the last week of the sprint, and settles it themselves at four in the afternoon.
Small habits carry most of this. Sit in on standup. Post work in progress in their channel rather than yours. Ask what would make this cheaper to build, then give something up when they answer: the custom animation, the sort order you wanted, the second step you were trying to remove. An engineer whose answer changes nothing stops answering honestly. Explain why, not only what — an engineer who understands the intent solves problems you will never hear about.
An engineer brought in at the sketch tells you what to draw. An engineer brought in at the end tells you what to cut.