Handing over finished designs to engineers is the slowest way to build a product.
Sketch together
On every project I invite an engineer to the first sketching session. They spot constraints early and often suggest simpler solutions than the ones designers would have found alone.
Review in the browser
Design reviews happen on the build, not on static screens. Spacing, motion and loading states only become real in code, and that is where most of the small decisions get made.
Engineers are not the audience for a design. They are co-authors.