It’s completely key that the designer is working in source code with the developer. (…) the cost of having somebody translate all of the designs is too high. It means that you can’t change things. It means that any time you want to make a change you have to convince somebody else and make somebody else understand exactly the change that you intend, and then follow up with up with them to make sure that they’re implementing it the way that you want. It’s really adding a lot of friction and weight to the feedback cycle.
Ryan Singer on what designers should do in application development