What developers need after prototype approval
A developer opens the approved design and asks what happens when the form fails. If the answer is not in the handoff, somebody will have to make it up. The handoff should explain the decisions a screenshot leaves out.
Final designs
Component details
Assets and specifications
Interaction notes
Make the approved version unambiguous
Provide one identified version with a date, a link, and a short decision record. Explain which screens and journeys are approved, which are still exploratory, and which comments have already been resolved. Otherwise, old screenshots can quietly become the source of truth.
Include reusable components and their variants: buttons, inputs, navigation, cards, notices, and loading states. Define the spacing, typography, colour, and image behaviour that make the pages feel like one product rather than separate compositions.
Describe behaviour beyond the happy path
Forms need required fields, validation rules, error placement, success feedback, and a decision about preserving entered information. Lists may need empty states, filters, pagination, and unavailable-item handling. These details should be agreed rather than improvised during build.
Document responsive choices and keyboard behaviour alongside the visual states. If a menu becomes a drawer on a phone, explain how it opens, closes, and returns focus. If a table needs a mobile alternative, show that alternative.
Separate the demonstration from the system
Mark sample data clearly. A chart in a prototype does not establish a data source, calculation, or permission model. A payment screen does not decide a provider or transaction flow. An account page does not prove authentication or recovery is implemented.
List the existing integrations that must be retained and the new ones that need scoping. Assign responsibility for credentials, content, legal approval, hosting, and operational checks without placing secrets in the design package.
Agree how the build will be checked
Turn important journeys into acceptance checks: the visitor can submit a valid enquiry; invalid fields show useful feedback; an unauthorised account cannot open private files; the agreed pages work without horizontal scrolling. Keep visual checks and functional checks separate so neither is mistaken for the other.
Finish with open questions, exclusions, and a practical owner for the next step. A clear handoff does not remove every uncertainty, but it prevents unresolved decisions from disappearing between design and development.