A polished mockup usually shows a screen with useful content and a successful action. Real use also includes missing data, interrupted connections, invalid input, and actions that take time.
For each important workflow, ask what a person sees before it begins, while it is happening, and when it cannot finish.
Feedback should explain what happened and what someone can do next. An error that only says something went wrong leaves the user to guess.
Keep input when an action fails. Put instructions beside the relevant controls. Do not rely on colour or animation alone to explain a change.
A short transition can show how two states relate. It should not delay access to content or become the only way information is communicated.
Design a static version too. Keyboard users, touch users, and people who prefer reduced motion should have the same meaningful actions available.
An editorial draft awaiting company review, not a client case study or a claim of guaranteed results. Project decisions should be evaluated in their own context.