Design the Homepage Viewport

Open the app, pick a profile, and the screen fills with rows. Continue Watching at the top, then Trending, then a run of genre and taste rows, each a horizontal strip of title tiles. "Design the homepage" sounds like it means "design the recommender," and that is the wrong instinct. The recommender decides what belongs in each row. This prompt is the layer above it: given rows that are already ranked, assemble a page, hand the client exactly the slice it can show, and never let the same title appear twice on the way down.

That reframing reads well. Say early that ranking is a solved, upstream concern you will call into and not rebuild, so the room knows you have scoped the problem correctly. What is left is genuinely hard on its own terms. A profile's full homepage can run to dozens of rows, and each row can hold hundreds of candidate titles. Sending all of it on first load would be slow, wasteful, and pointless, because the profile sees four or five rows before scrolling. So the design is about the viewport: compute and ship what is visible, defer the rest, and keep the page coherent as the profile scrolls. Make sure a title chosen for three different rows lands in only one of them.

The Netflix angle

The homepage is the product, and it is assembled per profile on every load. There is no single stored page to fetch. The rows a profile sees are stitched together at request time from many sources, Continue Watching from recent viewing, Trending from what is hot, a long tail of taste rows from the recommender. So the interviewer is watching how you compose that page under a real constraint. The profile is on a TV or a phone, waiting, and the first rows have to paint quickly while the rest stream in behind the scroll. Get the viewport and the dedup right and the page feels instant and clean. Get them wrong and it is either slow to first paint or full of the same show three rows apart.