optimizing-lazy-layouts

Add a stable key to every items() call using a server-side ID, supply contentType for mixed-type lists, and hoist painters and borders out of the items lambda. Then verify with Layout Inspector that item recomposition counts plateau during scrolling.

animateItem() binds animation state to the item's key, so without a stable key the animation silently no-ops. Add key = { it.id } to the items() call so inserts, removals, and reorders trigger the fade and placement animations.

contentType is a type discriminator analogous to RecyclerView view-types that lets lazy layouts reuse cached compositions across items of the same type. For mixed feeds of cards, headers, and ads, pass contentType = { it::class } so rows crossing type boundaries are recycled instead of rebuilt.

No. Index-based keys break state preservation and animations on insert or remove, and UUID.randomUUID() evaluated per emission discards the cached composition every recomposition. Use a stable server-side ID that outlives a single composition.

Prefetch tuning applies when the bottleneck is heavy items or high-velocity scrolling needing a wider ahead/behind window, not missing keys or contentType. Fix item-level identity and stability first, then use the sibling configuring-lazy-prefetch skill for prefetch adjustments.