Abortable Fetch and Request Cancellation

Write a client data helper that cancels stale requests. Fast typists and route changes should not apply an older response on top of a newer one. UI The interaction: [TYPEAHEAD | ROUTE CHANGE | WIZARD] Framework: [REACT] API: [URL SHAPE] DELIVER 1) A function that accepts an AbortSignal and passes it to fetch. Map abort to a typed error the UI can ignore, distinct from a real failure. 2) The React piece: create the controller in an effect, abort in the cleanup, and ignore setState after abort. Show the race: response for query "a" arriving after "ab". 3) Timeout via AbortSignal.timeout or a manual timer, and which errors the user sees (timeout versus offline versus 500). 4) What not to abort: a POST that already started a payment. Say why cancellation is a UI concern there, not a server undo. 5) A test with fake timers or a deferred promise that resolves out of order. Do not swallow all errors in an empty catch.