Async safety

No async failure in an Expo app is silent and no async result lands where it no longer belongs: every promise has an owner that sees its rejection, every effect cancels the work it started, overlapping calls resolve latest-wins, cancellation is read from the signal (with only the abort APIs a phone really has), every subscription and timer is released by whoever created it, and every wait has a deadline. A zero-dependency checker proves the parts ESLint and tsc cannot see, on iOS and Android code alike; race tests prove the rest.

Rules that must hold

The inline handler forms (no floating promise, no async handler, block-bodied handlers) are typescript-and-lint-rules rule 10 and its ESLint config; these rules close everything after them. Server data is read with useQuery (networking-and-server-state): no effect, no createLatestRequest, because query keys already give latest-wins and TanStack passes the signal. Rules 3 and 4 are for async work that is not server state: SQLite repositories, native SDKs, OS reads, device APIs.