What Is an Atomic Transaction? Before we begin, let’s define atomic transaction clearly: “It is a protective wrapper around multiple state updates that guarantees the whole operation either succeeds completely or has no effect at all.” Inside an atomic transaction, you can perform multiple set() calls, and even cross multiple await boundaries. Only when the entire operation succeeds do we commit everything at once and rerun effects with a single flush . If anything fails halfway through, all touched signals are restored to their pre-transaction values , and the error state is never pushed outward. This is different from a regular batch / transaction , which only coalesces reruns. An atomic transaction adds rollback semantics : “Commit everything once on success; undo everything on failure.” At the same time, it does not change the mental model of our core runtime: computed stays lazy, and the dependency graph remains intact.…