# updates() Starts the sync and returns a typed async sequence of progress snapshots. ``` func updates() -> BlockchainSync.Updates ``` ## Return Value A single-consumer [`BlockchainSync.Updates`](/documentation/BitcoinKernel/BlockchainSync/Updates) sequence. Iterating the same sequence concurrently is undefined behavior — call `updates()` again for a second consumer. ## Discussion Each call to `updates()` starts a fresh sync run — a `Task` spawns to drive the state machine. To stop a run, break the `for await` loop or cancel the enclosing `Task`; the iterator’s cleanup (via `AsyncStream.onTermination`) calls [`interrupt()`](/documentation/BitcoinKernel/Context/interrupt()) to unblock any in-flight kernel processing.