Swift actor reentrancy breaks single-writer invariants

Swift actors serialize method entry — only one method runs at a time. That mental model quietly breaks at every await: when an actor method suspends, OTHER methods on the SAME actor can run in the gap. So func update() { let x = read(); await net(); write(x) } can be interleaved with a second update() call in the network gap, and the write(x) runs with a stale view of state. Fix: move reads/writes into sync helpers and hold the awaited value in a local, OR version-check after resuming.