<skill_overview> <purpose>Write correct, deadlock-free concurrent Rust code</purpose> <triggers> <trigger>Spawning threads or tasks</trigger> <trigger>Sharing state across threads</trigger> <trigger>Using channels for message passing</trigger> <trigger>Writing async/await code</trigger> </triggers> <sources> <source url="https://doc.rust-lang.org/book/ch16-00-concurrency.html">The Rust Book - Concurrency</source> <source url="https://doc.rust-lang.org/book/ch17-00-async-await.html">The Rust Book - Async/Await</source> </sources> </skill_overview> <message_passing> <rules> <rule>Prefer channels to avoid shared mutable state</rule> <rule>Move ownership through channels to enforce safety</rule> </rules> <example> <code> use std::sync::mpsc;

let (tx, rx) = mpsc::channel(); tx.send(42).unwrap(); let value = rx.recv().unwrap(); </code> </example> </message_passing> <shared_state> <rules> <rule>Use Arc<Mutex<T>> or Arc<RwLock<T>> for shared mutable state</rule> <rule>Keep lock scopes minimal and consistent</rule> <rule>Handle poison errors explicitly</rule> </rules> </shared_state> <send_sync> <rules> <rule>Use types that implement Send and Sync across threads</rule> <rule>Avoid Rc and RefCell in multi-threaded code</rule> </rules> </send_sync> <async_guidelines> <rules> <rule>Use async/await for I/O-bound work</rule> <rule>Do not block inside async functions</rule> <rule>Async code still needs an executor to run</rule> </rules> </async_guidelines> <deadlocks> <rules> <rule>Lock in a consistent order</rule> <rule>Drop guards before calling into other code</rule> </rules> </deadlocks> <anti_patterns> <avoid name="rc_in_threads">Using Rc<T> across threads</avoid> <avoid name="long_lock_scope">Holding a lock across long operations</avoid> <avoid name="blocking_in_async">Blocking I/O inside async code</avoid> </anti_patterns>