rust-errors-async

Decodes the five recurring async error classes and gives one correct fix per class. Async errors are almost never bugs in async/.await itself: they are ordinary trait, Send, lifetime, or runtime-policy violations that surface only because async fn desugars into an anonymous state-machine Future. The fix targets the underlying violation, not the async keyword.

Cross-references: [[rust-syntax-async-await]] (async/await mechanics, desugaring), [[rust-impl-async-tokio]] (Tokio runtime setup, spawn, channels), [[rust-core-async-runtime]] (Future/Pin/Waker model), [[rust-agents-compile-fix]] (automated compile-fix loop).

When to use this skill

• The compiler reports future cannot be sent between threads safely or future is not Send.
• A tokio::spawn call fails with a Send bound error.
• The compiler reports cannot move out of a pinned value, or ... is not Unpin.
• A lifetime error appears only inside an async fn body or signature.
• The user asks "do I still need the async_trait crate".
• The program panics at runtime with Cannot start a runtime from within a runtime.
• An async program hangs, stalls, or one slow task freezes every other task.