`launch` vs `async` — what’s the difference in coroutines?

Deep dive

• `launch { ... }`: fire-and-forget *within a scope*; you get a `Job` to cancel/join.
• `async { ... }`: you expect a value; you get `Deferred<T>` and should `await()` it.

Exception behavior:

• Unhandled exceptions in `launch` cancel the parent scope.
• Exceptions in `async` are observed when you `await()` (or when the parent awaits/cancels).

Common pitfalls

• Starting `async` and never awaiting it (lost errors / work).
• Blocking inside coroutines on the default dispatcher.
• Using `GlobalScope` and leaking work beyond lifecycle.