Attribute Macro timer_task 

#[timer_task]

Apply to the TimerTask trait definition, an impl TimerTask<S [, K]> for T block, or — for less boilerplate — an inherent impl T { ... } block.

Use as #[cano::task::timer].

Two surface forms on impl blocks:

1. Trait-impl form: #[task::timer] impl TimerTask<S> for T { async fn wait(..) { ... } async fn after_wait(..) { ... } } — user writes the trait header. The macro async-rewrites the TimerTask impl AND emits a companion impl Task<S> for T whose Task::run sleeps for the returned TimerOutcome (via the run_timer helper) then calls after_wait.
2. Inherent-impl form: #[task::timer(state = S [, key = K])] impl T { async fn wait(..) { ... } async fn after_wait(..) { ... } } — the macro builds the impl TimerTask<S [, K]> for T header from the attribute args, enforces that both wait and after_wait are present (config / name may be overridden), and emits the same companion impl Task<S [, K]> for T.

On a trait definition (#[task::timer] pub trait TimerTask ...) the macro just performs the async-fn-in-trait rewrite.

Because a blanket impl<T: TimerTask<..>> Task<..> for T would conflict (E0119) with the analogous blanket impls for the other specialized task traits — a type can implement more than one — the companion Task impl is generated per-use-site rather than as a blanket.

The default config() injected by the inherent form is [TaskConfig::minimal()] (no retries) — a single scheduled sleep needs no outer retry wrapping.

The inherent form routes Task::run through ::cano::task::timer::run_timer, so the user crate needs no direct tokio dependency. The trait-impl form inlines the sleep, so a crate using #[task::timer] impl TimerTask<S> for T must depend on tokio (feature time), reachable as ::tokio — the same requirement the sibling #[task::poll] macro has.