Consider something like LifecycleWorker

Kotlin has LifecycleWorker that makes it easy to perform side-effects when the worker is started or stopped.

At the moment, this is essentially equivalent to doing the following in Swift:

func render(state: State, context: RenderContext<SomeWorkflow>) -> Rendering {
    let onStart: () -> Void = …
    let onEnd: () -> Void = …

    context.runSideEffect(key: "lifecycle") { lifetime in
        onStart()
        lifetime.onEnded(onEnd)
    }

    …
}

We might consider making some convenience for this in Swift land. I’d hesitate tying it to Worker specifically since that lives in WorkflowReactiveSwift and this could be built more generally.

Open to suggestions on API shape

Start by reading the linked Kotlin LifecycleWorker.kt and the Swift render example using RenderContext.runSideEffect. Review how lifecycle effects are currently represented in Swift, then clarify the proposed API shape and its scope beyond Worker. Done means an agreed, documented convenience API with tests covering worker start and stop behavior.