Make SleepSignal uncatchable to avoid breaking workflow suspension [gcp de feedback]

[jamescmartinez]

step.sleep interrupts execution by throwing a SleepSignal. This works for replay, but it creates a trap: if a user wraps workflow logic in a broad try { ... } catch (e) { ... }, they will accidentally catch the signal and break suspension. The engine relies on that exception escaping user code.

[n1ru4l]

Might be a wild idea, but have you considered using Generator or AsyncGenerator for the workflow handler function?

That way the workflow invoker can take over, however, the TypeScript experience here will be mediocre, as there is no great way to type the yields to automatically infer the return type of the step. 😢 Some workarounds exist, but they will make the API less straight-froward...

[jamescmartinez]

thanks for the suggestion @n1ru4l but I really want to keep the API straightforward. We'll probably end up needing to refactor sleeps a bit to not use exceptions as control flow, but I haven't spent time on this yet.