Idempotency / retrying?

[machty]

Perhaps I overlooked something obvious in the README but I couldn't find the following information:

1. What happens if the job/workflow runner process gets SIGKILL'd?
2. Do workflows start from the beginning, or do only the uncompleted jobs get run in a restart scenario?
3. If one of my jobs interacts with an external service that supports idempotence keys, is there a stable idempotency key that Gush provides, perhaps a Job idea that is stable between restarts of a particular workflow within a job?

Thanks in advance.