I'd say "gone" is a temporary state that exists shortly after task completion. A task shows as "gone" for, say, 15min, and then is deleted, producing a 404 in s

I'd say "gone" is a temporary state that exists shortly after task completion. A task shows as "gone" for, say, 15min, and then is deleted, producing a 404 in subsequent requests. On further thought, it seems to me that we necessarily need to keep completed tasks around until asked by a client to delete them. If a task produces an exception, we need to notate that for when the client next asks about the task's status. If the task ran successfully to completion, we need to notate that for when the client next asks. If the client needs to know all this, then it's the client who needs to ask for deletions as well - we shouldn't assume it's OK to remove records about tasks (unless there's a published policy that completed/error data will be purged after a certain period, e.g. 30, 60, 90 days...)