Async Activity Completion detail #4096
Description
Temporal Affiliation
* [x] I am a Temporal employee
Content Suggestion
The document here on {{Task Token}} https://docs.temporal.io/activity-execution#task-token explains that {{Async Activity Completion}} can accept an ActivityID _or_ a TaskToken, but doesn't clarify the distinction or risk.
Since TaskToken is actually unique for the _execution_, retries can actually cause a downstream caller that would use the {{task token}} handed to it to be no longer valid. For example, if an activity fails before returning the "complete async error" but after it has told the downstream/remote service to use the current task token to heartbeat or complete.
If you are concerned about this risk, prefer providing ActivityID+WorkflowID to that remote so that you don't have to worry about it. This discussion might be better in a different part of https://docs.temporal.io/activity-execution#asynchronous-activity-completion but I'll leave that to the experts 😀 .