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How old a signed message may be before it is refused.
What it means
A valid signature can be captured and sent again later. Signing a timestamp and refusing anything too old limits how long a captured message is useful.
How Onekey handles it
A webhook’s t is signed with the body. Refuse a t more than 300 seconds from your clock. Each retry is signed afresh with a new t; use Onekey-Delivery-Id (the same on every retry of one event) to de-duplicate. This is separate from the 24-hour idempotency window.