Archive EventBridge events and replay them back to the event bus for reprocessing

Steps

1. Create an archive on the source event bus with CreateArchive, optionally supplying an event pattern to filter which events are archived (omit it to archive all non-replayed events on that bus) and a retention period in days
2. Let EventBridge continuously capture matching events from that bus into the archive going forward
3. When you need to reprocess events, call StartReplay specifying the archive, a start and end time window, the destination event bus (the original source bus), and optionally specific rules to target during the replay
4. EventBridge resends matching archived events to the bus, tagging each replayed event with a replay-name metadata field so downstream targets can distinguish replayed events from live ones
5. Monitor replay progress and completion via the EventBridge console or DescribeReplay/ListReplays APIs
6. Design target Lambda functions/rules to be idempotent or to check the replay-name field, since replayed events can be reprocessed by the same rules that handle live traffic