Fan out an SNS FIFO topic to subscribed SQS FIFO queues and understand what message-group and dedup metadata propagates automatically

Steps

1. Publish to the SNS FIFO topic with a MessageGroupId — it is passed through automatically to subscribed SQS FIFO queues, but not to standard SQS queue subscribers
2. If content-based deduplication is enabled on the SNS FIFO topic, its dedup ID is likewise passed to subscribed SQS FIFO queues, which apply their own dedup on top
3. Decide whether to enable raw message delivery on the subscription — without it, SNS envelope metadata (including sequence number) is embedded in the SQS message body; with it enabled, that metadata is stripped
4. If fanning out to a standard (non-FIFO) SQS queue from the same SNS FIFO topic, expect only best-effort ordering and at-least-once delivery, since standard queues don't support message groups or dedup
5. For exactly-once processing end-to-end, ensure the SQS FIFO subscription has the correct SNS service-principal permissions, no message filtering configured, and that consumers delete messages before the visibility timeout expires
6. Remember ordering is only guaranteed within a message group — SNS FIFO delivers different message groups in parallel