[lmm]

> No. No it doesn’t. It has at-least-once delivery with client-side deduplication. That’s not new, it’s what TCP does FFS.

It's not just deduplication, you can atomically commit a consumer from one topic + produce of records resulting from that. Which is exactly the same exactly-once guarantee that you get from e.g. an SQL database in linearizable mode (a lot of SQL databases will do the same thing internally - optimistically execute transactions and then re-run them in the case of a conflict).