Writing back into a live system
This is the honest part. When a destination is a warehouse, a file, or a staging table, delivery is a solved problem and we treat it as one. When the destination is a live API or ERP, it is not, and the reason is worth stating plainly.
A remote system usually cannot offer a transaction across several requests. One call succeeds, a later one fails, and rollback may not exist. Handling that safely needs a delivery journal: a stable identifier per input record, captured response values, idempotency keys, attempt counts, and a visible permanent-failure state.
We have designed that and we have not shipped it. Until we have, we prefer warehouse, file, or staging handoffs wherever the destination allows, and we reduce exposure by reconciling against the source-faithful copy rather than trusting that a load went through.
What we will not do is describe stateful delivery as though it were finished. It is the single easiest thing to oversell in this category, and the failure mode lands on your data rather than ours.

