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Yes, that's why the @DBOS.Transaction is just for database operations, which (hopefully!) you've already optimized to not take unreasonable time. These are guaranteed to execute exactly-once. For other, potentially longer-running operations, use @DBOS.step, which is at-least-once. Documentation:

Transactions: https://docs.dbos.dev/python/tutorials/transaction-tutorial

Steps: https://docs.dbos.dev/python/tutorials/step-tutorial

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OK, I see I skipped that. Nevertheless, I would expect users to read "exactly once" and put an http call in the step. It's the type of knife people their hands with.

One of the features on our list is to actually warn people when they make external calls inside of a step for this exact reason. You're right, the developer does need to understand idempotency to be successful, but we do everything we can to make sure they are successful without that knowledge.

I, too, found this "exactly-once" language really unclear and a turn-off. What does it actually say that is meaningful and helpful? I can run a transaction in any language and I get, surprise, transactional semantics.

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