I know that when writing to a stream, you can assert on the current version, which works well for mimicking transactions and for optimistic concurrency. I've also seen that you can assert on there being no stream, but not seen a way to assert that the stream does exist, without specifying a version.
Having this would be useful in some cases where you want to add an event to an aggregate, but don't actually care about its current state, e.g. adding a note. Rather than loading the aggregate from events only to validate that it exists, you could attempt the write and reject it if the stream was not already created.
Is support for this somethings that has been considered / could easily be added? If not, is there any particular reason why this would be a bad idea?