Can a transaction appear in multiple layers?

[lrettig]

As discussed on today's design review call, we need to decide what happens if the same tx appears in blocks in multiple layers. Does the consensus layer output this tx in later layers, or ignore it entirely? Is gas charged for it? Does this depend upon whether the tx was contextually valid or not?

CC @noamnelke @tal-m @iddo333

[avive]

I think that the latest answer from research from our recent discussions about this is that technically duplicated transactions may be on multiple layers of the mesh (in the case that somehow a node that included the tx in a later block, didn't see that the same tx was already in a block in a previous recent layer but that such duplicated tx will never appear in the filtered sorted input list for the STF in the node. So part of the preparation rules of the input tx list for the stf is that the tx didn't appear in a previous layer already (and so was or will be proceed by STF for that layer. @tal-m - can you please confirm we got this right?

[lrettig]

Linking spacemeshos/api#8