The block-building phase should handle a case where transactions arrive with nonces out-of-order. This can only happen across multiple rounds, but may be common enough that it should be handled.
A good approach is to cache transactions with too-large nonces, and hold them for a fixed period of time (say 30 seconds) or perhaps in a fixed-size FIFO cache. If time is used, it must be the consensus timestamps on transactions, not the local clock.
The block-building phase should handle a case where transactions arrive with nonces out-of-order. This can only happen across multiple rounds, but may be common enough that it should be handled.
A good approach is to cache transactions with too-large nonces, and hold them for a fixed period of time (say 30 seconds) or perhaps in a fixed-size FIFO cache. If time is used, it must be the consensus timestamps on transactions, not the local clock.