Currently, the PlatformVM verifies ICM messages included in txs to be added to the mempool using the height returned by GetMinimumHeight. With introduction of ProposerVM epochs in ACP-181, this will no longer be viable because the P-Chain height to verify ICM messages in blocks will be the epoched height, which can vary significantly from the minimum height of a given node (which stays close to the tip of the chain).

To provide best effort mempool verification, ICM messages in transactions should be verified using the epoched height of a child block should one be created on top of the current preferred block.

This will require exposing the epoch height information to the manager from the ProposerVM.