How does Kaspa calculate transaction fee rates in the mempool?

Kaspa sets a transaction's fee rate priority in the mempool by taking the maximum of three mass values — compute mass, storage mass, and transient storage mass. The mempool is a temporary holding area where unconfirmed transactions wait before a miner picks them up and includes them in a block. To rank transactions by how costly they are per unit of mass, Kaspa uses the formula mass = max(compute_mass, storage_mass, transient_storage_mass), meaning whichever dimension of a transaction is heaviest is the one that drives its fee rate key. For anyone sending KAS, this matters because even a single heavy dimension — whether that is computation, storage, or transient storage — sets the effective fee rate you need to pay for timely confirmation.