What is the storage_mass field in a Kaspa transaction?

The storage_mass field is a binding declaration inside a Kaspa transaction that states how much storage space that transaction consumes on the network. Every transaction has two cost components — compute mass (processing cost) and storage mass (data-storage cost) — and wallets must commit to the storage_mass value when they construct a transaction; that value is locked in by being included in the transaction hash so it cannot be quietly changed later. Wallets can leave the field blank and let miners fill it in during block-template building, which keeps existing wallet software compatible. Understanding this field matters because it is how Kaspa enforces fair resource pricing: if the declared storage_mass turns out to be wrong, the entire transaction is thrown out.