A persisted credit ledger — the gate the metered AI path spends against
Credits became a real ledger of grants and debits rather than a number stored beside the balance, which is the gate the metered agent path will spend against.
Credits are now a real ledger rather than a number on a page: every grant and every debit is a row, and the balance is derived from them rather than stored beside them.
This is the thing the chat agent will spend against. Until it existed there was no way to meter model cost per customer, which meant there was no way to offer an agent whose inference we pay for.