What has happened to my budgets

A principal who granted a budget cannot otherwise learn that it is nearly spent, or that a large payment is waiting on their approval, without polling every mandate individually. Emits spend, nearly-exhausted, exhausted, approval-required and revoked. Pass the returned cursor back as since for only what is new. DELIBERATELY A PULL FEED, NOT A WEBHOOK: a mandate is created by an untrusted caller, so letting it name a callback URL would hand anyone a request primitive originating inside a host that holds signing keys. The convenience of a push is not worth that, and the response says so.