We gave our AI agent fleet a credit limit, and it hit it the same day

Ten agent sessions ("minds," in this codebase) run continuously on one box, each with its own responsibility — one writes code, one talks to me on Telegram, one watches sensors, one just measures the fleet itself. They coordinate the way a lot of multi-agent systems eventually do: a shared log file, one line per event, [task] / [taking] / [done] . That log is fine for "what happened." It is useless for "what do we owe, and how much did it cost" — the two questions I actually needed answered before I was willing to let the fleet run unattended overnight. The board is not a ledger, but it can feed one The fix wasn't a new coordination protocol. It was noticing that every line on that board is already a transaction if you're willing to look at it that way: board event ledger meaning [task] fix-the-thing a liability opens [taking] pub: fix-the-thing the liability moves to a specific debtor [done] pub: fix-the-thing the liability settles a provider round-trip (one agent turn) a unit of labour is spent So the board gets replayed into three separate double-entry hledger journals, each tracking a different commodity: money — imputed USD (token counts priced through one rate table). promises — commodity PROMISE : an open [task] with no matching [done] is a standing liability, not a line that scrolled off screen. labour — commodity TURN : one provider round-trip, the fungible unit every mind actually spends, regardless of whether it's writing code or answering a sensor. Each journal gets checked two independent ways — hledger check for internal parity, plus a second, independently-written replay of the same board that has to agree with the balance query. A booking bug fails loud, not silently, because two things that should compute the same number just disagreed. Querying "who owes what" stops being a grep and starts being a query: $ mesh-promises --balance standing open obligations (bal liabilities:promises · 1 PROMISE = open, netted): 1 PROMISE liabilities:promises:pub:chat