Home / The cost ABP
Every ABP so far bounds what. This one bounds how much
Four steps, twelve prompts, and one honest ending. For anybody who has watched an agent write forty files nobody asked for, push twelve commits where one would do, research a question that was already answered, and hand three people something to review. You are paying for all of it, and nothing in the grant says a word about any of it.
Cost is not a capability
A capability is in the grant or it is not. Cost is a property of every call the agent makes, whichever capability the call instances. The grammar has one primitive for money, write.budget.tenant, and 2 of 16 published shapes grant it, because it names spending against an account the agent holds, and an agent's own inference is billed to the deployer by the platform, not spent by the agent. There is no primitive for a count of anything.
So a cost ABP is the first ABP written over the runtime rather than over the grant. Its four objects are the same. Its mandate is a set of budgets in your words. Its grant is everything the agent can spend, which is everything it can do. Its delta is what it spent that you did not ask for. And its barrier, on nearly every row, is a sentence, because almost nothing in a deployment caps a count.
Five things it spends, and one of them is never on a bill
The fifth line is the one this walkthrough exists for. An agent that asks a question, produces a document for a person to read, opens something for review or delegates to another agent that then does the same has spent an hour that no meter records. Organisations are starting to notice it as overhead without a source. The accountant on step three is the pattern that gives it one.
Why this is an ABP and not another skill
| A skill | A behaviour policy | |
|---|---|---|
| What it says | how to do one task well | what may not be done, and how much the doing may cost |
| Scope | one task, whenever it comes up | one agent in one deployment, across every task |
| Who writes it | whoever knows the task | whoever pays: the deployer, in their own words |
| How they relate | runs under the ABP | is what every skill has to fit inside |
A deployer watching the bill does not need another skill. They need the clauses that every skill has to run within, and a ledger at the end of every turn that says what the turn cost in the units they can check.
The four steps
Step 1: What it has already spent
Ask the agent to count what it can count in this session, and to say which numbers it cannot see at all.
Step 2: What you actually paid for
Sort what it did into what you asked for, what it decided was needed, and what it would now call waste. Then say what waste means for you.
Step 3: Write the cost policy
Limits per turn, batching, research only when blocked, and a ledger at the end of every turn. Plus the accountant: a second agent whose only job is to read the ledger.
Step 4: What a clause over a count cannot do
A limit the agent cannot measure is an expectation twice over. What a turn cap, a spend limit and a pipeline budget actually are, and who can turn each one off.
What you will have at the end
- A ledger for one session: files, commits, fetches, subagents, questions asked and things handed to people, counted by the agent, with the numbers it cannot see named as such.
- A cost mandate: what you want it to spend freely on, what it should batch or ask about, and what it must never spend, including other people's time.
- A cost policy: limits per turn, a research rule, a delegation rule, a never-create-work-for-others rule, and the ledger clause that makes the rest checkable.
- And the straight answer: a limit the agent cannot measure is an expectation twice over, and what would actually cap it.
Your mailbox, the first walkthrough · The runtime universe · write.budget.tenant · The four barriers