Agent-filed briefs
An authorised system files a brief and settles the routing charge once the brief is accepted into scope, without creating a manual billing relationship first.
Direction · Machine Payments Protocol
Governed machine payments for AI-mediated research workflows.
True Primary is shaping its machine-side surface around the Machine Payments Protocol so authorised agents can file briefs, retrieve evidence, and handle metered research actions with policy-bound, receipt-backed exchange.
Status · pilot scoping open · endpoint on the build path
Designed to be machine‑readable · policy‑bound · receipt‑backed · audit‑ready
Why this matters now
As more work moves through AI interfaces and software agents.
The hard problem is no longer only retrieval or orchestration. It is how a machine-side action is allowed, constrained, paid for, and recorded without turning the workflow back into manual billing pages and account setup.
MPP is the open protocol model for that. True Primary is shaping its machine-side surface around MPP for the traffic that will sit underneath the human research workflow.
Worked exchange · target stateMPP · 402 → 200
> GET /transcripts/TR-L6A/summary HTTP/1.1
> Host: api.trueprimary.com
> Accept: application/json
< HTTP/1.1 402 Payment Required
< Date: Tue, 01 Sep 2026 12:00:00 GMT
< WWW-Authenticate: Payment
< id="q-7c19",
< realm="api.trueprimary.com",
< method="card", intent="charge",
< expires="2026-09-01T12:05:00Z",
< request="eyJhbW91bnQiOiI…"
··· agent signs within principal policy ···
> GET /transcripts/TR-L6A/summary HTTP/1.1
> Authorization: Payment
> eyJjaGFsbGVuZ2UiOnsi…
< HTTP/1.1 200 OK
< Payment-Receipt:
< eyJzdGF0dXMiOiJzdWNjZXNz…
<
< {
< "transcript": "TR-L6A",
< "summary": "…",
< "citations": 4
< }Header shape per the Payment HTTP authentication draft (draft-ryan-httpauth-payment), wrapped for display and sent as single field lines. Credential signed by the agent under the principal's policy; receipt issued by api.trueprimary.com and verifiable on its own. Values and host illustrative.
Architecture
Four layers. Each carries one responsibility.
Principal and policy at the top. Agent or application underneath. MPP carries the challenge, the payment credential, and the receipt; settlement happens on the chosen rail. The True Primary resource sits at the bottom, with verifiable receipts attached to every paid action.
Architecture · target stateReceipt-backed
- 01Layer 1 of 4
Principal · policy
Who may spend, on what, under which budget. Each request is signed under that policy and checked against its limits before settlement.
- 02Layer 2 of 4
Agent · application
An autonomous workflow, an internal service, or a human-in-the-loop request issued under the policy.
- 03Layer 3 of 4
MPP · challenge, credential, receipt
402 Payment Required → authorisation → receipt-bearing response. Verifiable end to end.
- 04Layer 4 of 4
True Primary resource · audit
Brief intake, transcript summary access, library query. Each paid action linked back to a receipt.
Machine-readablePolicy-boundReceipt-backedAudit-ready
The exchange
Four steps, one challenge and one retry.
- 01
Client requests a paid resource
An agent, application, or human asks for something the API offers. A transcript summary, a synthesis, a metered library query.
- 02
Server returns a payment challenge
402 Payment Required. The challenge names the accepted method and carries the payment request: amount, currency, recipient, expiry.
- 03
Client fulfils the challenge
Inside the policy and limits the principal has delegated to it. The protocol does not care which payment rail; it cares that the proof is verifiable. Card, bank and stablecoin rails all resolve to the same gate.
- 04
Server verifies and returns the resource
Plus a Payment-Receipt header. The whole transaction concludes in one challenge and one retry, machine-readable end to end.
Where MPP fits at True Primary
The human side stays human. MPP runs underneath it.
Briefs, source routing, expert interactions, and transcript-backed evidence remain a human workflow. MPP fits in the layer underneath: the machine-side traffic that files a brief on behalf of an authorised agent, retrieves a paid transcript summary, or runs a metered library query.
Per-transcript access
A downstream system requests a single transcript summary or piece of synthesis and receives a receipt-backed response.
Metered library queries
Short, machine-side synthesis queries can be priced at the request level instead of via surrounding account complexity.
Compliance by receipt
Every machine-side paid action ties back to a receipt-bearing event and an auditable workflow.
Governance and delegated authority
Not autonomous spending. Delegated authority with limits.
Principal and policy
Who may spend, on what, under which budget. The principal sets the policy; the agent operates within it.
Receipt-backed
Every machine-side paid action carries a receipt linked to a brief, a source, and a caveat.
Audit-ready
The audit trail is the protocol, not a screenshot. Every receipt is independently verifiable.
Open standard
MPP is an open specification published at mpp.dev, built on the Payment HTTP authentication scheme submitted to the IETF as an Internet-Draft. We build on that open base, so our machine-side surface depends on no single vendor's billing layer.
What is real today
Briefs reach us through /access today.
MPP-aware intake is on the build path. Settlement is agreed per pilot: card and bank rails by default, stablecoin where a client asks for it. Where an on-chain rail is used, our payee identifier is trueprimary.eth.
Today
Briefs reach True Primary through /access. Engagements run through True Primary's operating systems.
Build path
MPP-aware brief intake, transcript-summary access, and metered library queries are being scoped against the protocol.
Pilot scope
We are scoping integrations with teams designing agents on top of research. Talk to us about your principal, policy, and limits.
Building agents on top of True Primary?
If you are designing machine-side flows that need policy-bound, receipt-backed exchange, bring us your principal, policy, and limits — pilot scoping is open now.