CAST Field Guide

Both parties sign before the money moves. A bilateral coordination protocol for commercial payments — and the verification layer beneath an agentic economy.

This is the CAST Field Guide — our thinking on trust, settlement, and accountability, and the architecture beneath them. For the product itself, see cast.digitalfinancehq.com.

Both parties sign before the money moves.

CAST adds a mutual authorization step before a payment is released. Both parties co-author one cryptographically bound record of the transaction — who is paying, who is receiving, how much, and where it goes. That record becomes the authorization, and it travels with the payment through the ERP, the audit, the lender, and the insurer as tamper-evident proof.

The proof is produced once, at transaction time. Verification cost drops to near zero, because checking a hash is structurally cheaper than reconstructing a decision chain.

The problem

Every commercial payment today is authorized by one side. The payer approves an invoice internally; the counterparty learns of the transaction only when — or if — the money arrives. A process where only one party has confirmed the terms before value moves is not a bilateral authorization. It is a unilateral instruction with a hope attached.

The cost is concrete: roughly $2.9B in annual U.S. losses to Business Email Compromise, plus the reconciliation drag, audit archaeology, and lender friction that follow from records no downstream party can trust without re-checking. This is not a software bug to patch — the trust model under commercial payments was never bilateral.

The reframe

Stopping payment fraud is the door most people walk through. Behind it is a larger shift. As AI commoditizes execution — the cost of generating financial output approaches zero — the binding constraint moves from production to verification. The question stops being can we produce this output and becomes can we prove this output is trustworthy.

Verification is the invariant. CAST replaces opinion-based reconstruction — an auditor reading email threads — with proof-based verification: a lineage-hash check anyone can run, without contacting either counterparty. This is the verification-bottleneck thesis (Catalini, Hui & Wu, 2026) made concrete.

Start here

What is CAST?

The thesis in five minutes, and the shift from systems of record to systems of coordination.

The five primitives

Event, Policy Version, Work Order, Posting, Case. Everything else is a projection of these five objects.

The seven invariants

Structural impossibilities enforced in the schema — controls that remove the failure, not just throttle it.

Why Confirm & Pay first

Why accounts payable is the first deployable proof of a vertical-agnostic architecture.

The architecture, briefly

CAST is built on five canonical objects, with lineage — the immutable hash chain — running through all of them. The guarantees are enforced where they survive every refactor: in the schema, not the application.

The Vendor Event Layer

A portable proof history the counterparty owns and carries across every buyer — the network that compounds.

Agentic commerce

The settlement layer beneath an agentic economy: even a perfectly-secured agent’s payment requires bilateral co-authorship.

Perspectives

Original essays on deterministic commerce, zero trust, and liability as a service.

See it enforced

A working build — one bilateral payment, with a verifier that recomputes the proof in the browser.

The takeaway

Spend thirty minutes here and the conclusion should be unavoidable: CAST holds a fundamentally different model for how work, trust, settlement, AI, and accountability should operate — one where agreement is guaranteed by construction rather than reconstructed after the fact.

Talk to us

Book a walkthrough of the Layer 0 demo, or reach out with questions — [e-mail].