vision

The A2A stack: agent-to-agent commerce

Agents calling agents, paying for API access, and verifying each other's outputs. This is agent-to-agent commerce, and it needs new infrastructure.
Jithin Raj, Founder2025-12-032 min read

The problem: agents cannot coordinate

AI agents are already calling APIs, browsing websites, and executing code. But when Agent A needs to use Agent B's service, fundamental questions arise:

  • How to discover AI policy and pricing?
  • How to pay without human intervention?
  • How to verify work was performed?
  • How to maintain audit trails?

The A2A stack

The A2A (agent-to-agent) stack describes the layers needed for autonomous agent commerce. Each layer addresses a specific coordination problem:

  • Layer 1, AI policy discovery. Agents discover bot policy, crawling rules, and terms at /.well-known/peac.txt.
  • Layer 2, access control (HTTP 402). Gated endpoints return 402 with payment instructions (x402, Stripe).
  • Layer 3, receipts. Every transaction returns a signed, verifiable record as proof.
  • Layer 4, provenance. Chain of records creates auditable lineage for compliance.

An A2A transaction flow

How a complete agent-to-agent transaction works with PEAC:

  1. Policy check. Agent A fetches /.well-known/peac.txt to discover crawling policy and payment options.
  2. Access request. Agent A calls Agent B's API endpoint.
  3. 402 response. Agent B returns HTTP 402 with payment details.
  4. Payment. Agent A pays via configured method (x402, Stripe).
  5. Receipt. Agent B processes request and returns a signed record in headers.
  6. Verification. Agent A or operator verifies record at the verify endpoint.

Why records matter

In human-to-business transactions, receipts are obvious: email confirmations, PDF invoices, bank statements. Agent-to-agent transactions need the same thing, but machine-readable.

  • Proof of service. Cryptographic evidence of work performed.
  • Audit trail. Operators review agent spending.
  • Review and reconciliation. Shows exactly what was delivered.
  • Compliance. Bundled for regulatory reporting.

Getting started

If you are building agent infrastructure:

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