# Financial Comptroller — Agentic Commerce Protocol (ACP)

> Agentic KG Holdings → https://agent-kg.ai. This surface implements the rail it is named after. Nothing here is endorsed by any protocol's owner. Prices are placeholders set by the office.

The Agentic Commerce Protocol (ACP) is the checkout specification a merchant implements so an agent platform can buy on the buyer's behalf: a product feed, checkout session endpoints (create, update, complete, cancel, retrieve) versioned by an API-Version header, and a delegated payment — the platform hands the merchant an encrypted payment token from a payment service provider and the merchant charges it with its own processor. This surface implements the checkout session endpoints at API-Version 2025-09-12 as the specification read on 2026-09-19.

## Doors

- https://agent-acp.ai/api — the paid door (x402 v2: 402 without payment, the office door's statement and a signed receipt with PAYMENT-SIGNATURE)
- https://agent-acp.ai/offers.json — the two offers (placeholder prices)
- https://agent-acp.ai/x402/receipt/{nonce} — resolve a receipt
- https://agent-acp.ai/x402/settled.json — this host's register, four-host total beside it
- https://agent-acp.ai/x402/jwks.json — receipt key (kid fc-x402-2026-09)
- https://agent-kg.ai/mcp — the office door (Model Context Protocol (MCP)) — the product

## Rails on every host

- x402 — live, USDC on Base mainnet
- Machine Payments Protocol (MPP) — challenge, credential, receipt as the spec reads; settles in test mode once the office's Stripe test keys are placed
- Universal Commerce Protocol (UCP) — /checkout-sessions REST; /.well-known/ucp published when a handler can settle
- Agentic Commerce Protocol (ACP) — /checkout_sessions at API-Version 2025-09-12; /acp/feed.jsonl served when the rail can settle

## The four

- https://agent-x402.ai/
- https://agent-mpp.ai/
- https://agent-ucp.ai/
- https://agent-acp.ai/

## Kit

- https://agent-acp.ai/.well-known/agent-card.json · https://agent-acp.ai/.well-known/jwks.json · https://agent-acp.ai/.well-known/mcp.json · https://agent-acp.ai/.well-known/ai-catalog.json · https://agent-acp.ai/.well-known/security.txt · https://agent-acp.ai/facts.json · https://agent-acp.ai/health.json · https://agent-acp.ai/index.md (Markdown twin, also on Accept: text/markdown)

Surface 0.1.0 · as of 2026-09-19. No cookies. No tracking.