Protocols
Agorio is a quad-protocol SDK. A single ShoppingAgent can transact with merchants that speak
any of four commerce protocols, and the protocol clients auto-detect which transport a merchant
uses.
| Protocol | Lineage | What it covers | Client |
|---|---|---|---|
| UCP | Google / Shopify | Capability discovery, REST/MCP transport, payment handlers | UcpClient |
| ACP | OpenAI / Stripe | Checkout-session lifecycle, webhook order model | AcpClient |
| AP2 | FIDO | Signed payment mandates (Intent → Cart → Signed) | Ap2Client |
| MCP | Anthropic | Tool / resource / prompt transport | McpClient |
How auto-detection works
When you point an agent at a merchant domain, the UCP client first probes /.well-known/ucp. If a
UCP profile is found, its declared transport (REST or MCP) is used. If not, the agent falls back
to the protocol the configured adapter implements. ACP merchants are driven through AcpClient’s
checkout-session methods, and AP2 mandate signing is layered on top when you opt in with
ap2: true.
For the design rationale on how UCP and ACP overlap (and when they’re interchangeable), see ADR
docs/adr/0008-ucp-acp-overlap-and-interchangeability.md in the repository.