> ## Documentation Index > Fetch the complete documentation index at: https://docs.stateset.com/llms.txt > Use this file to discover all available pages before exploring further. # Intelligent Commerce Protocol (ICP) > StateSet's open protocol for agent-native commerce — intent verbs, signed mandates, verifiable JWS receipts, and ACP/UCP/MCP/A2A compatibility. # Intelligent Commerce Protocol (ICP) ICP is StateSet's open protocol for **agent-native commerce**: one wire contract that lets any autonomous agent discover merchants, quote baskets, authorize payment, complete checkout, track fulfillment, and handle returns — across currencies, jurisdictions, and payment rails, under a verifiable mandate. The current specification version is **`2026-04-21`**. ## Positioning ACP terminates ChatGPT checkout. UCP provides platform-neutral checkout interop. **ICP subsumes both** — it is the superset spec a globally-distributed fleet of agents can target as a single, stable contract, with the engine of record sitting *inside* the handler process. | Protocol | What it covers | What it leaves out | | --------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------- | | **[ACP](/stateset-acp/stateset-acp-async-processing)** (OpenAI, 2025) | ChatGPT Instant Checkout — session create, update, complete, plus delegated payment vault tokens | Agent identity, mandates, budgets, negotiation, returns, subscriptions, stablecoin payments, global jurisdictions, peer (A2A) commerce | | **[UCP](/stateset-ucp)** (StateSet, 2026-01) | Platform-neutral checkout interop with discovery, tokenization, OAuth identity linking, AP2 mandates, order webhooks | Negotiation, declarative intent model, verifiable receipts, embedded engine, peer-agent payments, first-class global commerce | | **MCP** (Anthropic) | Agent tool surface | Commerce semantics — MCP tools are untyped for the commerce lifecycle | | **A2A** (Google) | Agent-to-agent task protocol | Commerce semantics | ## Design principles * **Agent-first** — every request carries an identified agent plus a signed mandate. **No anonymous writes.** * **Intent-based** — a small, stable set of verbs rather than merchant-specific CRUD. * **Verifiable** — every state-changing response is a compact JWS receipt over the JCS-canonicalized body. Any party can verify it **offline**. * **Global** — multi-currency (fiat and stablecoin), multi-jurisdiction tax, and cross-border fulfillment as first-class concerns. * **Embedded engine** — the handler carries the full [iCommerce](/stateset-icommerce/stateset-icommerce-quickstart) engine in process. No separate database, no control plane, no network hop between protocol and execution. * **Interoperable** — one handler exposes ICP natively while speaking ACP, UCP, MCP, and A2A on compatibility paths that route into the same transaction and receipt pipeline. ## Intent verbs | Verb | Purpose | | ---------------------------- | ----------------------------- | | `intent.search` | Discover offers | | `intent.describe` | Describe an offer or merchant | | `intent.quote` | Quote a basket | | `intent.negotiate` | Negotiate terms | | `intent.revise` | Revise a quote | | `intent.authorize` | Authorize payment | | `intent.buy` | Complete a purchase | | `intent.pay` | Pay against an authorization | | `intent.track` | Track fulfillment | | `intent.confirm_receipt` | Confirm delivery | | `intent.return` | Start a return | | `intent.refund_request` | Request a refund | | `intent.subscribe` | Start a subscription | | `intent.renew` | Renew a subscription | | `intent.pause` | Pause a subscription | | `intent.cancel_subscription` | Cancel a subscription | | `intent.cancel` | Cancel an order | Vendor extensions use the `intent.ext.` namespace, e.g. `intent.ext.com.stateset.loyalty.redeem`. ## Architecture ```text theme={null} ┌──────────────────────────────────────────────────────┐ │ ICP Handler (Rust) │ Agents ──┬──▶ │ HTTP /icp/v1/intents ──┐ │ │ │ gRPC icp_handler.v1 │ │ │ │ SSE /icp/v1/events ─┤ ┌──────────────────┐ │ │ │ MCP /mcp ──┼──▶ │ IcpService │ │ │ │ A2A /a2a/v1 ──┘ │ (intent router) │ │ │ │ │ ▸ mandate │ │ ├──▶ │ Compat: │ ▸ quote │ │ │ │ ACP /checkout_sessions ───▶ │ ▸ authorize │ │ │ │ UCP /api/checkout-… ───▶ │ ▸ buy/pay │ │ │ │ │ ▸ return/track │ │ │ │ └─────────┬────────┘ │ │ │ ┌───────▼────────┐ │ │ │ │ stateset- │ │ │ │ │ icommerce │ │ │ │ │ (embedded) │ │ │ │ │ SQLite / PG │ │ │ │ └────────────────┘ │ │ │ Receipts → Ed25519 JWS → /.well-known/icp/jwks.json │ └────┘ │ └──────────────────────────────────────────────────────┘ ``` ## Receipts Every state-changing response is a compact **JWS receipt** signed with Ed25519 over the JCS-canonicalized body. The verification key set is published at: ``` /.well-known/icp/jwks.json ``` Because verification needs only the receipt and the JWKS, any party can verify a transaction **offline** — no call back to the merchant or the handler. ## Quickstart ```bash theme={null} git clone https://github.com/stateset/stateset-icp-handler cd stateset-icp-handler cargo build --release # Local demo: demo API key, relaxed request headers ICP_ENABLE_DEMO_KEYS=true \ ICP_REQUIRE_VERSION=false \ ICP_REQUIRE_MANDATE=false \ ICP_REQUIRE_REQUEST_ID=false \ ICP_REQUIRE_IDEMPOTENCY_KEY=false \ cargo run --release # HTTP → http://0.0.0.0:8082 # gRPC → 0.0.0.0:50052 ``` The demo flags above disable version negotiation, mandate verification, request ids, and idempotency keys. They exist to make a first local run easy — **never enable them on a deployment that accepts real agent traffic.** With `ICP_REQUIRE_MANDATE=false` there is no signed authority behind a write. ## Related * [UCP](/stateset-ucp) — platform-neutral checkout interop * [ACP](/stateset-acp/stateset-acp-async-processing) — ChatGPT Instant Checkout * [iCommerce](/stateset-icommerce/stateset-icommerce-quickstart) — the embedded engine