Agentic Commerce UCP clients

TypeScript/JavaScript and Python REST clients for Universal Commerce Protocol 2026-08-25. Discover a merchant, select shared capabilities, and call catalog, cart, checkout and order operations through its advertised endpoint.

Language	Package	Source
TypeScript / JavaScript (Node.js 20+)	@agentic-commerce-lab/ucp-client	Quick start
Python 3.10+	agentic-commerce-ucp-client	Quick start

What the clients provide

• Discovery at /.well-known/ucp with explicit protocol and REST binding selection.
• Twelve named operations for catalog search/lookup, carts, checkout sessions and orders.
• RFC 9421 request signing with Ed25519 or P-256, including the digest of the exact transmitted body.
• Prepared requests that retain the same body and idempotency key for a deliberate retry after an uncertain write.
• Structured HTTP errors with the original response and prepared request; business states and continue_url remain available to the caller.

Request and response payloads are JSON objects. Pair these transport clients with the official UCP schemas and model SDKs for composed payload validation. The first release covers REST calls and outgoing request signatures; webhook verification, payment-handler execution and schema composition are separate integration work.

Package availability

Version 0.1.0 is prepared for npm and PyPI. Until a registry release is visible, install the built tarball or wheel from a GitHub release, or build from source. The package names above are planned registry coordinates, not a claim that a registry publication already exists.

Development

cd packages/typescript
npm ci
npm run build
npm test
cd ../..
python3 -m venv .venv
.venv/bin/pip install -e 'packages/python[signing]' -r tests/requirements.txt
.venv/bin/python -m unittest discover -s packages/python/tests -v
.venv/bin/python tests/test_signatures.py

Tests compare operation paths to the pinned upstream OpenAPI artifact, exercise HTTP request behavior, and verify both signers with the independent http-message-signatures library. These checks do not establish full UCP conformance or interoperability with every merchant.

See release setup and scope and protocol reference.

Own source is MIT licensed. The upstream reference artifact retains its Apache-2.0 license; see reference attribution.