2026-04-08 historical release
Published 2026-04-09 · First observed 2026-09-28
Cart capability and capability-resolution changes.
Merchant impact: Pin profile and capability versions; verify provider support before migration.
Version source ↗Protocol intelligence / Commerce
Universal Commerce Protocol
A common model for agents and businesses to negotiate commerce capabilities.
Specification state: livePrimary evidence available
StewardGoogle / Shopify and ecosystem contributors
Stack layerCommerce
Version2026-08-25
Last evidence check28 September 2026
Merchant answer / Evidence review pending
A common model for agents and businesses to negotiate commerce capabilities. Connects catalog, cart, checkout and related commerce capabilities across implementations. Does not make every declared capability live on every shopping surface. Individual merchant eligibility and deployed configuration require confirmation.
What this establishes
The documented role and version scope in the source ledger.
What it cannot establish
An unresolved dependency remains. Treat affected claims as provisional. Live merchant deployment, private account eligibility, purchase completion or guaranteed AI selection.
Claim-to-source mapping
- description: A common model for agents and businesses to negotiate commerce capabilities. · verified · Checked 2026-09-28 · Sources: ucp-spec, ucp-google, google-september, shopify-june
- role: Connects catalog, cart, checkout and related commerce capabilities across implementations. · verified · Checked 2026-09-28 · Sources: ucp-spec, ucp-google, google-september, shopify-june
- version: 2026-08-25 · verified · Checked 2026-09-28 · Sources: ucp-spec, ucp-google, google-september, shopify-june
- version: 2026-08-25 · verified · Checked 2026-09-28 · Sources: v11-ucp-releases
Version-aware protocol intelligence
Current version. Clear scope.
Current version2026-08-25
Current statusreleased
Published date2026-08-25
First observed / last verified2026-09-28 / 2026-09-28
GitHub release published_at; distinct from the date encoded in a version tag.
Scope: Official repository release · Layer: Commerce · Steward: Google / Shopify and ecosystem contributors
Merchant impact
Multi-vertical structure, payment-security and constraint updates.
Pin profile and capability versions; verify provider support before migration.
Public implementation evidence: Google and Shopify describe scoped implementations
Merchant action today: Publish a versioned business profile where required by your integration.
Unknowns: Your enabled version, provider rollout, plan and region require merchant-side confirmation.
Source capture hashes
Previous versions
2026-01-23 historical release
Published 2026-01-23 · First observed 2026-09-28
Dated January maintenance release.
Merchant impact: Pin profile and capability versions; verify provider support before migration.
Version source ↗2026-01-11 historical release
Published 2026-01-23 · First observed 2026-09-28
Initial dated release retained in the official release log.
Merchant impact: Pin profile and capability versions; verify provider support before migration.
Version source ↗Documented role
What it helps with
Connects catalog, cart, checkout and related commerce capabilities across implementations.
Keep the scope clear
What it does not solve
Does not make every declared capability live on every shopping surface.
The merchant work
- Publish a versioned business profile where required by your integration.
- Choose supported capabilities and payment handlers.
- Verify surface eligibility and test in the partner sandbox.
Individual merchant eligibility and deployed configuration require confirmation.
| Version | 2026-08-25 |
|---|---|
| Discovery | /.well-known/ucp profile; optional catalog capability |
| Checkout | Commerce checkout capability |
| Payment | Payment handlers; complements authorization protocols |
| Authorization | Can work with AP2; capability-specific |
| Transport | REST, MCP and A2A bindings documented |
| Adoption | Google and Shopify describe scoped implementations |
| Regions | Surface-dependent |
Append-only history
What we observed, and when.
First house observation: 28 September 2026. Earlier dates, where known, are effective dates researched retrospectively.
Evidence improved
2026-08-25; 4 scoped version record(s) now linked.
V1 record: 2026-08-25; no structured prior-version timeline.
2026-08-25; 4 scoped version record(s) now linked.
Merchant impact: Pin profile and capability versions; verify provider support before migration.
Evidence ledger
Go to the source.
Primary documentation records what is publicly stated. It does not independently prove outcomes or your account’s eligibility.
Claim scope: Discovery profile and commerce capabilities
Version-pinned profile discovery; declared capabilities do not prove successful transactions.
Claim scope: Commerce semantics and interoperability
Claim scope: UCP merchant integration hub and AI performance insights
US rollout; later markets are future plans. Scale/performance statements are Google claims.
Claim scope: Developer UCP and Catalog access
Self-serve developer access. Conversion metrics in the article are vendor claims, not our results.
Claim scope: Version metadata and documented changes only; not merchant adoption.
SHA-256 of retrieved source response: a554d5a172bb62d0d22abda152b99817fddd9735f434866d1c49863274dc049c