OpenAI Updates ACP Spec to v1.1 – Added Multi-item Cart Support

ACP specification update for multi-item cart.

Published: January 29, 2026

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OpenAI Updates ACP Spec to v1.1 – Added Multi-item Cart Support

ACP specification update for multi-item cart.

Published: January 29, 2026

ACP v1.1 Highlights

The Agentic Commerce Protocol (ACP) specification was updated to support multi-item carts in a single checkout session. Previously, flows were largely single-item; the new behavior allows users to add several products and complete one combined purchase from within a conversation.

Implementation impact

If you have already implemented ACP endpoints, review your create_checkout_session (or equivalent) logic to accept an array of line items. The spec documents the expected payload shape and error handling for partial failures.

References

ACP specification (GitHub)
Stripe ACP documentation