# When the buyer is an agent. What already works in agentic commerce and what is still an experiment

> Agentic commerce in 2026. How AI agents find products, check facts and pay on a buyer's behalf, what is live, what is still a pilot, and what it means for sellers.

Page: https://opsalute.ai/en/blog/when-the-buyer-is-an-agent
Русская версия: https://opsalute.ai/llms/ru/blog/when-the-buyer-is-an-agent.md
Published: 2026-09-29 · Market

In late September 2025, ChatGPT got a Buy button, and agentic commerce showed up inside an ordinary chat. OpenAI and Stripe launched Instant Checkout, letting US users pay for items from Etsy sellers without leaving the chat. More than a million Shopify merchants were supposed to follow.

Six months later, OpenAI stepped back. In March 2026 the company wrote that the first version of Instant Checkout did not offer the flexibility it was aiming for. Merchants could now use their own checkout, and ChatGPT would focus on product discovery.

Modern Retail looked at why. A Walmart executive said in-chat conversion ran about three times lower than for items that sent shoppers to the retailer's site. Shoppers disliked checking out one item at a time, and retailers missed coupons, loyalty programs and store pickup.

Forrester reported that only about a dozen Shopify merchants were live with the ChatGPT catalog feature; Shopify later put the number closer to 30.

The episode is a good snapshot of where agentic commerce stands. Assistants already shape what people choose. The last step, payment, is still being assembled piece by piece. Below we go layer by layer: how an agent finds a product, how it checks facts, who pays, who is responsible when something goes wrong, and what this means for sellers.

## How an agent finds a product

A person scrolls a catalog and looks at photos. An agent reads data. That is why platforms ask merchants for product feeds: regularly updated files or APIs with items, prices, stock and terms.

OpenAI takes these feeds through the Agentic Commerce Protocol (ACP), an open protocol it released with Stripe. Google added a native_commerce attribute to Merchant Center: with it, a listing gets a Buy button in Gemini and AI Mode; without it, the listing stays a regular product card. In January 2026, Shopify opened its Catalog to brands that do not run their online store on Shopify, and lets merchants manage distribution to ChatGPT, Microsoft Copilot, AI Mode and Gemini from one admin.

Machine visitors are growing. In September 2026, Cloudflare said that more than half of the traffic reaching sites on its network was no longer human, and that daily requests from AI agents had grown by more than 1,700% in a year. That is one network, not the whole internet, but the direction is clear.

## How an agent checks facts

Agents compare what they find, and they do not always do it the way we expect. In August 2026, Wharton Generative AI Labs published a report on roughly 26,000 tests across six models. The agent had to pick a fitness watch from eight options.

On a bare product grid, models picked consistently. But a single review shown before the grid often overrode everything else. Reordering the same sources changed the outcome for some models.

One sentence of user memory, such as "I love hiking," pulled most models away from the objectively best product. The authors summed it up: the more context they added, the less predictable the final choice became.

Two takeaways for sellers. Product facts need to match everywhere an agent might find them: the feed, the website, marketplaces, reviews. And the only way to know how agents see your product is to test it, asking them the questions your customers ask.

## Who pays, and who says yes

In most live scenarios, a person still makes the final call. On October 15, 2026, Google launched Universal Cart in the US: a cart in Search and the Gemini app that holds items from different retailers.

Shoppers can pay with Google Pay in a few taps or move items to the retailer's own cart. The merchant remains the seller of record. Checkout runs on the Universal Commerce Protocol (UCP), an open standard Google developed with Shopify, Etsy, Wayfair, Target and Walmart.

With Shopify, an agent can build a cart, but under general access it gets a link, and the buyer completes checkout on the merchant's storefront.

Card networks are going further. In July 2026, Visa announced that AI agents were making live purchases from merchants in Europe, with more than 30 issuing banks involved. Agents act within limits the cardholder set and approved, and each transaction is authenticated with Visa Payment Passkeys.

In March 2026, Mastercard and Santander completed what they called Europe's first end-to-end payment executed by an AI agent. It ran in a controlled environment and was not a commercial rollout.

Purchases with no human present at the moment of payment exist mostly in specs and roadmaps. In April 2026, Google released version 0.2 of its Agent Payments Protocol (AP2) with a "human not present" flow: the agent buys under instructions given in advance, for example tickets the moment they go on sale.

In May, Google showed Gemini Spark, an assistant with planned support for payments within a set budget and list of merchants. At the time it was in early testing and, according to Google, designed to check with the user before major actions.

## Who is responsible when something goes wrong

The market is still working this out. In both the OpenAI and Google setups, the merchant remains the seller: it accepts the order, ships it, issues refunds and handles customer support.

The first high-profile dispute is about who lets an agent into a store at all. In March 2026, a federal court in San Francisco granted Amazon a preliminary injunction blocking Perplexity's Comet browser agent from password-protected parts of Amazon.

The judge found strong evidence that the agent accessed accounts with the user's permission but without Amazon's authorization. Amazon also alleged that Comet presented itself as an ordinary Chrome browser. The ruling is preliminary, and Perplexity has appealed.

That is why agent identification is becoming its own layer. In autumn 2025, Visa and Cloudflare introduced the Trusted Agent Protocol: the agent signs its requests with a cryptographic key, so a merchant can tell a registered agent from a malicious bot. Mastercard Agent Pay builds on the same technology.

AP2 adds a chain of signed instructions recording what the user authorized and for how much. That trail matters when a dispute has to be resolved.

## B2B: procurement is delegating too

In a Deloitte survey of more than 1,000 US suppliers and buyers, nearly 40% of B2B buyers said they already use agentic AI in purchasing. 24% of suppliers use agents in their sales process.

The first payments are here as well. On October 20, 2026, Visa, BILL and Billtrust launched a live pilot in which a buyer's agent logs in to a supplier portal and pays invoices.

The caveat matters: the agent does not decide what to pay. It only executes payments the buyer has already approved, and it does so without shared employee logins.

Another data point is Anthropic's Project Deal. 69 employees let agents trade personal items on their behalf, and the agents closed 186 deals worth just over $4,000.

The stronger model sold for more and bought for less than the weaker one. People represented by the weaker model did not notice: they rated their deals as just as fair.

## What works in agentic commerce today and what is still an experiment

Already live:

- product search and comparison in AI assistants, based on merchant feeds;
- carts and payment with a human confirming, as in Universal Cart in the US or via a hand-off to the merchant's checkout;
- agent-initiated card payments in Europe within limits set by the cardholder.

Still a pilot or an experiment:

- purchases with no human present at the moment of payment;
- agent payments between businesses, as in the Visa, BILL and Billtrust pilot;
- agents negotiating prices with each other.

## What becomes a seller's advantage

We are not going to guess which protocol wins. How they differ is covered in our guide to [agentic commerce protocols](https://opsalute.ai/en/blog/agentic-commerce-protocols). But what is already live shows what each side needs.

The agent needs accurate facts from a single source of truth: price, stock, delivery, returns. The platform needs a merchant that can accept an order without manual work. The buyer needs a clear moment to confirm the purchase.

And the Instant Checkout story shows that retailers are reluctant to give up checkout, loyalty and customer data. In March 2026, Forrester explicitly advised merchants to hold on to the checkout process.

We put together a detailed checklist in a separate article: [how a store can prepare for AI shopping agents](https://opsalute.ai/en/blog/prepare-store-for-ai-agents).

## Where Opsalute fits

We build Shelfport, a tool that helps a store prepare its catalog and purchase path for AI assistants and test that path on its own products. It is currently in beta. It does not guarantee placement in assistant answers; the assistant decides what to recommend. [See Shelfport](https://opsalute.ai/en/shelfport).

## Sources

- [Stripe: Instant Checkout in ChatGPT and the Agentic Commerce Protocol, September 29, 2025](https://stripe.com/newsroom/news/stripe-openai-instant-checkout)
- [OpenAI: Powering Product Discovery in ChatGPT, March 24, 2026](https://openai.com/index/powering-product-discovery-in-chatgpt/)
- [Modern Retail: What went wrong with ChatGPT's Instant Checkout, March 27, 2026](https://www.modernretail.co/technology/what-went-wrong-with-chatgpts-instant-checkout/)
- [Forrester: What It Means That The Leader In Agentic Commerce Just Pulled Back, March 2026](https://www.forrester.com/blogs/what-it-means-that-the-leader-in-agentic-commerce-just-pulled-back/)
- [OpenAI: Agentic Commerce documentation](https://developers.openai.com/commerce)
- [Google Merchant Center: native_commerce attribute](https://support.google.com/merchants/answer/17251586)
- [Shopify: AI commerce at scale, January 11, 2026](https://www.shopify.com/news/ai-commerce-at-scale)
- [Cloudflare: The Internet has a second audience, September 30, 2026](https://blog.cloudflare.com/agentic-web/)
- [Wharton Generative AI Labs: Agentic Shopping is Complicated and Contingent, August 27, 2026](https://gail.wharton.upenn.edu/research-and-insights/technical-report-agentic-shopping/)
- [Google: Universal Cart launches in the US, October 15, 2026](https://blog.google/products-and-platforms/products/shopping/universal-cart-launch/)
- [Google for Developers: Under the hood of the Universal Commerce Protocol, January 11, 2026](https://developers.googleblog.com/under-the-hood-universal-commerce-protocol-ucp/)
- [Shopify: Checkout MCP](https://shopify.dev/docs/agents/carts-and-checkout/checkout-mcp)
- [Visa: live agentic commerce transactions across Europe, July 2, 2026](https://www.visa.co.uk/about-visa/newsroom/press-releases.3457328.html)
- [Santander and Mastercard: Europe's first live end-to-end payment executed by an AI agent, March 2, 2026](https://www.santander.com/en/press-room/press-releases/2026/03/santander-and-mastercard-complete-europes-first-live-end-to-end-payment-executed-by-an-ai-agent)
- [Google: AP2 v0.2 and the FIDO Alliance donation, April 28, 2026](https://blog.google/products-and-platforms/platforms/google-pay/agent-payments-protocol-fido-alliance/)
- [Google: 100 things announced at I/O 2026, May 20, 2026](https://blog.google/innovation-and-ai/technology/ai/google-io-2026-all-our-announcements/)
- [AP2: Agent Payments Protocol](https://ap2-protocol.org/)
- [Agentic Commerce Protocol](https://www.agenticcommerce.dev/)
- [Search Engine Journal: Amazon wins preliminary injunction against Perplexity's Comet, March 2026](https://www.searchenginejournal.com/amazon-wins-preliminary-injunction-against-perplexitys-comet/569256/)
- [Cloudflare: Trusted Agent Protocol and Web Bot Auth, October 2025](https://blog.cloudflare.com/secure-agentic-commerce/)
- [Deloitte: Agentic commerce in B2B, June 26, 2026](https://www.deloitte.com/us/en/what-we-do/capabilities/applied-artificial-intelligence/articles/b2b-agentic-commerce.html)
- [Visa, BILL and Billtrust: first live pilot for trusted AI agent payments, October 20, 2026](https://usa.visa.com/about-visa/newsroom/press-releases.releaseId.22856.html)
- [Anthropic: Project Deal, April 24, 2026](https://www.anthropic.com/features/project-deal)