What each AI shopping assistant needs from your feed

The table summarizes each AI shopping surface as of 17 October 2026. In-chat checkout means the shopper pays without leaving the assistant.

What each surface asks before you go live

Checkout is US-only almost everywhere, but a merchant in Germany, the Netherlands or the UK first wants to know whether products can be found. The short answer from official documentation: the assistants are available in Europe, while country lists for AI product discovery are not published.

Google outside the US

AI Mode is listed in many countries in the Americas, APAC and EMEA, including the UK, Germany, France and the Netherlands⁷³, but buying in AI Mode, Universal Cart, virtual try-on and the agentic features in Search Labs are all US only^1,11,15. Merchant Center's AI performance insights cover only the US, Canada, Australia, India and New Zealand⁷⁴. Redirect Checkout links, a Buy Now button that sends shoppers to the merchant's cart, expanded on 1 July 2026 to countries including France, Poland and Australia, but the page does not name the Netherlands, Germany or the UK and does not mention AI Mode⁷⁵. Even inside AI Mode, the premium model tier lists the UK but not EU states¹³. In the EEA, Google Shopping is an optional linked service under the DMA⁷⁶.

OpenAI outside the US

A product's currency, URL or sizing system does not choose its market, so a EUR price or a .nl URL does not make a product eligible in the Netherlands¹⁶. The store_country field records the seller's country and does not override the US target⁷. OpenAI's merchants page says shopping in ChatGPT is live in the US and will expand to more regions over time²¹.

Other routes for EU merchants

Klarna's APP covers 13 markets, 12 of them in Europe including Germany, the Netherlands and the UK⁵⁹. Stripe's Agentic Commerce Suite is available in 34 countries⁸. In the UK, PayPal powers in-app checkout for the Hey Savi fashion search app, a smaller app rather than one of the assistants above⁷⁷. Shopify notes that AI channels might still show products from stores outside its programme through ordinary web crawling⁴⁰, which is the subject of the crawler section below.

The first table compares the feeds of the assistants that run their own catalog, with Google Merchant Center as the baseline. The second covers the feeds used by protocols and enablement services. Not in sources means none of the verified sources states the value; it does not mean the field is unsupported.

Field limits side by side

If you already run a clean Merchant Center feed, these are the additions each surface asks for. Items marked new attribute are not part of Google's main product data specification today.

Products that cannot use AI checkout

Products that a Google checkout integration must leave out include subscriptions and installments, personalized goods, used or final-sale items, pre-orders, age-restricted items, rentals and goods that need software installation¹⁹. OpenAI prohibits adult content, alcohol, nicotine, gambling, weapons and prescription-only medicines across ChatGPT shopping¹⁶. Shopify Catalog excludes alcohol, tobacco, weapons, adult content, live animals, event tickets and uncategorized products from every AI channel⁸⁸.

The OpenAI product feed

OpenAI's file-upload spec has nine required fields: item_id, title, description, url, brand, seller_name, image_url, availability and price⁷⁸. In the OpenAI format, OpenAI asks you to aim for titles of at most 150 characters and descriptions of at most 5,000; on the Google-compatible profile those are hard limits⁷. Prices are written as an amount and an ISO 4217 code, such as 79.99 USD⁷⁸. Variants share a group_id that must differ from item_id⁷⁸. GTIN is optional, but when sent it must be 8, 12, 13 or 14 digits with a valid check digit, and OpenAI asks merchants not to invent an MPN to replace a missing GTIN⁷⁸. Unknown optional values should be left out rather than filled with placeholders such as n/a⁷⁸.

Delivery and refresh

Feeds are full snapshots pushed to OpenAI over SFTP. Parquet with zstd compression is preferred, and gzipped JSONL, CSV and TSV also work³⁹. OpenAI recommends up to 500,000 items and about 500 MB per shard, and keeps a product for up to 14 days after it disappears from a snapshot³⁹. A Products API takes intraday upserts, and promotions can only be sent through the API^16,99. OpenAI suggests testing a sample of about 100 items first³⁹.

Markets and access

The standard upload targets the US. The shared format currently represents the US, Canada and Mexico, and other markets need OpenAI's confirmation¹⁶. Feed onboarding is limited to approved partners⁹. OpenAI says recommended attributes such as rich media and reviews improve ranking, and that eligibility does not guarantee display²⁴.

Checkout

ChatGPT checkout runs on ACP³¹. OpenAI is not the merchant of record: the merchant brings its own PSP, calculates tax, charges the payment and accepts or declines each order²⁴. The checkout spec lists Stripe, Adyen and Braintree as providers and cards as the only method¹⁰⁰. Each session supports one shipping address and one shipping option⁶³. Merchants that handle card data directly through the Delegated Payment spec must be a PSP or PCI DSS Level 1¹⁰¹.

In practice, OpenAI's merchants page says it is "moving away from a standalone Instant Checkout experience" and that purchases are completed on merchant-owned websites or apps²¹. OpenAI's plugin docs recommend external checkout on the merchant's own domain and keep the ChatGPT payment sheet in private beta for select marketplaces²². Shopify's help pages treat ChatGPT as a discovery channel with no ChatGPT-specific fee and send shoppers to the store's own checkout²³. The 2025 launch covered US shoppers buying from US Etsy sellers¹⁰²; no source fetched for this report confirms the current status of Etsy or Walmart in ChatGPT checkout.

Organic results

OpenAI's commerce docs describe discovery only through submitted feeds and do not mention schema.org markup or crawling¹⁶. Sites appear in ChatGPT search through OAI-SearchBot, which follows robots.txt²⁶.

ChatGPT Ads

ChatGPT Ads can reuse a product feed when products carry is_ads_eligible set to true, sent as UTF-8 CSV with HTTPS page and image URLs¹⁰³. Bidding options are CPM, CPC and conversion-optimized bidding (in open beta) billed per valid click, with no published rate card¹⁰⁴. Product-feed campaigns target by country, and the Ads developer docs publish no list of markets they can target¹⁰³. OpenAI's Help Center does list where advertisers can use self-service Ads Manager: 63 countries, based on where the billed legal entity is, including the US, UK, Germany, France and the Netherlands¹⁰⁵. That list covers advertisers, not the shopper markets a product-feed campaign can reach.

Where it works

Buying directly in AI Mode is limited to signed-in users aged 18 or over in the US, in English, with eligible US merchants¹. Shoppers pay with Google Pay from Google Wallet⁴¹. Universal Cart, announced at Google I/O on 19 May 2026, began rolling out in the US across Search and the Gemini app on 15 October 2026, with checkout through Google Pay or a transfer to the merchant's cart^106,11. For checkout at launch, Google names Nike, Sephora, Target, Ulta Beauty, Walmart, Wayfair and many Shopify merchants, and says merchants remain the seller of record¹¹. Select US merchants support account linking for loyalty points and member pricing at checkout¹.

In May 2026, Google said UCP checkout would reach Canada and Australia in the coming months and the UK later¹⁰⁶. By 16 September 2026 that had moved to early 2027 for Australia and Canada, with no UK date⁴³, and the Merchant Center hub page says the same⁴².

Feed and account

Google's route reuses the existing Merchant Center feed⁴⁴. For checkout you add checkout_eligibility per product, consumer_notice for items with regulatory warnings and merchant_item_id when IDs differ¹⁹. The account needs return policies with cost, window and a link, and at least one support contact¹⁹. In its September 2026 holiday guidance, Google also asks retailers to add the video link attribute, submit conversational attributes and connect loyalty data⁴³.

New attributes for conversational search

From 31 January 2027 Google enforces a minimum image size of 500 x 500 px⁵.

Checkout integration

Merchants publish a UCP profile at /.well-known/ucp⁶⁵ and implement the native checkout endpoints¹¹⁰. Google sets service levels of at least 95% availability, with p95 latency of 4 seconds for create, 5 for update and 10 for complete¹¹¹. Payment uses the Google Pay handler version 2026-01-23¹¹², connected through a supported PSP, or directly for PCI DSS Level 1 merchants with documentation; the handler page does not mention PayPal, Klarna or Affirm¹¹³. Only PAN_ONLY authentication is used on AI surfaces³³. Order updates are signed webhooks, and shipped events need a tracking number and URL¹¹⁴. Google must approve the integration before go-live⁶⁴. No fee for UCP checkout appears in any fetched Google source.

Scale and payment options

Google wrote in September 2026 that UCP "already enables direct checkout for hundreds of thousands of brands and retailers"⁴³, while its developer docs still describe the Merchant Center hub as early access for select merchants⁴². PayPal was announced as a coming payment option¹¹⁵, and Affirm and Klarna inside Google Pay were announced in May 2026^116,117; none was confirmed live in the pages fetched.

Other Google programs

Google first rolled out agentic checkout on Search in the US on 13 November 2025, before UCP¹¹⁸. Business Agent, a branded AI agent on Search, went live for eligible US retailers on 12 January 2026⁴¹. Direct Offers is a Google Ads pilot that shows exclusive offers in AI Mode⁴¹. AP2 spending guardrails were announced for Google products, starting with Gemini Spark¹⁰⁶. In its Universal Cart launch post of 15 October 2026, Google put the Shopping Graph at more than 60 billion continually refreshed listings¹¹. In November 2025 it had given more than 50 billion listings, 2 billion of them refreshed every hour¹¹⁸.

Where it works

Copilot Checkout was announced on 8 January 2026 and began rolling out in the US on Copilot.com¹⁷. It is now available on Copilot.com and the Copilot mobile app². Only English-language merchants who sell to US buyers in USD are eligible². Bing, MSN and Edge were named as planned expansion, but the current page does not list them as live^17,2.

How to onboard

Microsoft names two routes: directly through Microsoft Merchant Center with an MMC account and a UCP-compliant feed, or through PayPal, Stripe or Shopify². Beyond a standard feed, Microsoft lists three checkout signals: native checkout eligibility, product warnings and a Merchant Item ID². Store settings for returns, customer support and Copilot Checkout are a pilot for select customers². Onboarding is confirmed per domain, and each merchant uses one PSP checkout partner². Shopify merchants have been enrolled automatically, with controls in the Shopify admin²; Shopify's Copilot checkout takes card payment through Pay now and does not mention Shop Pay⁹². Stripe describes its Copilot checkout as using ACP and Shared Payment Tokens¹¹⁹.

Microsoft Merchant Center UCP readiness fields

Microsoft documents UCP readiness in two help articles, 60282 and 51084, which do not agree on every name^66,20.

The Content API Products resource has no UCP fields, and whether UCP attributes can be sent as custom attributes is not documented¹⁸. Microsoft's 47 MB playbook Prepare for the Age of AI Shopping was not read for this report¹²⁰.

The Microsoft Merchant Center feed

The base feed is close to Google's, with differences. Descriptions can run to 10,000 characters, and offerId and itemGroupId are capped at 50 characters¹⁸. Additional image links and several other Google fields are ignored¹⁸. Shipping is required only for Germany, adult products are rejected, and apparel sizes are required for France, Germany, the UK and the US¹⁸. The feed accepts 93 target countries and 27 content languages, far wider than Copilot Checkout¹⁸. A Google Merchant Center feed can be imported after the domain is claimed⁸⁵.

Fees and usage

Microsoft says it takes no commission or affiliate fee today, and the merchant's PSP fees still apply². In Microsoft's US data for April to June 2026, shopping and product research made up 12.2% of Copilot chats, and product cards appeared in about 14% of shopping sessions¹⁰.

Where it works

Instant Buy lets US users search and buy from many merchants on Perplexity³. It is open to all US users except the Enterprise Pro and Enterprise Max plans³. PayPal and Perplexity launched it on 25 November 2025³⁷. No source fetched for this report shows Instant Buy outside the US or Perplexity adopting ACP or UCP; Perplexity's own site returned HTTP 403 to every automated fetch.

How products get in

Merchant catalogs reach Perplexity through PayPal Store Sync, and payment runs through PayPal Agent Ready³⁷. Store Sync takes a Google Shopping CSV or a similar structured format over API or SFTP, with no published list of required fields⁴⁶. It is live in the US and the UK, with Germany planned⁴⁶. Only merchants compatible with Perplexity's agentic checkout are supported³. PayPal's own developer docs document ChatGPT and Google integrations but not Perplexity⁴⁵.

Ranking and crawlers

Perplexity ranks listings on relevance and ratings, and advertisers cannot pay for placement in the related products section³. Merchants that share richer availability, review, pricing and specification data are more likely to be recommended³. PerplexityBot respects robots.txt, while Perplexity-User, which fetches pages a user asked for, generally does not²⁷.

Amazon renamed Rufus to Alexa for Shopping on 13 May 2026⁴⁸. It answers from Amazon's catalog, customer reviews, community Q&A and information from across the web⁴⁸, and it is documented for US customers only⁴, although Alexa+ itself runs in 12 countries¹²¹. Through Shop Direct it shows products sold on other stores⁴⁷. For eligible products, Buy for Me has Amazon complete the purchase on the brand's own site, passing encrypted name, address and payment details, and the brand handles delivery, returns and service⁴⁹. Amazon says brands have the choice to take part, but publishes no enrolment process, feed spec or field list⁴⁹.

Amazon Ads has announced a paid route into the assistant instead: Branded Conversations, which it calls "the next evolution of Sponsored Brands prompts", let brands add their own product expertise to sponsored conversations in Alexa for Shopping in the US from January 2027¹²². That does not change the missing Buy for Me enrolment process.

Amazon and third-party agents

Toward other companies' agents, Amazon is restrictive. Its robots.txt blocks about 99 AI and crawler user agents from the whole site¹²³. The Agent Terms that Amazon added to its Conditions of Use on 30 May 2025, as quoted in its court filings, require every agent request to identify itself in the user-agent string as Agent/[agent name]¹²⁴. From 20 September 2026, according to GeekWire, Amazon showed people shopping on Amazon.com through Meta's Muse agent a popup saying that access by an unauthorized AI agent violates its Conditions of Use, and said it had asked Meta to remove Amazon from Muse¹²⁵. No Amazon page on the block was found.

Amazon v. Perplexity: case timeline

Amazon sued Perplexity over the Comet browser's shopping agent. The case shows how far a site can go in restricting AI agents in the US. The status below comes from court records up to 15 October 2026.

The Ninth Circuit held that, on this record, the user and not Perplexity accesses Amazon's computers, so Amazon is unlikely to win under the CFAA or CDAFA²⁹. The court said the ruling creates no new legal regime for agentic AI and that Amazon may still regulate access through its terms of service²⁹. As of 17 October 2026 no injunction is in force and no settlement appears in the record^133,29.

Meta AI itself has no documented shopping feature⁵⁷. Meta's separate Muse agent, launched in the US on 8 September 2026, can check out on websites with Link by Stripe, and Meta describes no merchant programme or feed for it⁵⁰. At Connect 2026 on 23 September 2026, Meta said Muse launched with dozens of partners and the whole Shopify catalog, named ten retailers it is adding, among them Walmart, Best Buy, Sephora and Wayfair, and said it is adding Shop Pay and PayPal for payments⁵¹. That post states no countries, merchant programme or fees⁵¹. A later Meta post lists Muse in the US and Canada⁵³. Stripe says US consumers can connect Link to Muse and pay directly at more than 1 million Link businesses¹³⁴.

Meta Business Agent recommends products from a business's catalog in WhatsApp and Messenger⁵⁴, and is bundled in Meta One from USD 14.99 a month⁵⁷. The Meta catalog requires id, title, description, availability, condition, price, link, image_link and brand²⁵.

Shopify added Meta as an AI channel on 8 September 2026¹³⁵. Shopify merchants can offer direct checkout on Meta surfaces, with Muse named as an example, to shoppers in the US, Canada and Mexico^12,52. Shopify's pages do not say which Meta surface serves shoppers in Canada and Mexico. Shop Pay can appear in Muse "when available"¹². Separately, Stripe powers one-click checkout on Facebook ads, built on ACP⁵⁵.

Klarna's Agentic Product Protocol, launched on 15 December 2025, takes one existing feed in Google, Shopify, Meta, CSV or JSON format and exposes it to approved AI partners^60,59. At launch Klarna cited more than 100 million products and 400 million prices⁶⁰; its undated APP product page now claims more than 500 million offers⁶⁸. The APP API covers 13 markets: 12 in Europe and the US⁵⁹. Offers carry price as a string, one of seven stock statuses and a delivery window in days⁵⁹.

The underlying Search & Compare feed is imported 1 to 4 times a day and billed per click⁶². Klarna's shopping app in ChatGPT, launched on 20 May 2026, redirects shoppers to the merchant to buy and sells labeled sponsored placements⁵⁸. Klarna's flexible payments inside Google Pay on AI Mode and Gemini were announced for the US on 12 May 2026¹¹⁷.

Merchants without an approved feed can still be read by AI assistants through their websites. OpenAI, Google, Perplexity and Meta document separate user agents for purposes such as search indexing, model training and user-triggered fetches, and treat robots.txt differently for each.

Blocking a training crawler does not remove you from AI search. Google-Extended does not affect Search inclusion¹³⁶, blocking ChatGPT-User does not remove a site from ChatGPT search²⁶, and Meta's citation crawler is separate from its training crawler¹⁴¹. Google documents no shopping agent called GoogleAgent-Shopping, although Amazon's robots.txt blocks a user agent by that name^142,123.

Structured data

Google says AI Overviews and AI Mode need no special schema.org markup and no llms.txt file, and that Merchant Center feeds help products appear in AI responses^137,143. Product markup still matters for merchant listings, which need name, image and an Offer with a price above zero and a currency¹⁴⁴. Merchant Center can also update price, availability and condition automatically from markup in the server-returned HTML^145,146. Where feed and markup disagree on shipping or returns, the feed wins¹⁴⁴. Googlebot reads only the first 2 MB of a page¹⁴⁷.

Bing's 2025 guidance says Product and Offer markup plus IndexNow can replace a separate merchant feed for web search and shopping¹⁴⁸, but Copilot Checkout still requires an MMC account and feed². Bing's data-nosnippet attribute keeps marked text out of Copilot answers¹⁴⁹. OpenAI's commerce docs and Meta's crawler docs give no schema.org guidance for merchants^16,141.

ACP

ACP started with checkout and delegated payment specs and no feed spec¹⁶⁶. Version 2026-04-17 added a push Feed API, carts, native orders, delegated 3DS2 authentication and an MCP binding with five checkout tools, and made an Idempotency-Key header mandatory on POST requests¹⁵⁰. ChatGPT is the first AI platform to implement it and Stripe the first PSP³¹.

UCP

UCP covers catalog search and lookup, cart, checkout, order, fulfillment, discounts and identity linking, over REST, MCP, A2A or embedded transport⁹³. Its catalog requires no brand field, and GTIN is only an optional barcode⁸⁶. Release v2026-08-25 added a loyalty extension, 3DS2 and payment schedules including installments, and replaced signing_keys with keys as a breaking change¹⁵⁴. Surfaces trail the spec: Google's docs are versioned 2026-04-08⁶⁵, while Shopify storefronts already support 2026-08-25³⁴. Representatives of Amazon, Meta, Microsoft, Stripe and Salesforce joined UCP's Tech Council on 24 April 2026, and a Payments Technical Council with PayPal, Stripe, Adyen and others formed on 2 September 2026³⁶.

AP2

AP2 is a payment authorization layer and plugs into UCP as an extension¹⁶⁷. Its v0.2 spec defines a Checkout Mandate and a Payment Mandate¹⁵⁸.

Agent identity and payments

Visa Intelligent Commerce bundles the Trusted Agent Protocol and an MCP server and is still being deployed¹⁵⁹. x402 lets a server ask for payment with HTTP 402 and charges no protocol fee¹⁶⁵. Stripe supports x402 on Base alongside its own Machine Payments Protocol¹⁶⁸. On 30 September 2026 Mastercard added trust and intelligence services to Agent Pay; the first is a score of how likely it is that an AI agent initiated a transaction, rolling out for testing in the US, with Cloudflare and Skyfire named as partners¹⁶⁹. Mastercard gives no general availability date¹⁶⁹. In our view, these matter more for APIs and digital goods than for retail product feeds today.

Shopify

Shopify connects stores to ChatGPT, Microsoft Copilot, Google AI Mode and Gemini, Meta surfaces and its own Shop app⁵². Since 13 October 2026, Shop MCP also lets any AI agent search Shopify Catalog's more than 1 billion products, build carts and complete Shop Pay checkout through one MCP connection; search needs no API key, and the agent completes a purchase only after the shopper confirms the total and payment method¹⁷⁰. The changelog states no countries and no merchant opt-out for this route¹⁷⁰. Agentic storefronts are active by default for eligible stores¹⁷¹, and merchants cannot opt out of Shopify Catalog itself, only of each channel's access⁹⁵. Since 11 May 2026 an admin page tracks presence and sales across ChatGPT, Shop and Copilot¹⁷².

Shopify Catalog needs a title, at least one image and a price above zero, and does not require a GTIN^88,89. Since 9 October 2026 merchants can share compare-at prices with AI agents⁹⁰. Direct checkout does not support subscriptions, bundles, customizable products, local delivery or pickup⁹². The Agentic plan, for brands without a Shopify online store, has no monthly fee and card rates from 1.9% + EUR 0.25 online on the page served to us¹⁷⁴. The Global Catalog REST API stops serving traffic on 2 November 2026³⁴.

On fees, the help pages say there are none per channel, but the Agentic Storefronts terms, updated 6 October 2026, let Shopify charge per-channel fees on Agentic Storefronts transactions, listed in the admin, and allow those fees to be waived or discounted during promotional periods^23,38. The terms do not say whether today's no-fee position is such a promotional waiver.

Stripe

Stripe's Agentic Commerce Suite is available in 34 countries: the US, Canada and 32 European countries⁸. In our comparison, its catalog feed spec is the most detailed of the enablement routes, with limits for each field and enrichment fields for agents⁶. Sellers request a connection to each agent in the Dashboard, and the agent must accept⁸. Stripe's platform programme is US-only and needs waitlist approval¹⁷⁵. On Stripe's Dutch pricing page, a Shared Payment Token costs EUR 0.15 per issued token¹⁷⁶. Stripe also lets businesses sell in AI Mode and the Gemini app through its Google collaboration¹⁷⁷.

PayPal

PayPal Store Sync takes a Google Shopping CSV and feeds Perplexity and Copilot^46,178. PayPal adds no Store Sync fee beyond its transaction fees but may pass through AI-platform fees⁴⁶. Merchants that already accept PayPal count as agent ready⁹⁴. In Copilot Checkout, PayPal offers its wallet, cards and guest checkout¹⁷⁹.

BigCommerce, WooCommerce and others

BigCommerce offers storefront MCP servers but names no consumer AI channel^180,181. Feedonomics sends feeds to ChatGPT, Perplexity, Gemini and Copilot for Shopify, BigCommerce, Salesforce Commerce Cloud, Adobe Commerce and WooCommerce stores¹⁸². WooCommerce's MCP is a developer preview, and no shipped first-party AI channel was found^183,184. Salesforce Commerce Cloud's product page names no external AI assistant channel¹⁸⁵.

The main dates behind the tables above, from Google's first agentic checkout in November 2025 to the dates already set for 2027.

Google's UCP checkout for Australia and Canada is planned for early 2027, with no date for the UK^43,42.

The research recorded 64 conflicts between sources. These are the ones that change what a merchant should do.

• ChatGPT checkout status. OpenAI's merchants page says it is moving away from a standalone Instant Checkout and that purchases complete on merchant-owned sites or apps²¹, and its plugin docs recommend external checkout²², while its developer commerce docs still describe Instant Checkout in the ChatGPT interface²⁴. Shopify sends ChatGPT shoppers to the store checkout²³. In 2025 Stripe said Shopify merchants were coming to Instant Checkout soon¹⁰². We treat in-chat checkout on ChatGPT as being phased out, not generally available.
• OpenAI field limits. OpenAI's feed spec frames 150 and 5,000 characters as targets in the OpenAI format and as enforced limits on the Google-compatible profile⁷, while the file-upload reference lists them as plain maximums⁷⁸.
• Which protocol Copilot uses. Microsoft's January 2026 launch post said it was adopting ACP¹⁷, and Stripe describes its Copilot checkout as ACP-based¹¹⁹. The current agentic commerce page asks for a UCP-compliant feed and does not mention ACP².
• Whether Copilot needs Microsoft Merchant Center. The launch post said MMC was not required¹⁷. The current page says an MMC account is required to onboard².
• Microsoft attribute names. Help 60282 names product warnings consumer_notice_type and consumer_notice_message, while help 51084 uses consumer_message_type and consumer_message_content^66,20. The exception label appears as both return_policy_label and return_policy_labels^66,20.
• Google's non-US timing and scale. In May 2026 Google said Canada and Australia would get UCP checkout in the coming months and the UK later¹⁰⁶; by September it said early 2027 for Australia and Canada and did not mention the UK⁴³. The same September post speaks of hundreds of thousands of brands, while the developer docs describe an early access programme⁴².
• Payment options in Google checkout. PayPal, Affirm and Klarna were announced^115,116, but Google's current handler docs name only Google Pay¹¹³. Google gives no country for Affirm and Klarna; Klarna says US¹¹⁷.
• Discovery outside the US. AI Mode and AI Overviews list the UK and all EU states, but no Google page says whether AI Mode shows product units there^13,15.
• Markup or feed for Microsoft. Bing's 2025 guidance says markup plus IndexNow can skip a merchant feed¹⁴⁸; Copilot Checkout requires a feed².
• Meta Muse countries. Meta's launch post scopes Muse to the US⁵⁰, a later post lists the US and Canada⁵³, and Shopify's Meta checkout covers the US, Canada and Mexico¹².
• Shopify defaults and fees. Direct checkout is on by default on standard plans and off on the Agentic plan⁹⁸. Channel help pages say there are no fees, while the supplemental terms allow per-channel transaction fees^23,38.
• UCP versions. The open spec's latest release is v2026-08-25¹⁵⁴, Google's implementation is pinned to 2026-04-08⁶⁵, and session statuses differ between the two^111,91. The spec also adds installments, which Google's checkout still excludes¹⁹.
• Availability spelling. The OpenAI format uses pre_order and accepts unknown⁷⁸; the Google-compatible profile and Stripe use preorder and reject unknown^78,6.
• Feed freshness. OpenAI asks for a daily snapshot⁹, Stripe for price and inventory every 15 minutes⁸. Klarna markets its data as real time but its FAQ says feeds are imported 1 to 4 times a day^61,62.
• Perplexity channel lists. PayPal's newsroom names Perplexity as a live Store Sync channel¹⁷⁸, but PayPal's Agent Ready developer docs do not document it⁴⁵. Shopify's marketing pages name Perplexity as a channel, while its help center channel list does not^186,52.
• Amazon v. Perplexity. The parties disagree on whether Amazon's letter of 31 October 2025 revoked Comet's access and on whether the Agent Terms bind Perplexity at all; the court has not decided either point^132,124.
• AP2 mandates. The 2025 launch post described Intent and Cart mandates¹⁵⁵; the v0.2 spec uses Checkout and Payment mandates¹⁵⁸.
• Klarna scale. Klarna cited 400 million prices in December 2025⁶⁰ and 400 million listings in May 2026⁵⁸; its undated APP page claims 500 million offers⁶⁸.

Sources

Seven topic lanes collected rows on OpenAI, Google, Microsoft, Perplexity, Amazon with Meta and Klarna, protocols, and platform enablement. Five follow-up lanes then closed gaps that a first review found: 2026 news for each surface, the Amazon v. Perplexity case, discovery coverage by country, the crawler and structured data route, and Microsoft Merchant Center checkout attribute names. Each row records one value with its scope, effective date, source URL, source type, evidence and confidence. Court documents were read through CourtListener's RECAP mirror of PACER, which can lag the official docket¹²⁷.

Of the 673 rows, 638 rest on primary sources (the operator's own documentation, help center, legal terms, newsroom, blog, repository or court documents), 25 on official secondary sources (a partner's own pages cited for another company's surface, such as Shopify's documentation cited for ChatGPT) and 10 on secondary sources such as press articles. We used the operator's own page wherever one existed, and secondary sources only where no primary page could be read, such as Amazon's block on Meta's Muse¹²⁵.

Verification

A second pass on 17 October 2026 fetched every source URL again. 565 of the 663 lane rows matched as written and 98 were corrected to match the page; no row is marked unverifiable. An independent reviewer then re-fetched 24 primary sources behind the headline findings and found no numeric errors. A freshness sweep on the same day added nine changes from seven new sources. Some pages could not be read by automated fetches (openai.com, help.openai.com, perplexity.ai and amazon.com's Conditions of Use); a few were read in a browser, and facts that only those pages hold are left out rather than estimated.

Deduplication and refresh

Where several lanes recorded the same fact, we kept one canonical row, so 673 lane rows became 521 facts. Surface status (checkout availability, countries, fees) should be re-checked monthly. Field-level specs and protocol versions should be re-verified quarterly, or within a week of a new ACP or UCP release. The Amazon v. Perplexity rows should be re-checked after the hearing on 20 November 2026¹³².