#BlinkTank: Shopify and Google change AI infrastructure, again
A quick update before we get started - Blink won Best SEO Agency at the National Digital Awards on Friday. The biggest thanks goes to the clients we have worked with over the last year, without whom none of this happens. Thanks also to our team at Blink, and to everyone who reads this newsletter, forwards it, or replies to it. There is a short note on the blog if you would like to find out more.
Now that we’ve got the self-congratulation over with, let’s get on to the news.
Last week’s issue covered two parallel moves: Google publishing AI search guidance that said you can skip llms.txt, and Shopify rolling llms.txt out on every store. Inside seven days both have moved.
Shopify has redirected llms.txt to a new agents.md across every store, and the I/O announcements have been read across the industry as making AI Mode the default for Google Search, which is not what was announced. Google also released a broad core update on the same day, which got far less attention but is the one moving rankings, including on some client sites.
This issue covers what Google actually announced about AI Mode, the May 2026 core update that started rolling out the same day, the llms.txt-to-agents.md redirect on Shopify, Universal Cart at I/O, and UCP turning on by default across every Shopify store.
What Google actually announced at I/O
At I/O last week, Google announced what it called its biggest update to the Search box in over 25 years. Gemini 3.5 Flash is now the default model inside AI Mode, the Search box accepts text, images, files, videos and Chrome tabs as inputs, and a question on an AI Overview can flow into a conversational AI Mode follow-up. Each of those is a substantive change.
The industry reaction, though, has gone much further than the announcement justifies. Many opinions have been shared based on the idea that AI Mode is now the default for Google Search.
That is not what Google said. Instead, Gemini 3.5 Flash is the default model inside AI Mode, not the default for standard search. Google’s announcement says: “you’ll continue to get a range of results from Search, just like you do today.”
Google is exteemely cautious about wholesale changes to the search results page, because that page is where the ad revenue is. The pattern across past I/Os is consistent: a big stage announcement, followed by a slower incremental rollout, often dialled back further once the impact on the SERP is measured.
For example, SGE was announced at I/O 2023 with much fanfare, the query coverage collapsed from around 84% to 7% in the weeks after launch before being rebranded as AI Overviews.
None of this amounts to AI Mode replacing standard search tomorrow, or to organic results being deprecated. For large-catalogue Shopify stores, the most important thing is to show up across the range of results, which is wider than blue links plus SERP features now.
🔗 Google’s I/O search announcement
Google’s May 2026 core update is rolling out now
Google released a broad core update on Thursday 21 May. It is the second core update of 2026 after the March release, and the expected rollout window is up to two weeks, with completion around 4 June.
Lots of the talk in the SEO community is that this update targets AI-generated content with no expertise behind it. We have seen some of those cases, but we have also seen stores with good-quality content affected, which doesn’t fit that explanation neatly.
The more consistent pattern across our client base is that the shift is happening at the category level - the categories Google treats as relevant for a given store have changed, and that has carried through to the individual product pages within those categories rather than each page being judged on its own.
We are seeing ranking volatility across client sites, more so than usual in the eCommerce space. If your store is showing unexpected click or position changes since 21 May, the core update is the most likely explanation.
Google’s standard advice applies: don’t make sweeping technical or content changes during the rollout. Wait for it to complete, then compare the right Search Console date ranges.
We’ll be continuing to monitor this and we’ll share our thoughts once things are clearer.
🔗 Google Search Status Dashboard
🔗 Search Engine Land coverage of the May 2026 core update
Shopify replaces llms.txt with agents.md
A few weeks ago, we reported that Shopify had added an LLMs.txt file to all stores. /llms.txt is now being redirected to a new /agents.md file across every store at the server level. The agentic discovery sitemap has been consolidated down to a single URL pointing at /agents.md, weekly changefreq, where a fortnight ago it was three.
This is an interesting shift. llms.txt is a discovery file telling AI agents what a store sells. agents.md is a transaction interface, telling the agent how to use UCP, how to add to cart, and how to trigger checkout through Shop Pay without a human touching the site.
agents.md itself isn’t new. It’s an open standard already used by over 60,000 open source projects as what its creators call a “README for AI coding agents” - originally developed for tools like Codex, Cursor and Aider, and now stewarded by the Linux Foundation’s Agentic AI Foundation.
The updated agents.md also points agents at a new file at shop.app/SKILL.md, described as the recommended route for browser-using agents and personal shopping assistants to transact across Shopify stores: buyer-approved checkout via Shop Pay, cross-store catalogue search, order tracking, and reuse of identity and payment-method the buyer has already authorised.
Two things stand out. The format is SKILL.md, the markdown-skill convention Anthropic uses for Claude and that has spread across the agent landscape; Shopify is adopting it rather than building a proprietary alternative, which makes sense. And it positions Shop Pay as the cross-Shopify agent payment rail, the counterpart to Universal Cart’s Google Wallet on Google’s surfaces.
Merchants are left with the work that was always there, now that the transaction protocol is handled at platform level. The default agents.md is a boilerplate, identical on every store; it tells an agent how to buy, but nothing about your brand, what you sell, or why an agent should recommend you. At the moment, it is not editable. But as usual, this could change quickly.
It is worth opening yourstore.com/agents.md to see what your store is currently telling agents.
🔗 Theagents.md open standard
Google launches Universal Cart at I/O
The retail-side I/O announcement got less attention than the AI Mode story, but is arguably the more consequential piece for ecommerce. Universal Cart is a Gemini-powered shopping cart that follows the shopper across Search, the Gemini app, YouTube and Gmail, with checkout handled through the Universal Commerce Protocol. The retailer remains merchant of record regardless of whether the shopper completes purchase on Google or gets passed back to the store.
Launch retailers named include Nike, Sephora, Target, Ulta, Walmart, Wayfair, Fenty and Steve Madden. Background features include price-drop monitoring, compatibility flagging, restock alerts, and payment-method optimisation via Google Wallet. Gemini Spark, also announced at I/O, is the consumer-side agent that can authorise payments within user-set budgets and merchant-set limits.
Universal Cart is the consumer-facing surface that consumes the agentic infrastructure that has been arriving in pieces over the last few months: Shopify’s Agentic Storefronts dashboard, the ChatGPT and Claude store connectors, agents.md, and UCP at the platform level. It is the first major search and inbox surface to wrap multi-merchant shopping into a single persistent cart, with the merchant relationship and revenue preserved on the retailer side rather than disintermediated.
🔗 Google’s Universal Cart announcement
UCP is now on by default for every Shopify store
On the same day as the Universal Cart announcement, Shopify confirmed that the Universal Commerce Protocol is now automatically enabled across every store on the platform. Every Shopify store now speaks UCP from product discovery to checkout, with no merchant-by-merchant integration required. The Catalog API now covers billions of products with built-in clustering and similarity search.
Two weeks ago UCP was an emerging standard that early adopters were configuring. Today, if you are on Shopify, you are already part of the UCP graph that Universal Cart and other agent surfaces can read from. There is no opt-in screen and no setup step. The work that needs doing is the same as before: getting the underlying product data, taxonomy and policies in order so that when an agent queries your store, the answer it gets is the one you want it to give.
If you want to see what your store is currently exposing, there is a UCP Explorer tool that fetches /.well-known/ucp on any URL, connects to the MCP endpoint and lists the tools the store exposes to AI agents. It is useful for a sanity check on your own store, or for a look at how a competitor’s is set up.
Jobs
Hiring:
Attersee are hiring someone to lead e-commerce at the fashion brand. 🔗 Job post on LinkedIn
Blakely Clothing are hiring an Ecommerce Assistant in Norwich. The role sits across product listings, collections, landing pages, SEO and GEO work, Klaviyo and on-site performance.
If you are hiring and the role fits someone with large-catalogue Shopify experience, or you are looking and have that background, send me a message.
As ever, thanks for reading.
If you found this useful, I would love it if you could share it with someone you think would find it interesting - whether that is someone managing a large-catalogue Shopify store or anyone else who follows this kind of thing.
See you next week.
Sam
Who am I and what does Blink do?
I’m Sam Wright, Managing Director and co-founder of Blink SEO. We’re a search marketing agency that works exclusively with large-catalogue Shopify stores - the kind where the challenge isn’t just visibility, but helping customers find the right product in the first place.
We specialise in SEO and PPC for merchants managing hundreds or thousands of products. Most of our work starts with taxonomy: how a store is structured and categorised, and what that means for organic performance, paid efficiency, and on-site discovery.
If you found this useful and aren’t already subscribed, you can sign up at blinkseo.co.uk/blinktank.
If you run a large-catalogue Shopify store and want to talk about organic or paid performance, reply to this email or find me at blinkseo.co.uk.