Amazon blocked Muse at checkout. Shopify opened the door.

On the night of September 20, Meta's Muse users who asked the agent to buy something on Amazon stopped getting a cart. They got a popup instead: "Continued access by an unauthorized AI agent violates Amazon's Conditions of Use, to which our customers have agreed."

Within 72 hours, four other companies did the opposite of Amazon. Shopify connected Muse to Shop Pay and its merchant catalog. PayPal opened checkout across its merchant network. Expedia announced hotel bookings through Muse. Instacart connected grocery ordering to it.

Same agent. Same technology. Opposite decisions.

The difference was not the software. It was permission. Amazon refused it; the others granted it. And for Shopify merchants, the decision was mostly made for them already: discovery is automatic, and direct checkout on Meta is on by default for eligible stores. If you run a Shopify store, you do not need to join. You need to decide whether to stay in, and on what terms.

A week, day by day

The timeline matters because early coverage blurred it.

Two dates here correct earlier trade reporting: both the Expedia and Instacart announcements were reported September 22, not September 23.

Muse became the number one free app in Apple's U.S. App Store about a week after launch, ahead of ChatGPT, according to GeekWire. Shopify shares gained 15 percent in the two days after the deal news. Instacart's stock slid 2.1 percent the day after its announcement, according to Barron's. Investors appear to read Muse partnerships as distribution for agents and margin pressure for incumbents.

Why Amazon said no

Amazon's reasons, as stated to GeekWire, were specific. Meta never told Amazon that Muse would access its store. The agent did not identify itself as automated while browsing. And it appeared to capture and store customer credentials, which Amazon said could create privacy and security risks. Amazon asked Meta to remove Amazon from the shopping experience. Meta declined, and Amazon blocked it unilaterally.

Meta's published position is the opposite. Its launch materials say Muse has no visibility into passwords or payment methods, and that credentials go into secure storage the agent can use without seeing the values.

Both sides describe the same architecture and draw different conclusions about whether it is acceptable. Amazon's concern about credential handling echoes a real pattern: our reporting on an open-source agent campaign that breached 27 companies and stole 600,000 cards shows what goes wrong when agents mishandle payment data. That said, Amazon's claims are allegations, not independent findings, and Meta did not respond to GeekWire's request for comment.

Amazon also has a legal backstory. It sued Perplexity over its Comet browser agent, won a preliminary injunction in March, then lost it on August 4 when the Ninth Circuit ruled that the user, not the AI company, is the one accessing the computer under federal anti-hacking law. Amazon's rehearing petition was denied September 10. That ruling took away the hacking argument, so the new popup argues something narrower: the shopper's own contract. Muse users are not accused of breaking in. They are told their agent violates the Conditions of Use they accepted.

This is also competitive positioning. Amazon launched Alexa for Shopping in May and runs Buy for Me, which finds items on external brands' sites. Amazon points out that its own agent identifies itself and lets brands opt out. Amazon generated more than $68 billion in ad revenue last year, a business that depends on people browsing its pages and seeing sponsored products. An agent that checks out on its behalf is not just a security question for Amazon. It is a revenue question.

Why Shopify said yes

Lütke's announcement did not say "Muse can now reach Shopify stores." It said Muse could check out with Shop Pay. The reach was already there. Shopify's Catalog feeds product data to AI channels automatically for eligible merchants, and Shopify is the merchant rails underneath: it co-developed the Universal Commerce Protocol with Google, an open standard for agent-driven commerce that Shopify describes as a common layer for discovery and checkout.

For merchants, the important detail is that the defaults are set. When a store is eligible, Meta direct checkout is active by default in the Shopify admin, and Catalog discovery needs no action at all. Shop Pay shows up in Muse for stores that use it, without any merchant-specific activation. You stay the merchant of record. Orders show up in your admin, attributed to Meta. Fulfillment, returns, and customer service stay yours. And Shopify's documentation says there are no Meta direct-checkout fees beyond standard payment processing.

That is the opposite of a marketplace referral model, and it explains why the Fool's framing says Shopify "gets paid on every checkout." Shopify keeps its normal transaction fees on platform payments. It did not announce a new Muse surcharge, and Meta has not disclosed any take rate of its own.

Shopify's own agent-payment story matters here too: Muse completes purchases using one-time-use cards at launch, with wallets like Shop Pay as the payment path. The questions around agent payment identity we reported earlier this month are now moving from standards meetings into real checkout flows.

The contrast with Amazon is the story. Two companies looked at the same agent. One concluded the customer relationship was worth defending by force. The other concluded that being the rails under every agent's checkout was worth more than controlling the browser session. For a Shopify merchant, the practical result is simple: when a Muse user asks for something you sell, your store is in the pool and Amazon's listings are not. Being in the pool and being the product Muse picks are different problems, and Meta has published nothing about how it ranks recommendations.

What Meta wants to be paid

On September 23, Zuckerberg told the Connect audience: "I expect over time that will be a big business for us... we'll be able to take a small fee from transactions and commerce, and that's going to be a great way for us to finance a lot of the AI development that we're building here."

That is a monetization strategy, not a pricing sheet. TheStreet, citing Yahoo Finance's account from the room, reported that the fee will come from merchants rather than users. The rate, the mechanics, and the timing were not disclosed. The Instacart example is the reporter's illustration, not a disclosed term. Nobody has disclosed full commercial terms: not Meta, not Shopify, not PayPal, not any partner.

This is the piece merchants should watch hardest. Today, Shopify documents no extra fees for Meta direct checkout. Nothing stops Meta from introducing one later. When it does, merchants who built volume through Muse will learn the terms at the same time as everyone else.

What you actually control

The early reporting on this story assumed Shopify's merchant controls, fees, and attribution were undocumented. They are not. Shopify's help center documents all three, and the picture is better than the rumor. The real work is auditing the defaults before Q4 volume hits them.

Catalog discovery. Your eligible products are automatically discoverable by AI channels through Shopify Catalog, which sends structured title, description, options, images, price, and availability. You can disable Catalog access for Meta under Sales channels, then Agentic. But disabling it does not guarantee invisibility: Shopify says products can still surface through web crawling and other feeds. Setting a product's status to Unlisted is the only complete-hide path. If you sell items you never want an agent to surface, regulatory-sensitive products, price-tested SKUs, or anything that should not be recommended without a human conversation, Unlisted is the switch, not the Meta toggle.

Direct checkout. Active by default for eligible stores. Turning it off keeps discovery on but sends the buyer to your own online store to complete the purchase. This is the single most important decision: Muse can recommend you either way, but where the money changes hands is your call. The separation exists precisely because not every catalog belongs in a chat checkout.

Unsupported products. Meta's direct checkout does not support subscriptions, bundles, customizable products, B2B-only products, checkout blocks, local delivery, pickup, or stores that force account sign-in. If your catalog is heavy on subscriptions or build-your-own bundles, Muse can still send those shoppers your way. It just cannot close inside the chat. Audit this before October, not after a wave of failed checkouts.

Analytics and attribution. Google Analytics and custom browser pixels do not fire inside Meta direct checkout. Only server-to-server checkout-started and checkout-completed events fire. Measure Muse orders in the Shopify admin, where they are attributed to Meta, rather than relying on client-side pixels. If your dashboards are pixel-first, you will undercount this channel from day one.

Geography. Direct checkout is shown only to customers in the United States, Canada, or Mexico. Muse itself rolled out in the U.S. first. PayPal's claim that Muse can shop "across PayPal merchants worldwide" is a vendor statement; PayPal's own Store Sync documentation limits eligibility to existing PayPal merchants selling physical goods to U.S. customers in USD, and access is limited with a request form. Treat the worldwide framing as marketing until Meta's rollout says otherwise.

Product data quality. Shopify's docs say to focus on complete, well-structured product information plus SEO best practices, and they call Catalog the authoritative feed, but Meta has published nothing about how Muse ranks or selects products. It also auto-serves agent discovery files (/agents.md, /llms.txt) for every store. If key attributes live only in a paragraph of description text, agents have to guess. Structured fields are the new shelf placement. Our earlier reporting on agents reading instructions from the web is worth revisiting as you open these files: discoverability and manipulability travel together.

Policies. Shopify requires your Terms of Service, Privacy Policy, and return policy to be filled in under Settings, not just published on a page somewhere. Product descriptions should carry legal disclosures in the first 6,000 characters. These are small setup items that silently gate eligibility.

What is still unknown

Honesty requires listing what nobody has answered. Meta has not published how Muse ranks or selects products, so no partner's "preferred placement" can be verified. No partner has disclosed commercial terms, so the economics of every announced deal are opaque. Amazon has not said whether its block is permanent, or whether a permissioned deal like Shopify's is possible. Nobody has published Muse transaction counts, conversion rates, or failure rates. And Meta's "small fee" has no rate, payer, or start date.

This piece is documentation-based research, not a live test. We did not run a Muse purchase, inspect a Shopify admin, or observe a real checkout flow. The docs say the defaults are on; only real traffic will say whether they convert.

The bottom line

The agentic-commerce split is not agents versus no agents. It is permissioned integration versus uninvited browser automation. Amazon is defending its customer account with contract law. Shopify is renting out its rails to every agent that will take them. Both strategies are rational, and both are bets.

For merchants, the decision tree is short. Keep Catalog discovery on unless you have a product, legal, or channel-conflict reason not to. Treat direct checkout as a separate decision from discovery, and make it deliberately. Audit unsupported products and checkout dependencies now. Fix attribution before the holiday spike so Muse orders do not vanish from your reporting. And watch two things that are still blank: Meta's transaction fee and Muse's ranking logic. Everything else in this story is a press release. Those two are the business.