The same week, two of the biggest names in e-commerce gave Meta’s new Muse agent opposite answers. Amazon cut it off. Shopify turned it on, for every store on the platform, by default. Which one applies to you now depends entirely on which platform you’re on — not on anything you configured.

Amazon: blocked by contract, not by lawsuit

On the night of September 20, 2026, people using Muse to shop on Amazon started seeing a popup instead of a checkout: “Continued access by an unauthorized AI agent violates Amazon’s Conditions of Use, to which our customers have agreed” (TechCrunch).

Amazon’s stated reasons, from a company spokesperson: Meta never told Amazon that Muse would access its store, Muse “doesn’t identify itself when it browses,” and it appears to capture and store customer credentials — a privacy and security risk in Amazon’s framing (GeekWire). “Agentic third-party applications such as Muse have the same obligations, and we’ve requested that Meta remove Amazon from the experience,” the spokesperson said. Amazon drew the comparison to food-delivery apps and online travel agencies: fine to buy on a customer’s behalf, but only with the merchant’s agreement.

The legal route matters as much as the block itself. Amazon lost its CFAA-based injunction against Perplexity’s Comet browser on August 4, and the Ninth Circuit declined to rehear that ruling on September 10 — we covered both rulings here. That left one door open, per GeekWire: “claims built on contracts and terms of service.” The Muse popup doesn’t accuse anyone of hacking; it cites Amazon’s own Conditions of Use. A month after the CFAA theory stopped working, the Terms-of-Use theory is the one actually running in production.

Shopify: opted in, on all stores, the same week

On September 21, Shopify CEO Tobi Lütke announced the opposite move: “We are excited to announce we are partnering deeply with Muse to enable agentic checkout with Shop Pay on all Shopify stores, offering people an easy and delightful way to shop and check out with Muse” (@tobi on X). The mechanism is the Universal Commerce Protocol (UCP), which we’ve covered as one of the two rails agents use to check out — Muse reads a store’s Shopify catalog and completes payment through Shop Pay without the merchant building anything new.

Lütke’s wording — “on all Shopify stores” — describes a platform-wide default, not a merchant opt-in flow. Neither the announcement nor the coverage we could fetch describes a per-store toggle; if Shopify publishes merchant-level controls for this, they’ll be in your Shopify admin’s Shop Pay or UCP settings, not in this article.

What this means for your store

If you sell on Shopify with Shop Pay enabled, Muse can plausibly already complete a purchase on your store — you didn’t request it and, as far as the sources here show, you didn’t approve it either. It shops the way we described when Muse launched: no user-agent string, no separate approval step for the merchant. If that’s not a checkout experience you want unvetted agents walking through unsupervised, that’s worth confirming directly with Shopify rather than assuming.

If you’re not on Shopify, Amazon just field-tested the alternative: a Conditions-of-Use clause requiring agents to identify themselves, enforced the moment one doesn’t. Amazon’s block is the first large-scale case of a merchant actually using that route since the CFAA theory closed.

FAQ

Is my Shopify store now buyable by Meta’s Muse?

If your store uses Shop Pay, very likely yes. Shopify’s September 21 announcement describes the integration as live “on all Shopify stores,” and the sources fetched for this article describe no separate merchant sign-up step for the rollout.

Why did Amazon block Muse if it just won its CFAA appeal?

The CFAA ruling only settled who “accesses” a computer under federal anti-hacking law — it said nothing about a merchant’s own Terms of Use. Amazon’s block cites its Conditions of Use directly, a contract-law route the August ruling left untouched.

Can other merchants use the same Conditions-of-Use approach Amazon used?

The legal mechanism — requiring agents to identify themselves and conditioning access on that in your own terms — isn’t exclusive to Amazon. Whether it holds up depends on your own terms actually saying so and on jurisdiction; see our earlier piece on what the Ninth Circuit ruling did and didn’t decide.

Sources

Whether an AI agent can already buy from your store just became a platform default decided somewhere above your admin panel — which is exactly the access-pillar fact the transaction audit checks for, instead of assuming.