Reported 21 Sept 2026 Commerce

Amazon shut Meta's AI agent out of its store and told a court that Perplexity's agent had lied about how it gets in.

On Sunday night September 21 Amazon blocked Meta's Muse assistant from shopping on Amazon.com, showing users a message that continued access by an unauthorised AI agent violates Amazon's conditions of use. The same day Amazon filed an amended complaint against Perplexity in California federal court alleging its Comet browser copies shoppers' Amazon session cookies to Perplexity's own servers, which then reach Amazon directly, contradicting what Perplexity told the court.

The caveat that matters is that one of these is a business decision Amazon can reverse tonight and the other is an unproven allegation in a case Amazon has already lost once on appeal.

Until now

Agentic shopping was being fought over as a legal question about who counts as the visitor to a website.

Now

Read the store's own terms of use and its ability to switch an agent off as the operative control, and treat the law as the slower second front.

Amazon lost the argument it wanted to win. In March it had an injunction that kept Perplexity's Comet off its site; on August 4 the Ninth Circuit took it away, on the reasoning that when an agent shops with your credentials it is you doing the shopping, not the company that wrote the agent. Rehearing was refused on September 10. Eleven days later Amazon came back with two things the appeal cannot touch. One is a new factual allegation that moves the access from the shopper's device to Perplexity's servers, which if true puts Perplexity's own computers on Amazon's system and puts a statement Perplexity made to the appeals court in question. The other is contract, the one theory the Ninth Circuit explicitly left standing.

The block on Muse is the same lesson without the lawyers. Meta shipped the most downloaded app in the country on September 8; on September 21 the largest retailer in the country switched it off at the door with a popup, and no court was involved. What Amazon said about it is worth reading twice, because it is not a safety argument or a security argument. It is that a service provider gets to decide whether or not to participate. That is a claim about who owns the counter, and it applies to every agent, not just Meta's. Read the store's own terms of use and its ability to switch an agent off as the operative control, and treat the law as the slower second front.

How it got here

Mar 2026
Amazon wins a preliminary injunction blocking Perplexity's Comet browser from shopping on Amazon.com. The Ninth Circuit lifts it on August 4, holding that under the federal anti-hacking law the user, not the AI company, accesses Amazon's computers.
Sep 8
Meta launches Muse. A week later it is the most downloaded free app in the United States, ahead of ChatGPT. Carded in Edition 027.
Sep 10
Amazon's petition for rehearing is denied. Contract-based claims are left open.
Sep 21
Amazon blocks Muse from Amazon.com and files a 41-page amended complaint against Perplexity alleging its servers, not just its users, reach Amazon.
Who has to react
Meta, which now has the country's most popular agent and nowhere to spend money with it; Perplexity, whose statement to a federal appeals court is now the subject of an allegation; OpenAI and Shopify, whose agentic checkout goes international on September 23 with Amazon's position freshly stated; every retailer smaller than Amazon that was waiting to see whether refusing agents was viable; the payment networks building agent credentials on the assumption that merchants want the traffic; and the Ninth Circuit, whose August ruling just got answered with facts instead of arguments.

The evidence

Reported. Amazon's statement and the on-screen message are quoted identically by two independent outlets, and the amended complaint's date, length and claims come from MLex and The Next Web, but we did not read the filing: the docket aggregator refused automated access this morning, so the case number and the exact wording of the new allegations are unconfirmed. Amazon's own newsroom, checked this morning, carries nothing on either action. Verification event: the amended complaint appearing on the public docket, or Amazon publishing a statement or policy on third-party agent access, by October 22, 2026.

ObservedSunday September 21, 2026. Two Amazon actions in one day.

The whole observation, as recorded

First: Amazon cut off Meta's Muse agent from Amazon.com. Users attempting a purchase through Muse were shown the message: Continued access by an unauthorized AI agent violates Amazon's Conditions of Use, to which our customers have agreed. Amazon's statement on it: We think it's fairly straightforward that third-party applications that offer to make purchases on behalf of customers from other businesses should operate openly and respect service provider decisions about whether or not to participate. Muse launched on September 8 across iOS, Android, the web and WhatsApp, and was the most downloaded free app in Apple's United States store a week later, ahead of ChatGPT, carded in Edition 027. Meta had previously said it has no visibility into people's passwords or payment methods and that shared credentials go into secure storage. Second: Amazon filed a 41-page amended complaint against Perplexity AI in California federal court, pleading computer fraud, violation of California's computer data access statute and tortious interference with contract. The new allegation is that Perplexity's Comet for iOS, released March 18, 2026, copies a user's Amazon session cookies to Perplexity's servers, which then access Amazon directly, and that this contradicts Perplexity's representation to the court that no Perplexity computer ever has direct access to an Amazon computer. Amazon's framing: Perplexity chose to disguise an automated agentic browser as a human user, to evade Amazon's technological barriers, and to access private customer accounts without Amazon's permission. And: this is not about stifling innovation; it is about unauthorized access and trespass. The procedural history matters. Amazon won a preliminary injunction against Comet in March 2026. The Ninth Circuit lifted it on August 4, holding that under the federal anti-hacking statute it is the user, not the AI company, who accesses Amazon's computers. Amazon's petition for rehearing was denied on September 10, eleven days before this filing. The appeals court left contract-based claims open, and that is the door this complaint walks through.

Established

Amazon blocked Meta's Muse agent from purchasing on Amazon.com on the night of September 21, 2026, and displayed a message calling it an unauthorised AI agent under Amazon's conditions of use.
Amazon stated publicly that third-party purchasing applications should operate openly and respect service provider decisions about whether or not to participate.
Amazon filed an amended complaint against Perplexity on September 21, 2026 in California federal court pleading computer fraud, California computer data access and tortious interference.
The Ninth Circuit lifted Amazon's injunction against Comet on August 4, 2026 and denied rehearing on September 10, leaving contract claims open.

Not established

That Perplexity did what Amazon says. The session-cookie allegation is new, unproven and contested, and Amazon has already been wrong once in this case in the view of an appeals court.
That Muse is blocked for good. Nothing stops Amazon reinstating it tomorrow, and the two companies have obvious reasons to negotiate.
That agentic shopping is in trouble generally. Amazon is one merchant, and OpenAI's Shopify checkout expands internationally two days from now with retailers who want the traffic.
That Amazon is acting on security. Amazon's own stated reason is participation and permission, not harm to customers, and it sells competing AI services of its own.

Why it weighs this much

Signal strength

CostMedium

CommitmentMedium

ReversibilityEasy

PersistenceMonths

Cost is medium. Blocking Muse costs Amazon whatever those shoppers would have spent and some goodwill; the amended complaint costs legal fees on a case it has already lost once. Commitment is medium: Amazon put its name on a stated principle about who decides participation, which is harder to walk back than the block itself. Reversibility is easy, and that is the honest limit on this card. A block implemented in an evening can be lifted in an evening, and these two companies have every commercial reason to end up with a deal. Persistence is months rather than years for the same reason, with the litigation the part that could outlast it. We score the actions, not the outcome.

What to watch

strengthens A second top-ten retailer by revenue publicly blocks or conditions access for a named third-party shopping agent, or Amazon publishes terms setting out how agents may participate, by March 31, 2027.
weakens Amazon restores Muse's access, or announces a partnership or paid participation arrangement with Meta or another agent provider, by March 31, 2027.

The words

Agentic shopping: Software that browses, chooses and buys on a person's behalf, using that person's logged-in account rather than an official interface.
Session cookie: The small file a website gives your browser to prove you are still logged in. Whoever holds it can act as you until it expires.
Computer Fraud and Abuse Act: The American anti-hacking law. It turns on who accessed a computer without authorisation, which is why the Ninth Circuit's answer that the user did, not the agent's maker, mattered so much.
Tortious interference with contract: A claim that an outsider deliberately caused someone to break an agreement, here Amazon's conditions of use. It survives even where the hacking claim fails.

Your call

If the amended complaint is confirmed on the docket, which explanation do you believe?

A call is final. Other people's calls show after yours.