The cart is the other side's gate
Muse can enter a service through the browser and proceed as a user would when no API exists. Amazon closed that door: it said Meta had not sought an agreement to participate and the agent did not identify itself. The user also saw a terms-of-use warning. Muse's shopping task therefore broke at the external gate between choosing a product and paying for it.[1]
This friction begins after the ability to click the screen. When a merchant does not recognize who is acting or which rules govern the action, pressing the correct button does not complete the task. Amazon points to security and customer-account concerns. A desire to retain control over the store and its customer relationship could also explain the same decision.[1]
The user needs a way back
Meta says Muse asks for approval before a purchase and Sentinel reviews outbound actions. Those controls did not overcome Amazon's block. In the flow reported by GeekWire, the user has to leave the task in Muse and continue on Amazon. If the cart, product selection, and session context do not survive that transition, a few minutes of help turn into a new start-over task.[1]
The companies were in direct talks at publication time. The concrete signal for a user is not another Muse capability; it is a handoff that carries the selected product into Amazon when a block appears, clearly identifies the agent, and leaves payment control with the user. When that path is visible, the shopping agent moves closer to a product that remains useful at the moment of failure.[1]