A failure taxonomy for machine-mediated shopping

Why a shared vocabulary

When a shopping agent fails in a store, three groups need to talk about it: the store, the people building the agent and the researchers measuring both. Without shared words, each tells a different story about the same failure.

We publish this taxonomy so any team can apply it to its own traces.

The seven classes

Seven classes of failure a shopping agent can meet in a store.

CodeFailure class

Unresolvable element

The agent could not locate or interact with a required page element.

E.g. A price rendered as an image. A button that only appears on hover.

Variant ambiguity

The agent could not tell which variant to choose from the signals it had.

E.g. Size and color selectors that do not expose machine-readable state.

Cart state loss

Items were added to the cart but were missing at checkout.

E.g. Session expiry or a redirect that dropped the cart.

Payment wall

The agent reached payment but could not go on, because the step needed a human-scale interaction.

E.g. A CAPTCHA. A 3D Secure modal with no programmatic path.

Dynamic content race

A price, availability status or form field changed between the agent reading it and acting on it.

E.g. The agent acts on a value that is no longer true.

Navigation dead end

The agent reached a page or state with no way forward toward the task, and no error was shown.

E.g. A page that neither advances nor fails.

Data inconsistency

Structured data disagreed with the rendered page, so the agent acted on incorrect information.

E.g. A feed, schema.org markup or meta tags that differ from what the page shows.

How the codes are used

Each failure in a trace can be tagged with one or more taxonomy codes. The codes can appear in a scorecard and in the raw trace. A store can use them to decide what to fix first.

Versioning

The taxonomy is versioned and open. It will be extended as new failure modes are observed, and additions will be announced as minor version increments.