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Stall library

A stall is the point at which an AI agent stops making progress towards a purchase on a store. This is every stall an Ottom scan can report, grouped by the journey stage it happens in: discover, evaluate, compare and buy. Each page carries the mechanism that causes the stall, the steps to see it yourself, and the change that removes it.

The codes below are the same identifiers that appear in a report, and they are stable. Codes are added and deprecated but never renamed, because the code is what ties a finding to its fix and to any later comparison. The list is version stall-v3.

The Ottom Stall Taxonomy

Use it, quote it, build on it. It is published under CC BY 4.0, so the only condition is attribution, which is the point: a quoted code should carry where it came from.

Cite it as:

The Ottom Stall Taxonomy (stall-v3), Ottom

Machine readable at /taxonomy.json: every code with its stage, severity, mechanism and fix, carrying the version so you can pin to it.

Discover

Stall	Code	Severity
robots.txt blocks AI shopping agents	`robots_blocks_agent`	critical
Bot protection blocks the agent before the storefront loads	`bot_wall`	critical
No products found for an agent to read	`no_catalogue`	critical
Products only appear after JavaScript runs	`catalogue_requires_js`	critical
Product pages did not answer when the agent asked for them	`product_pages_unreadable`	high
No sitemap for agents to crawl	`no_sitemap`	high
No machine-readable product feed	`no_product_feed`	high
Product pages have no schema.org markup	`missing_schema_org`	high
No llms.txt to orient agents	`no_llms_txt`	low

Evaluate

Stall	Code	Severity
The store refused the product page to the agent	`product_page_refused`	high
Price is not readable without running the page	`missing_price_data`	high
Stock status is not exposed to agents	`missing_availability`	high
Returns or shipping policy is only in an image	`policy_in_image`	high
Variants are not described in structured data	`no_variant_data`	high
Product feed is out of date with the storefront	`stale_feed`	medium
Products have no GTIN or MPN to match against	`missing_gtin`	medium

Compare

Stall	Code	Severity
Feed price and storefront price disagree	`inconsistent_pricing`	high
Shipping cost cannot be determined before checkout	`missing_shipping_terms`	high
Catalog has no category structure to compare within	`no_category_structure`	medium

Buy

Stall	Code	Severity
A control an agent needs is not exposed as one	`control_not_exposed`	low
Agent could not reach the payment step	`payment_step_unreachable`	critical
Checkout requires creating an account	`forced_account_creation`	critical
The cart can only be paid with an express wallet	`express_only_checkout`	high
CAPTCHA stops the agent at checkout	`captcha_at_checkout`	critical
Checkout returned an error	`checkout_error`	critical
Size or colour can only be chosen by hovering	`hover_only_variant_picker`	high
Choosing a variant needs JavaScript the agent cannot run	`variant_js_required`	high
A popup blocks the path to the cart	`popup_blocks_flow`	high
Add to cart needs JavaScript the agent cannot run	`cart_requires_js`	medium
The store refused the agent’s add to cart	`cart_add_refused`	high
An age check asks for a date of birth	`age_gate_requires_dob`	high
A simpler agent stopped at a step an AI agent got past	`agent_needed_to_recover`	low
An agent can buy only the option already selected	`variant_choice_unavailable`	low
A popup covers a button on the way to checkout	`popup_covers_control`	medium
A cookie banner covers the page until it is answered	`consent_overlay_covers_page`	low
The first press of checkout does nothing	`checkout_press_dropped`	medium
One item cannot be checked out below your minimum order	`minimum_order_not_met`	medium
Nothing we picked could be bought	`no_buyable_product`	info

How often each of these happens

Not in this library. These pages describe what each stall is and how to fix it, and a frequency only means something beside the cohort it was counted over. Where a category has enough stores measured at every stage, the share of them showing each stall is published on its benchmark page, with the methodology beside it.

Find out which of these your store has