Open Door

The Open Door is what a Zero Information Casualty site keeps for every sent agent. The web increasingly puts bot walls, JavaScript gauntlets, crawler blocks and rate limits between information and the people who send agents to get it, and "to the person waiting for an answer, the technical category of the obstruction is irrelevant."

The Open Door doesn't oblige a publisher to permit search indexing or training, and doesn't bypass conditions that apply equally to human visitors. It requires that public content available to a person is available, without agent-specific obstruction, to the reader that person sent.

Its three parts

• Service: known user-directed agents are explicitly allowed, and not challenged, degraded, delayed or cloaked.
• Orientation: a map in the form agents natively read, Markdown at /llms.txt, with Markdown copies of the content where practical.
• Policy clarity: the licence is stated, and indexing and training are each declared separately. Permission for one is never inferred from another.

The standard is honest that, as of mid-2026, most AI crawlers don't fetch llms.txt and its effect on AI search is about zero. It is required anyway: "the standard specifies what a well-formed site is, not what current crawlers happen to reward."

The switch with the wrong default

In September 2026 the largest edge network began recommending, by default, that the "agent" category be blocked on pages carrying advertising, on the reasoning that an advertised page is one a person was meant to land on and see. The person who sent the agent has landed there; she is simply not looking. ZIC names this an Admission Casualty, whoever sets it: "The premise that she must also see it is the premise this specification was written to remove."

Behind the scenes

A real idea, from Zero Information Casualty v1.7, the design standard by Charli-Jo Tyrer and Claude, §1.6 and §2.2. This entry summarises it; the standard is the authority. charli.info was the first site to operationalise the Open Door.