Every established measure of a digital property assumes a human reader: someone who arrives, looks, and decides. That assumption held for twenty years. It stopped holding in the eighteen months when the majority of requests stopped being people.
Nothing about the old measures became inaccurate. They became irrelevant to the population they were measuring. Every metric on the left describes an impression; every requirement on the right describes an outcome, and only one of the two survives contact with a machine client.
Each of these was true enough to build an industry on. None of them survives a client that cannot see, does not browse, and is measured by whether it finished.
An agent does not skim, hesitate or get persuaded. It either finishes the task it was sent for or it reports a failure to the customer who sent it.
A control that only exists after a paint, a hover or a client-side branch is not reachable. The interface an agent sees is the set of operations it can call.
Identity, eligibility, confirmation and receipt are separate steps, and any single one of them can dead-end the whole journey with everything before it wasted.
Agent volume arrives without the patience or the brand memory that made human traffic worth paying for. Served requests with no outcome attached are an expense line.
The replacement is not another checklist. It is a simulation: send the same frozen agents at the same real journeys, count what they finished, and hold the result to a governance gate and a cost line.
A value-weighted task either completed or it did not. Partial credit for a well-rendered dead end is how a property scores well and converts nothing.
Real traffic arrives with stale sessions, changed copy and slow third parties. A number produced only under clean conditions is a number about a lab.
Tokens, retries and latency are now unit economics. A journey that succeeds at ten times the cost is a different commercial result from one that succeeds.
The Webzero Agent Readiness Index is the index this shift produced: one governed number for whether an agent left with the outcome it was sent for.