Signal 06 of 09 · Nebula Diagnostic Spec v1.0.0
Above-Fold Clarity
Can a visitor understand the offer and next action in the first viewport?
Decision rule
Within the initial viewport a first-time visitor must be able to answer three questions: what is offered, who it is for, and what to do next. A run flags pages where any of these answers requires scrolling or inference.
What the engine inspects
- ·viewport-height slice of rendered DOM
- ·headline, subhead, CTA presence in that slice
How to check it yourself
- Screenshot the initial viewport on desktop and at 390px mobile width.
- Ask whether a stranger could answer three questions from that slice alone: what is offered, who it is for, what to do next.
- Any answer that requires scrolling or inference fails the signal.
The engine automates this inspection and attaches measured evidence to every failing condition. A manual pass is not a substitute for the recorded evidence trail, but it should agree with it.
Pass / fail examples
Pass
Offer, audience, and CTA all legible in the first desktop and mobile viewport. Clear.
Fail
First viewport contains only a full-screen illustration and a logo; offer and action require scrolling. Flagged.