What the thermometer reads

Every signal below is observable from one public fetch of one URL, with no login and no crawl of the rest of the site. The table is generated from the engine at page load, so it cannot describe a check that is no longer running.

That last part matters more than it sounds. The usual failure mode for a page like this is that it gets written once, the tool changes twice, and eighteen months later the site is publicly describing a methodology it abandoned. Rendering it from the registry means adding a signal to the code adds a row here in the same deploy, and removing one removes it.

How a signal becomes a temperature

Each of the four readings is scored as a percentage of its own available weight, and the overall temperature is the weighted blend of those four percentages. It is deliberately not one pool of 37 weights. A single pool would let a reading made of many small signals quietly outvote one made of few large ones, and then the four readings would stop meaning what they say.

Weights are ordinal, not scientific. They encode a judgement about how much each signal costs you when it is missing, based on twenty years of watching which ones actually keep pages out of results. A page blocked by robots.txt is not slightly less visible than a page missing an og:image, and the weights say so.

What it does not read

Everything here is observable from one public fetch of one URL, without logging into anything. That is the boundary, and it is a real one. This thermometer does not know your rankings, your traffic, your backlinks, your Core Web Vitals, or how the page renders after JavaScript runs. It does not crawl the rest of the site. It does not judge whether the writing is any good.

Those are real questions and several of them matter more than anything on this page. They are also not thermometer questions. The Visibility Diagnostic covers the site rather than the page, and treatment is where the ones that need building rather than measuring go.