v152 · suspicious site warnings

What a page can observe

The answer is nothing, and an answer like that has to be earned. Every plausible place a verdict might be exposed is checked here, with controls that prove the checking works — because "I looked and did not find it" is only useful from someone who can demonstrate they would have.

Places a verdict could have been

Each candidate, probed
candidatepresent?reads asnote
Not checked yet.
Press the button.

The two control rows are the point of the exercise. One names something that certainly exists and one something that certainly does not, so a table of absences means something rather than being the shape a broken probe would also produce.

Things this is not

Real mechanisms that get mistaken for a safety signal
mechanismpresent?what it actually reports

Every one of these is real and useful, and none of them will ever mention Safe Browsing. They report your page's own policy violations back to you — a different question, asked by a different party, about a different thing.

Why the absence is the design

A detectable warning is a defeatable warning. A page that could read the verdict could change its behaviour when it is being watched — show benign content to a flagged load, keep the deceptive flow for everyone else — and the signal would be worth less than nothing, because it would now also be a reliable way to detect the safety system.

The same argument rules out an opt-out, and it is the reason the operational path runs through an account you have to prove you own rather than through an API. That is slower on purpose.

see also