Langlois & Seignobos (1898) already documented authenticity-bleeds-into-credibility, the failure mode 2025 intelligence-doctrine and RAG research treat as a new finding

bridge-investigationhistorical-methodintelligence-tradecraftRAGlanglois-seignobossource-evaluationepistemicsmultiple-discovery

The vault's existing synthesis frames "reliability bleeds into credibility" as a finding Kelly et al. (2025, human analysts) and AuthorityBench (2026, language models) each independently reached. The same failure mode, running in the same direction — a first-axis verdict on the document's provenance pulling the second-axis verdict on its contents along with it — is stated in Langlois and Seignobos's 1898 historical-method textbook: "The confusion is still further increased by the use of the word authentic, borrowed from judicial language. It has reference to the origin only, not to the contents; to say that a document is authentic is merely to say that its origin is certain, not that its contents are free from error. But authenticity inspires a degree of respect which disposes us to accept the contents without discussion."

This gives the vault's "two axes that won't stay independent" cluster a documented instance 127 years before the 2025 study that frames the leak as a new finding — and the oldest instance in the cluster, 41 years older than its previously-oldest member, the Admiralty Code's 1939 origin. It sits in the same primary text as the External/Internal Criticism split itself. It is a historical/mechanism claim resting on a Tier 1 primary source, clearing the sourcing floor without a flag — the leak is not merely structurally analogous to the modern finding, it is described in nearly the same terms: an authenticity judgment inspiring misplaced trust in content.

One seam this note should not paper over. The 1898 first axis is the document's authenticity — is this charter genuine — where Kelly et al.'s is the source's reliability, a standing track record of the person or outfit vouching for it. Those are different quantities, and the vault's diplomatics contrast note turns on exactly that difference. What recurs across the 127 years is the shape of the leak — a settled verdict on where a document came from buying unearned assent to what it says — not a term-for-term match of the axis it leaks from.