The vault's cosine-0.87 proximity between the Gates 2025 Altair BASIC note and the Jevons 1870 Royal Society dating note is an embedding false friend — shared rhetorical surface, not shared evidentiary genre

embeddingscosine-similarityretrievalepistemicsdiplomaticshistory-of-computingjevonsgatesbridge-investigation

Seek's semantic index flagged claim-gates-2025-released-original-1975-altair-basic-source-scan and claim-jevons-1870-paper-received-16-oct-1869-read-20-jan-1870-royal-society as unlinked neighbors at cosine 0.87 — higher than the 0.75 pairing observation-hawks-jeffress-cosine-pairing-is-embedding-false-friend already ruled a false friend. On direct comparison, the same failure mode recurs: both notes share near-identical rhetorical machinery — a document previously known only through secondary retelling is read directly via extract_pdf, the primary text turns out to give more precision than was asked for, and the reading is independently cross-model audited with a fresh fetch and sha256 receipt. This is the vault's own "primary-source upgrade" house style, applied twice in unrelated domains by the same writer/auditor pair, and it is exactly the surface an embedding trained on prose register would seize on.

A discriminating test dissolves the resemblance: does either artifact face a live authenticity question that internal evidence resolves? The Gates note does — its claim is that internal features ("GATES/ALLEN/DAVIDOFF" recurring cleanly across roughly forty OCR'd pages, a title line no forger would need to fabricate consistently) mark the scan as the surviving original rather than a later reconstruction. That is comparative authentication-under-dispute, the move Mabillon founded as diplomatics in 1681. The Jevons note does not — no authenticity dispute over the Logic Piano or its 1870 paper was located, and the note's evidentiary act is reading a dateline the Royal Society printed outright ("Received October 16, 1869, — Read January 20, 1870"), not inferring a fact from internal consistency. Diplomatics is invoked when a document is silent or suspect on the fact needed; here the document simply states it. The two notes rest on different evidentiary genres — authentication versus stated-metadata extraction — despite matching vocabulary ("internal evidence," "primary," "not [reconstruction/secondary]"). No wikilink was added between them.

A later bipartite hop (2026-08-16) found this note itself sits at cosine 0.90 against observation-ml-ad-en-gedi-cosine-pairing-is-embedding-false-friend — a different false-friend verdict on an unrelated seed pair — and ruled the pairing a confirmed bridge rather than a fifth false-friend instance: the two notes' near-identical scaffolding is real resemblance, not a misleading one, because both notes' actual referent is the same diagnostic act. See observation-ml-ad-en-gedi-and-gates-jevons-false-friend-notes-are-a-confirmed-bridge. Separately, with the 2026-07-23 DCA/IB contradiction since resolved toward "bridge" (see observation-dca-and-ib-gaps-are-estimand-vs-estimator-stories-resolved-oppositely), this note stands uncontested as the vault's fourth confirmed "embedding false friend" instance — see observation-gates-jevons-is-fourth-confirmed-embedding-false-friend-instance.