Dup-risk stub: the LeCun-1989/Werbos-1968 note pair (cosine 0.87) is cluster density, not a bridge

Subject: whether claim-lecun-1989-first-practical-recognition and claim-werbos-1968-cybernetica-earliest-germ (cosine 0.87, unlinked) share a genuine, capture-worthy connection beyond both being about backpropagation.

Finding: not a bridge. vault_bridge on the pair returns bridge_candidate: false — both notes sit inside the same already-dense entity-backpropagation / moc-backpropagation-origins cluster (60+ notes), already linked to each other indirectly via the backpropagation hub note and several intermediate notes (e.g. the RHW-1986 note, at cosine 0.78–0.83 to both). The apparent resemblance is explained by shared vault house-vocabulary — "first," "earliest," hedged sourcing-floor language about unreachable primaries — a pattern that already recurs at least three times in the same cluster (claim-werbos-tsp-manual-first-publication: citation real, document unlocatable; claim-perceptrons-1969-standalone-scan-not-freely-available; claim-speelpenning-1980-does-not-cite-linnainmaa's OCR wall).

max_cosine: 0.822 (Werbos note) / 0.829 (LeCun note) between the pair directly. A synthesized candidate note articulating "both notes bracket a 21-year arc between an unrecoverable origin claim and a partially-recoverable application claim, and both hit the identical evidentiary problem" gated at max_cosine 0.822, novelty_percentile 91.9 — duplicate-risk against vault_novelty.

Closest existing note: claim-werbos-1968-cybernetica-earliest-germ itself (0.822), followed by claim-werbos-tsp-manual-first-publication (0.79) and claim-werbos-1988-rhw-special-case-of-dynamic-feedback (0.781) — all inside the same cluster, confirming the "unreachable primary" framing is already vault knowledge, not a new finding.

Hop chain: seed (both claim-notes read directly) -> vault_bridge on the pair (bridge_candidate: false) -> vault_novelty on a synthesized "unrecoverable-origin-vs-verified-application" framing (91.9 percentile, duplicate-risk) -> closed, no capture, no wikilink added between the two notes. Chain continued outward from the Werbos side instead (see 2026-07-30-hop-karl-deutsch-political-cybernetics.md).

Disposition: per the seed's own instruction, this outcome — "the resemblance is superficial" — is the deliverable. No wikilinks added to either source note.