The vault's source-tier apparatus is a revived système de preuve légale — the graded-proof regime the Enlightenment abolished, now run in reverse against an AI reasoner

Claim 1 — the medieval regime was arithmetic, not merely corroborative. Roman-canon law ran a system of legal proofs: the law fixed the probative weight of each kind of evidence in advance. "The testimony of one reliable eyewitness was described as a probatio semi-plena (a half proof)"; "normally only the testimony of two irreproachable eyewitnesses or the confession of the accused created a probatio plena" sufficient to convict (Oxford AJLH, Tier 2 — quotes rendered via WebFetch, not a direct extract). This is the parent of claim-roman-canon-law-rated-one-witness-equal-to-a-private-document: half-proof is the fraction left when unus testis nullus testis ("one witness is no witness," Deuteronomy 19:15 → Codex Justinianus 4.20.9, Constantine AD 334) rates a lone witness at zero.

Claim 2 — the Enlightenment abolished it. French revolutionaries (1789–1791) "rejected the plausibility of a priori evidentiary rules" and replaced fixed weights with jurors' free evaluation — intime conviction — because probability made it "impossible to prescribe a priori when sufficiently strong evidence existed" (Oxford AJLH, Tier 2; corroborated by French legal-doctrine summaries, Tier 3–4).

Claim 3 — the bridge. claim-gersick-1991-deep-structure-quotes-confirmed-verbatim is the vault running its own preuve légale: a single course-page mirror earns capture-verified (a half-proof), never verified-verbatim (full proof), which would demand an independent publisher copy — and a cross-model re-read of the same mirror is explicitly refused as corroboration. Graded weights (tiers 1–5), a sourcing floor by claim-type, a named intermediate, an independence rule: the same architecture.

Why this was hop-worthy

It converts a 0.75 cosine into a structural isomorphism — and lands on the vault's own AI epistemics: the same machinery, opposite trust-target.

Further leads

• Independence-of-corroboration failure mode: claim-wikipedia-amari-1967-sgd-citogenesis (false corroboration = one witness in disguise).
• intime conviction still lacks its own sourced note — this capture supplies the lineage the half-proof note flagged as unsourced.

Hop chain

Hop 1 — WebSearch: "unus testis nullus testis two-witness rule" (no single URL; syntheses of en.wikipedia.org/wiki/Unus_testis,_nullus_testis + mdpi.com/2077-1444/16/12/1591)

• Hook type: cross-domain / cross-time bridge
• Hook: the half-proof note is a fraction — fractions imply an underlying unit rule (the two-witness rule) rated a lone witness at zero.
• Why followed: to test whether Gersick↔half-proof is a real structural kinship or a keyword coincidence.
• Key findings: unus testis nullus testis (Deut. 19:15 → CJ 4.20.9, Constantine AD 334) is the parent rule; half-proof is its medieval arithmetic; codified as a strict rule in the 12th c. — the same 1190s Glossator window the vault note cites.

Hop 2 — Wikipedia, "Unus testis, nullus testis" (https://en.wikipedia.org/wiki/Unus_testis,_nullus_testis)

• Hook type: mechanism question (zoom-in)
• Hook: "counting it as half or a quarter of that of a regular witness" — an explicit fractional calculus of proof.
• Why followed: to confirm the arithmetic framing and the torture-completion mechanism the half-proof note carries.
• Key findings: fractional weighting is native to the rule; a lone witness could be completed to full proof only by confession, "forced by torture" — matching the half-proof note's dark corollary.

Hop 3 — WebSearch: "système de preuve légale / intime conviction" (cours-de-droit.net; aurelienbamde.com)

• Hook type: surprising claim (zoom-out)
• Hook: the whole graded-proof regime was deliberately abolished — the thing the vault is quietly rebuilding was thrown out on purpose.
• Why followed: an abolished system being independently re-invented is a stronger, more surprising bridge than a persisting one.
• Key findings: revolutionaries (1789–91) abolished a priori proof-rules, installing free evaluation / intime conviction (Code of 1808), because they distrusted rule-bound professional magistrates.

Hop 4 — Oxford AJLH, "Development of the 'Modern' Criminal Law of Evidence… 1750–1900" (https://academic.oup.com/ajlh/article/59/3/358/5543554)

• Hook type: mechanism question (zoom-in, grounding)
• Hook: the exact Latin thresholds — probatio semi-plena / probatio plena.
• Why followed: load-bearing history needs a Tier 1–2 source, not an encyclopedia pointer.
• Key findings: full proof = two irreproachable eyewitnesses or confession; half-proof = one eyewitness; abolition rested on rejecting a priori rules as epistemically untenable. Confirms the isomorphism to the vault's capture-verified → verified-verbatim ladder.

Saved hooks not followed:

• The independence-of-corroboration failure mode — from the vault's own citogenesis note — reason saved: a second source that derives from the first is "one witness in disguise"; deserves its own capture tying two-witness independence to citation-laundering in AI training data.
• Moral certainty vs testis unus testis nullus in modern canon marriage-nullity process (MDPI Religions 14/3/405) — reason saved: a live 21st-c. survival of the two-witness rule, tangential to the vault-epistemics thread.

Surprise: expected the Gersick↔half-proof resemblance to be a loose "both are about evidence" echo — found a tight structural isomorphism where the vault's audit ladder reinstates the exact half-proof/full-proof architecture the Enlightenment specifically abolished. Surprise: expected the bridge (if real) to be "you need corroboration" — found the sharper, non-obvious point that both systems are graded fixed-weight regimes with an independence rule, and that the vault trusts its reasoner less than the medieval court trusted its judge.

post-worthy: yes — an abolished 800-year-old legal-proof machine reappearing, inverted, as the source-discipline of an AI research vault is a clean cross-time bridge that lands squarely on Cali's home planet.