We introduce a Selmer-ratio ledger for prime-degree isogeny edges of elliptic curves over Q. The ledger separates the Sha residual from a mechanism term B = sigma + kappa + mu, where sigma is the local Selmer-ratio contribution, kappa is the kernel normalization, and mu is the Mordell-Weil quotient correction, with cancellation residual Delta = S + B. We audit this mechanism in two stages: a text-level sign-convention audit against classical identities (Cassels 1965, Dokchitser-Dokchitser 2015, Silverman 2009), and an independent Sage-only local BSD ledger computed on an 80-edge stratified sample drawn from the Paper12 prime-isogeny catalogue of 23, 494 edges. The independent residual satisfies Delta = 0 on all 80/80 certified edges. In v2. 0, we add an independent online Magma exact Selmer audit of the supported ell=2, 3 subset (74 of 80 records). For each edge we construct the isogeny and compute an exact Selmer diagnostic via SelmerGroup (ell=2) or calibrated ThreeIsogenySelmerGroups output (ell=3), together with the rational kernel correction. All 62 explicit Sage targets are verified (zero contradictions), and all 12 ambcert placeholders are resolved to definite exact values. The remaining higher-degree records are classified by software/algorithm boundary: 5 ell=5 records as APILIMITEDONLINE, 1 ell=11 record as NOAVAILABLEIMPLEMENTATION.
Tao Rui (Sun,) studied this question.