{
  "item": "C4",
  "verdict": "UNMEASURED",
  "target_selmer_line": {
    "group": "H¹_f(Q, Q₁₁(χ₈)(1))",
    "dimension": 1,
    "generator": "κ(ε), ε = 1 + √2",
    "source": "RUN-092"
  },
  "transverse_extension": {
    "constructed": false,
    "extension_group": "Ext¹(1, ψ) = H^1(Q, Q_11(chi_8)(1))",
    "cocycle": "c(gh) = ψ(g)c(h) + c(g)",
    "which_entry": "the upper-right entry c(g)",
    "basis_frame": "e₁ spans the sub; e₂ is any lift of the quotient — the class is independent of that lift",
    "local_conditions": "all four vacuous — membership automatic (this gate)",
    "nonzero_witness": null
  },
  "membership": "AUTOMATIC",
  "nonvanishing": "UNMEASURED",
  "scalar": "UNMEASURED",
  "split_status": {
    "C4-membership": "CLOSED — automatic, all four local conditions computed vacuous",
    "C4-nonvanishing": "OPEN — no witness for the transverse class",
    "C4-exact-scalar": "OPEN — not attempted, by instruction"
  },
  "gate": "src95 · c4-transverse",
  "level": "E",
  "mutation": "claim nonvanishing without a witness, or guess the scalar from log₁₁(ε)/(11√2) ≡ 5",
  "agrees": true
}