Fibre Admissibility and Exact Pair-Exponent Doubling

0.5em The O-series has established that the Weil-block capacity exponent δ̂exact ≈ 3.72 ± 0.06 falls systematically below the phenomenological comparison range δ ∈ [7.4, 10.6], and that no reweighting of block data can raise the exponent. The present paper identifies a distinct fibre-level observable. The non-injectivity of the projection Π, established from the Born–Infeld constraint, implies that admissibility is a property of complete fibres of Π, not of individual preimage configurations. In the Weil realisation of Heis₃(Z/qZ), these fibres are organised as conjugate pairs , q-c\ under the exact identity ρq-c = ρc̄. The pair-level observable σₚₐᵢᵣ(n) = σc(n)\,σq-c(n) follows a clean power law with exponent δₚₐᵢᵣ = 2\,δc ≈ 7.44 ± 0.12, confirmed numerically with R² > 0.9999 and a factor-of-six reduction in slope variance under the production log(n+1) fitting convention. On the same finite windows, conversion to the paper-level log n definition gives approximately $6.6$–$6.9$. The exact doubling is a fibre-side result; it does not derive a native Heisenberg growth process carrying the pair observable and therefore does not establish the capacity-to-rate transfer.