Scoped negative result: X4 target-forest floor holds for all dyadic parent coefficients (no new kappa)

[woklerx]

The pinned PR799 X4 target-forest result (#932) establishes a 10,883-primitives-per-real-component optimum only for signed-unit parent coefficients. This research note extends that exact floor to every nonzero dyadic parent coefficient under the same independent binary-Horner lowering and leaf-before-parent forest schedule. No new kappa or supplier integration is claimed.

Two elementary tail bounds reduce all dyadics to 1,086 coefficients. Two separately implemented exact checkers cover 13,501,152 ordered coefficient/target-pair cases. 970 nonunit edges beat their original root, but every nonunit edge is strictly dominated by a root or signed-unit edge to the same parent. A forest exchange argument transfers the 10,883 floor; independent Prim/Kruskal and 12,544 cycle inequalities recheck the attaining signed-unit graph.

Reproduce offline, standard-library Python 3.10+:

python -I -O -B research/complex-x4-dyadic-forest-seed31/verify.py
python -I -O -B research/complex-x4-dyadic-forest-seed31/test_package.py

The full checker passes with CPython 3.11.0 and 3.14.5; nine package tests pass. The original PR932 full scalar witness and selected-record verifier also pass. Selected-result tests pass; two existing symlink tests skip in the Windows sandbox. Full repository/cold-supplier suites and hosted CI were not run because no existing supplier or generator changes.

Base: 018418f; source/dependency pins, complete coefficient certificate, proof, local sprint claim (seed 31), controls and scope are in the new package. Credit Ross Richardson #932, ToikY #909, the restored-pair/forest predecessors and Jeremy Kothe/Chafik Boukhalfa/icekylinx supplier lineage. Substantial OpenAI Codex assistance, including a separate checker implementation and mathematical review, is disclosed. No independent human review or full multiplication-theorem formalization is asserted.

Multiple parents, helper-basis changes, arbitrary sequential shears, shared coefficient work and other lowerings remain outside scope. The selected frontier and upstream/ remain unchanged.