Structural Obstruction in a Seven-Operator Lie Algebra: Derivation Rigidity and the CoreX Spark Spectral Constant
This paper establishes G₄(φ) ⊕ su(2) as the unique admissible closed Lie algebra structure over a seven-operator system. Three core theorems are formally proven: (T1) Jacobi identities close uniquely — the key commutator [F,N] = −i·tan(φ)·Cyc is derived rather than postulated; (T2) the spectral obstruction tensor is non-vanishing, rigorously ruling out semidirect product decomposition; (T3) the outer derivation algebra is one-dimensional and uniquely realised at the CoreX Spark constant φ★ = (1+√5)/2, identified as the Perron-Frobenius spectral radius of the structure matrix. All results are verified via SymPy with reproducible code in the appendix. Zero self-citations; bibliography contains only standard mathematical references.