Six-Point Star Witness at D5: Z-Tension Waist Selection and Shadow Corridors under a G–Σ–P–L Contract

Foundational. This presentation formalizes a single structural upgrade for G–Sigma–P–L corridors on platforms with multiple nearly degenerate switching routes: the D5 witness need not resolve as a bowtie with one waist, but may resolve as a six-point star with several candidate crossings. A canonical waist is selected by a z-tension maximization rule under fixed budgets, promoting one arm to the primary LRS anchor while recording the remaining arms as shadow corridors with their associated Tz\* values inside the same contract. The result converts qualitative star switching pictures into a repeatable, token-emitting decision object that supports cross-platform comparison, internal consistency checks, and falsifier-first mapping without moving thresholds, while preserving secondary structure as audit-relevant shadows rather than discarding it as noise.