Field Notes from the Substrate — Translations No. 3: Cosmic Expansion as Whole-Scale Relation Carry

This working note is the third installment in Field Notes from the Substrate, a series translating physics-facing concepts through Structural Flow. The note translates cosmic expansion as Whole-Scale Relation Carry: the substrate-level condition under which an already-coherent shared density-held geometry carries an authorized update of large-scale relational structure as one lawful update of the whole geometry/source accounting relation, without converting that update into ordinary local motion through fixed space and without erasing local bounded governance. The core claim is that cosmic expansion is whole-scale relation carry under structural answerability. The Structural Flow object is Whole-Scale Relation Carry. The classical-facing phenomenon is cosmic expansion. The primary classical representative is the cosmological scale factor a(t). The rate translator is H = ȧ/a. Redshift is an observational trace. FLRW geometry and the Friedmann equations are model and dynamics layers. This note separates Whole-Scale Relation Carry from Baseline Geometry Contribution and Structural Answerability Condition. Baseline Geometry Contribution, translated in Field Notes No. 1, names the Λ / dark-energy-facing baseline geometry role. Structural Answerability Condition, translated in Field Notes No. 2 as SF-Pressure, names the must-answer / not-dictated relation created when carried status remains live for later accounting. Whole-Scale Relation Carry names the expansion-facing scale-relation object. The proposed failure signature is: the whole-scale relation updates; the accounting mislevels the update. The primary failure regime is Shear. This is a role-shape translation, not a full cosmological derivation. It does not derive the Hubble constant, solve the Hubble tension, derive the Friedmann equations, derive FLRW geometry, close inflation, replace ΛCDM, solve the cosmological constant problem, close dark-energy mechanism, close full General Relativity, close quantum gravity, or settle observational cosmology. Its contribution is narrower: it locates the structural object carried by the cosmic-expansion-facing role and names its distinctive failure signature.