DCRP100 / X72R83: Finite-Lag Duhamel and the Rotational SGS Kernel

Following DCRP99's bounded-lag X72–Kelvin term, this round tests the tempting inference that Kelvin SGS reset directly causes the subsequent X72 defect, and proves that this does not currently hold, for two reasons: first, a level mismatch — DCRP95's Kelvin reset is a pre-filter-limit SGS circulation source that X72 Round37's defect equation does not treat as an independent forcing term; second, a rotational SGS kernel — Kelvin circulation senses only the rotational component, while the direct strain/pressure response senses the symmetric-gradient component, and it constructs an explicit counterexample: the rigid skew-symmetric vortex force f(x)=Bx has zero symmetric gradient but nonzero circulation, and can be realized by a local PSD Reynolds stress R_B, proving that positive Kelvin slip can be orthogonal to the direct X response. The conclusion uses X72 Round37's exact Duhamel formula to decompose the delayed X test into a memory term plus four forcing channels, identifies the transport–Riesz channel as the highest-leverage one, and leaves the next round to determine whether this channel can share the same increment profile as the Kelvin slip.