Conjecture S.1 — Emergent Relativity, not proven here

IF (L1) “frame” is restricted to linear, homogeneous reparametrizations of $(r,t)$; (L2) coherence-preserving transformations map uniform (non-dissipating) motion to uniform motion; and (L3) the admissible transformation set is isotropic (no preferred spatial direction) — THEN the standard relativity-derivation argument (e.g. Einstein 1905; Pal, “Nothing but Relativity,” 2003) implies the admissible group is either the Galilean group or the Lorentz group with invariant speed $c_{\mathrm{eff}}$. None of (L1)–(L3) is established from the closure framework itself in this appendix; each is an additional physical assumption. No proof is given here.