The Knösch Model: Validation Appendix (Comparison with Modified Gravity Frameworks)

This technical appendix presents the Knösch model, a scalar–tensor framework where gravity and cosmic expansion are interpreted as manifestations of the same reactive cosmic field. The document contains: The proposed action and field equations. Strong-field and weak-field limits (recovery of GR, MOND-like regime). A parametrization for background cosmology consistent with ΛCDM at late times. A comparison table contrasting the Knösch model with RAQUAL, TeVeS, bimetric/massive gravity, and Horndeski/EFT approaches. Context within the literature (Milgrom 1983, Bekenstein 2004, Clifton 2012, Baker 2019, Skordis & Zlośnik 2021). This appendix is intended as a validation note: it demonstrates that the Knösch model is consistent with key constraints (PPN, $c_T=1$) while offering novel weak-field predictions. It is not a final publication, but a preliminary reference for further discussion and development.