Shell 6: A Boundary-Interaction Framework for Pattern Selection, with a Pre-Registered Thin-Film Buckling Test

Shell 6 proposes that the form a constrained pattern-forming system takes is set by how its boundaries meet, balance, and pack, rather than by the geometry of any single boundary. The hypothesis is stated operationally, with each of the three terms defined as a measurable quantity, so that it can be falsified. Test beds are classified as reconstruction checks, dynamic reconstruction checks, or genuine predictions. Soap foams and shear-driven ripples are reconstruction checks; thin-film buckling is the first genuine prediction. The prediction, the forbidden mode, the null models, and the analysis plan are to be deposited in a timestamped, immutable record before outcome data are accessed. The pre-registration form is included as an appendix and is left blank, to be completed by an independent selector or from a pre-specified published elasticity model. The hypothesis is not claimed to be established. The paper claims only that the hypothesis is operationally precise, that the test is pre-registered, and that the outcome will be decisive.