A Compression-Based Scaling for Environment-Dependent Electron-Capture Decay: One Calibrated Constant, Three Blind Tests Against Published ⁷Be Data

This manuscript presents a phenomenological compression-based scaling for environment-dependent electron-capture (EC) decay. The proposed relation separates the electron density at the nucleus into an incompressible core contribution and a compressible valence contribution, leading to a simple scaling law relating decay-rate changes to the bulk compression of the surrounding host material. The model is calibrated once using the 1973 high-pressure ⁷BeO experiment and subsequently tested without further adjustment against three independent published datasets, including pressure measurements and lattice-confinement effects. The manuscript explicitly states its assumptions, limitations, and falsification criteria. An accompanying Prediction Register documents advance quantitative predictions for additional EC isotopes and host materials before future measurements. The manuscript is presented as a working paper intended to document the current formulation of the compression-scaling framework and to provide a citable archival record for future examination, criticism, and experimental testing. A Danish companion version is included as supplementary material.