Predictions for DESI five-year BAO data from a slice–matter energy exchange model with no free exchange parameters

We state, before the release of new DESI data, fixed predictions of a cosmological model in which energy is exchanged between dark matter and a vacuum-like component ("slice energy"). The exchange law has two constants, both set by principles rather than fitted: balance between the pull of matter and the push of the slice energy (zero deceleration) gives k = 2, and growth of slice energy following the expansion in the matter era gives b = 1. With these values the model has the same six free parameters as LCDM. With Planck 2018 (plik-lite, tau prior), Planck lensing, DESI DR2 BAO and Pantheon+, it gives chi2 = 2012.5 against 2019.8 for LCDM. We give the predictive distribution of D_M/r_d and D_H/r_d at the DESI effective redshifts, conditioned on data independent of DESI, and a decision protocol fixed in advance. The main target is the DESI five-year BAO analysis expected in 2027. Code and fit outputs are included.