The a0(z) tests: does the MOND acceleration scale track the cosmic horizon? A preregistered record

Four preregistered tests of whether the MOND acceleration scale a0 tracks the cosmic expansion rate. Each was SHA-256 hash-locked before the data were handled and scored exactly as locked. Two were scored. Option A, using the four binned a0 values published in MUSE-DARK III plus the SPARC z=0 anchor, returns O2: evolution is present but not horizon-shaped, a verdict that is fragile to an error-bar convention the source figure does not state; both readings are reported. RC100, using 100 rotation-dominated galaxies at z=0.6–2.5, returns O5: no model is adequate to the scatter, and within that, the horizon-shaped scaling is disfavoured against a constant a0 by ΔAIC 37. Two reconstruction attempts failed their calibration gates and were therefore not scored, as their locks require. Both are included with their gate output. The bundle contains the four locked preregistrations with their hashes, the analysis code, the scored results, the run logs, and a manifest. Third-party copyrighted material is deliberately excluded; see README_DEPOSIT.md.