Pre-Registered Predictions for the Gaia DR4 Wide-Binary Gravity Test: Two Falsifiable Branches and a Decision Rule

Gaia Data Release 4 (December 2, 2026) is expected to sharply improve the contested wide-binary test of gravity at low accelerations, where the current literature is genuinely split between claims of a MOND-like velocity boost and Newtonian null results. This note registers falsifiable predictions for that measurement in advance of the data. It derives no new mechanism, fits nothing to wide binaries, and takes no side in the ongoing data-quality dispute. Two branches are registered with distinct numbers: a zero-free-parameter smooth crossover, fixed in advance from the galactic radial-acceleration relation (SPARC a₀) with full external-field screening, predicting a rise-and-saturate boost profile with γ = 1.39 ± 0.06 at saturation; and a sharp-threshold branch predicting γ ≤ 1.06, flat. A complete decision rule partitions all outcomes, including a global rejection band (γ > 1.5 or γ < 0.95) under which the underlying model is falsified in its entirety. Every number reproduces from stated inputs in under one hour; verification is invited. The predictions can be evaluated without accepting the underlying model, which is summarized in one paragraph and archived separately. Companion registration: doi:10.5281/zenodo.21890749.