AMSER pre-registration: twenty-one frozen tests of the 20 GeV Galactic halo excess — estimands, nulls, thresholds and falsification rules for Gaia DR4, Fermi-LAT, AMS-02 and multi-messenger data

Pre-registration of twenty-one tests bearing on the 20 GeV Galactic halo excess and on a Gaia-tracer / gamma-residual alignment, frozen before the corresponding data exist. It fixes the region of interest, the estimator (partial rank correlation with |b| and θ_GC controlled), two null generators with a fixed seed, and a pre-declared threshold and falsification condition for every item — including a rule under which the author publicly withdraws her own finding, and an inference table that fixes the conclusion for each combination of outcomes in advance. Fifteen further analyses on data already in hand are listed separately as pre-specified rather than pre-registered. Procedural commitments cover blind construction of the DR4 tracer, negative controls, declared power, frozen quality cuts, a ban on rescue forks after an outcome is known, disclosure of failed calibrations, pinned external-dataset and software versions, and publication of all outcomes. The record contains the frozen analysis apparatus, a self-test reproducing all five published values of the v6 release, the target-map provenance script, and a SHA-256 manifest.