Version 4 updates DES-SN5YR Foundation-only low-z robustness record with a Pantheon+ minus-Foundation RA_Q3-band comparison

Version 4 adds a Pantheon+ minus-Foundation RA_Q3-band comparison to the consolidated RA_Q3 diagnostic synthesis. This update follows the DES-SN5YR Foundation RA_Q3 sector through a broader overlap-aware comparison. The DES RA_Q3 band is defined as RA = 200.780011° to 234.641762°. In Pantheon+ low-z minus Foundation, the same RA band remains more negative than the rest of the low-z sample: n=586 total, n=68 in band, band mean residual=-0.217379 mag, non-band mean residual=-0.133816 mag, band-minus-non-band=-0.083563 mag, band negative fraction=0.838235, non-band negative fraction=0.789575, Cohen d=-0.333326. The Hubble-flow minus-Foundation subset shows a stronger contrast, but with smaller band statistics: n=152 total, n=14 in band, band-minus-non-band mean residual=-0.120951 mag, band negative fraction=1.000000, Cohen d=-0.817784. The non-calibrator minus-Foundation subset weakens the contrast: n=509 total, n=42 in band, band-minus-non-band mean residual=-0.029971 mag, Cohen d=-0.142335. Updated interpretation: object-pair robust, sector sensitive, RA_Q3 negative-residual dominated, partially metadata-associated, velocity-frame persistent but strength-sensitive, externally echoed in Pantheon+ minus Foundation, but origin unresolved and not independently replicated. This update does not establish cosmological anisotropy, a preferred axis, URSF confirmation, independent replication, causal explanation, or elimination of local-flow / velocity-frame / calibration systematics. Version 4 adds a Pantheon+ minus-Foundation RA_Q3-band comparison to the consolidated RA_Q3 diagnostic synthesis. The DES Foundation RA_Q3 band, defined as RA = 200.780011° to 234.641762°, also shows a negative-residual excess in Pantheon+ low-z after removing Foundation-overlap objects. In Pantheon+ low-z minus Foundation, the DES RA_Q3 band contains 68 objects and has mean residual -0.217379 mag, compared with -0.133816 mag outside the band. The band-minus-non-band contrast is -0.083563 mag. The Hubble-flow minus-Foundation subset shows a stronger contrast, while the non-calibrator minus-Foundation subset weakens substantially, suggesting possible calibrator / very-low-z / low-z construction contributions. The updated interpretation is: object-pair robust, sector sensitive, RA_Q3 negative-residual dominated, partially metadata-associated, velocity-frame persistent but strength-sensitive, externally echoed in Pantheon+ minus Foundation, but origin unresolved and not independently replicated. DES-SN5YR_zenodo_des_r3_foundation_ra_q3_diagnostic_synthesis_bundle_v4_ready.tar.gz v4-ready RA_Q3 diagnostic synthesis bundle. Contains the consolidated RA_Q3 diagnostic synthesis, sky-sector leaveout checkpoint, RA_Q3 anatomy checkpoint, RA_Q3 metadata inventory checkpoint, RA_Q3 controlled regression checkpoint, RA_Q3 velocity-frame checkpoint, Pantheon+ minus-Foundation RA_Q3-band checkpoint, and key plots for sector sensitivity, RA_Q3 residual structure, metadata differences, controlled regression behavior, velocity-frame persistence, and Pantheon+ minus-Foundation RA_Q3-band comparison. SHA256:c27f759f8fe7854950d0bf129b8b586c0325c97453eedd7b13a629d914bc0c71 Version 4 updates the DES-SN5YR Foundation-only low-z robustness record with a Pantheon+ minus-Foundation RA_Q3-band comparison, showing that the RA_Q3 negative-residual sector is externally echoed in Pantheon+ low-z minus Foundation, while remaining caveated by low-z calibration, selection, local-flow, compilation, and calibrator structure. Prepared by Malin Hess with assistance from OpenAI’s ChatGPT for code-structuring, documentation, formatting, archive organization, visual generation, and wording review. Scientific interpretation and final responsibility remain with the author.