v5 — RA_Q3 diagnostic synthesis with robustness stress-test ladder

Version 5 consolidates the DES-SN5YR Foundation RA_Q3 diagnostic ladder and Pantheon+ minus-Foundation RA_Q3-band follow-up tests into a single synthesis bundle. This update summarizes the full progression from Foundation-only object-pair robustness to sky-sector sensitivity, RA_Q3 anatomy, metadata inventory, controlled residual regression, velocity/redshift-frame diagnostics, Pantheon+ minus-Foundation RA_Q3-band comparison, duplicate-name collapse, redshift-floor and calibrator-removal stress tests, same-width RA-window look-elsewhere comparison, and redshift-matched outside-band resampling. The updated interpretation is that the Foundation-only DES-SN5YR RA_Q3 sector remains object-pair robust but sector sensitive. In Pantheon+ minus Foundation, the same RA band shows an external negative-residual echo that survives duplicate-name collapse, calibrator removal, redshift-floor stress, same-width RA-window look-elsewhere comparison, and redshift-matched outside-band resampling. In cleaner non-calibrator high-floor cuts, the DES RA_Q3 band lies in the negative tail of same-width RA windows and is rarely reproduced by redshift-matched outside-band draws. For example, in the non-calibrator zHD >= 0.023 cut, the same-width RA-window fraction is 3/338 = 0.008876, and only 1/20,000 redshift-matched outside-band draws is as negative or more negative than the observed RA_Q3 contrast. In the non-calibrator zHD >= 0.025 cut, the same-width RA-window fraction is 2/327 = 0.006116, and 0/20,000 redshift-matched outside-band draws are as negative or more negative than the observed RA_Q3 contrast. This update remains a robustness and reproducibility synthesis only. It does not establish cosmological anisotropy, a preferred cosmic axis, URSF confirmation, independent Pantheon+ replication, causal explanation, or elimination of local-flow, calibration, selection, or compilation systematics. Version 5 adds a consolidated RA_Q3 diagnostic synthesis and robustness stress-test ladder. The synthesis summarizes the DES-SN5YR Foundation-only RA_Q3 sector result and the Pantheon+ minus-Foundation RA_Q3-band follow-up tests. The diagnostic ladder includes object-pair robustness, grouped sky-sector leaveout, RA_Q3 anatomy, metadata inventory, controlled residual regression, velocity/redshift-frame sensitivity, Pantheon+ minus-Foundation band comparison, duplicate-name collapse, redshift-floor and calibrator-removal stress tests, same-width RA-window look-elsewhere comparison, and redshift-matched outside-band resampling. The main updated interpretation is that the Foundation-only DES-SN5YR RA_Q3 sector remains object-pair robust but sector sensitive. In Pantheon+ minus Foundation, the same RA band shows an external negative-residual echo that survives several mundane-composition stress tests, including duplicate-name collapse, calibrator removal, redshift-floor stress, same-width RA-window look-elsewhere comparison, and redshift-matched outside-band resampling. The strongest cleaner-cut Pantheon+ minus-Foundation results occur in non-calibrator high-redshift-floor subsets. In the non-calibrator zHD >= 0.023 cut, only 3 out of 338 same-width RA windows are as negative or more negative than the DES RA_Q3 band, and only 1 out of 20,000 redshift-matched outside-band draws is as negative or more negative. In the non-calibrator zHD >= 0.025 cut, only 2 out of 327 same-width RA windows are as negative or more negative, and 0 out of 20,000 redshift-matched outside-band draws are as negative or more negative. This remains a robustness clue only. It does not claim discovery, cosmological anisotropy, a preferred axis, URSF confirmation, independent replication, or causal explanation. DES-SN5YR_zenodo_des_r3_foundation_ra_q3_diagnostic_synthesis_v5_bundle.tar.gz v5 RA_Q3 diagnostic synthesis bundle. Contains the consolidated DES_R3_FOUNDATION_RA_Q3_DIAGNOSTIC_SYNTHESIS_V5.md document, prior RA_Q3 diagnostic synthesis file, checkpoint documents for sky-sector leaveout, RA_Q3 anatomy, metadata inventory, controlled regression, velocity-frame diagnostics, Pantheon+ minus-Foundation RA_Q3-band comparison, duplicate-name collapse, redshift-floor and calibrator-removal stress, same-width RA-window look-elsewhere control, and redshift-matched outside-band resampling. Also includes key diagnostic figures for duplicate collapse, redshift-floor stress, look-elsewhere comparison, and redshift-matched resampling. SHA256:400a0666f153c9bb5a61b01be30648f7acefa75be6c322c46e1c14fea69380df