# 490d Mirror checkpoint after C277

24 September 2026. Latest completed: **C277 — Coverage of the cross-index598 alignment.**

New result: H_j=F_(j−2) holds on cumulative j2–7. Both regular counterparts exist only for j4–7, giving four cross-Gear comparisons. Rows j2/3 require Noah indices0/1, centers3703/3704, which remain generated. The four successful pairs lower the Noah Gear by one and retain primary/start or companion/close selector. Absolute placement remains free.

## Standing context

C276: the selected cross-index alignment fixes δ=h−f=598; source transport alone does not. Absolute placement remains a separate premise. Preserve source and map roles, annual indices and ±1/4 phase ancestry. Co-located images do not identify events.

K=529; E=25/23; P=70/69. Global Mirror January AD 1; established local junction x=1, January AD 2; no civil year zero. Regular Gears Noah/Shem/Flood only. No cumulative/upstream Gears, primer reopening, canonical/graph changes or new global axis/z-law. Capture now, canonize later.

Supplement: LXX Creation 5494 BC +8464→AD 2970 versus reflected Conquest AD 1406 gives1564→1700 by25/23; Jared4534→AD3930 versus reflected Exodus1446 gives2484→2700. LXX Creation→Jared960, MT460; offsets1380/880; difference920→1000. AD3746/2300 superseded. Awareness only.

C-series reports remain distinct from original unprefixed Reports01–10 and unestablished interrupted Reports11–25. The superseded AD1905–1911 lookup remains unexecuted.

## Verification

37 mathematical/domain checks and 9 source authentication checks passed; two generated readouts replay byte identically. Author review only. File_18, File_09, C265 certificate and C127 unchanged; graph208 nodes/382 duration edges.

## Best next bounded step

C278: audit the reverse602 relation and the finite domains of the two-year shifts, alongside the retained598/600 comparisons.

Reason for selecting it after C277: The four successful lower-index correspondences suggest an inverse shift; checking its actual domain will distinguish a partial relation from a closed register action.

High is sufficient unless a later dependency requires reassessment. The next step was not executed as part of C277. The authorized batch continues through C310.