# 490d Mirror checkpoint after C278

24 September 2026. Latest completed: **C278 — The finite598/600/602 correspondence.**

Indices2–7 split into companion/close2→4→6 and primary/start3→5→7. Width600+i−j gives598 at i=j−2,600 at i=j,602 at i=j+2. J1M=T+2 and MJ1=T−2 on the ambient line; the source register supports only partial restrictions, with no extra Gear to complete them.

## 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 AD3746/2300 superseded.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 The superseded AD1905–1911 lookup remains unexecuted.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

32 mathematical/domain checks and 7 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

C279: test the shared endpoint triangle linking the existing8395 and8993 correspondences through the tagged598 source relation.

Reason for selecting it after C278: The cumulative598 partners remain available even where their regular Noah counterpart is absent; the documented8395 family may therefore retain all six Flood endpoints.

High is sufficient unless a later dependency requires reassessment. The next step was not executed as part of C278. The authorized batch continues through C310.