# 490d Mirror checkpoint after C305

24 September 2026. Latest completed: **C305 — Annual parity of the joint600-year comparison.**

C305 derives N=3703+i from17K and P=3108−i from fixed2832 plus the650 MT→SP frame, soN−P595+2i. Joint source support is i2/3: SPGear1 companion→start599 andprimary→close601. Matched-selector600 remains valid separately. Exact600 for both fixed interfaces requires inadmissible annualcenteri5/2.

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 AD3746/2300 superseded.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 The superseded AD1905–1911 lookup remains unexecuted.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

10 mathematical/domain checks and 8 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

C306: Audit the actual phase components and all admitted Gear1 Noah-rail/Flood-boundary alternatives, recording which fixed interface each600-year alternative changes.

Reason for selecting it after C305: The integer-center obstruction is established; checking the available phase and selector choices will determine whether it is a labeling issue or a stable compatibility boundary.

High is sufficient unless a later dependency requires reassessment. The next step was not executed as part of C305. The authorized batch continues through C310.