# 490d C351 — Cumulative counterpart of the600 endpoint repairs

24 September 2026. Step 8 of 10 in the C344–C353 authorization.

**All four complete cumulative paths admit460+598→458+600 while keeping1058 fixed.** The two primary regular counterparts admit the same partition change, with both17K outer comparisons unchanged.

Let S be native-ON cumulative Shem at i+2, P the OFF-Shem member at i+2, and q the OFF-Flood member at i. Their retained dissection is `P−S=460`, `q−P=598`.

| Cumulative repair | Existing replacement | New partition | Outer span |
|---|---|---|---:|
| Hold q; enlarge598 to600 | P moves to OFF-Shem at i | **458+600** | **1058** |
| Hold P; enlarge598 to600 | q moves to OFF-Flood at i+2 | **460+600** | **1060** |

The replacements exist for i2,i3,i4,i5, with both inherited matching components. No cumulative Gear is assigned. The458 leg compares different Cainan states **and different annual indices**; same-index Cainan insertion remains460.

On the regular primary side, holding R and selecting the next-Gear MT Noah similarly gives `N−M_new=458` and `M_new−R=600`. At i3/i5, both sides can therefore use458+600 while all four original outer endpoints remain fixed. Their2K sides and17K cross-spans are untouched. The altered interior is not a new independent529 relation.

The cumulative construction also works at the two companion indices; the regular300/299 counterpart does not, because its input is599. That asymmetry remains explicit.

The original cumulative460+598 dissection was already retained, including C90. This step adds the source-member repair comparison. It does not assert that File_02 prescribes applying both repairs together. The final research control is whether requiring598 on both sides supplies a new selector, or simply restates the conditions already imposed on the2K structure.

## Verification and limits

30 main checks and 18 frozen-input/predecessor authentication checks passed. A second main replay produced byte-identical DATA/RESULTS. These checks and the source interpretation were performed by the root agent; no new independent-agent review is claimed. All frozen originals and standing controls remain unchanged. Verification counts are not independent-witness counts.

Same retained annual and Gear domains; no new cumulative Gear, lifespan, phase, anchor or prescribed joint operator.

Mirror/529 focus: K=529, E=25/23, P=70/69. Global paired Mirror January AD1; local junction January AD2; no civil year zero. Regular Gears are Noah/Shem/Flood only. SP minus-one person companions remain local to SP Noah/Shem; Flood close is a separate boundary. No upstream/cumulative Gear, new endpoint or phase, fitted anchor, global axis, primer reopening, canonical or graph edit. Capture now; canonize later. Source identity, context, modal binding, generated coordinates and phase ancestry stay distinct.

## Decision after this result

**C352, proposed and unexecuted:** Test the paired598-input requirement in C319’s fixed a,b menu and identify its exact dependency on the existing2K conditions. Recheck File02’s regular-gap and cumulative-propagation permissions before assigning any coupled source-rule status.

The paired600 partitions are now source-qualified numerically. The last unresolved research issue is whether this pairing establishes more than conditional selection from the already chosen input gaps.