# 490d Mirror checkpoint after C321

24 September 2026. **C321 complete. C322 unexecuted.** 2 steps remain in the current C314–C323 authorization. Read this checkpoint and its report first; use the frozen predecessor checkpoint and certificate for inherited state. Do not repeat completed work or follow stale archived next-step paragraphs.

## Current finding

NativeLXX_ON yields3complete17K600rectangles at i3/5/7 inMTON/T60/full430. Allfourcorners shift−460 fromtheOFFSPprimaryfamily, withsixexactphase matches. ThreeFloodcloses have noMTNoah counterparts.

The native LXX_ON600 field has **three complete17K rectangles**, all in restored regular MT CainanON/Terah60/full430. This context emerges from the full528-record census.

| i | Native cumulative Shem /Flood, signed | Regular Flood /Noah, BC | Result |
|---:|---|---|---|
|0|−6350 /−5750|2643 /3243|Both absent|
|1|−6349 /−5749|2644 /3244|Both absent|
|2|−6348 /−5748|2645 /3245|MTG1 close only|
|3|−6347 /−5747|2646 /3246|MTG1 start /Noah|
|4|−6346 /−5746|2647 /3247|MTG2 close only|
|5|−6345 /−5745|2648 /3248|MTG2 start /Noah|
|6|−6344 /−5744|2649 /3249|MTG3 close only|
|7|−6343 /−5743|2650 /3250|MTG3 start /Noah|

At i3/5/7 every corner lies460 below the corresponding C320 OFF/SP-primary rectangle in the declared signed-cumulative/reflected-regular frame. Both17K translations, both600 sides and exact component offsets survive. Six phase rectangles are source-admitted.

The two sides reach this common displacement differently. Cumulative OFF→nativeON uses−460. On the regular side, same-Gear SP→MT comparison uses−650, regular Cainan restoration adds130 and Terah adds60:−650+130+60=−460. Both Noah and Flood intermediate source states are admitted. This is a typed composition; it is not a regular Cainan460 operator or an identification of cumulative nativeON with regular restoredON.

The three SP companions at i2/4/6 do not transport as complete MT biographies. Their translated Flood closes are admitted, but their required MT Noah births3245/3247/3249 are absent. These are point successes and path failures. No MT companion, new annual member or endpoint repair is introduced.

This step checks Noah birth and Flood only. It does not yet establish that Shem birth/death or the entire SP500-year relation moves uniformly by460. Preserving a600 rectangle is weaker than preserving a full Noah/Shem biography.

## Retained context

C277–C310 and C311–C313 remain completed. C311 found no prescribing annual selector in its three-source audit; C312 admitted four complete cumulative transports and five SP targets; C313 found a center500 match only at j5 and no same-ancestry exact component500 match. The +155 regular normalization is local. C287 complete four-node indices remain2…5; direct17K admission is weaker. The original AD1905–1911 proposal remains unexecuted. Supplemental Engine ReportIII explicitly derives the LXX OFF field; older182/777 and mixed Cainan headings yield to File_18. Corrected LXX crossover8464 observations remain awareness only:1564→1700 and2484→2700, difference920→1000; AD3746/2300 is superseded. C-series and original unprefixed/Engine report series remain distinct.

Mirror/529 remains the focus: K=529, E=25/23, P=70/69. Global paired Mirror January AD1; local junction x=1 January AD2; no civil year zero. Regular Gears remain Noah/Shem/Flood only. SP minus-one companion is local to SP Noah/Shem. No cumulative/upstream Gear, new endpoint or phase, fitted anchor, global axis, z-law, canonical or graph edit. Capture now; canonize later. Source state, event identity, generated coordinate and phase ancestry remain distinct. Exact arithmetic and source membership do not establish intention or independent historical witnesses.

## Verification

35 main assertions and 15 frozen-input/predecessor checks passed. A second main replay produced byte-identical DATA and RESULTS. Separate review scope and agreement are recorded in the evidence. All frozen originals and standing controls remain unchanged. These are verification counts, not independent-witness counts.

## Best next bounded question

C322: Test whether these three nativeON/MT600 counterparts extend to the complete sourceNoah/Shem biography under the same460 comparison. Then give one joint support table forOFF600, ON600, reversed500 andC287, distinguishing source co-existence from a uniform biography transport.

C321 proves a two-event correspondence. Checking the remaining already admittedNoah/Shem endpoints is the necessary final diagnostic before a synthesis can safely describe the combined structure.

Continue within the authorized batch, reassessing after the next result.