# 490d Mirror checkpoint after C316

24 September 2026. **C316 complete. C317 unexecuted.** 7 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

All five8395 routes work uniquely with h=i−2 and matching Noah ancestry phase. The existingC271 route instead starts at cumulativeShem_i via17K. Equal outputs do not merge these antecedents. RegularGear descent agrees in only three cases.

Keeping8993=17K and8395 fixed, all five selected Flood boundaries have a unique derived cumulative Flood antecedent **h=i−2**, with the same cumulative phase as Noah. The five h values are5,4,3,2,1 as j increases3…7. They are already admitted annual stations. This is selection of another cumulative station, not a cumulative Gear operation.

The two-year ancestor difference supplies exactly the missing amount:

`N−f = (8993−8395)+(q_i−q_h) =598+2=600`.

This succeeds in all ten exact components, but changes the ancestor. It does not repair C315's failure under a common ancestor.

**C271's actual Flood ancestry must remain distinct.** It is cumulative LXX_OFF **Shem at indexi**, not cumulative Flood at h. Write `p_i=−5890+i`, `q_h=−5290+h`. Then

`p_i+8993 = q_h+8395 = f`, with `q_h−p_i=598`.

Both routes reach the same source Flood coordinate and phase. Their starting roles, indices and declared paths differ. C271's local translation5888/reflection layer is retained; the endpoint T8993 comparison does not erase that intermediate provenance.

| Shem j | Noah i / derived Flood h | SP state | C287 at i / j / h | Regular descent available |
|---:|---|---|---|---|
|3|7 /5|G3 primary|No /Yes /Yes|No starting alias|
|4|6 /4|G3 companion|No /Yes /Yes|No starting alias|
|5|5 /3|G2 primary|Yes /Yes /Yes|G3 start→G2 start|
|6|4 /2|G2 companion|Yes /No /Yes|G3 close→G2 close|
|7|3 /1|G1 primary|Yes /No /No|G2 start→G1 start|

Where C315's same-i8395 candidate is an admitted next-Gear Flood, the permitted regular one-Gear descent subtracts2 and agrees with the h-selection endpoint. This is a partial correspondence in three cases. At the upper boundary no initial alias exists; one cannot descend from an unadmitted G4. The five-case cumulative selection therefore has a larger domain than this regular descent. Full C287 support at all three tested indices survives only j=i5,h3.

## 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

54 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

C317: Verify the five inherited same17K rectangles using cumulativeShem_i/Flood_i and source regularSP Flood/Noah, with exact phases and comparison to the strongerC287 form.

The source audit recovered an already recorded17K ancestry for the Flood endpoint. A full typed rectangle now tests whether the600 biography has a coherent529 transport without the alternate8395 re-expression.

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