# C272 evidence packet

Completed 24 September 2026. Continues the existing 490d Unified Chronology research after C271.

Read `490d_C272_Fixed_Charts_and_Outer_Radius_Selection_20260924.md`, then `490d_Mirror_Checkpoint_After_C272_20260924.md`. C273 is proposed, not executed.

## Reproduce the calculation

From this directory, using Python 3 and its standard library:

```sh
python evidence/check_c272.py --output /tmp/490d_c272_replay
```

The verifier uses fourteen frozen inputs in `sources/`, listed with sizes and SHA-256 values in `SOURCE_MANIFEST.json`. It passes 326 assertions and writes six files:

- `SCAN.json`: eighteen source-qualified local input points and all 72 signed chart images, with exact target matches.
- `MATCH_CLASSIFICATION.json`: counts by family, all ten hit instances, eight distinct target records and two repeated stage junctions.
- `STAGE_RELATIONS.json`: interval widths, midpoint steps, overlap and the shared-endpoint condition.
- `LIMITS.json`: target range, generated status, source/phase distinctions and calibration dependence.
- `RESULTS.json`: complete assertion ledger and bounded outcomes.
- `SCAN.csv`: compact table of every image and target status.

`REPLAY.json` records byte-identical reproduction of the six outputs. The authored report and checkpoint are not replay outputs. Independent mathematical, source-role and final reviews are in `evidence/`.

## Integrity and scope

`SCOPE.json` states the domain fixed by C271: six positive radius triples, two inherited charts, two inherited anchors and the exact 48-record reflected target register. `CONTROL_INTEGRITY.json` records unchanged original inputs, the 208-node/382-duration-edge C127 graph and the C265 certificate. Absolute original paths record provenance; reproduction uses the included frozen files and does not require those paths.

`CERTIFICATE.json` chains to C271 and binds the report, checkpoint, source manifest, results, replay and control-integrity record. `ARTIFACT_MANIFEST.json` hashes all other payloads, including the certificate, and excludes itself. The certificate does not hash itself or the artifact manifest.

All ten hits reproduce C268's radius-six results; no new target source record is found. The first chart's 299 midpoint remains sourced and the second chart's 325 midpoint remains generated. Because the charts were calibrated at radius six, the result is a finite extension limit, not independent statistical evidence or global uniqueness. Every inner input retains its C271 ancestry even when its chart outputs do not match the target register.

No absolute-value matching, new scale or anchor, wider historical lookup, new graph edge, canonical edit or C273 calculation is included. Regular Gears remain Noah/Shem/Flood only; both primers remain quarantined.