# Linux 110 — open-air tunnel shell

Candidate evaluator v257, source stamp `04e9180521ab0963da5f1cabbf7c4646e32311edf1439c2dea514d3a61e7e464`.

## Cause and fix

The bands are the end profiles of per-control-span shell capsules. The affected 452.408 m open-air section touches 50 control spans: chord lengths are 8.520–10.076 m (median 9.353 m, mean 9.324 m). The visible band pitch follows that roughly 9.35 m span spacing. Radius delta is 0 across those spans, and the floor depth is constant, so radius/floor interpolation does not explain it. The 8 m tiles, 0.25 m voxels, and 0.75 m shell do not match the period. The pattern remains with tile skirts off; wall relief is unchanged. The chord/Catmull mismatch is not the periodic source.

The shell now smooth-unions adjacent spans over 6 m and reuses the chord distance already calculated for the passage interior. A 0.60 m shell clearance fades in from 5 m to 20 m from each mouth. Interior carving still takes precedence, and the shell is written only into host air. The repeated bands are removed from the exposed shell close-ups. Regular faceting on tunnel-facing interior walls remains visible in both L109 and v257 station captures.

## Captures

The [capture index](captures/INDEX.md) flags every **OPEN AIR** view. The [verification](captures/capture-verification.json) passes all 106 images: per before/after set, 6 mouths, 9 stations, 27 open-air views, and 11 open-air close-ups. All 22 close-ups have a measured 4.000 m standoff. Nine images in each set are marked low contrast, with visible geometry. Paired bytes changed in 24/27 open-air views, 10/11 close-ups, 4/6 mouths, and 1/9 stations.

The [contact sheets](captures/contact-sheets/INDEX.md) cover all views. The target 4 m close-ups are [before 1](captures/before/passage-0-1-0-openair-4-closeup-1.png), [after 1](captures/after/passage-0-1-0-openair-4-closeup-1.png), [before 2](captures/before/passage-0-1-0-openair-4-closeup-2.png), [after 2](captures/after/passage-0-1-0-openair-4-closeup-2.png), [before 3](captures/before/passage-0-1-0-openair-4-closeup-3.png), and [after 3](captures/after/passage-0-1-0-openair-4-closeup-3.png).

## Readiness

Five interleaved L80 pairs per cell; times are medians in seconds (`LOD0–2 near-ready / whole-view-ready`). All base/candidate tile counts matched.

| Strate | W8 near | W8 whole | W12 near | W12 whole |
|---|---:|---:|---:|---:|
| SW | 0.778 → 0.854 (+9.7%) | 1.767 → 1.829 (+3.5%) | 0.807 → 0.906 (+12.3%) | 1.722 → 1.843 (+7.0%) |
| FI | 0.937 → 1.010 (+7.8%) | 1.811 → 1.903 (+5.1%) | 0.883 → 0.995 (+12.6%) | 1.700 → 1.798 (+5.8%) |
| TN | 0.979 → 1.090 (+11.4%) | 1.806 → 1.932 (+7.0%) | 0.920 → 1.006 (+9.3%) | 1.709 → 1.790 (+4.7%) |
| VS | 0.797 → 0.871 (+9.2%) | 1.699 → 1.765 (+3.9%) | 0.758 → 0.835 (+10.2%) | 1.575 → 1.659 (+5.3%) |

## Checks

- Owner four-strata walk audit: all 3 interfaces pass; zero blocked, unsupported, or grade-failure samples. Shell audit: 89,365 floor, 8,423 wall, and 10,527 interior samples; zero violations; 22,755 open-air shell samples.
- Clang/GCC determinism: all 18 W1/W8/W12 hash runs match across owner4 Surface World, owner2 Surface World, and owner2 Floating Islands.
- Fast tier: PASS, 259 checks plus 5 diagnostic-only results; no failed gates.
- Linux VFHostEditor: PASS, 27 actions, 69.0 s, `-NoUBA -MaxParallelActions=4`. Unreal was run without `prlimit`.
- `git diff --check`: PASS. No run exceeded 30 minutes.

## Failed experiments

A clearance ramp delayed to 80–120 m left 6 owner2 wall samples uncovered. A 1.2 m mouth join produced 23 wall violations. Both were rejected; the final 6 m join with the 5–20 m clearance ramp passes owner2 and owner4 audits.