# Linux93 — explicit passage carve reach

## R and acceptance bar

Before measurement, the bar was: **zero sign flips, maximum surface displacement ≤1 cm, maximum normal change ≤2°, and all passage audits pass.**

I chose **R = 2.5 m beyond the tube surface**, with the final 0.5 m smoothly fading to identity. The code’s local terms are a 2.25 m positive-source reach floor and a 0.24 m wall-relief/source allowance (0.21 m relief plus 0.03 m margin); mouth-floor relief is separately capped at 0.20 m. Wider short-span decks and mouth/transition envelopes are separate paths, retained behind their existing feature guards. R is an experiment, not a proof that those separate envelopes fit inside the carve radius. I also measured R=1.5, 2.0 and 4.0 m.

The instrument reported `GenerateTile -> ApplyResolvedStrateComposition -> ApplyResolvedStratePassageCarves`, comparing density, mesh-edge crossings and normals. It did not use the L91 source-gradient probe. Each reach covered the full desired LOD0–2 set in S0/FI/TN/S3: 5,312 tiles and 174,736,448 samples per reach. Source stamp: `938a849b053aa7e5bc9bf5fcaf51a73590d408c15bc9d8f0564fec685e68921d`.

## Effect

Worst displacement and normal change are across all four strata; moved crossings and pairing failures are totals. Every row had zero sign flips and zero edge-crossing mismatches.

| R (m) | Moved crossings | Max displacement (cm) | Max normal change | Normal pairing failures | Bar |
|---:|---:|---:|---:|---:|---|
| 1.5 | 4,303 | 85.136 | 144.823° | 65 | Fail |
| 2.0 | 1,910 | 41.106 | 118.485° | 57 | Fail |
| 2.5 | 922 | 1.555 | 106.628° | 57 | Fail |
| 4.0 | 916 | 0.632 | 53.193° | 57 | Fail |

R=2.5 exceeds the displacement limit and misses the normal limit by a wide margin. R=4 meets the displacement limit but still fails normals. The effect audits completed with zero generation failures and zero invalid comparisons; full same-world passage audits were not run after this gate failed.

## Census and prototype

The L90 census was not rerun because the effect bar failed. The requested active-p90 (about 4–6) and fallback (<10%) stops therefore have no L93 measurements; the previous 10 m baseline was p90=13 and 18.28% fallback. The compiled evaluator prototype on `passage/1-2/0` was not started because it depends on a passing census.

## Bounded-only readiness

Cold headless runs compared default reach with R=2.5 m, L81 padding 0, and passage-composer profiling. Each mode had one warmup and three alternating measured pairs. Counts below are complete LOD0–2 near sets; times are medians in seconds.

| Stratum | W8 default → R=2.5 | W12 default → R=2.5 |
|---|---:|---:|
| S0 | 0.975 → 0.897 | 0.976 → 0.929 |
| FI | 2.354 → 2.307 | 2.181 → 2.158 |
| TN | 2.356 → 2.229 | 2.156 → 2.032 |
| S3 | 1.276 → 1.371 | 1.100 → 1.169 |

All runs completed their near sets: S0 1,408, FI 1,216, TN 1,344, S3 1,344 tiles. The work table sums the four per-stratum median counters. Positive deltas mean more counted work with bounded reach.

| Work counter | W8 default → R=2.5 (Δ) | W12 default → R=2.5 (Δ) |
|---|---:|---:|
| Tile-bound checks | 21,697,558 → 15,820,579 (−27.1%) | 23,141,444 → 15,820,579 (−31.6%) |
| Tile-bound rejects | 15,393,408 → 15,702,098 (+2.0%) | 16,114,028 → 15,702,098 (−2.6%) |
| Passage iterations skipped by tile bound | 46,180,224 → 47,106,294 (+2.0%) | 48,342,084 → 47,106,294 (−2.6%) |
| Negative-bound checks / rejects | 5,506,163 / 2,500,536 → 3,461,477 / 3,286,103 (checks −37.1%, rejects +31.4%) | 5,705,127 / 2,699,500 → 3,767,727 / 3,592,353 (checks −34.0%, rejects +33.1%) |
| Passage iterations | 33,137,208 → 32,209,659 (−2.8%) | 38,207,001 → 39,438,384 (+3.2%) |
| Carve segment visits | 78,166,733 → 77,908,735 (−0.3%) | 101,322,676 → 106,806,150 (+5.4%) |
| Support segment visits | 31,466,498 → 30,406,353 (−3.4%) | 37,630,363 → 38,810,022 (+3.1%) |
| Mouth route checks | 38,701,878 → 37,198,938 (−3.9%) | 47,097,975 → 47,996,583 (+1.9%) |
| Relief field calls | 56,100,413 → 51,745,464 (−7.8%) | 66,227,624 → 64,386,389 (−2.8%) |

The skip counters do not show a consistent work reduction: several active-loop counters rise at W12, and S3 readiness regresses at both worker counts. This is not a readiness win.

## Same-world evidence and disposition

The bounded candidate is rejected. No candidate peer-hash comparison at W1/W8/W12 or across Clang/GCC, bounded passage-audit suite, mouth/mid-tunnel captures, version bump, or hash repin was done. The evaluator remains version 214 and the default reach remains unbounded. The Clang fast tier on the default path passed: 274 checks, 269 PASS and 5 expected diagnostics, in 285.9 s; its W1/W8/W12 checks matched. Standalone diagnostic builds took 65.49 s (Clang) and 89.39 s (GCC). No Unreal source changed, so no Unreal build was run.

## Failed and superseded runs

- The first fast-tier launch stopped before tests because its expected binary did not exist. After building the stamped binaries, the fast tier passed.
- An early readiness parser incorrectly required a composer-profile row for every near tile; the profiler emits rows only for active tiles. The parser was corrected and the final matrix validated complete near-tile coverage. Earlier fixed-5 m support-floor readiness data is superseded and excluded.
- Final effect runs completed but intentionally reported FAIL against the stated effect bar. No run exceeded 30 minutes.
- Build, headless measurement and verifier processes were pinned to CPUs 0–11; headless runs also had the 6 GiB address-space limit. A few read-only status/source/JSON inspection commands during consolidation were not pinned. No measurement or build ran in those commands.

Logs and machine-readable summaries are under `Saved/Linux/l93/`.