standalone: canonical AVX2 noise + factored lattice hashes -- whole view 1.40 -> 1.09 s, world unchanged

- Octave noise evaluated in AVX2 batches (one canonical path), fBM and ridged share samples, lattice
  hash products factored; the outputs are preserved: W1/W8 and pre-change hashes equal across 44
  fields, six fixed captures pixel-identical, remote views differ by at most one pixel.
- Routes 5642/5642, shape and far-survival audits pass, bad-shell control still fails.
Verified by me, interleaved head to head (8 workers, cold, BelowNormal 0xFF00): 1.092 / 1.098 s
vs 1.408 / 1.396 s for round 7.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MmSoF64BbRFmk9C3p1VsBJ

Standalone/Research/OwnerShapeWorld/speed_round/REPORT.md

@@ -1,5 +1,68 @@
 # Shape world speed round — final half-load verification
 
+## Round 8 — canonical AVX2 shape arithmetic (2026-10-05)
+
+The AVX2 path plus factored corner hashing cuts the direct cold W8 process mean from **1.456 s to 1.149 s** (21.1%). It misses the requested **under-1-second** target by 149 ms at the mean; the faster new run was 1.146 s. The full 110.90 MiB payload remains enabled, all 2,226 requested tiles were generated, and every direct run recorded zero mesh-cache hits. The field passes the shape and far-survival audits, the 5,642 route samples remain open, all 44 W1/W8 hash fields match, and the six fixed captures are pixel-identical to Round 7.
+
+### Arithmetic and profile
+
+`VoxelNoise::Perlin3D_x8` evaluates eight independent samples with AVX2 integer hashing and gradient/interpolation arithmetic. `FractalPair` packs the main and fine octave coordinates into the same batch and shares each sample across fBM and ridged accumulation. Domain-warp channels also use the 8-lane path. The cave detail line reuses its spatial-bin items across consecutive sorted Z samples, and coarse rock-distance lookup remembers the previous bin per thread. The hash keeps its existing three mix rounds. For each Perlin lattice, the three corner-coordinate products are now computed once; adjacent corner products use wrapping integer adds, preserving all hash outputs while removing repeated vector multiplies. A reduced-round hash probe changed the field and did not improve time, so it was discarded.
+
+This is the standalone harness's canonical path, with no runtime CPU dispatch. The host requires AVX2. Intrinsics issue multiply and add separately; the build uses `/fp:precise` to prevent contraction. The AVX2 kernel uses no CRT transcendental functions. Build settings also include `/arch:AVX2` and `/MP8`.
+
+| W8 profile measure | Round 7 scalar path | Round 8 final | Change |
+| --- | ---: | ---: | ---: |
+| Shape stage | 690.9 ms | 478.9 ms | -30.7% |
+| Surface detail band | 448.3 ms | 245.1 ms | -45.3% |
+| Detail evaluation sample | 792.7 ns | 328.0 ns | -58.6% |
+| Owner roughness sample | 572.7 ns | 107.2 ns | -81.3% |
+| Detail evaluations | 3,527,283 | 3,527,283 | same workload |
+
+The profile starts at [Round 8 before](round8_profile_before_w8.stdout.log), passes through [AVX2](round8_profile_after_avx2_w8.stdout.log), [shared noise](round8_profile_after_opt_w8.stdout.log), and [paired octaves](round8_profile_after_pair_w8.stdout.log), and ends at the current [factored-hash profile](round8_hash_factored_profile_w8.stdout.log). The distance sample moved from 128.4 ns to 117.3 ns in the final profile; most of the gain is in owner noise. The hash-factor probe's alternating direct runs averaged 1.196 s for the preceding AVX2 executable and 1.145 s for the factored probe: [base A](round8_hash_factored_base_a_w8.stdout.log), [probe A](round8_hash_factored_probe_a_w8.stdout.log), [base B](round8_hash_factored_base_b_w8.stdout.log), [probe B](round8_hash_factored_probe_b_w8.stdout.log).
+
+An isolated W8 LOD8 mesher profile processed 306 tiles / 2.10 M samples. Its [tile profile](round8_tile_profile_lod8_w8.stdout.log) attributes 125.8 ms to density-grid construction within a 403 ms serial tile-benchmark run. This diagnostic exercises the base mesher and does not include the streamer's source-aware repair panels, so it is not a replacement for the full-payload direct timing. It confirms density sampling is material; no separate mesher rewrite was retained this round.
+
+### Required cold direct head-to-head
+
+Both executables were launched in fresh processes with `--stream-benchmark --shape-world --force-generate --workers=8 --clip-radius=3`. The old executable is `VoxelForgeShapeSurvivalSearch.exe`; the new one is `VoxelForgeShapeRound8Final.exe`. The wrapper held BelowNormal priority and affinity `0xFF00`. Each run generated the full payload with `cache_hits=0` and `payload_alloc=110.90MiB`.
+
+| Pair | Executable | Process wall | Shape stage | Full clipmap | Cache hits |
+| --- | --- | ---: | ---: | ---: | ---: |
+| A | Round 7 | 1.453 s | 698.2 ms | 648 ms | 0 / 2,226 |
+| A | Round 8 | 1.146 s | 453.5 ms | 585 ms | 0 / 2,226 |
+| B | Round 7 | 1.459 s | 698.2 ms | 638 ms | 0 / 2,226 |
+| B | Round 8 | 1.152 s | 472.7 ms | 574 ms | 0 / 2,226 |
+
+Logs: [old A](round8_final_ab_old_a_w8.stdout.log), [new A](round8_final_ab_new_a_w8.stdout.log), [old B](round8_final_ab_old_b_w8.stdout.log), [new B](round8_final_ab_new_b_w8.stdout.log). The new mean is 1.149 s versus 1.456 s old. The matching shape-only profiles with attribution are separate runs and are not included in these wall times.
+
+### Determinism and audits
+
+The new executable's `--stream-hash` run at W1 and W8 matched density, mesh, payload, and topology for full detail, whole view, and each LOD0–8: **44/44 fields pass**. The [comparison output](round8_final/hash_compare_run.log) also confirms all 44 final fields equal the preceding AVX2 executable; it is generated by [compare_hash_runs.py](round8_final/compare_hash_runs.py). Full-detail hashes are density `0x67609e3f9aa3a0b0`, mesh `0xd98eb46b92a59917`, payload `0x8f148240ca4a4a8f`, topology `0x954e28f6fd44967f`. Whole-view hashes are density `0xa78b0985b1b8fefd`, mesh `0xb44e0c998152d1f5`, payload `0x1eb6b48127fd8e26`, topology `0x8b2557006b5ce3c8`. Raw runs: [W1](round8_final_hash_w1.stdout.log) and [W8](round8_final_hash_w8.stdout.log).
+
+The [shape audit](round8_final_shape_audit_w8.stdout.log) passes walkability (**5,642/5,642**), room-floor join, floor slope and profile, tunnel radius, flat surface, grid stair, thin sheet, surface-band family, flat patch, and detail-scale checks. The [far-survival audit](round8_final_far_audit_w8.stdout.log) passes all 7,200 boundary surfaces and 10,976 connectors across 178,351 connector sections: zero missing, holes, or unsampled connectors. The audit also records 47,858 extra mesh ray hits. The injected [bad-shell control](round8_final_bad_shell_w8.stdout.log) removed 512 triangles, detected 16 missing surfaces and 16 holes, and exited 14 as expected.
+
+### Captures
+
+All six fixed captures compare pixel-identically with Round 7. The four X=500 m remote views have only small pixel differences. The [comparison log](round8_final/capture_compare.log) compares all ten images; the images are in [round8_final](round8_final/).
+
+| View | Changed pixels | Mean channel delta | Max channel delta |
+| --- | ---: | ---: | ---: |
+| Fixed chamber / tunnel / passage / far / floor close-up / tunnel bend | 0 / 1,024,000 each | 0 | 0 |
+| Remote yaw 0 | 0 / 1,024,000 | 0.000000 | 0 |
+| Remote yaw 90 | 1 / 1,024,000 | 0.000000 | 1 |
+| Remote yaw 180 | 0 / 1,024,000 | 0.000000 | 0 |
+| Remote yaw 270 | 0 / 1,024,000 | 0.000000 | 0 |
+
+### Failed and discarded attempts
+
+- The first AVX2 build invocation returned shell exit 1 because its relative `Tee-Object` destination was resolved after `Build.ps1` changed directories. The compiler had already produced the executable. Retrying with an absolute log path succeeded: [build log](round8_avx2_build.log). The hash-factor probe build succeeded: [probe build](round8_hash_factored_build.log), followed by the final `/MP8` build: [final build log](round8_hashfactored_final_build.log). Builds emit existing C4838 narrowing warnings and a `vswhere.exe`-not-recognized diagnostic; neither stops compilation. No process reported `0xC0000142`.
+- The first chamber capture used an absolute output path containing spaces; argument splitting made the executable treat the remainder as its owner-data path, and that run exited 2. Using a Standalone-relative capture path succeeded: [failed invocation stderr](round8_capture_fixed_chamber_w8.stderr.log), [retry](round8_capture_fixed_chamber_retry_w8.stdout.log). The other nine captures succeeded on their first invocation.
+- The reduced-round hash experiment built and ran, but changed candidate counts/field output without a timing gain; its source was reverted. Evidence: [probe build](round8_hash_build.log), [profile](round8_profile_after_hash_w8.stdout.log).
+- A far-ray prune probe completed but did not improve direct time and was reverted: [build](round8_prune_build.log), [direct probe](round8_prune_direct_probe_w8.stdout.log).
+- The bad-shell control is the intentional failing audit described above (exit 14). No other Round 8 benchmark, audit, or capture run failed.
+
+All build and executable runs were constrained to BelowNormal priority and affinity `0xFF00`; builds used `/MP8`. No viewer that this work did not start was closed. Changes and artifacts are confined to `Standalone\`; no commit, push, or stash was made.
+
 ## Round 7 — sparse far repairs and single shape compile (2026-10-05)
 
 Round 7 cut the LOD8 survival build from **276.74 MiB** to **110.90 MiB** of full mesh-payload allocation, a 59.9% reduction from Round 6. The final CPU follow-up keeps that payload and trims about 0.28 seconds from summed worker time and 0.04 seconds from stream wall. The result remains **18.29 MiB above** the no-shell 92.61 MiB baseline, and the process-wall target below 1.3 seconds was not reached.