# Linux14 — far spawn work

No mesh or density code changed. The source changes add opt-in profiling for far-shell column
lookups; counter snapshots are behind the existing profile guard, with no added timing or counter
increments when profiling is off. The final plain build has the same output as L13.

## Far LOD cost and ranking

The first table is from five interleaved, W12, hashing-off pairs: L13 binary before and L14 binary
after. Values are median worker-sums across that LOD; per-tile time is the L14 median divided by
tile count. The ranking is L6, L8, L4, L5, L7 on both binaries.

| LOD | Tiles | L13 → L14 median worker-s (s) | L14 worker-ms/tile |
|---:|---:|---:|---:|
| 4 | 320 | 1.600 → 1.572 | 4.91 |
| 5 | 144 | 1.421 → 1.411 | 9.80 |
| 6 | 96 | 2.624 → 2.585 | 26.93 |
| 7 | 48 | 1.152 → 1.158 | 24.13 |
| 8 | 153 | 2.044 → 2.046 | 13.37 |

Phase detail below is one W12 `--profile-lod-work` run on the final Clang binary. Cache counters
include all column work for that LOD, not just refinement. A “shared hit” is a hit from the
world-shared cache; formula evaluations equal local misses minus shared hits.

| LOD | Calls | Local hits / misses | Shared hits | Formula evaluations (per tile) | Column compute (ms) | MC non-column (ms) | Ground/cap non-column (ms) | Connector shell non-column (ms) | Skirt (ms) | Assembly (ms) |
|---:|---:|---:|---:|---:|---:|---:|---:|---:|---:|---:|
| 4 | 1,845,787 | 1,579,868 / 265,919 | 175,805 | 90,114 (282) | 521 | 472 | 385 | 0 | 186 | 3 |
| 5 | 877,542 | 701,124 / 176,418 | 105,477 | 70,941 (493) | 408 | 135 | 705 | 0 | 159 | 2 |
| 6 | 760,952 | 418,443 / 342,509 | 63,209 | 279,300 (2,909) | 1,594 | 90 | 474 | 210 | 158 | 2 |
| 7 | 337,328 | 257,969 / 79,359 | 8,878 | 70,481 (1,468) | 395 | 59 | 514 | 0 | 145 | 4 |
| 8 | 644,565 | 508,799 / 135,766 | 29,545 | 106,221 (694) | 608 | 374 | 783 | 0 | 278 | 6 |

MC and refinement column-compute / non-column times (ms) were L4 `221/472` MC and `281/385`
ground/cap; L5 `199/135` MC and `209/705` ground/cap; L6 `196/90` MC and `205/474` ground/cap;
L7 `184/59` MC and `211/514` ground/cap; L8 `413/374` MC and `195/783` ground/cap. The column
compute column overlaps those column portions. Timers are worker sums and may differ by a few ms
from their subphase sums.

Stratum shells made zero field calls at LOD4–8 and took under 0.03 ms total. The profiler run
measured about 1.408 s whole-view-ready; the unprofiled interleaved runs below are the timing result.

## Connector-shell repair

`AppendFarConnectorShells` is guarded to LOD6 and above. Coarse marching cubes can leave gaps in a
route connector wall, so the repair checks four axial rays at connector stations and adds only the
panels where the nearest coarse-mesh hit misses the source-field radius tolerance. LOD6 checks at
128-voxel stations; LOD7–8 use 256-voxel stations. Only LOD6 had repair candidates in this spawn
view: 5,066 triangles were added. The shell took 1.403 worker-s, including 1.193 s of column
evaluation (about 0.210 s shell work outside those evaluations).

The LOD6 repair made 251,475 source/column calls: 44,596 worker-local hits, 206,879 local misses,
30 shared-cache hits, and 206,849 formula evaluations. Thus 82.3% of calls evaluated a formula;
the work is mostly uncached. A cache miss can include a point evicted by the four-way worker cache,
so these counters do not prove every evaluated XY is unique. The L13-bound base evaluator already
feeds the shared exact-XY cache; neighboring LOD samples mostly use different XY coordinates, and
only 30 repair samples hit the shared cache. Reducing stations or rays would change the repair
geometry, and no bit-identical reduction was proved.

## Ground and cap refinement

Ground refinement starts at LOD5 (32-voxel grid there, 64 at LOD6, then 128 at LOD7–8). Cap
refinement starts at LOD4 (16-voxel grid there, then 128 at LOD5–7; LOD8 may use its configured
interior override). Both query exact `Heightfield2D` columns and use those values for heights,
normals, materials, clipping, and replacing nearby coarse faces. The existing shared cache is keyed
by recipe/plan and exact XY, so aligned samples can already be reused across tiles and levels. The
LOD-wide shared-hit counts are in the table above; they are not refinement-only counts.

Current safe skips are the plan Z-range check for ground and the cap-height-bound check for caps.
No additional tile/cell skip was shown to preserve every sample that affects output; a grid point
can also supply a neighboring normal or clipped cell. No new refinement sharing or skip was built.

## Ranked exact-output work

No exact-output change with a measured saving above 3% was proved, so no geometry optimization was
built. The ranked work buckets are:

1. Ground/cap refinement across LOD4–8: about 3.95 worker-s including its column work. Removing all
   of it would be an unrealistic idealized 23% of 1.419 s at 12-way division; the sampled values
   currently affect geometry/materials/normals.
2. LOD6 connector repair: 1.403 worker-s inclusive, an idealized upper bound near 8.2% at 12-way
   division. Most calls are uncached, and the missing panels are required for the current mesh.
3. Far-LOD column formula work: 3.53 worker-s across LOD4–8, overlapping the two buckets above.
   Exact-XY sharing is already active; no redundant set large enough to remove was demonstrated.
4. Marching-cubes non-column work is 1.13 worker-s and skirts 0.93 worker-s. Assembly is only
   0.017 worker-s; stratum shells are negligible. No exact reduction was established.

These idealized conversions divide worker-s by 12 and are not predicted wall-time gains. The L6
screen-space gate was not used because this round made no geometry change.

## Interleaved cost, builds, and hashes

Five hashing-off W12 pairs ran in one session, alternating
`Standalone/bin/linux/VoxelForgeCoreHeadless-linux13-clang` and
`Standalone/bin/linux/VoxelForgeCoreHeadless-linux14-clang`. Every run generated 2,553 tiles at
seed 0 and camera `0,-35,-487.94,0,-22`.

| Pair | L13 whole-view-ready (s) | L14 whole-view-ready (s) |
|---:|---:|---:|
| 1 | 1.416 | 1.410 |
| 2 | 1.436 | 1.388 |
| 3 | 1.416 | 1.424 |
| 4 | 1.429 | 1.419 |
| 5 | 1.430 | 1.426 |

Median was 1.429 s before and 1.419 s after (−0.7%, within this run spread). The telemetry is
opt-in; the plain run shows no measurable cost when off.

Final binaries `Standalone/bin/linux/VoxelForgeCoreHeadless-linux14-clang` and
`Standalone/bin/linux/VoxelForgeCoreHeadless-linux14-gcc` were rebuilt with `Standalone/BuildLinux.sh`,
`-j12`, CPUs 0–11, and a 6 GiB address-space cap: Clang 19 with FP contraction off and GCC 14 with
default contraction. Builds passed. Runtime peak RSS was 926,520 KiB; largest individual
build-process RSS was 901,968 KiB (GCC), with a 4,557,196 KiB process-group peak. Governor remained
`powersave`.

The final hash matrix passed 28/28: SurfaceWorld seed 0 and FloatingIslands seed 0, Clang/GCC,
W1/W8/W12, with five W12 repeats per recipe/compiler. Full-detail, whole-view, all nine per-LOD,
and exact-query rows match L13 exactly. Route parity also passed for SurfaceWorld seeds 0,
1, and 17 and FloatingIslands seed 0: page/native-only routes, edits, history, higher-LOD exact
queries, and proof checks had zero mismatches. The final 24 m crossing hash matched at W1/W12 on
both compilers: `0x337ca62131576728 / 0x7612f48e2ddbbaab / 0x69a67ed4add83b87 / 0xf11ac1ebd0f7ddb8`
(density/mesh/payload/topology).

| Recipe | Full-detail D/M/P/T | Whole-view D/M/P/T | Exact density / unclamped / detail / collision |
|---|---|---|---|
| SurfaceWorld | `0x0ee0579bd15cbbe4 / 0x32e5d4964d610fee / 0x1932b96ee4b1d910 / 0x69743c6bad3447dc` | `0xc10697a8f48380c7 / 0xe75c9119a1498cd5 / 0x49a9a8d1835a6c8c / 0xedcb23288b5e8724` | `0xe4d4a8eb95b35933 / 0xe4d4a8eb95b35933 / 0xefcba20c0c70c415 / 0xe604823a249029bf` |
| FloatingIslands | `0x6d842d2878b08ef6 / 0x4b868a3184f08035 / 0x2cedf2236788752d / 0xeac17d5e0cb5044a` | `0x5be4d8cde79b2a76 / 0x96f75041f6861b3a / 0x3700a516cc89d50c / 0x6b99948d6eab4f21` | `0x61daded9c303becb / 0x61daded9c303becb / 0xefcba20c0c70c415 / 0x84d37463be9b0573` |

Hash logs and the 28-row comparator are in `Saved/Linux/l14-final-hash-*.log` and
`Saved/Linux/l14-final-hash-audit.txt`. Final route logs are `Saved/Linux/l14-final-route-*.log`;
crossing and pair logs use the `l14-final-crossing-*` and `l14-final-cost-*` names.

## Failed or retried runs

- The first SurfaceWorld hash matrix and first crossing checks omitted the spawn camera and used the
  headless origin. Their comparisons differed from L13; all 14 SurfaceWorld configurations and all
  four crossing configurations were rerun with the spawn camera and passed. FloatingIslands used
  its auto-surface camera and matched on the first run.
- The first route probes also used the wrong camera selection. A later seed-1 probe used the fixed
  seed-0 camera, exited 9 on two LOD2 exact-query checks, and was rerun with `--auto-surface-camera`;
  the corrected seed-1 and seed-17 audits passed. The origin-camera route probes returned success
  but were not used as reference results.
- Clang was rebuilt after the connector counters were added and again after folding aggregation
  into the existing opt-in guard. Both Clang builds and the final GCC build succeeded. No run hit
  the RSS, 15-minute stuck-step, or 30-minute limits.

Owner note: the highest measured far cost is still LOD6 connector repair, but its formula work is
mostly uncached and its panels preserve the coarse route wall. The final interleaved plain runs show
no measurable diagnostic overhead; no geometry change or L6 budget claim is made.

## Orchestrator review (Claude)

- Accepted as a counting round. Interleaved W12, no hashing: L13 1.429 s vs L14 1.419 s median, so the
  opt-in counters cost nothing measurable when off; committed with the report.
- Conclusion: exact-output far work has no remaining lever above 3%. The big buckets
  (ground/cap refinement ~3.95 worker-s, LOD6 connector repair ~1.40 worker-s) produce visible
  geometry. Further far savings need geometry changes, judged against today's same-LOD mesh within
  the owner's budget (1 px at 1440p, at the LOD's closest display distance, display only).