far shells: 3D cell bins for HasDownwardHit/HasUpwardHit candidates (L104, exact)

Near tiles legitimately need floor/ceiling boundary patches, but every hit query scanned the
tile's whole XY column. Direction-specific 3D cell bins conservatively index triangle bounds; the
existing predicates still decide every hit. Candidate visits per query -88..-99%; identical query
and hit counts. Hit-function cost ~1.7-1.9 -> ~0.35 s per FI/TN run. Near-ready @W12: FI 1.63 ->
1.52, TN 1.51 -> 1.38, VS 1.00 -> 0.92 s. All tile/whole hashes equal L103 (Clang/GCC W1/W8/W12).
The 24-28% "idle" is in the serial base-shape (~0.24 s) and far-parent (~0.13 s) phases; the
LOD0-1 drain is >= 99.4% busy. Fast tier PASS; Linux UE builds; FI Unreal arrival 1.96-1.98 s.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016dhxM43dnWvUu2B5Ph1iG1

Standalone/Research/WorldAssemblerM3/Linux104/RunL104ProbeStats.py

@@ -0,0 +1,80 @@
+#!/usr/bin/env python3
+"""Measure exact far-hit triangle probes with the L104 memo disabled/enabled."""
+from __future__ import annotations
+
+import json
+import os
+import re
+import subprocess
+import time
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parents[4]
+OUT = ROOT / "Saved/Linux/l104/probes"
+DATA = ROOT / "Standalone/data/owner_world.json"
+BINARY = ROOT / "Saved/Linux/l104/bin/VoxelForgeCoreHeadless-l104-clang"
+CAMERAS = {
+    "SW": (8.0, 16.0, -372.2626953125),
+    "FI": (25.8369140625, 3.19921875, -737.0),
+    "TN": (19.166015625, -14.2001953125, -753.3740234375),
+    "VS": (-20.0625, -5.068359375, -900.353515625),
+}
+
+
+def run(stratum: str, cache: str) -> dict:
+    OUT.mkdir(parents=True, exist_ok=True)
+    log = OUT / f"{stratum.lower()}-{cache}.log"
+    camera = ",".join(f"{value:.12f}" for value in CAMERAS[stratum]) + ",0,0"
+    command = [
+        "taskset", "-c", "0-11", "prlimit", "--as=6442450944", "--",
+        "env", f"VOXELFORGE_L104_FAR_HIT_CACHE={0 if cache == 'off' else 1}",
+        "VOXELFORGE_L104_FAR_HIT_STATS=1", "timeout", "1740s", str(BINARY), str(DATA),
+        "--world-assembler-prototype", "--stream-benchmark", "--stream-pipeline",
+        "--workers=12", "--clip-radius=3", "--max-clip-level=8", "--max-level=8",
+        f"--camera={camera}", "--stream-scheduler-policy=3",
+    ]
+    started = time.monotonic()
+    with log.open("w", encoding="utf-8") as stream:
+        result = subprocess.run(command, cwd=ROOT, stdout=stream, stderr=subprocess.STDOUT,
+                                check=False, timeout=1740)
+    content = log.read_text(encoding="utf-8", errors="replace")
+    rows = []
+    pattern = re.compile(
+        r"^\[FarHitQueryStats\] lod=(\d+) origin=\(([^)]*)\) "
+        r"down_queries=(\d+) down_candidate_tests=(\d+) down_hit_queries=(\d+) "
+        r"up_queries=(\d+) up_candidate_tests=(\d+) up_hit_queries=(\d+)$", re.M)
+    for match in pattern.finditer(content):
+        rows.append({
+            "lod": int(match.group(1)), "origin": match.group(2),
+            "down_queries": int(match.group(3)), "down_candidate_tests": int(match.group(4)),
+            "down_hit_queries": int(match.group(5)), "up_queries": int(match.group(6)),
+            "up_candidate_tests": int(match.group(7)), "up_hit_queries": int(match.group(8)),
+        })
+    if result.returncode or not rows:
+        raise RuntimeError(f"probe stats failed or missing: {log}; exit={result.returncode}")
+    row = {"stratum": stratum, "cache": cache, "exit_code": result.returncode,
+           "source_stamp": re.search(r"^\[VoxelForgeSourceStamp\] sha256=(\S+)$", content, re.M).group(1),
+           "wall_s": round(time.monotonic() - started, 3), "indices": len(rows),
+           "stats": rows, "log": str(log.relative_to(ROOT))}
+    (OUT / f"{stratum.lower()}-{cache}.json").write_text(
+        json.dumps(row, indent=2) + "\n", encoding="utf-8")
+    print("[L104ProbeStatsRun] " + json.dumps(
+        {key: value for key, value in row.items() if key != "stats"}, sort_keys=True), flush=True)
+    return row
+
+
+def main() -> int:
+    if not BINARY.is_file() or not DATA.is_file():
+        raise SystemExit(f"missing input: {BINARY} or {DATA}")
+    rows = []
+    for stratum in CAMERAS:
+        for cache in ("off", "on"):
+            rows.append(run(stratum, cache))
+            (OUT / "runs-partial.json").write_text(
+                json.dumps(rows, indent=2) + "\n", encoding="utf-8")
+    (OUT / "runs.json").write_text(json.dumps(rows, indent=2) + "\n", encoding="utf-8")
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())