passages: contiguous BVH node ranges + child-bound reuse (L83); scaling and serial floor measured

Exact through LOD2 (all near tile hashes equal L82). W8 LOD0-2: SW 1.09->1.06, FI 2.47->2.34,
TN 2.39->2.43 (noise), VS 1.20->1.18 s. Fast tier PASS.
Scaling W4/W8/W12/W16 (LOD0-2, FI): 3.59 / 2.48 / 2.33 / 2.34 s - flattens past W8-W12.
Estimated infinite-worker floor ~1.0 s FI/TN = shape compile (0.35-0.41 s, not overlapped:
no shape-free tiles in these views) + slowest single LOD0 tile service (0.51-0.59 s).

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

Standalone/Research/WorldAssemblerM3/Linux83/RunL83Census.py

@@ -0,0 +1,78 @@
+#!/usr/bin/env python3
+"""Run three L77 sampler censuses per passage-heavy stratum."""
+from __future__ import annotations
+
+import json
+import re
+import subprocess
+import sys
+import time
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parents[4]
+OUT = ROOT / "Saved/Linux/l83/census"
+DATA = ROOT / "Standalone/data/owner_world.json"
+POST = len(sys.argv) > 1 and sys.argv[1] == "--post"
+BINARY = (ROOT / "Saved/Linux/l83/profile-bin/VoxelForgeCoreHeadless-l83-profile-clang19"
+          if POST else ROOT / "Saved/Linux/l82/profile-bin/VoxelForgeCoreHeadless-clang19")
+LABEL = "post" if POST else "pre"
+CAMERAS = {
+    "FI": (25.8369140625, 3.19921875, -737.0),
+    "TN": (19.166015625, -14.2001953125, -753.3740234375),
+}
+SAMPLE = re.compile(r"^\[L77Sample\] pc=(0x\w+) lod=(\d+) .*?phase=(\S+) .*?weight=(\d+)$", re.M)
+SAMPLER = re.compile(r"^\[L77Sampler\] action=stop .*?samples=(\d+).*?status=PASS$", re.M)
+
+
+def run(world: str, rep: int) -> dict:
+    OUT.mkdir(parents=True, exist_ok=True)
+    log = OUT / f"{LABEL}-{world.lower()}-r{rep}.log"
+    camera = ",".join(f"{value:.12f}" for value in CAMERAS[world]) + ",0,0"
+    command = [
+        "taskset", "-c", "0-11", "prlimit", "--as=6442450944", "--",
+        "env", "VOXELFORGE_L81_PASSAGE_BOUND_PADDING_VOXELS=0", "timeout", "1740s",
+        str(BINARY), str(DATA), "--world-assembler-prototype", "--stream-benchmark",
+        "--stream-pipeline", "--workers=8", "--clip-radius=3", "--max-clip-level=8",
+        "--max-level=8", f"--camera={camera}", "--profile-lod-work", "--linux77-profile",
+    ]
+    start = 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)
+    output = log.read_text(encoding="utf-8", errors="replace")
+    samples = [(int(lod), phase, int(weight))
+               for _pc, lod, phase, weight in SAMPLE.findall(output)]
+    sampler = SAMPLER.search(output)
+    if result.returncode or not samples or sampler is None:
+        raise RuntimeError(f"census failed: exit={result.returncode} {log}")
+    near = [row for row in samples if row[0] <= 2]
+    passage = sum(weight for _, phase, weight in near if phase == "passages")
+    total = sum(weight for _, _, weight in near)
+    row = {
+        "world": world, "replicate": rep, "exit_code": result.returncode,
+        "wall_s": round(time.monotonic() - start, 3),
+        "sampler_samples": int(sampler.group(1)), "near_lod_samples": len(near),
+        "near_lod_weighted_ticks": total, "near_lod_passage_weighted_ticks": passage,
+        "near_lod_passage_share_pct": 100.0 * passage / total,
+        "log": str(log.relative_to(ROOT)),
+    }
+    print("[L83CensusRun] " + json.dumps(row, 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 = [run(world, rep) for rep in (1, 2, 3) for world in CAMERAS]
+    by_world = {}
+    for world in CAMERAS:
+        values = [row["near_lod_passage_share_pct"] for row in rows if row["world"] == world]
+        by_world[world] = {"runs_pct": values, "mean_pct": sum(values) / len(values)}
+    (OUT / f"{LABEL}-summary.json").write_text(json.dumps(
+        {"runs": rows, "near_lod_passage_share": by_world}, indent=2) + "\n",
+        encoding="utf-8")
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())